I’m currently working in the Climate Change Cluster (C3) as an ARC DECRA Fellow. My work focuses on understanding seagrass responses to wide environmental fluctuations including light and eutrophication stress through functional genomic approaches. My doctoral thesis work broadly dealt with the critical aspects of eco-physiology, acclimation strategies and tolerance mechanisms at both biochemical and molecular level of benthic marine macrophytes (seaweeds and seagrasses) reeling under diverse environmental and anthropogenic stresses. My postdoctoral experience further expanded by expertise in transcriptomics and epigenitic regulation of marine and terrestrial plants under abiotic stress conditions at Ben-Gurion University (Israel).
Prior to joining UTS, I’ve worked as a Visiting Scientist for two years (2012-2014) at The Agriculture Research Organization (Israel) and focused on studying the Phyto-Hormone Signaling in plants in response to environmental stress.
2014 - ARC DECRA Fellowship (Early Detection of Seagrass Habitat Loss Caused by Eutrophication)
2013 - Outstanding ARO Postdoctoral Research Fellowship, Israel
2012 - Prestigious Blaustein Postdoctoral Fellowship, Israel
- New Phytologist
- Physiologia Plantarum
- Environmental and Experimental Botany
- Journal of Applied Phycology
- Marine Biology, Hazardous Materials
- Plant Physiology and Biochemistry
- Environmental Science and Pollution Research
Can supervise: YES
- Impacts of Global Climate Change (global warming, ocean acidification, environmental fluctuatuations, and Anthropogenic forces) on Eco-physiology of plants and marine macro algae (seaweeds): Understanding on acclimation and adaptive responses, reactive oxygen metabolism (ROM), and epigenetic regulations in marine macroalgae at biochemical and molecular level against adverse environmental and anthropogenically induced oxidative stress conditions such as salinity (hypo and -hyper), desiccation, heavy metal (copper and cadmium), industrial toxicants and eutorphication. (10 - Publications)
- Marker assisted selection, epigenetic regulations and phylogenetic studies of plants and algae. (4 - publications)
- Micropropagation of marine algae: Tissue culture, protoplast isolation and spore culture from marine seaweeds for their use as seed stock in mass culture and cultivation practices (3 - Publications)
- Bioethanol and phycolloids production from algae: Extraction and characterization of alkali tolerant cellulases (efficient in hydrolyzing macroalgal biomass) and sulfohydrolases from marine microbes associated with marine macroalgae. (4 - Publications)
- Nutritional and Pharmaceutical aspects of plants and algae: In search of species rich in antioxidant, minerals, plant growth regulators, infochemicals, nutrients and PUFAs. (3- Publications)
This book describes the latest advances in systems biology in four plant-based marine ecosystems: seaweeds, seagrasses, microalgae, and corals. Marine organisms that inhabit the oceanic environment experience a diverse range of environmental fluctuations, anthropogenic stress, and threats from invasive species and pathogens. System biology integrates physiology, genomics, transcriptomics, proteomics, and metabolomics into numerical models and is emerging as an important approach to elucidate the functional adaptations of marine organisms to adverse environmental conditions. This book focuses on how ecophysiology, omics platforms, their integration (a systems biology perspective), and next generation sequencing tools are being used to address the stress response of marine seaweeds, seagrasses, corals, marine microbe diversity, and micro-and macroalgae/corals-bacterial interactions to global climate change and anthropogenic activities. The contents of the book are of special interest to graduate and postgraduate marine biology students and marine biology researchers, particularly those interested in marine ecology, stress physiology of marine macrophytes/corals/phytoplankton, and environmental microbiology. This book would also be of interest to marine engineers engaged in the management and conservation of our valuable marine resources.
Kumar, M & Reddy, CRK 2012, Oxidative stress tolerance mechanisms in marine macroalgae (Seaweeds): Oxidative stress in seaweeds., LAP Lambert Academic Publishing.
Buapet, P, Mohammadi, NS, Pernice, M, Kumar, M, Kuzhiumparambil, U & Ralph, PJ 2019, 'Excess copper promotes photoinhibition and modulates the expression of antioxidant-related genes in Zostera muelleri.', Aquatic toxicology (Amsterdam, Netherlands), vol. 207, pp. 91-100.View/Download from: Publisher's site
Copper (Cu) is an essential micronutrient for plants and as such is vital to many metabolic processes. Nevertheless, when present at elevated concentrations, Cu can exert toxic effects on plants by disrupting protein functions and promoting oxidative stress. Due to their proximity to the urbanised estuaries, seagrasses are vulnerable to chemical contamination via industrial runoff, waste discharges and leachates. Zostera muelleri is a common seagrass species that forms habitats in the intertidal areas along the temperate coast of Australia. Previous studies have shown the detrimental effects of Cu exposure on photosynthetic efficiency of Z. muelleri. The present study focuses on the impacts of sublethal Cu exposure on the physiological and molecular responses. By means of a single addition, plants were exposed to 250 and 500g Cu L-1 (corresponding to 3.9 and 7.8 M, respectively) as well as uncontaminated artificial seawater (control) for 7 days. Chlorophyll fluorescence parameters, measured as the effective quantum yield (PSII), the maximum quantum yield (Fv/Fm) and non-photochemical quenching (NPQ) were assessed daily, while Cu accumulation in leaf tissue, total reactive oxygen species (ROS) and the expression of genes involved in antioxidant activities and trace metal binding were determined after 1, 3 and 7 days of exposure. Z. muelleri accumulated Cu in the leaf tissue in a concentration-dependent manner and the bioaccumulation was saturated by day 3. Cu exposure resulted in an acute suppression of PSII and Fv/Fm. These two parameters also showed a concentration- and time-dependent decline. NPQ increased sharply during the first few days before subsequently decreasing towards the end of the experiment. Cu accumulation induced oxidative stress in Z. muelleri as an elevated level of ROS was detected on day 7. Lower Cu concentration promoted an up-regulation of genes encoding Cu/Zn-superoxide dismutase (Cu/Zn-sod), ascorbate peroxidase (apx), catalase (cat)...
Biccard, B.M., Madiba, T.E., Kluyts, H.L., Munlemvo, D.M., Madzimbamuto, F.D., Basenero, A., Gordon, C.S., Youssouf, C., Rakotoarison, S.R., Gobin, V., Samateh, A.L., Sani, C.M., Omigbodun, A.O., Amanor-Boadu, S.D., Tumukunde, J.T., Esterhuizen, T.M., Manach, Y.L., Forget, P., Elkhogia, A.M., Mehyaoui, R.M., Zoumeno, E., Ndayisaba, G., Ndasi, H., Ndonga, A.K.N., Ngumi, Z.W.W., Patel, U.P., Ashebir, D.Z., Antwi-Kusi, A.A.K., Mbwele, B., Sama, H.D., Elfiky, M., Fawzy, M.A., Pearse, R.M., Abadagan, H., Abbas, N., Abdelatif, A.I., Abdoulaye, T., Abd-rouf, A., Abduljalil, A., Abdulrahman, A., Abdurazig, S., Abokris, A., Abozaid, W., Abugassa, S.O.A., Abuhdema, F., Abujanah, S.A., Abusamra, R., Abushnaf, A., Abusnina, S.A., Abuzalout, T.S., Ackermann, H.M., Adamu, Y.B., Addanfour, A., Adeleke, D.M., Adigun, T.A., Adisa, A.O., Adjignon, S.V., Adu-Aryee, N.A., Afolabi, B.B., Agaba, A.F.X., Agaba, P.K.A., Aghadi, K., Agilla, H., Ahmed, B., Ahmed, E.Z., Ahmed, A.J., Ahmed, M., Ahossi, R., Aji, S.A., Akanyun, S., Akhideno, I., Akhter, M., Akinyemi, O.A., Akkari, M., Akodjenou, J., AL Samateh, A.L., al Shams, E.S., Alagbe-Briggs, O.T., Alakkari, E.A., Alalem, R.B., Alashhab, M., Alatise, O.I., Alatresh, A., Alayeb Alayeb, M.S.I., Albakosh, B.A., Albert, F., Alberts, A.N.J.D., Aldarrat, A.D., Alfari, A., Alfetore, A., Algbali, M., Algddar, A., Algedar, H.A., Alghafoud, I.A., Alghazali, A., Alhajj, M., Alhendery Alhendery, A., Alhoty, F.F.H., Ali, A. & Ali, Y.A. 2018, 'Perioperative patient outcomes in the African Surgical Outcomes Study: a 7-day prospective observational cohort study', The Lancet, vol. 391, no. 10130, pp. 1589-1598.View/Download from: Publisher's site
© 2018 Elsevier Ltd Background: There is a need to increase access to surgical treatments in African countries, but perioperative complications represent a major global health-care burden. There are few studies describing surgical outcomes in Africa. Methods: We did a 7-day, international, prospective, observational cohort study of patients aged 18 years and older undergoing any inpatient surgery in 25 countries in Africa (the African Surgical Outcomes Study). We aimed to recruit as many hospitals as possible using a convenience sampling survey, and required data from at least ten hospitals per country (or half the surgical centres if there were fewer than ten hospitals) and data for at least 90% of eligible patients from each site. Each country selected one recruitment week between February and May, 2016. The primary outcome was in-hospital postoperative complications, assessed according to predefined criteria and graded as mild, moderate, or severe. Data were presented as median (IQR), mean (SD), or n (%), and compared using t tests. This study is registered on the South African National Health Research Database (KZ_2015RP7_22) and ClinicalTrials.gov (NCT03044899). Findings: We recruited 11 422 patients (median 29 [IQR 10–70]) from 247 hospitals during the national cohort weeks. Hospitals served a median population of 810 000 people (IQR 200 000–2 000 000), with a combined number of specialist surgeons, obstetricians, and anaesthetists totalling 07 (02–19) per 100 000 population. Hospitals did a median of 212 (IQR 65–578) surgical procedures per 100 000 population each year. Patients were younger (mean age 385 years [SD 161]), with a lower risk profile (American Society of Anesthesiologists median score 1 [IQR 1–2]) than reported in high-income countries. 1253 (11%) patients were infected with HIV, 6504 procedures (57%) were urgent or emergent, and the most common procedure was caesarean delivery (3792 patients, 33%). Postoperative complications occurred i...
Jiang, Z, Liu, S, Zhang, J, Zhao, C, Wu, Y, Yu, S, Zhang, X, Huang, C, Huang, X & Kumar, M 2017, 'Newly discovered seagrass beds and their potential for blue carbon in the coastal seas of Hainan Island, South China Sea.', Marine Pollution Bulletin, vol. 125, no. 1-2, pp. 513-521.View/Download from: UTS OPUS or Publisher's site
Eight new seagrass beds were discovered along the coastline of Hainan Island in South China Sea with an area of 203.64ha. The leaf N content of all seagrasses was above the median value, indicative of N limitation, with their C:N ratio recorded significantly lower than the limiting criteria. This suggested that N is not limiting but in replete status. Further, the lower C content observed in the seagrass leaves was accompanied by higher nutrient concentration. The mean seagrass biomass C was 0.23±0.16MgCha-1, while the average sediment organic carbon (SOC) stock was 7.02±3.57MgCha-1. The entire SOC stock of the newly discovered seagrass beds was 1306.45 Mg C, and the overall SOC stock of seagrass bed at Hainan Island was 40858.5 Mg C. These seagrass beds are under constant threats from sea reclamation, nutrient input, aquaculture activities for oyster and snail farming, and fishing activities.
Kumar, M, Padula, MP, Davey, P, Pernice, M, Jiang, Z, Sablok, G, Contreras-Porcia, L & Ralph, PJ 2017, 'Proteome Analysis Reveals Extensive Light Stress-Response Reprogramming in the Seagrass Zostera muelleri (Alismatales, Zosteraceae) Metabolism.', Frontiers in Plant Science, vol. 7, pp. 1-19.View/Download from: UTS OPUS or Publisher's site
Seagrasses are marine ecosystem engineers that are currently declining in abundance at an alarming rate due to both natural and anthropogenic disturbances in ecological niches. Despite reports on the morphological and physiological adaptations of seagrasses to extreme environments, little is known of the molecular mechanisms underlying photo-acclimation, and/or tolerance in these marine plants. This study applies the two-dimensional isoelectric focusing (2D-IEF) proteomics approach to identify photo-acclimation/tolerance proteins in the marine seagrass Zostera muelleri. For this, Z. muelleri was exposed for 10 days in laboratory mesocosms to saturating (control, 200 mol photons m-2 s-1), super-saturating (SSL, 600 mol photons m-2 s-1), and limited light (LL, 20 mol photons m-2 s-1) irradiance conditions. Using LC-MS/MS analysis, 93 and 40 protein spots were differentially regulated under SSL and LL conditions, respectively, when compared to the control. In contrast to the LL condition, Z. muelleri robustly tolerated super-saturation light than control conditions, evidenced by their higher relative maximum electron transport rate and minimum saturating irradiance values. Proteomic analyses revealed up-regulation and/or appearances of proteins belonging to the Calvin-Benson and Krebs cycle, glycolysis, the glycine cleavage system of photorespiration, and the antioxidant system. These proteins, together with those from the inter-connected glutamate-proline-GABA pathway, shaped Z. muelleri photosynthesis and growth under SSL conditions. In contrast, the LL condition negatively impacted the metabolic activities of Z. muelleri by down-regulating key metabolic enzymes for photosynthesis and the metabolism of carbohydrates and amino acids, which is consistent with the observation with lower photosynthetic performance under LL condition. This study provides novel insights into the underlying molecular photo-acclimation mechanisms in Z. muelleri, in addition to identify...
Jiang, Z, Kumar, M, Padula, MP, Pernice, M, Kahlke, T, Kim, M & Ralph, PJ 2017, 'Development of an Efficient Protein Extraction Method Compatible with LC-MS/MS for Proteome Mapping in Two Australian Seagrasses Zostera muelleri and Posidonia australis.', Frontiers in Plant Science, vol. 8, pp. 1-14.View/Download from: UTS OPUS or Publisher's site
The availability of the first complete genome sequence of the marine flowering plant Zostera marina (commonly known as seagrass) in early 2016, is expected to significantly raise the impact of seagrass proteomics. Seagrasses are marine ecosystem engineers that are currently declining worldwide at an alarming rate due to both natural and anthropogenic disturbances. Seagrasses (especially species of the genus Zostera) are compromised for proteomic studies primarily due to the lack of efficient protein extraction methods because of their recalcitrant cell wall which is rich in complex polysaccharides and a high abundance of secondary metabolites in their cells. In the present study, three protein extraction methods that are commonly used in plant proteomics i.e., phenol (P); trichloroacetic acid/acetone/SDS/phenol (TASP); and borax/polyvinyl-polypyrrolidone/phenol (BPP) extraction, were evaluated quantitatively and qualitatively based on two dimensional isoelectric focusing (2D-IEF) maps and LC-MS/MS analysis using the two most abundant Australian seagrass species, namely Zostera muelleri and Posidonia australis. All three tested methods produced high quality protein extracts with excellent 2D-IEF maps in P. australis. However, the BPP method produces better results in Z. muelleri compared to TASP and P. Therefore, we further modified the BPP method (M-BPP) by homogenizing the tissue in a modified protein extraction buffer containing both ionic and non-ionic detergents (0.5% SDS; 1.5% Triton X-100), 2% PVPP and protease inhibitors. Further, the extracted proteins were solubilized in 0.5% of zwitterionic detergent (C7BzO) instead of 4% CHAPS. This slight modification to the BPP method resulted in a higher protein yield, and good quality 2-DE maps with a higher number of protein spots in both the tested seagrasses. Further, the M-BPP method was successfully utilized in western-blot analysis of phosphoenolpyruvate carboxylase (PEPC-a key enzyme for carbon metabolism). ...
Kumar, M, Kuzhiumparambil, U, Pernice, M, Jiang, Z & Ralph, PJ 2016, 'Metabolomics: an emerging frontier of systems biology in marine macrophytes', ALGAL RESEARCH-BIOMASS BIOFUELS AND BIOPRODUCTS, vol. 16, pp. 76-92.View/Download from: UTS OPUS or Publisher's site
Kumar, M, Reddy, CRK & Ralph, PJ 2015, 'Polyamines in morphogenesis and development: a promising research area in seaweeds.', Frontiers in plant science, vol. 6, pp. 27-27.View/Download from: UTS OPUS or Publisher's site
Kumar, M, Pandya-Kumar, N, Dam, A, Haor, H, Mayzlish-Gati, E, Belausov, E, Wininger, S, Abu-Abied, M, McErlean, CSP, Bromhead, LJ, Prandi, C, Kapulnik, Y & Koltai, H 2015, 'Arabidopsis response to low-phosphate conditions includes active changes in actin filaments and PIN2 polarization and is dependent on strigolactone signalling', Journal of Experimental Botany, vol. 66, no. 5, pp. 1499-1510.View/Download from: UTS OPUS or Publisher's site
Strigolactones (SLs) are plant hormones that regulate the plant response to phosphate (Pi) growth conditions. At least part of SL-signalling execution in roots involves MAX2-dependent effects on PIN2 polar localization in the plasma membrane (PM) and actin bundling and dynamics. We examined PIN2 expression, PIN2 PM localization, endosome trafficking, and actin bundling under low-Pi conditions: a MAX2-dependent reduction in PIN2 trafficking and polarization in the PM, reduced endosome trafficking, and increased actin-filament bundling were detected in root cells. The intracellular protein trafficking that is related to PIN proteins but unassociated with AUX1 PM localization was selectively inhibited. Exogenous supplementation of the synthetic SL GR24 to a SL-deficient mutant (max4) led to depletion of PIN2 from the PM under low-Pi conditions. Accordingly, roots of mutants in MAX2, MAX4, PIN2, TIR3, and ACTIN2 showed a reduced low-Pi response compared with the wild type, which could be restored by auxin (for all mutants) or GR24 (for all mutants except max2-1). Changes in PIN2 polarity, actin bundling, and vesicle trafficking may be involved in the response to low Pi in roots, dependent on SL/MAX2 signalling.
Kumar, M, Pandya-Kumar, N, Kapulnik, Y & Koltai, H 2015, 'Strigolactone signaling in root development and phosphate starvation', Plant Signaling and Behavior, vol. 10, no. 7.View/Download from: UTS OPUS or Publisher's site
Strigolactones (SLs), have recently been recognized as phytohormone involve in orchestrating shoot and root architecture. In, roots SLs positively regulate root hair length and density, suppress lateral root formation and promote primary root meristem cell number. The biosynthesis and exudation of SLs increases under low phosphate level to regulate root responses. This hormonal response suggests an adaptation strategy of plant to optimize growth and development under nutrient limitations. However, little is known on signal-transduction pathways associated with SL activities. In this review, we outline the current knowledge on SL biology by describing their role in the regulation of root development. Also, we discuss the recent findings on the non-cell autonomous signaling of SLs, that involve PIN polarization, vesicle trafficking, changes in actin architecture and dynamic in response to phosphate starvation.
Pandya-Kumar, N, Shema, R, Kumar, M, Mayzlish-Gati, E, Levy, D, Zemach, H, Belausov, E, Wininger, S, Abu-Abied, M, Kapulnik, Y & Koltai, H 2014, 'Strigolactone analog GR24 triggers changes in PIN2 polarity, vesicle trafficking and actin filament architecture', New Phytologist, vol. 202, no. 4, pp. 1184-1196.View/Download from: UTS OPUS or Publisher's site
SummaryStrigolactones (SLs) are plant hormones that regulate shoot and root development in aMAX2-dependent manner. The mechanism underlying SLs' effects on roots is unclear.We used root hair elongation to measure root response to SLs. We examined the effects ofGR24 (a synthetic, biologically active SL analog) on localization of the auxin efflux transporterPIN2, endosomal trafficking, and F-actin architecture and dynamics in the plasma membrane(PM) of epidermal cells of the primary root elongation zone in wildtype (WT) Arabidopsis andthe SL-insensitive mutant max2. We also recorded the response to GR24 of trafficking (tir3),actin (der1) and PIN2 (eir1) mutants.GR24 increased polar localization of PIN2 in the PM of epidermal cells and accumulation ofPIN2-containing brefeldin A (BFA) bodies, increased ARA7-labeled endosomal trafficking,reduced F-actin bundling and enhanced actin dynamics, all in a MAX2-dependent manner.Most of the der1 and tir3 mutant lines also displayed reduced sensitivity to GR24 with respectto root hair elongation.We suggest that SLs increase PIN2 polar localization, PIN2 endocytosis, endosomal traffick-ing, actin debundling and actin dynamics in a MAX2-dependent fashion. This enhancementmight underlie the WT root's response to SLs, and suggests noncell autonomous activity ofSLs in roots
Kumar, M, Kumari, P, Reddy, CRK & Jha, B 2014, 'Salinity and Desiccation Induced Oxidative Stress Acclimation in Seaweeds', Advances in Botanical Research, vol. 71, pp. 91-123.View/Download from: UTS OPUS or Publisher's site
Marine macroalgae, commonly known as seaweeds, are assemblage of diverse groups of phototrophic marine plants and form the base of the marine trophic pyramid. Rocky intertidal zones are the most dynamic and comprises of highly stressful habitats for marine life including seaweeds. They often experience severe environmental stress as a result of periodic exposure to a wide range of ambient conditions including intense radiation, high temperature, desiccation and salinity with turning tides. The relative abundance, survivability and distribution of seaweeds in such environments are principally determined by their tolerance abilities to diverse environmental stresses. Any adverse effect on seaweeds as a result of fluctuating environmental conditions can directly or indirectly lead to perturbations at higher trophic levels and eventually affect the integrity and sustainability of aquatic ecosystems. The recent proteome, transcriptome, metabolome and other biochemical analysis of seaweeds under oxidative stress have suggested the involvement of mannitol, proline, abscisic acid, polyamines, polyunsaturated fatty acids, oxylipins and fatty acid desaturases among others defending the seaweeds from diverse environmental stress. Both salinity and desiccation stresses are comparable in the context of a reduction of cellular water potential but differ in physiological process of ions uptake and their ratio determines the acclimation potential of seaweeds. In this chapter, we describe various tolerance and adaptive strategies of seaweeds in response to salinity fluctuations and desiccation induced oxidative stress at both biochemical and molecular levels enabling them to endure successfully for extended periods of stresses. Further, the new opportunities that became available from whole genome sequences of the brown alga Ectocarpus siliculosus and the red alga Chondrus crispus, in gaining newer insights into the cellular mechanisms of stress tolerance at molecular level in se...
Flores-Molina, MR, Thomas, D, Lovazzano, C, Núñez, A, Zapata, J, Kumar, M, Correa, JA & Contreras-Porcia, L 2014, 'Desiccation stress in intertidal seaweeds: Effects on morphology, antioxidant responses and photosynthetic performance', Aquatic Botany, vol. 113, pp. 90-99.View/Download from: UTS OPUS or Publisher's site
Seaweeds are differentially distributed between the upper and lower limits of the intertidal zone of rocky coasts around the world. Daily changes in tide height cause water loss, triggering desiccation stress as a consequence. How this stress affected some of the morp hological characteristics and physiological responses in representative intertidal seaweeds with contrasting vertical distributions was explored in the present work. The selected species were Mazzaella laminarioides (upper-middle distribution), Scytosiphon lomentaria and Ulva compressa (middle distribution), and Lessonia spicata and Gelidium rex (lower distribution). To assess tolerance response to desiccation, cellular and morphological alterations, ROS production, enzymatic activity of catalase (CAT) and ascorbate peroxidase (AP) and photosynthesis performance were measured after a simulated emersion stress experiment. Results show different tolerance responses to desiccation, with seaweeds having higher intertidal distributions displaying greater antioxidant enzymatic activity, suggesting a higher capacity to buffer ROS excess induced during desiccation. Contrarily, this capacity seems to be absent or deficient in low intertidal species (i.e. L. spicata and G. rex), where AP and CAT activities were below detection limits, ROS were higher than normal and caused an over-oxidation of bio-molecules and photosynthetic disarray, explaining from a functional stand point their low distribution in the intertidal zone. © 2013 Elsevier B.V.
Kumari, P, Kumar, M, Reddy, CRK & Jha, B 2014, 'Nitrate and Phosphate Regimes Induced Lipidomic and Biochemical Changes in the Intertidal Macroalga Ulva lactuca (Ulvophyceae, Chlorophyta)', Plant and Cell Physiology, vol. 55, no. 1, pp. 52-63.View/Download from: UTS OPUS or Publisher's site
This study was carried out in order to understand the lipid and biochemical alterations resulting from different nutritional regimes of nitrate and phosphate in Ulva lactuca. The algal thalli cultured in artificial seawater (ASW) showed higher levels of carbohydrates and non-polar lipids and increased phosphatase activities, accompanied by degradation of polar lipids, proteins and pigments. Further, higher levels of lipid hydroperoxides indicated reative oxygen species (ROS)-mediated non-enzymatic lipid peroxidation due to nutritional limitation-induced oxidative stress. Those thalli cultured in ASW supplemented with nitrate showed responses corresponding to nitrate addition, such as an increase in pigments, monogalactosyldiacylglycerols, polyunsaturated fatty acids and nitrate reductase. In addition, these thalli showed partial induction of phosphatases, low phospholipids, and high sulfolipid and 1,2-diacylglyceryl-3-O-4-(N,N,N-trimethyl)-homoserine (DGTS) due to phosphate limitation. Similarly, algal thalli cultured in ASW supplemented with phosphate showed down-regulation of phosphatases, an increase in phospholipids due to availability of phosphate as well as a decrease in nitrate reductase, pigment, monogalactosyldiacylglycerols and polyunsaturated fatty acids due to nitrate limitation. On the other hand, algal thalli cultured in ASW supplemented with both nitrate and phosphate showed recovery of lost pigments and proteins, a high monogalactosyldiacylglycerol/digalactosyldiacylglycerol ratio, high unsaturation and high oxylipin levels (both C18 and C20). Further, the accumulation of indole-3-acetic acid in nutrient-limited thalli and of kinetin and kinetin riboside in nutrient-supplemented thalli indicated their antagonistic roles under nutrient stress. Thus, U. lactuca copes with nitrate and phosphate nutritional stress by altering the metabolic pathways involved in lipid biosynthesis including a shift in lipid classes, fatty acids, oxylipins and indole-3-...
Kumar, M, Reddy, CRK & Jha, B 2013, 'The ameliorating effect of Acadian marine plant extract against ionic liquids-induced oxidative stress and DNA damage in marine macroalga Ulva lactuca.', Journal of Applied Phycology, vol. 25, no. 2, pp. 369-378.View/Download from: UTS OPUS or Publisher's site
Ionic liquids (ILs) are generally considered as the green replacement for conventional volatile organic solvents. Nonetheless, their high solubility in water with proven toxic effects on aquatic biota has questioned their green credentials. In the present study, the detoxification potential of Acadian marine plant extract powder (AMPEP) prepared from the brown alga Ascophyllum nodosum was investigated against the 1-alkyl-3-methylimidazolium bromide [C12mim]Br ionic liquid-induced toxicity and oxidative stress in marine macroalga Ulva lactuca. The IL ([C12mim]Br) at LC50 (70 M) exposure triggered the generation of reactive oxygen species (ROS) such as O 2 · , H2O2 and OH· causing membrane and DNA damage together with inhibition of antioxidant systems in the alga. The supplementation of AMPEP (150 g mL1) to the culture medium significantly reduced the accumulation of ROS and lipid peroxidation together with the inhibition of lipoxygenase (LOX) activity specially LOX-2 and LOX-3 isoforms. This is for the first time wherein comet assay was performed to ascertain the protective role of AMPEP against DNA damage in algal tissue grown in medium supplemented with IL and AMPEP. The AMPEP showed protective role against DNA damage (5–45 % tail DNA) when compared to those of grown in IL alone (45–70 % tail DNA). Further, specific isomorphs of different antioxidant enzymes such as superoxide dismutase (Mn-SOD-1, ~150 kDa), ascorbate peroxidase (APX-4, ~55 kDa), glutathione peroxidase (GSH-Px-2, ~55 kDa) and glutathione reductase (GR-1, ~180 kDa) responded specifically to AMPEP supplementation. It is evident from these findings that AMPEP could possibly be used for circumventing the negative effects arising from ILs-induced toxicity in marine ecosystem.
Gupta, V, Trivedi, N, Kumar, M, Reddy, CRK & Jha, B 2013, 'Purification and characterization of exo--agarase from an endophytic marine bacterium and its catalytic potential in bioconversion of red algal cell wall polysaccharides into galactans', Biomass and Bioenergy, vol. 49, pp. 290-298.View/Download from: UTS OPUS or Publisher's site
An extracellular exo--agarase was characterized from an endophytic bacterial strain Pseudomonas sp. isolated from the red alga Gracilaria dura. The enzyme was purified to homogeneity with a recovery of 28.2% and a purity fold of 8.33. The purified enzyme was composed of single polypeptide with a molecular mass of about 66 kDa. The enzyme exhibited a maximum activity of 81.74 U mL-1 and a specific activity of 615.5 U mg-1. The optimal pH and temperature for its maximum activity were 9.0 and 35 °C respectively. The enzyme stabilized its activity in alkaline pH 7-11 and high salt concentration up to 4 mol dm-3. The enzymatic hydrolyzed product of agar was characterized as neoagarobiose while the bacterium when incubated with G. dura biomass yielded galactose 20% on dry wt basis. The agarolytic ability of the former was further confirmed by release of protoplasts from G. dura tissue through digestion of cell wall polysaccharides. The bacterium investigated in this study could possibly be used for bioconversion of marine red algal polysaccharides into energy feedstock and the purified enzyme for preparation of compounds having pharmaceutical importance. © 2013 Elsevier Ltd.
Kumar, M, Bijo, AJ, Baghel, RS, Reddy, CRK & Jha, B 2012, 'Selenium and spermine alleviate cadmium induced toxicity in the red seaweed Gracilaria dura by regulating antioxidants and DNA methylation', Plant Physiol Biochem., vol. 51, pp. 129-138.View/Download from: UTS OPUS or Publisher's site
The protective role of exogenously supplied selenium (Se) and polyamines (PAs) such as putrescine (Put) and spermine (Spm) in detoxifying the cadmium (Cd) induced toxicity was studied in the marine red alga Gracilaria dura in laboratory conditions. The Cd exposure (0.4 mM) impede the growth of alga while triggering the reactive oxygen species (ROS viz. O2* and H2O2) generation, inhibition of antioxidant system, and enhancing the lipoxygenase (LOX) activity, malondialdehyde (MDA) level and demethylation of DNA. Additions of Se (50 M) and/or Spm (1 mM) to the culture medium in contrast to Put, efficiently ameliorated the Cd toxicity by decreasing the accumulation of ROS and MDA contents, while restoring or enhancing the level of enzymatic and nonenzymatic antioxidants and their redox ratio, phycobiliproteins and phytochelatins, over the controls. The isoforms of antioxidant enzymes namely superoxide dismutase (Mn-SOD, 150 kDa; Fe-SOD 120 kDa), glutathione peroxidase (GSH-Px, 120 and 140 kDa), glutathione reductase (GR, 110 kDa) regulated differentially to Se and/or Spm supplementation. Furthermore, it has also resulted in enhanced levels of endogenous PAs (specially free and bound insoluble Put and Spm) and n-6 PUFAs (C20-3, n-6 and C20-4, n-6). This is for the first time wherein Se and Spm were found to regulate the stabilization of DNA methylation by reducing the events of cytosine demethylation in a mechanism to alleviate the Cd stress in marine alga. The present findings reveal that both Se and Spm play a crucial role in controlling the Cd induced oxidative stress in G. dura.
Gupta, V, Bijo, AJ, Kumar, M, Reddy, CRK & Jha, B 2012, 'Detection of epigenetic variations in the protoplast-derived germlings of Ulva reticulata using methylation sensitive amplification polymorphism (MSAP).', Marine biotechnology (New York, N.Y.), vol. 14, no. 6, pp. 692-700.View/Download from: UTS OPUS or Publisher's site
Regeneration of protoplasts into de novo plants was reported for a large number of seaweed species. The regeneration of protoplasts into different morphotypes as a result of epigenetic variations was discussed for the first time in this study. The loci assessed for methylation modifications in normal filamentous thalli showed a frequency of 32.43% as unmethylated DNA, 24.32% as a hemimethylated, and 20.27% as a methylation of internal cytosine at both the strands. The corresponding methylation values for disk-type thalli were 27.02%, 32.43%, and 14.86%, respectively. The hypermethylation condition was apparent in the disk-type thalli with methylation ratio of 72.97% compared to that of normal filamentous thalli with 67.56%. The frequency of methylation polymorphic sites among the two morphotypes was 53%. The present study reveals the distinct expression of cytosine methylation and is thus correlated to differential morphogenesis of plants regenerated from cultured cells. The number of protoplasts regenerating into filamentous thalli declined with increasing temperature from 15°C, 20°C, 25°C, and 30°C. The disk-type variant had higher thermal stability at 30°C over normal filamentous thalli. Further, this variant could maintain itself for more than a year in the laboratory indicating its suitability for in vitro germplasm maintenance and propagation.
Singh, RP, Gupta, V, Kumari, P, Kumar, M, Reddy, CRK, Prasad, K & Jha, B 2011, 'Purification and partial characterization of an extracellular alginate lyase from Aspergillus oryzae isolated from brown seaweed', Journal of Applied Phycology, vol. 23, no. 4, pp. 755-762.View/Download from: UTS OPUS or Publisher's site
The extracellular enzyme alginate lyase produced from marine fungus Aspergillus oryzae isolated from brown alga Dictyota dichotoma was purified, partially characterized, and evaluated for its sodium alginate depolymerization abilities. The enzyme characterization studies have revealed that alginate lyase consisted of two polypeptides with about 45 and 50 kDa each on 10% sodium dodecyl sulfate polyacrylamide gel electrophoresis and showed 140-fold higher activity than crude enzyme under optimized pH (6.5) and temperature (35°C) conditions. Zn2+, Mn2+, Cu2+, Mg2+, Co2+and NaCl were found to enhance the enzyme activity while (Ca2+, Cd2+, Fe2+, Hg2+, Sr2+, Ni2+), glutathione, and metal chelators (ethylenediaminetetraacetic acid and ethylene glycol tetraacetic acid) suppressed the activity. Fourier transform infrared and thin-layer chromatography analysis of depolymerized sodium alginate indicated the enzyme specificity for cleaving at the -1,4 glycosidic bond between polyM and polyG blocks of sodium alginate and therefore resulted in estimation of relatively higher polyM content than polyG. Comparison of chemical shifts in13C nuclear magnetic resonance spectra of both polyM and polyG from that of sodium alginate also showed further evidence for enzymatic depolymerization of sodium alginate. © 2010 Springer Science+Business Media B.V.
Kumar, M, Trivedi, N, Reddy, CRK & Jha, B 2011, 'Toxic effects of imidazolium ionic liquids on the green seaweed Ulva lactuca: oxidative stress and DNA damage.', Chemical research in toxicology, vol. 24, no. 11, pp. 1882-1890.View/Download from: UTS OPUS or Publisher's site
The green credentials of ionic liquids (ILs) are being increasingly questioned due to the growing evidence of their toxicity to aquatic ecosystems, although the mechanisms of toxicity are unknown. This study provides insights into the mechanism of toxicity and biological effects of 1-alkyl-3-methylimidazolium bromide [C(n)mim]Br (n = 4 to 16) on the marine macroalga Ulva lactuca. The cell viability of this alga during IL exposure was found to be negatively correlated to the chain length of the alkyl group. The IL ([C(12)mim]Br) exposure triggers the generation of reactive oxygen species (ROS viz. O(2)(*-), H(2)O(2), and OH(*)), damage of the membrane and DNA, and inhibition of antioxidant systems in the alga. The enhanced production of ROS and lipid peroxidation in the alga subjected to LC(50) concentration for 4 days was largely attributed to lipoxygenase (LOX) activity coupled with the induction of two LOX isoforms (~80 kDa and ~55 kDa). Pretreatment of the algal thallus with enzyme inhibitors such as diphenylene iodonium, sodium azide, cantharidin, and oxadiazoloquinoxalin-1-one, prior to [C(12)mim]Br exposure showed the regulation of ROS by the activation of membrane bound NADPH-oxidase and cytochrome oxidase. The IL exposure resulted in the accumulation of n-3 and n-6 fatty acids at 0.5 LC(50) concentration indicating the induction of desaturase enzymes. Furthermore, antioxidant enzyme activities such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR) were enhanced by 1.3-2.0-fold, while glutathione peroxidase (GSH-Px) diminished, together with a higher regeneration rate of reduced ascorbate and glutathione. The isoforms of antioxidant enzymes, namely, Mn-SOD (~85 kDa), APX (~125 and 45 kDa), and GR (~135 kDa) regulated differentially to IL exposure. The comet assay performed for the first time for seaweeds revealed the significant induction of DNA damage (>50-70% increase in % tail DNA over control) in alga exposed to ...
Kumar, M, Gupta, V, Trivedi, N, Kumari, P, Bijo, AJ, Reddy, CRK & Jha, B 2011, 'Desiccation induced oxidative stress and its biochemical responses in intertidal red alga Gracilaria corticata (Gracilariales, Rhodophyta)', Environmental and Experimental Botany, vol. 72, no. 2, pp. 194-201.View/Download from: UTS OPUS or Publisher's site
Intertidal alga Gracilaria corticata growing in natural environment experiences various abiotic stresses during the low tides. The aim of this study was to determine whether desiccation exposure would lead to oxidative stress and its effect varies with exposure periods. This study gives an account of various biochemical changes in G. corticata following the exposure to desiccation for a period of 0 (control), 1, 2, 3 and 4. h under controlled conditions. During desiccation, G. corticata thalli showed dramatic loss of water by almost 47% when desiccated for 4. h. The enhanced production of reactive oxygen species (ROS) and increased lipid peroxidation observed during the exposure of 3-4. h were chiefly contributed by higher lipoxygenase (LOX) activity with the induction of two new LOX isoforms (LOX-2, ~85. kDa; LOX-3, ~65. kDa). The chlorophyll, carotenoids and phycobiliproteins (phycoerythrin and phycocyanin) were increased during initial 2. h exposure compared to control and thereafter declined in the succeeding exposure. The antioxidative enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), glutathione peroxidase (GPX) and the regeneration rate of reduced ascorbate (AsA) and glutathione (GSH) increased during desiccation up to 2-3. h. Further, the isoforms of antioxidant enzymes Mn-SOD (~150. kDa), APX-4 (~110. kDa), APX-5 (~45. kDa), GPX-1 (~80. kDa) and GPX-2 (~65. kDa) responded specifically to the desiccation exposure. Compared to control, a relative higher content of both free and bound insoluble putrescine and spermine together with enhanced n-6 PUFAs namely C20:4(n-6) and C20:3(n-6) fatty acids found during 2. h exposure reveals their involvement in defence reactions against the desiccation induced oxidative stress. © 2011 Elsevier B.V.
Kumar, M, Kumari, P, Trivedi, N, Shukla, MK, Gupta, V, Reddy, CRK & Jha, B 2011, 'Minerals, PUFAs and antioxidant properties of some tropical seaweed from Saurashtra coast of India', Journal of Applied Phycology, vol. 23, no. 5, pp. 797-810.View/Download from: UTS OPUS or Publisher's site
Twenty-two tropical seaweeds from the Rhodophyta, Phaeophyta and Chlorophyta were examined for their possible use as nutritional supplements. All seaweeds contained balanced Na/K and C/N ratio and high amounts of macroelements (Na, K, Ca, and Mg) as compared to the terrestrial vegetables. Among the microelements, Fe was the highest followed by Zn, Mn, Cu and other trace elements. Fatty acid distribution showed high level of n-6 and n-3 polyunsaturated fatty acids (PUFAs), and their ratios were within the WHO prescribed limits. The higher ratios of PUFA/SFA (>0.4) are in agreement with the recommendations of nutritional guidelines. Most of the species, especially the Chlorophyta and Phaeophyta, had permissible intake values of unsaturation, atherogenic and thrombogenic indexes comparable to milk-based products. Principal component analysis demonstrated a correlation between total phenolic content, total antioxidant activity, DPPH, and O 2 * radical scavenging activity, suggesting polyphenols as the chief contributor to the antioxidant activity in seaweeds. These results indicate that these seaweeds could be a potential source of natural antioxidants, minerals and high-quality PUFAs and may be efficiently used as ingredients in functional foods.
Gupta, V, Kumar, M, Brahmbhatt, H, Reddy, CRK, Seth, A & Jha, B 2011, 'Simultaneous determination of different endogenetic plant growth regulators in common green seaweeds using dispersive liquid-liquid microextraction method.', Plant physiology and biochemistry : PPB, vol. 49, no. 11, pp. 1259-1263.View/Download from: UTS OPUS or Publisher's site
A simple and rapid HPLC-based method was developed for simultaneous determination of major classes of plant growth regulators (PGRs) in Monostroma and different species of Ulva. The plant growth regulators determined included gibberellic acid (GA(3)), indole-3-acetic acid (IAA), abscisic acid (ABA), indole-3-butyric acid (IBA), salicylic acid and kinetin riboside (KR) and their respective elution time was 2.75, 3.3, 3.91, 4.95, 5.39 and 6.59 min. The parameters optimized for distinct separation of PGRs were mobile phase (60:40 methanol and 0.6% acetic acid in water), column temperature (35°C) and flow rate (1ml/min). This method presented an excellent linearity (0.2-100g/ml) with limit of detection (LOD) as 0.2g/ml for ABA, 0.5g/ml for KR and salicylic acid, and 1g/ml for IAA, IBA and GA(3). The precision and accuracy of the method was evaluated after inter and intra day analysis in triplicates. The effect of plant matrix was compensated after spiking and the resultant recoveries estimated were in the range of 80-120%. Each PGR thereby detected were further characterized by ESI-MS analysis. The method optimized in this study determined IBA along with IAA for the first time in the seaweed species investigated except Ulva linza where the former was not detected. In all the species studied, ABA level was detected to be the highest while kinetin riboside was the lowest. In comparison to earlier methods of PGR analysis, sample preparation and analysis time were substantially reduced while allowing determination of more classes of PGRs simultaneously.
Shukla, MK, Kumar, M, Prasad, K, Reddy, CRK & Jha, B 2011, 'Partial characterization of sulfohydrolase from Gracilaria dura and evaluation of its potential application in improvement of the agar quality', Carbohydrate polymers., vol. 85, no. 1, pp. 157-163.View/Download from: UTS OPUS or Publisher's site
Sulfohydrolase extracted from Gracilaria dura was purified to homogeneity and investigated for improving the quality of commercial agar. The purified enzyme (50kDa) showed optimum activity at pH 8.0 and temperature 35°C. The agar treated with 50U of purified enzyme exhibited 1.66-fold increase in 3,6-AG content with 60% sulfate removal and also resulted an increase of 2-fold in viscosity and gel strength with a recovery of 90% agar. Further, the gelling and melting temperatures were markedly decreased to 31°C and 82°C respectively over the control values of 39°C and 90°C. The scanning electron microscopy revealed higher cross-linking and rigidity in the treated agar while FT-IR spectral analysis confirmed the increased 3,6-AG content with decreased sulfate. Therefore, the possibility for cloning of sulfohydrolase encoding gene(s) for its commercial production and exploitation in desulfation of agar could be an eco-friendly and alternative method to alkali treatment.
Trivedi, N, Gupta, V, Kumar, M, Kumari, P, Reddy, CRK & Jha, B 2011, 'An alkali-halotolerant cellulose from Bacillus flexus isolated from green seaweed Ulva lactuca.', Carbohydrate Polymers, vol. 83, no. 2, pp. 891-897.View/Download from: UTS OPUS or Publisher's site
An extracellular alkali-halotolerant cellulase from the strain Bacillus flexus NT isolated from Ulva lactuca was purified to homogeneity with a recovery of 25.03% and purity fold of 22.31. The molecular weight of the enzyme was about 97 kDa and the Vmax and Km was 370.17 U/ml/min and 6.18 mg/ml respectively. The optimum pH and temperature for enzyme activity was 10 and 45 °C respectively. The enzymatic hydrolysis of the CMC was confirmed with GPC and GC-MS analysis. The stabilized activity of the enzyme even at high pH of 9.0–12.0 and residual activity of about 70% at salt concentration (NaCl 15%) revealed for its alkali-halotolerance nature. The metal ions Cd2+ and Li1+ were found as inducers while Cr2+, Co2+, Zn2+ and metal chelator EDTA have significantly inhibited the enzyme activity. Enzyme activity was insensitive to ethanol and isopropanol while partially inhibited by acetone, cyclohexane and benzene.
Gupta, V, Baghel, RS, Kumar, M, Kumari, P, Mantri, VA, Reddy, CRK & Jha, B 2011, 'Growth and agarose characteristics of isomorphic gametophyte (male and female) and sporophyte of Gracilaria dura and their marker assisted selection', Aquaculture (Amsterdam, Netherlands), vol. 318, no. 3-4, pp. 389-396.View/Download from: UTS OPUS or Publisher's site
The characteristics of agarose and growth for three isomorphic life phases of G. dura with their bio-molecular marker assisted selection have been described in this study. The tetrasporophyte showed superior quality of agarose over gametophytes and recorded growth rate was highest for females. The genetic relatedness studied with ISSR markers showed quadratic line of correlation between these phases (R² =1). Their genetic diversity determinants as percentage of polymorphic loci (PPL), average heterozygosity (He) and Shannon's Weaver index (I) were 55.55%, 0.5±0.07 and 0.33 respectively. The cytological analysis for chromosome count revealed 8 chromosomes in haploid gametophytic thallus (N) and 16 for diploid tetrasporophyte (2N) together with genetic structure analysis confirmed to their sexual mating behaviour. Their marker assisted selection based on ISSR generated characteristic band of 430bp specific to male, 860bp for female and two bands of 800 and 1600bp for tetrasporophytic thallus from primer 'A'. Similarly ISSR primer 'E' also generated bands specific to male, female and tetrasporophytes while others gave bands specific to either of life phase. Interestingly, endogenic ABA content was significantly higher for haploid gametophytes (female more than male) than diploid tetrasporophyte while no significant difference was observed in IBA content. Thus the study described not only the features of three life phases of G. dura but also reliable biomarkers for differentiating such isomorphic life phases which could be beneficial for the selection of cultivar and in breeding programmes.
Khan, N-UH, Pandya, N, Maity, NC, Kumar, M, Patel, RM, Kureshy, RI, Abdi, SHR, Mishra, S, Das, S & Bajaj, HC 2011, 'Influence of chirality of V(V) Schiff base complexes on DNA, BSA binding and cleavage activity.', European journal of medicinal chemistry, vol. 46, no. 10, pp. 5074-5085.View/Download from: UTS OPUS or Publisher's site
New chiral V(V) Schiff base complexes (S)-[VO(OMe)L] and (R)-[VO(OMe)L] were synthesized and characterized by microanalysis, infrared (IR), UV-Visible, Circular dichroism (CD) spectroscopy and single crystal X-ray studies. The interaction of these complexes with calf thymus (CT) DNA and bovine serum albumin (BSA) protein showed chiral expression DNA/protein binding strength. The influence of chirality was also observed in cytotoxicity assay of Hep 2 cells. (R)-[VO(OMe)L] enantiomer exhibited higher binding constant (5 ± 1 × 10(5) M(-1)) as compared to (S)-[VO(OMe)L] (8 ± 1 × 10(4) M(-1)). The fluorescence quenching, thermal melting and viscosity data suggest DNA surface and/or groove binding nature of the complexes and electrophoresis studies also showed greater activity for (R)-[VO(OMe)L] in cleaving DNA and protein as against (S)-[VO(OMe)L].
Gupta, V, Kumar, M, Kumari, P, Reddy, CRK & Jha, B 2011, 'Optimization of protoplast yields from the red algae Gracilaria dura (C. Agardh) J. Agardh and G. verrucosa (Huds.) Papenfuss', Journal of Applied Phycology, vol. 23, no. 2, pp. 209-218.View/Download from: UTS OPUS or Publisher's site
This study reports on the optimization of protoplast yield from two important tropical agarophytes Gracilaria dura and Gracilaria verrucosa using different cell-wall-degrading enzymes obtained from commercial sources. The conditions for achieving the highest protoplast yield was investigated by optimizing key parameters such as enzyme combinations and their concentrations, duration of enzyme treatment, enzyme pH, mannitol concentration, and temperature. The significance of each key parameter was also further validated using the statistical central composite design. The enzyme composition with 4% cellulase Onozuka R-10, 2% macerozyme R-10, 0.5% pectolyase, and 100 U agarase, 0.4 M mannitol in seawater (30‰) adjusted to pH 7.5 produced the highest protoplast yields of 3.7±0.7 × 106cells g-1fresh wt for G. dura and 1.2±0.78×106cells g-1fresh wt for G. verrucosa when incubated at 25°C for 4-6 h duration. The young growing tips maximally released the protoplasts having a size of 7-15 m in G. dura and 15-25 m in G. verrucosa, mostly from epidermal and upper cortical regions. A few large-size protoplasts of 25-35 m, presumably from cortical region, were also observed in G. verrucosa. © 2010 Springer Science+Business Media B.V.
Trivedi, N, Gupta, V, Kumar, M, Kumari, P, Reddy, CRK & Jha, B 2011, 'Solvent tolerant marine bacterium Bacillus aquimaris secreting organic solvent stable alkaline cellulase.', Chemosphere, vol. 83, no. 5, pp. 706-712.View/Download from: UTS OPUS or Publisher's site
The organic solvent tolerant bacteria with their physiological abilities to decontaminate the organic pollutants have potentials to secrete extracellular enzymes of commercial importance. Of the 19 marine bacterial isolates examined for their solvent tolerance at 10vol.% concentration, one had the significant tolerance and showed a relative growth yield of 86% for acetone, 71% for methanol, 52% for benzene, 35% for heptane, 24% for toluene and 19% for ethylacetate. The phylogenetic analysis of this strain using 16S rDNA sequence revealed 99% homology with Bacillus aquimaris. The cellulase enzyme secreted by this strain under normal conditions showed an optimum activity at pH 11 and 45°C. The enzyme did show functional stability even at higher pH (12) and temperature (75°C) with residual activity of 85% and 95% respectively. The enzyme activity in the presence of different additives were in the following order: Co(+2)>Fe(+2)>NaOCl(2)>CuSO(4)>KCl>NaCl. The enzyme stability in the presence of solvents at 20vol.% concentration was highest in benzene with 122% followed by methanol (85%), acetone (75%), toluene (73%) and heptane (42%). The pre-incubation of enzyme in ionic liquids such as 1-ethyl-3-methylimidazolium methanesulfonate and 1-ethyl-3-methylimidazolium bromide increased its activity to 150% and 155% respectively. The change in fatty acid profile with different solvents further elucidated the physiological adaptations of the strain to tolerate such extreme conditions.
Kumar, M, Gupta, V, Kumari, P & Reddy, CRK 2010, 'Assesment of nutrient composition and antioxidant potential of seaweeds from Caulerpaceae.', Journal of Food Composition and Analysis, vol. 24, no. 2, pp. 270-278.View/Download from: Publisher's site
The proximate nutrient composition, mineral contents, enzymatic and non-enzymatic antioxidant potential of three Caulerpa species were investigated. All three species were high in ash (24.20–33.70%) and carbohydrate content (37.23–48.95%) on dry weight basis (DW). The lipid content ranged between 2.64 and 3.06% DW. The mineral contents varied marginally among the species but were in the order of Na > K > Ca > Mg. The Na/K ratio among the species varied from 1.80 to 2.55 and was lowest in C. scalpelliformis. A 10 g DW of Caulerpa powder contains 11–21% Fe, 52–60% Ca and 35–43% Mg, which is higher than the recommended daily allowance (RDA), compared with non-seafood. The percentage sum of PUFAs (C18:2, C18:3, C20:4 and C20:5) in total fatty acids was highest in both C. scalpelliformis (39.25%) and C. veravelensis (36.73%) while it was the lowest in C. racemosa (24.50%). The n6/n3 ratio among the species varied from 1.44 to 7.72 and remained within the prescribed WHO standards (<10). Further, the higher enzymatic dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) and non-enzymatic antioxidant potential of Caulerpa species found in the present study confirm their usefulness in terms of nutrients and antioxidants.
Kumar, M, Kumari, P, Gupta, V, Anisha, PA, Reddy, CRK & Jha, B 2010, 'Differential responses to cadmium induced oxidative stress in marine macroalga Ulva lactuca (Ulvales, Chlorophyta).', Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine, vol. 23, no. 2, pp. 315-325.View/Download from: Publisher's site
This study describes various biochemical processes involved in the mitigation of cadmium toxicity in green alga Ulva lactuca. The plants when exposed to 0.4 mM CdCl(2) for 4 days showed twofold increase in lipoperoxides and H(2)O(2) content that collectively decreased the growth and photosynthetic pigments by almost 30% over the control. The activities of antioxidant enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione peroxidase (GPX) enhanced by twofold to threefold and that of catalase (CAT) diminished. Further, the isoforms of these enzymes, namely, Mn-SOD (approximately 85 kDa), GR (approximately 180 kDa) and GPX (approximately 50 kDa) responded specifically to Cd(2+) exposure. Moreover, the contents of reduced glutathione (3.01 fold) and ascorbate (1.85 fold) also increased substantially. Lipoxygenase (LOX) activity increased by two fold coupled with the induction of two new isoforms upon Cd(2+) exposure. Among the polyunsaturated fatty acids, although n - 3 PUFAs and n - 6 PUFAs (18:3n - 6 and C18:2n - 6) showed relatively higher contents than control, the latter ones showed threefold increase indicating their prominence in controlling the cadmium stress. Both free and bound soluble putrescine increased noticeably without any change in spermidine. In contrast, spermine content reduced to half over control. Among the macronutrients analysed in exposed thalli, the decreased K content was accompanied by higher Na and Mn with no appreciable change in Ca, Mg, Fe and Zn. Induction of antioxidant enzymes and LOX isoforms together with storage of putrescine and n - 6 PUFAs in cadmium exposed thallus in the present study reveal their potential role in Cd(2+) induced oxidative stress in U. lactuca.
Kumar, M, Kumari, P, Gupta, V, Reddy, CRK & Jha, B 2010, 'Biochemical responses of red alga Gracilaria corticata (Gracilariales, Rhodophyta) to salinity induced oxidative stress', Journal of Experimental Marine Biology and Ecology, vol. 391, no. 1-2, pp. 27-34.View/Download from: Publisher's site
The biochemical responses of Gracilaria corticata (J. Agardh) J. Agardh to salinity induced oxidative stress were studied following the exposure to different salinities ranging from 15, 25, 35 (control), 45 to 55 in laboratory conditions. The growth was highest under 25 (3.14±0.69% DGR) and 35 (3.58±0.32% DGR) and decreased significantly in both extreme lower (15) and hyper (55) salinities. Both phycoerythrin (PE) and allophycocyanin (APC) were significantly higher in hyper-salinity (45) with an increase of almost 70% and 52% from their initial contents. Conversely, the level of increase of the same in hypo-salinities was considerably lower as compared with that of hyper-salinity. Both hypo- and hyper-salinity treatments induced almost two fold increase in the contents of polyphenols, proline and the activities of antioxidative enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) especially for 6d exposure. The Na+ ions readily displaced the K+ and Ca2+ from their uptake sites at extreme hyper-salinity (55) and accounted for substantial increase in the ratio of Na+/K+ and Na+/Ca2+ that impeded the growth under long term exposure (>6d). The survivability at salinity 45 even with considerably higher ratio of Na+/K+ and Na+/Ca2+ suggests the compartmentalization of Na+ into the vacuoles. Further, the micro nutrients such as Zn, Fe and Mn were decreased at both high and low end salinities with highest at extreme hyper-salinity. The C18:1(n-9) cis, C18:2(n-6), C18:3(n-3) and C20:4(n-6) were found in significant amounts in hyper-salinities. The C18:1(n-9) cis in particular increased by 60.25% and 70.51% for salinities 45 and 55, respectively from their initial amounts. The ratio of total unsaturated to saturated fatty acids (UFA/SFA) also increased linearly with increasing salinity. These results collectively suggest the potential role of antioxidative enzymes, phycobiliproteins, PUFAs and mineral nutrients to combat the...
Kumari, PUJA, Kumar, MANOJ, Gupta, VISHAL, Reddy, CRK & Jha, BHAVANATH 2010, 'Tropical marine macroalgae as potential sources of nutritionally important PUFAs', Food chemistry, vol. 120, no. 3, pp. 749-757.View/Download from: Publisher's site
The lipid and fatty acid compositions of 27 tropical macroalgae belonging to the three phyla, Chlorophyta, Phaeophyta and Rhodophyta, were studied from a nutritional and chemotaxonomic perspective. The lipid content varied widely among the species and ranged from 0.57% to 3.5% on a dry weight basis (p 0.01). Chlorophyta members showed higher C18PUFAs contents than did C20 PUFAs while for Rhodophyta the trend was opposite. The Phaeophyta members displayed a profile of C18PUFAs similar to that of Chlorophyta and of C20PUFAs to that of Rhodophyta. Both Phaeophyta and Rhodophyta species were rich in arachadonic acid (AA) and eicosopentaenoic acid (EPA) and Ulvales in docosahexaenoic acid (DHA) content. Most of the species studied had a nutritionally beneficial n6/n3 ratio (0.61-5.15:1). Further, the principal component analysis clearly segregated the three phyla by their FA composition and hierarchical cluster analysis altogether classified them into six distinct groups, suggesting that FAs can be used as a tool for chemotaxonomic studies.
Khan, N-UH, Pandya, N, Kumar, M, Bera, PK, Kureshy, RI, Abdi, SHR & Bajaj, HC 2010, 'Influence of chirality using Mn(III) salen complexes on DNA binding and antioxidant activity.', Organic & biomolecular chemistry, vol. 8, no. 19, pp. 4297-4307.View/Download from: Publisher's site
Chiral Mn(iii) salen complexes S-1, R-1, S-2, R-2, S-3 and R-3 derived from the respective chiral salen ligands, viz., (1S,2S)-N,N'-bis-[3-tert-butyl-5-chloromethyl-salicylidine]-1,2-cyclohexanediamine S-1'/(1R,2R)-N,N'-bis-[3-tert-butyl-5-chloromethyl-salicylidine]-1,2-cyclohexanediamine R-1'/(1S,2S)-N,N'-bis-[3-tert-butyl-5-N,N'N'triethylaminomethyl-salicylidine]-1,2-cyclohexanediamine dichloride S-2'/(1R,2R)-N,N'-bis-[3-tert-butyl-5-N,N'N'triethylaminomethyl-salicylidine]-1,2-cyclohexanediamine dichloride R-2'/(1S,2S)-N,N'-bis-[3,5-di-tert-butylsalicylidene]-1,2-cyclohexanediamine S-3' and (1R,2R)-N,N'-bis-[3,5-di-tert-butyl-salicylidene]-1,2-cyclohexanediamine R-3', were synthesized. Characterization of the complexes was done by microanalysis, IR, LC-MS, UV-vis. and circular dichroism (CD) spectroscopy. Binding of these complexes with calf thymus DNA (CT-DNA) was studied by absorption spectroscopy, competitive binding study, viscosity measurements, circular dichroism measurements, thermal denaturation study and observation of their different antioxidant activities. Among all the complexes used, the best result in terms of binding constant (intercalative) (130.4 x 10(4)) was achieved with the complex S-1 by spectroscopic titration. The complex S-1 showed strong antioxidant activity as well.
Mantri, VAIBHAVA, Thakur, MUKUNDC, Kumar, MANOJ, Reddy, CRK & Jha, BHAVANATH 2009, 'The carpospore culture of industrially important red alga Gracilaria dura (Gracilariales, Rhodophyta)', Aquaculture., vol. 297, no. 1-4, pp. 85-90.View/Download from: Publisher's site
Gracilaria dura occurring in Indian waters has been reported to be potential sources of agarose (US Patent 2005/0267296A1). The scanty biomass and restricted occurrence at the bottom of deep tide pools along few locations of the northwestern coast of India limited its exploitation for industrial utilization. The paper describes carpospore output, their viability and early stages of development in the laboratory as well as out-planting and field cultivation of tetrasporophytic plants of G. dura. The maximum spore liberation took place on day four with output of 808 (±22) per cystocarp. The percentage spore viability ranged from 22 to 36% (r ² =0.1008, n =30) at the end of first week and 17-27% (r ² =0.0011, n =30) at the second week of carpospores culture. The spores underwent germination immediately without any resting period and followed the Dumontia type developmental pattern. The erect thallus developed from the multicellular basal disc. After 6months under laboratory culture, the erect cylindrical thallus attained the minimum size of field transplantation with about 3-4cm frond length. The out-planting of laboratory-grown tetrasporophytes showed fast adaptation to the sea with satisfactory average growth rate of 4.67% d¹. The present investigation has demonstrated the possibility of field cultivation of this species using carpospores under the realistic culture conditions. The scaling up of this method could result into commercial farming of this industrially important red alga.
Reddy, CRK, Gupta, MK, Mantri, VA & Jha, B 2008, 'Seaweed protoplasts: status, biotechnological perspectives and needs', JOURNAL OF APPLIED PHYCOLOGY, vol. 20, no. 5, pp. 619-632.View/Download from: Publisher's site
Kumar, M, Ralph, P & Kuzhiumparambil, U 2017, 'Polyamines-stress metabolites in marine macrophytes' in ALGAL GREEN CHEMISTRY: RECENT PROGRESS IN BIOTECHNOLOGY, Elsevier.View/Download from: UTS OPUS or Publisher's site
Kuzhiumparambil, U, Kumar, M & Ralph, P 2017, 'Gas and liquid chromatography-mass spectrometry-based metabolic profiling of marine angiosperm Zostera Muelleri (alismatales, zosteraceae)' in Systems Biology of Marine Ecosystems, pp. 189-203.View/Download from: UTS OPUS or Publisher's site
© Springer International Publishing AG 2017. Seagrasses are monocotyledonous marine flowering plants that are considered lungs of the sea and are the most intense carbon sinks on the planet, delivering a range of ecologically and economically valuable biological services. In this study, we report the chemical fingerprint of Zostera muelleri using an untargeted metabolomic approach. High-performance liquid chromatography-mass spectrometry (HPLC-MS) and gas chromatography-mass spectrometry (GC-MS) were performed to study the metabolic profile of Z. muelleri. A total of 98 metabolites belonging to various chemical classes including flavonoids, phenolics, lipids, fatty acids, sugar alcohols and amino acids were identified, including two characteristic marker compounds of the genus, zosteric acid and rosmarinic acid. Chromatographic profiling yield a comprehensive map for the chemical constituents of Z. muelleri, and this method can be used as an effective and convenient approach to gain insights into the chemical composition of other seagrasses.
Contreras-Porcia, L, Meynard, A, López-Cristoffanini, C, Latorre, N & Kumar, M 2017, 'Marine metal pollution and effects on seaweed species' in Systems Biology of Marine Ecosystems, pp. 35-48.View/Download from: UTS OPUS or Publisher's site
© Springer International Publishing AG 2017. Heavy metals are significant pollutants continuously released into the biosphere, both naturally and anthropogenically. Conceptually, metal speciation, bioavailability, and associated toxicity in marine organisms depend on a wide array of abiotic and biotic factors. Among these, pH variation is one of the most important environmental factors influencing metal speciation and toxicity. Due to this, ocean acidification is expected to modify metal speciation, altering the effects these nondegradable contaminants have on marine organisms, such as seaweeds. One clear effect of heavy metals on seaweeds is the rapid formation of reactive oxygen species (ROS). The production of ROS beyond the physiological tolerance threshold causes an oxidative stress condition that, if not attenuated, can irreversibly damage cellular constituents such as DNA/RNA, proteins, and lipids. To cope with heavy metal excess, several mechanisms exist in tolerant seaweed species, including the activation of an efficient ROS-scavenging system constituted by metal-binding compounds, antioxidant enzymes, and oxygenated polyunsaturated fatty acids, among others. Another adaptive mechanism involves the participation of ATP-binding cassette (ABC) transporter proteins in translocating a wide variety of compounds across cell membranes, including heavy metals. In contrast, an excessive heavy metal presence can inhibit photosynthesis, reduce pigment concentration and growth, induce cation losses, and disrupt gametophyte development in non-tolerant seaweed species. In a scenario of lowered ocean pH and increased heavy metal toxicity, the important roles played by non-tolerant seaweed species in structuring communities could be severely compromised, with unknown consequences for associated organisms. Therefore, in the upcoming decades, marine pollution could majorly shift and rearrange community compositions and the distributional ranges of species.
Contreras-Porcia, L, López-Cristoffanini, C, Meynard, A & Kumar, M 2017, 'Tolerance pathways to desiccation stress in seaweeds' in Systems Biology of Marine Ecosystems, pp. 13-33.View/Download from: Publisher's site
© Springer International Publishing AG 2017. Seaweeds are sessile organisms that inhabit coastal benthic systems and are key species for the equilibrium of marine communities. Rocky intertidal zone seaweeds are distributed in marked patterns determined by interactions between biotic and abiotic factors influenced by tide levels. It has been proposed that the distribution and abundance of organisms in the upper intertidal zones, with longer emersions, are mostly regulated by abiotic factors. Desiccation is a particularly noteworthy abiotic factor since, during low tide, algae of the upper intertidal zones can lose more than 90% of cellular water content, which can ultimately induce oxidative stress. Considering the necessary activation of several desiccation tolerance mechanisms, these algal species are ideal research models in ecophysiology. In fact, several studies using physiological, transcriptomic, and proteomic approaches have determined that desiccation tolerance mechanisms are expressed within a well-coordinated network that includes morphological and cell wall changes, photosynthetic activity diminishment, increased expression of desiccation-associated proteins, hormone accumulation, ROS scavenging by antioxidant enzymes and compounds, and osmolyte and protein synthesis. These mechanisms explain the permanence of tolerant algae species in the upper intertidal zone in comparison with lower intertidal species. Therefore, this chapter focuses on identifying tolerant algal species, and explaining the mechanisms underlying the high capacity of these species to cope with desiccation- induced oxidative stress.
Kumari, P, Kumar, M, Reddy, CRK & Jha, B 2013, 'Algal lipids, fatty acids and sterols' in Functional Ingredients from Algae for Foods and Nutraceuticals, Woodhead Publishing Limited, USA, pp. 87-134.View/Download from: UTS OPUS or Publisher's site
Algae are photosynthetic organisms with ubiquitous distribution and contain varied forms of lipids owing to their extreme habitat diversity. This chapter presents detailed information on the structure and distribution of lipids, fatty acids and sterols in algae together with the genes and enzymes involved in their metabolism. The developments in acclimatory roles of lipids, fatty acids and sterols in response to changes in environmental factors such as nutrients, light, temperature and salinity have been discussed. Further, the current status of lipidomics in algae has also been discussed presuming its promising implications in elucidation of novel lipids and understanding of complex metabolic pathways. © 2013 Woodhead Publishing Limited All rights reserved.
Natarajan, S., Kumar, M.A. & Sundareswaran, A.U.M. 2017, 'Computational Analysis of an Early Direct Injected HCCI Engine Using Bio Ethanol and Diesel Blends as Fuel', Energy Procedia, pp. 350-357.View/Download from: Publisher's site
© 2017 The Authors. Published by Elsevier Ltd. In this paper the work deals with the Experimental analysis of the early direct injected HCCI. The computational analysis of the engine was carried out using CHEMKIN-PRO Software. The computational analysis was carried out using the auto ignition chemistry by means of reduced chemical kinetics. For these investigations, the neat diesel and bio ethanol - diesel blend (E20) fuels were used as fuel and the pressure, combustion and emission characteristics were studied in the equivalence ratio of 0.6 (= 0.6). The injection timing was advanced to 18°rather than the normal 23°before top dead centre (BTDC) as specified engine conditions. Since pressure and temperature profiles plays a vital role in reaction path at certain operating conditions, an effort has been made here to present a comprehensive reaction path analysis on the formation/destruction of chemical species at peak temperature and pressure conditions.