Khandaker (Rayhan) Mahbub is an environmental microbiologist with specialization in microbial heavy metal tolerance, ecotoxicity and bioremediation. He started his research career in 2009 as a scientist in Bangladesh Council of Scientific and Industrial Research. In 2013 he commenced his PhD course in the University of South Australia that he finished from the University of Newcastle in 2017. His doctoral research has focused on the ecotoxicity, monitoring and bioremediation of heavy metals in soil environments, which resulted in number of publications. His current research at the University of Technology Sydney in the lab of Dr Maurizio focuses on microbial antibiotic resistance, metal driven co-selection of drug resistance in environments and remediation of antibiotic resistance gene containing soils.
Awards and Scholarships:
- UNIPRS Scholarship, Australia
- University President’s Scholarship (UPS), Australia.
- CERAR Scholarship (Australia)
- CRC-CARE top up scholarship (Australia)
- SETAC Europe 26th Annual Meeting in Nantes, France from 22 -26 May 2016.
- The 6th International Contaminated Site Remediation Conference, CleanUp 2015, Melbourne 2015
- The 5th International Conference on Microbiology of Food, Health and Environment: Problems and Prospects in Developing Countries. Dhaka, Bangladesh 2010
- The 26th Annual Conference of Bangladesh Society of Microbiologists. Chittagong, Bangladesh 2011.
- 3RD ASM Conference on AMR in Zoonotic Bacteria and Foodborne Pathogens, Page 141, Abstract 123C, June 26-29, 2012.
- Antimicrobial Agents and Chemotherapy (ICAAC) of American Society for Microbiology (ASM)
- Member of American Society of Microbiologists (ASM)
- Life time member of Microbiology Association of Bangladesh (MAB)
Can supervise: YES
Antibiotic resistance, Integrons, Heavy metal microbiology, Bioremediation, Ecotoxicity
Bahar, MM, Mahbub, KR, Naidu, R & Megharaj, M 2020, 'A simple spectrophotometric method for rapid quantitative screening of arsenic bio-transforming bacteria', Environmental Technology and Innovation, vol. 19.View/Download from: Publisher's site
© 2020 A simple spectrophotometric technique for inorganic arsenic speciation of known total arsenic has been developed for application in quantitative screening of arsenite-oxidizing and arsenate-reducing bacteria from the wide range of environmental isolates. The technique is based on the spectrophotometric absorbance measurement of the color intensity in the arsenic and potassium permanganate mixture. Since arsenate does not react with potassium permanganate, the intensity of color decreases proportionately with the increasing concentration of arsenite in the total arsenic. The speciation method can be used over a pH range of 4–9. The validity of the results obtained from this spectrophotometric method was confirmed with the Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry (LC-ICP-MS). This method has great potential for the screening of arsenite-oxidizing bacteria.
Mahbub, KR, King, WL, Siboni, N, Nguyen, VK, Rahman, MM, Megharaj, M, Seymour, JR, Franks, AE & Labbate, M 2020, 'Long-lasting effect of mercury contamination on the soil microbiota and its co-selection of antibiotic resistance', Environmental Pollution, vol. 265, pp. 115057-115057.View/Download from: Publisher's site
King, WL, Siboni, N, Kahlke, T, Dove, M, O'Connor, W, Mahbub, KR, Jenkins, C, Seymour, JR & Labbate, M 2020, 'Regional and oyster microenvironmental scale heterogeneity in the Pacific oyster bacterial community', FEMS MICROBIOLOGY ECOLOGY, vol. 96, no. 5.View/Download from: Publisher's site
Viet, KN, King, WL, Siboni, N, Mahbub, KR, Dove, M, O'Connor, W, Seymour, JR & Labbate, M 2020, 'The Sydney rock oyster microbiota is influenced by location, season and genetics', AQUACULTURE, vol. 527.View/Download from: Publisher's site
Bahar, MM, Mahbub, KR, Naidu, R & Megharaj, M 2018, 'As(V) removal from aqueous solution using a low-cost adsorbent coir pith ash: Equilibrium and kinetic study', Environmental Technology & Innovation, vol. 9.View/Download from: Publisher's site
Mahbub, KR, Bahar, M, Megharaj, M & Labbate, M 2018, 'Are the existing guideline values adequate to protect soil health from inorganic mercury contamination?', Environment International, vol. 117, pp. 10-15.View/Download from: Publisher's site
Mahbub, KR, Kannan Krishnan, Ravi Naidu, Stuart Andrews & Mallavarapu Megharaj 2017, 'Mercury toxicity to terrestrial biota', Ecological Indicators, vol. 74, pp. 451-462.View/Download from: Publisher's site
The heavy metal mercury is a non-essential hazardous element which concentrates up the food chain. It is necessary to assess the ecological risk of mercury to establish proper regulatory guideline levels. Most of the toxicological assessment of mercury has been focused on aquatic organisms, however in terrestrial bodies the information is limited. Hence this review critically discusses the toxicity of inorganic mercury to key terrestrial biota from recent literature and evaluate whether these information are adequate to establish safe regulatory limits or precautionary values which is invaluable for risk assessment of mercury in soil. Till date soil microorganisms, plants and invertebrates have been utilized for assessing mercury toxicity; among them, microorganisms have been observed to be the most sensitive indicators to mercury stress. Large inconsistency among the measured toxic concentrations indicates that measuring mercury toxicity in soil may be influenced by soil characteristics and ageing period of contamination. This review warrants more studies to obtain widely acceptable safe limit of soil mercury.
Mahbub, KR, Krishnan, K, Andrews, S, Venter, H, Naidu, R & Megharaj, M 2017, 'Bio-augmentation and nutrient amendment decrease concentration of mercury in contaminated soil', SCIENCE OF THE TOTAL ENVIRONMENT, vol. 576, pp. 303-309.View/Download from: Publisher's site
Mahbub, KR, Krishnan, K, Naidu, R & Megharaj, M 2017, 'Development of a whole cell biosensor for the detection of inorganic mercury', Environmental Technology and Innovation, vol. 8, pp. 64-70.View/Download from: Publisher's site
Mahbub, KR, Krishnan, K, Naidu, R & Megharaj, M 2017, 'Mercury remediation potential of a mercury resistant strain Sphingopyxis sp. SE2 isolated from contaminated soil.', Journal of Environmental Sciences, vol. 51, pp. 128-137.View/Download from: Publisher's site
A mercury resistant bacterial strain SE2 was isolated from contaminated soil. The 16s rRNA gene sequencing confirms the strain as Sphingopyxis belongs to the Sphingomonadaceae family of the α-Proteobacteria group. The isolate showed high resistance to mercury with estimated concentrations of Hg that caused 50% reduction in growth (EC50) of 5.97 and 6.22mg/L and minimum inhibitory concentrations (MICs) of 32.19 and 34.95mg/L in minimal and rich media, respectively. The qualitative detection of volatilized mercury and the presence of mercuric reductase enzyme proved that the strain SE2 can potentially remediate mercury. ICP-QQQ-MS analysis of the remaining mercury in experimental broths indicated that a maximum of 44% mercury was volatilized within 6hr by live SE2 culture. Furthermore a small quantity (23%) of mercury was accumulated in live cell pellets. While no volatilization was caused by dead cells, sorption of mercury was confirmed. The mercuric reductase gene merA was amplified and sequenced. Homology was observed among the amino acid sequences of mercuric reductase enzyme of different organisms from α-Proteobacteria and ascomycota groups.
Mahbub, KR, Krishnan, K, Naidu, R & Megharaj, M 2017, 'Mercury toxicity to Eisenia fetida in three different soils.', Environmental science and pollution research international, vol. 24, no. 2, pp. 1261-1269.View/Download from: Publisher's site
Three different soils were spiked with 12 different concentrations of inorganic mercury (Hg). Sub-chronic Hg toxicity tests were carried out with Eisenia fetida in spiked soils by exposing the worms for 28 days following standard procedures. The toxicity studies revealed that Hg exerted less lethal effect on earthworms in acidic soil with higher organic carbon (S-3 soil) where water soluble Hg recovery was very low compared to the water soluble Hg fractions in soils with less organic carbon and higher pH (S-1 and S-2 soils). The concentrations of total Hg that caused 50 % lethality to E. fetida (LC50) after 28 days of exposure in S-1, S-2 and S-3 soils were 152, 294 and 367 mg kg-1, respectively. The average weight loss of E. fetida in three soils ranged from 5 to 65 %. The worms showed less weight loss in the organic carbon-rich soil (S-3) compared to less organic carbon containing soils (S-1 and S-2). The bioconcentration of Hg in E. fetida increased with increased Hg concentrations. The highest bioaccumulation took place in the acidic soil with higher organic carbon contents with estimated bioaccumulation factors ranging from 2 to 7.7. The findings of this study will be highly useful for deriving a more robust soil ecological guideline value for Hg.
Mahbub, KR, Subashchandrabose, SR, Krishnan, K, Naidu, R & Megharaj, M 2017, 'Mercury alters the bacterial community structure and diversity in soil even at concentrations lower than the guideline values', Applied Microbiology and Biotechnology, vol. 101, no. 5, pp. 2163-2175.View/Download from: Publisher's site
This study evaluated the effect of inorganic mercury (Hg) on bacterial community and diversity in different soils. Three soils—neutral, alkaline and acidic—were spiked with six different concentrations of Hg ranging from 0 to 200 mg kg−1 and aged for 90 days. At the end of the ageing period, 18 samples from three different soils were investigated for bacterial community structure and soil physicochemical properties. Illumina MiSeq-based 16s ribosomal RNA (rRNA) amplicon sequencing revealed the alteration in the bacterial community between un-spiked control soils and Hg-spiked soils. Among the bacterial groups, Actinobacteria (22.65%) were the most abundant phyla in all samples followed by Proteobacteria (21.95%), Bacteroidetes (4.15%), Firmicutes (2.9%) and Acidobacteria (2.04%). However, the largest group showing increased abundance with higher Hg doses was the unclassified group (45.86%), followed by Proteobacteria. Mercury had a considerable negative impact on key soil functional bacteria such as ammonium oxidizers and nitrifiers. Canonical correspondence analysis (CCA) indicated that among the measured soil properties, Hg had a major influence on bacterial community structure. Furthermore, nonlinear regression analysis confirmed that Hg significantly decreased soil bacterial alpha diversity in lower organic carbon containing neutral and alkaline soils, whereas in acidic soil with higher organic carbon there was no significant correlation. EC20 values obtained by a nonlinear regression analysis indicated that Hg significantly decreased soil bacterial diversity in concentrations lower than several guideline values.
Mahbub, KR, Bahar, MM, Labbate, M, Krishnan, K, Andrews, S, Naidu, R & Mallavarapu, M 2017, 'Bioremediation of mercury: not properly exploited in contaminated soils!', Applied Microbiology and Biotechnology, vol. 101, no. 3, pp. 963-976.View/Download from: Publisher's site
Mahbub, KR, Kader, M, Krishnan, K, Labbate, M, Naidu, R & Megharaj, M 2017, 'Toxicity of Inorganic Mercury to Native Australian Grass Grown in Three Different Soils', Bulletin of Environmental Contamination and Toxicology, vol. 98, no. 6, pp. 850-855.View/Download from: Publisher's site
Kader, M, Lamb, DT, Mahbub, KR, Megharaj, M & Naidu, R 2016, 'Predicting plant uptake and toxicity of lead (Pb) in long-term contaminated soils from derived transfer functions', ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, vol. 23, no. 15, pp. 15460-15470.View/Download from: Publisher's site
Mahbub, KR, Krishnan, K, Megharaj, M & Naidu, R 2016, 'Bioremediation potential of a highly mercury resistant bacterial strain Sphingobium SA2 isolated from contaminated soil', CHEMOSPHERE, vol. 144, pp. 330-337.View/Download from: Publisher's site
Mahbub, KR, Krishnan, K, Megharaj, M & Naidu, R 2016, 'Mercury Inhibits Soil Enzyme Activity in a Lower Concentration than the Guideline Value', BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY, vol. 96, no. 1, pp. 76-82.View/Download from: Publisher's site
Mahbub, KR, Krishnan, K, Naidu, R & Megharaj, M 2016, 'Mercury resistance and volatilization by Pseudoxanthomonas sp. SE1 isolated from soil', Environmental Technology and Innovation, vol. 6, pp. 94-104.View/Download from: Publisher's site
© 2016 Elsevier B.V. A mercury resistant bacterial strain SE1 isolated from contaminated soil was identified as Pseudoxanthomonas based on 16s rRNA sequencing. The Hg resistance was examined in both nutrient-rich media as well as low nutrient media and expressed as EC 50 and MIC values. Estimated EC 50 and MIC values in nutrient-rich media and low nutrient media had the following respective recordings — 22.6 mg L −1 ; 23.1 mg L −1 and 1.4 mg L −1 and 1.7 mg L −1 . The isolate was able to volatilize inorganic mercury demonstrated by a modified photographic film experiment and subsequently revealed its ability to remove mercury from the solution. The ICP-QQQ-MS analysis of SE1 inoculated solution showed almost 60% of 1.5 mg L −1 mercury was volatilized in 6 h and almost 40% were accumulated in cell pellets. The mercuric reductase gene merA was identified in the genome of isolate SE1 and sequenced. The deduced amino acid sequence of merA gene indicated a sequence homology with different organisms from the alpha proteobacteria group and eukaryotic fungi. merA encoded enzyme mercuric reductase activity was evident in the crude protein of the isolate. The isolate's ability to resist Hg, it's Hg volatilization potential and the presence of merA gene and mercuric reductase enzyme demonstrates the potential application of this strain in mercury bioremediation.
Ahmed, S, Mahbub, KR, Ahmed, MM, Rahman, M & Hoque, MM 2014, 'Microbiological Quality of Street Vended Drinking Water in Dhaka City and Screening for Antibiotics Resistance of Isolated Salmonella spp and Pseudomonas spp.', Journal of Scientific Research, vol. 6, no. 2, pp. 359-371.View/Download from: Publisher's site
The present study was aimed to assess the microbiological quality of street vended drinking water of Dhaka city. The water samples were collected from street vendors in different areas of Dhaka city. All of the 30 samples were found having microorganisms higher than WHO limits for drinking water. Four (13.34%) samples were confirmed to have Salmonella contamination and twenty (66.67%) samples were contaminated with Pseudomonas. Based on morphological and biochemical characterization Salmonella isolates were identified as Salmonella choleraesuis and Salmonella bongori. Among the isolates of Pseudomonas, fourteen were identified as Pseudomonas alcaligens and six were as Pseudomonas aeruginosa. During antibiogram for Salmonella, 100% of the isolates were found resistant to Penicillin. Chloramphenicol, doxycycline, Gentamycin, Neomycin were sensitive to all of the isolates. The Pseudomonas isolates showed a significant drug resistance to Penicillin (100%), Ampicillin (95%), Amoxicillin (95%) and Nalidixic acid (85%). The present study demonstrates that drinking water samples from street vendors in Dhaka city are not complying with microbiological specifications of WHO and indicates that street vending drinking water in Dhaka city may not be safe for human consumption and also shows that these are the potential sources of drug resistance Salmonella and Pseudomonas. Keywords: Street vended drinking water; Antibiotic resistance; Salmonella; Pseudomonas. © 2014 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v6i2.17640 J. Sci. Res. 6 (2), 359-371 (2014)
Shafiul Azam, AKM, Saha, D, Asadujjaman, M, Mahbub, KR & Minar, HM 2014, 'Fishing gears and crafts commonly used at Hatiya Island: A coastal region of Bangladesh', Asian Journal of Agricultural Research, vol. 8, no. 1, pp. 51-58.View/Download from: Publisher's site
The study was conducted on traditional fishing nets and crafts that are used by professional fishermen (including small, medium and large scale fishing) at Hatiya in the district of Noakhali, Bangladesh. Primary data were collected from local fishermen through Personal Interview (PI), Focus Group Discussion (FGD) and observation; secondary data were collected from District Fisheries Officer (DFO) and Upazila Fisheries Officer (UFO). The study reveals different types of fishing nets including fixed purse nets, gill nets, dip nets and cast net are used in the locality. The mesh size of the fixed purse nets vary in 0.1-2.5 inch (anterior end) and 0.2-0.5 inch (posterior end), gill nets vary in 0.5-15 inch, dip nets vary in 0.1-0.2 inch and cast net 0.5-1 inch during study. Generally these nets are lasting in 2-3 years. For nets preservation no chemical or medicine are used, only the net is dried under the sun and put it on a safe and dry place. The present study suggests that different types of boats such as chandi, kosha, balam, tempu and dinghi nauka are being used at Hatiya. Traditionally sundari, jarul, gamari, chaplas and garjan woods and bamboos are used in boat making which are locally available and last for 5-10 years. Usually 90% of the boats are propelled by the engine and 10% of the boats are propelled by the sail and row. Most of the boats have no license which reflects lack of awareness and weak control by the regulatory agency. © 2014 Knowledgia Review, Malaysia.
Ahmed, MM, Mahbub, KR, Mohammad, A & Begum, S 2012, 'Decolorization of Synthetic Dyes Using Bacteria Isolated from Textile Industry Effluent', Asian Journal of Biotechnology, vol. 4, no. 3, pp. 129-136.View/Download from: Publisher's site
Akhtar, N, Ahmeda, MM, Sarker, N, Mahbuba, KR & Sarker, AM 2012, 'Growth response of Spirulina platensis in papaya skin extract and antimicrobial activities of Spirulina extracts in different culture media', Bangladesh Journal of Scientific and Industrial Research, vol. 47, no. 2, pp. 147-152.View/Download from: Publisher's site
Growth response of Spirulina platensis in papaya skin extract media and their antimicrobial activity were studied. Five different concentrations e.g. 10gm/L, 8gm/L, 6 gm/L, 4 gm/L and 2gm/L of Papaya (Carica papaya) skin extract media and BD1 (control) medium were used in this study. After 8 days of cultivation, the optical density (0.33) was recorded in BD1 medium and among the five different concentrations of papaya skin extract media the maximum was found (0.31) in 6gm/L. Antimicrobial activity of Spirulina platensis grown in three media namely Zarrouk, BD1 media and media made from papaya skin extract was also studied. Only freeze dried Spirulina platensis powder extract showed inhibitory effect against bacteria and no antifungal activity was observed. DOI: http://dx.doi.org/10.3329/bjsir.v47i2.11445 Bangladesh J. Sci. Ind. Res. 47(2), 147-152, 2012
Hossain, M, Adhikary, RK, Mahbub, KR, Begum, M & Ul Islam, MR 2012, 'Effect of 10% concentrations of salt, garlic and coriander on the quality of smoked Hilsa fish (Tenualosa ilisha)', American Journal of Food Technology, vol. 7, no. 8, pp. 501-505.View/Download from: Publisher's site
The present study was conducted to evaluate the quality of smoked Hilsa fish (Tenualosa ilisha). The fishes were grouped into three parts. One part contains 10% salt, 10% garlic and 10% coriander and treated as Treatment 1 (T-l). Another named was Treatment 2 (T-2) and contained 10% salt and 10% garlic. The other parts contained 10% salt only and treated as Treatment 3 (T-3) to evaluate the quality of the smoked Hilsa with these ingredients for preparing a ready food item. All three treatments were found microbiologic ally acceptable since indicator organisms and Salmonella were not detected. However, from the results of overall acceptability, taste, colour and texture of the products, Treatment 2 had the best acceptance and significantly different when compared to the other treatments and selected the item as a quick but ready food item in laboratory condition. The moisture content, protein content, fat content, ash content, total volatile nitrogen and salt content of treatment 2 were found 39.65±0.19, 25.65±0.17, 24.85±0.17, 3.50±0.30, 2.55±0.22 and 16.20±0.14, respectively. All three treatments were found microbiologic ally acceptable since indicator organisms and Salmonella were not detected. However, from the results of overall acceptability, taste, colour and texture of the products, Treatment 2 had the best acceptance and significantly different when compared to the other treatment and selected the item as a quick but ready food item in laboratory condition. © 2012 Academic Journals Inc.
Islam, MM, Masum, SM & Mahbub, KR 2011, 'In vitro antibacterial activity of shrimp chitosan against Salmonela paratyphi and Staphylococcus aureus', Journal of the Bangladesh Chemical Society, vol. 24, no. 2, pp. 185-190.View/Download from: Publisher's site
Antimicrobial properties of chitosan extracted from indigenous shrimp processing waste were determined against one gram-negative (Salmonella Paratyphi) and one gram-positive bacterium (Staphylococcus aureus) in vitro. The antimicrobial activities of chitosan were explored by calculation of the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) in media supplemented with 128, 138, 168, 192, 240, 288, 300 and 320 ppm chitosan solution adjusted to pH 6 or 7. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the prepared chitosan was 288 and 300 ppm for both bacterial strains. These results indicate that chitosan from indigenous shrimp processing waste could be used as an effective antibacterial agent in the food industry. DOI: http://dx.doi.org/10.3329/jbcs.v24i2.9707 Journal of Bangladesh Chemical Society, Vol. 24(2), 185-190, 2011
Mahbub, KR, Nahar, A, Ahmed, MM & Chakraborty, A 2011, 'Quality Analysis of Dhaka WASA Drinking Water: Detection and', Journal of Environmental Science and Natural Resources, vol. 4, no. 2, pp. 41-49.View/Download from: Publisher's site
KR Mahbub added as the First author on 08/08/2012 and corrected PDF loaded on 08/08/2012.The aim of the study was to assess the microbiological quality of Dhaka WASA drinking water. A total of 45 samples were collected from different outlets of WASA water supply chain. Among the these samples 29 samples were collected from house tap, 5 samples from street pipe line tap and 11 samples from WASA source pump. The results of the Total Viable Count (TVC) showed that 62 % samples of house tap water, 60 % pipeline water and 45.45 % WASA pump water were exceeded the BDS standard (1240:2001) and WHO Guideline for drinking. The highest count was 2 × 106 cfu/ml in the house tap water of Gandaria. Total coliform and E. coli count ranged from <1.8 (MPN) /100 ml to >1600 (MPN)/100 ml. Among all the tested samples, 57.78 % water samples were positive for coliform and 51.11 % samples were positive for E. coli bacteria. Out of twenty three E. coli isolates, 8 isolates were subjected to biochemical and microscopic examination for confirmation. All 8 isolates were detected as E. coli based on biochemical parameters. The antibiotic sensitivity pattern of those isolates was determined. Most of them were found resistant to Ampicillin, Amoxicillin, kanamycin, Penicillin, Sulphomethoxazole antibiotics. Nearly all of them were found sensitive to Gentamycin and Nalidixic acid. The samples collected from different house tap water and road side tap water were more contaminated than WASA source pump water. It may therefore be concluded that distribution lines of Dhaka WASA supply chain might be the main source of microbiological contamination of drinking water. In this regard further investigations with more representatively drawn samples are required.DOI: http://dx.doi.org/10.3329/jesnr.v4i2.10133J. Environ. Sci. & Natural Resources, 4(2): 41-49, 2011
Viet, KN, King, WL, Siboni, N, Mahbub, KR, Dove, M, O'connor, W, Seymour, J & Labbate, M 2019, 'The Sydney rock oyster microbiome is influenced by local environmental parameters and QX disease resistance', FISH & SHELLFISH IMMUNOLOGY, ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, pp. 438-438.View/Download from: Publisher's site
Mahbub, KR, Krishnan, K, Naidu, R & Mallavarapu, M 2016, 'Divalent metal resistance of mercury resistant bacterial isolates and their potential for mercury bioremediation', Environmental contaminants from land to sea: continuities and interface in environmental toxicology and chemistry, SETAC Europe 26th Annual Meeting, SETAC, Nantes, France, pp. 316-316.
Mahbub, KR, Krishnan, K, Naidu, R & Mallavarapu, M 2015, 'Bioremediation of Mercury by bacterial isolates recovered from Contaminated soil', 6th International Contaminated Site Remediation Conference, CleanUp 2015, Melbourne, Australia, pp. 397-397.
Mahbub, KR, Hossain, Z, Ahmed, MM & Morshed, B 2012, '3RD ASM Conference on AMR in Zoonotic Bacteria and Foodborne Pathogens', 3rd ASM Conference on Antimicrobial Resistance in Zoonotic Bacteria and Foodborne Pathogens in Animals, Humans and the Environment, USA, pp. 141-141.