I am a microbial ecologist, my research interests include: marine microbial ecology, microbial interactions, microbe-host interactions, microbial oceanography, and pelagic interactions. My most recent work has been on elucidating the complex interactions occurring between a marine microalga (Emiliania huxleyi) and its bacterial symbiont (Phaeobacter inhibens).
I recently graduated with a Ph.D. in Ecology from the University of Alberta, Canada. My M.Sc. and previous research focused on investigating the microbial consortia of the sub-glacial lakes of the SW Yukon Territory and the perennially ice-covered lakes of Antarctic Dry Valleys.
Ph.D. Ecology 2012-2018
University of Alberta, Canada
Supervisor: Dr. Rebecca Case
M.Sc. Microbiology and Biotechnology 2009-2012
University of Alberta, Canada
Supervisor: Dr. Brian Lanoil
B.A. Honors in biology and minor in chemistry 2003-2007
Carroll College, Montana U.S.A.
Honors Thesis Supervisor: Dr. Samuel Alvey
Can supervise: YES
Bramucci, AR & Case, RJ 2019, 'Phaeobacter inhibens induces apoptosis-like programmed cell death in calcifying Emiliania huxleyi.', Scientific reports, vol. 9, no. 1.View/Download from: Publisher's site
The model coccolithophore, Emiliania huxleyi, forms expansive blooms dominated by the calcifying cell type, which produce calcite scales called coccoliths. Blooms last several weeks, after which the calcified algal cells rapidly die, descending into the deep ocean. E. huxleyi bloom collapse is attributed to E. huxleyi viruses (EhVs) that infect and kill calcifying cells, while other E. huxleyi pathogens, such as bacteria belonging to the roseobacter clade, are overlooked. EhVs kill calcifying E. huxleyi by inducing production of bioactive viral-glycosphingolipids (vGSLs), which trigger algal programmed cell death (PCD). The roseobacter Phaeobacter inhibens was recently shown to interact with and kill the calcifying cell type of E. huxleyi, but the mechanism of algal death remains unelucidated. Here we demonstrate that P. inhibens kills calcifying E. huxleyi by inducing a highly specific type of PCD called apoptosis-like-PCD (AL-PCD). Host death can successfully be abolished in the presence of a pan-caspase inhibitor, which prevents the activation of caspase-like molecules. This finding differentiates P. inhibens and EhV pathogenesis of E. huxleyi, by demonstrating that bacterial-induced AL-PCD requires active caspase-like molecules, while the viral pathogen does not. This is the first demonstration of a bacterium inducing AL-PCD in an algal host as a killing mechanism.
Bramucci, AR, Labeeuw, L, Orata, FD, Ryan, EM, Malmstrom, RR & Case, RJ 2018, 'The bacterial symbiont Phaeobacter inhibens Shapes the life history of its algal host emiliania huxleyi', Frontiers in Marine Science, vol. 5.View/Download from: Publisher's site
© 2018 Bramucci, Labeeuw, Orata, Ryan, Malmstrom and Case. Marine microbes form host-associated biofilm communities that are shaped by complex interactions between bacteria and their host. The roseobacter Phaeobacter inhibens exploits both symbiotic and pathogenic niches while interacting with its microalgal host Emiliania huxleyi. During co-cultivation over extended periods with E. huxleyi, we show that P. inhibens selectively kills two host cell types, the diploid calcifying strain and the haploid flagellated strain. Meanwhile, various non-calcifying diploid strains are resistant to this pathogen or the pathogen is avirulent to this cell type. This differential pathogenesis has the potential of dramatically altering the composition of E. huxleyi blooms, which are typically dominated by the roseobacter-susceptible calcifying strain. This cell type makes calcite plates, which are an important sink in the marine carbon cycle and forms part of the marine paleobotanic record. P. inhibens kills the haploid cells, which have been proposed as critical to the survival of the algae, as they readily escape both eukaryotic predation and viral infection. Consequently, bacteria such as P. inhibens could influence E. huxleyi's life history by selective pathogenesis, thereby altering the composition of cell types within E. huxleyi populations and its bloom-bust lifestyle.
Labeeuw, L, Khey, J, Bramucci, AR, Atwal, H, de la Mata, AP, Harynuk, J & Case, RJ 2016, 'Indole-3-Acetic Acid Is Produced by Emiliania huxleyi Coccolith-Bearing Cells and Triggers a Physiological Response in Bald Cells', FRONTIERS IN MICROBIOLOGY, vol. 7.View/Download from: Publisher's site
Mayers, TJ, Bramucci, AR, Yakimovich, KM & Case, RJ 2016, 'A Bacterial Pathogen Displaying Temperature-Enhanced Virulence of the Microalga Emiliania huxleyi', FRONTIERS IN MICROBIOLOGY, vol. 7.View/Download from: Publisher's site
Orata, FD, Rosana, ARR, Xu, Y, Simkus, DN, Bramucci, AR, Boucher, Y & Case, RJ 2016, 'Draft genome sequences of four bacterial strains isolated from a polymicrobial culture of naked (N-Type) Emiliania huxleyi CCMP1516', Genome Announcements, vol. 4, no. 4.View/Download from: Publisher's site
© 2016 Orata et al. Strains of Sulfitobacter spp., Erythrobacter sp., and Marinobacter sp. were isolated from a polymicrobial culture of the naked (N-type) haptophyte Emiliania huxleyi strain CCMP1516. The genomes encode genes for the production of phytohormones, vitamins, and the consumption of their hosts' metabolic by-products, suggesting symbiotic interactions within this polymicrobial culture.
Rosana, ARR, Orata, FD, Xu, Y, Simkus, DN, Bramucci, AR, Boucher, Y & Case, RJ 2016, 'Draft genome sequences of seven bacterial strains isolated from a polymicrobial culture of coccolith-bearing (C-Type) Emiliania huxleyi M217', Genome Announcements, vol. 4, no. 4.View/Download from: Publisher's site
© 2016 Rosana et al. Strains of Rhodobacteraceae, Sphingomonadales, Alteromonadales, and Bacteroidetes were isolated from a polymicrobial culture of the coccolith-forming (C-type) haptophyte Emiliania huxleyi strain M217. The genomes encode genes for the production of algal growth factors and the consumption of their hosts' metabolic by-products, suggesting that the polymicrobial culture harbors many symbiotic interactions.
Bramucci, AR, Labeeuw, L, Mayers, TJ, Saby, JA & Case, RJ 2015, 'A Small Volume Bioassay to Assess Bacterial/Phytoplankton Co-culture Using WATER-Pulse-Amplitude-Modulated (WATER-PAM) Fluorometry', JOVE-JOURNAL OF VISUALIZED EXPERIMENTS, no. 97.View/Download from: Publisher's site
Bramucci, A, Han, S, Beckers, J, Haas, C & Lanoil, B 2013, 'Composition, diversity, and stability of microbial assemblages in seasonal lake ice, Miquelon Lake, Central Alberta', Biology, vol. 2, no. 2, pp. 514-532.View/Download from: Publisher's site
The most familiar icy environments, seasonal lake and stream ice, have received little microbiological study. Bacteria and Eukarya dominated the microbial assemblage within the seasonal ice of Miquelon Lake, a shallow saline lake in Alberta, Canada. The bacterial assemblages were moderately diverse and did not vary with either ice depth or time. The closest relatives of the bacterial sequences from the ice included Actinobacteria, Bacteroidetes, Proteobacteria, Verrucomicrobia, and Cyanobacteria. The eukaryotic assemblages were less conserved and had very low diversity. Green algae relatives dominated the eukaryotic gene sequences; however, a copepod and cercozoan were also identified, possibly indicating the presence of complete microbial loop. The persistence of a chlorophyll a peak at 25-30 cm below the ice surface, despite ice migration and brine flushing, indicated possible biological activity within the ice. This is the first study of the composition, diversity, and stability of seasonal lake ice. © 2013 by the authors; licensee MDPI, Basel, Switzerland.
Labeeuw, L, Bramucci, AR & Case, RJ 2017, 'Bioactive small molecules mediate microalgal-bacterial interactions' in Systems Biology of Marine Ecosystems, Springer, Germany, pp. 279-300.View/Download from: Publisher's site
© Springer International Publishing AG 2017. Microalgae are a diverse group of photosynthetic microorganisms found throughout the eukaryote tree. Although unicellular, they have complex relationships with the bacteria that surround them. These interactions can range from obligate symbiosis, where the bacterium is required for host survival, to pathogenic, where the bacterial pathogen can kill the host alga. The nature of these algal-bacterial interactions appear to be tightly regulated by both algal and bacterial bioactive molecules, creating a complex system of chemical interactions through which these different species can chemically communicate with each other and directly alter the other physiology. In this way the bacterium is able to exploit (and manipulate) its host to become a more conducive habitat (e.g. algal phycosphere, aquatic biofilms, etc.) for bacterial survival. However, the identity of many of these small molecules and the mechanisms by which they control these exchanges are often overlooked or misunderstood. The ability to eavesdrop on the chemical cross talk occurring between algae and bacteria may open up a vast potential for new knowledge, relating to understanding bacterial-algal relationships, evolution and possibly hijacking this communication to better control microbes in commercial systems. This chapter outlines some of the known bioactive chemicals that mediate these microalgal-bacterial interactions, highlighting what is currently known about these systems and areas that need further investigation.