Glen Gerald D'Souza

Last Name

D'Souza

First Name

Glen Gerald

ORCID

0000-0002-9123-101X

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Publications1 - 6 of 6

Antagonism as a foraging strategy in microbial communities
Stubbusch, Astrid K.M.; Peaudecerf, François J.; Lee, Kang Soo; et al. (2025)
Science
In natural habitats, nutrient availability limits bacterial growth. We discovered that bacteria can overcome this limitation by acquiring nutrients by lysing neighboring cells through contact-dependent antagonism. Using single-cell live imaging and isotopic markers, we found that during starvation, the type VI secretion system (T6SS) lysed neighboring cells and thus provided nutrients from lysing cells for growth. Genomic adaptations in antagonists, characterized by a reduced metabolic gene repertoire, and the previously unexplored distribution of the T6SS across bacterial taxa in natural environments suggest that bacterial antagonism may contribute to nutrient transfer within microbial communities in many ecosystems.
Verständnis der mikrobiellen Interaktionen beim Abbau von Polysacchariden
D'Souza, Glen Gerald (2024)
Biospektrum
Polysaccharides are the dominant stocks of bioavailable carbon on the planet. While much progress has been made in understanding the enzymatic mechanisms of polysaccharide breakdown by microbes, the role of cell-cell interactions in enabling microbes to breakdown complex polysaccharides is less understood. Leveraging microfl uidics coupled to automated microscopy allows an understanding the role of cell-cell interactions in polysaccharide degradation by microbes.
Polysaccharide breakdown products drive degradation-dispersal cycles of foraging bacteria through changes in metabolism and motility
Stubbusch, Astrid Katharina Maria; Keegstra, Johannes; Schwartzman, Julia; et al. (2024)
eLife
Most of Earth's biomass is composed of polysaccharides. During biomass decomposition, polysaccharides are degraded by heterotrophic bacteria as a nutrient and energy source and are thereby partly remineralized into CO2. As polysaccharides are heterogeneously distributed in nature, following the colonization and degradation of a polysaccharide hotspot the cells need to reach new polysaccharide hotspots. Even though many studies indicate that these degradation-dispersal cycles contribute to the carbon flow in marine systems, we know little about how cells alternate between polysaccharide degradation and motility, and which environmental factors trigger this behavioral switch. Here, we studied the growth of the marine bacterium Vibrio cyclitrophicus ZF270 on the abundant marine polysaccharide alginate, both in its soluble polymeric form as well as on its breakdown products. We used microfluidics coupled to time-lapse microscopy to analyze motility and growth of individual cells, and RNA sequencing to study associated changes in gene expression. We found that single cells grow at reduced rate on alginate until they form large groups that cooperatively break down the polymer. Exposing cell groups to digested alginate accelerates cell growth and changes the expression of genes involved in alginate degradation and catabolism, central metabolism, ribosomal biosynthesis, and transport. However, exposure to digested alginate also triggers cells to become motile and disperse from cell groups, proportionally increasing with the group size before the nutrient switch, and this is accompanied by high expression of genes involved in flagellar assembly, chemotaxis, and quorum sensing. The motile cells chemotax toward polymeric but not digested alginate, likely enabling them to find new polysaccharide hotspots. Overall, our findings reveal cellular mechanisms that might also underlie bacterial degradation-dispersal cycles, which influence the remineralization of biomass in marine environments.
MicrobioRaman: an open-access web repository for microbiological Raman spectroscopy data
Lee, Kang Soo; Landry, Zachary; Athar, Awais; et al. (2024)
Nature Microbiology
Cell aggregation is associated with enzyme secretion strategies in marine polysaccharide-degrading bacteria
D'Souza, Glen Gerald; Ebrahimi, Ali; Stubbusch, Astrid Katharina Maria; et al. (2023)
The ISME Journal
Polysaccharide breakdown by bacteria requires the activity of enzymes that degrade polymers either intra- or extra-cellularly. The latter mechanism generates a localized pool of breakdown products that are accessible to the enzyme producers themselves as well as to other organisms. Marine bacterial taxa often show marked differences in the production and secretion of degradative enzymes that break down polysaccharides. These differences can have profound effects on the pool of diffusible breakdown products and hence on the ecological dynamics. However, the consequences of differences in enzymatic secretions on cellular growth dynamics and interactions are unclear. Here we study growth dynamics of single cells within populations of marine Vibrionaceae strains that grow on the abundant marine polymer alginate, using microfluidics coupled to quantitative single-cell analysis and mathematical modelling. We find that strains that have low extracellular secretions of alginate lyases aggregate more strongly than strains that secrete high levels of enzymes. One plausible reason for this observation is that low secretors require a higher cellular density to achieve maximal growth rates in comparison with high secretors. Our findings indicate that increased aggregation increases intercellular synergy amongst cells of low-secreting strains. By mathematically modelling the impact of the level of degradative enzyme secretion on the rate of diffusive oligomer loss, we find that enzymatic secretion capability modulates the propensity of cells within clonal populations to cooperate or compete with each other. Our experiments and models demonstrate that enzymatic secretion capabilities can be linked with the propensity of cell aggregation in marine bacteria that extracellularly catabolize polysaccharides.
Ecology and evolution of metabolic cross-feeding interactions in bacteria
D'Souza, Glen Gerald; Shitut, Shraddha; Preussger, Daniel; et al. (2018)
Natural Product Reports

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Glen Gerald D'Souza

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