Glen D’Souza

Postdoc | ETH Zurich | glen.dsouza@eawag.ch

Bio

My core research interests are focused on understanding the role of interactions in driving organismal evolution in nature. Associations between multiple genotypes, both antagonistic and synergistic, are ubiquitous in nature. However, the evolutionary trajectories that led to the emergence of these associations are often unclear. This is because extant species are often snapshots of long term coevolutionary processes. A classical example of close knit associations is the metabolic exchanges between bacterial species within microbial communities. These complex interactions drive important ecosystem processes, and influence the health and disease of humans, animals and plants in the context of host-microbe interactions. Often, such interactions result in different bacterial genotypes being completely dependent on each other to fulfill their metabolic needs. Thus a key goal of my research is to elucidate general principles that govern the emergence of metabolic interdependencies between bacterial cells and populations in nature. To this end, I use combination of techniques involving classical bacterial genetics, experimental evolution, and single cell approaches using microfluidics and high throughput microscopy.

Selected Publications:

1. D’Souza G, Povolo V, Keegstra J, Stocker R and Ackermann M. Nutrient complexity triggers transitions between solitary and colonial growth in bacterial populations. (The ISME Journal, accepted for publication)

Significance: Bacteria form multicellular collectives or exist as solitary individuals in nature. However, the ecological roles of such behaviors are not clearly understood. We show that cells of the aquatic bacterium Caulobacter crescentus display distinct behavioral modes depending on nutrient complexity. Cells form aggregates when grown on the plant polysaccharide xylan, whereas they exhibit solitary behaviors on the constituent monomer xylose. Aggregative behaviors are beneficial on polysaccharides because a cell can benefit from the degradative activities of other neighboring cells. When simpler substrates become available, cells can rapidly transition from aggregative to solitary behaviors. These results indicate that cells can alter their phenotypes to suit the nutrient composition and provide insight into the functional roles of such behaviors in nature.

Research Interests

Ecology, Microfluidics, Microscopy, Experimental Evolution

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Glen D’Souza