The School of Biological Sciences Spring 2023 Seminar Series presents Dr. Glen D’Souza

Live via Zoom

How intercellular interactions emerge at the microscale and determine the functionality of microbial communities

Microbial cells operate as part of collectives, engage in interactions and their activity at the microscale influences biogeochemical processes at the global scale ultimately affecting health of plants, humans or animals. Despite the ubiquity of collective behaviors and interactions within microbial assemblages, the emergence and the role of the underlying regulatory mechanisms is poorly understood. My work bridges these knowledge gaps by combining quantitative investigations of microbial growth and behaviour at the level of single cells with comparisons of gene expression. In this talk, I will present three emerging principles on the development of collective behaviours and interactions in microbial communities. I will show that bacterial cells form collectives in order to degrade complex polysaccharides but disperse when simpler oligosaccharides become available in the environment. I will show how the strength of collective behaviors is dependent on the ability of cells to secrete extracellular enzymes that degrade polysaccharides. I will show that bacterial cells that lack polysaccharide degrading enzymes use antagonism systems to lyse neighboring cells and acquire nutrients for growth. Taken together, the findings from my work elucidate how ecological functionality is governed by collective dynamics emerging from intercellular interactions in natural microbial communities. Finally, I will discuss future research that will measure ecological dynamics between species at the microscale, integrate findings across distinct levels of biological organization and map the evolution of functional capabilities in microbial communities. The ultimate goal of my work will be to decipher general principles that explain the role of intercellular interactions in driving the evolution of metabolic, genomic and ecosystem functionalities of microbial communities

Host: Dr. Joel Kostka