Bacterial Interspecies Interactions and Microbial Community Assembly
Name
ortiz-tonyfol-phd-microbiology-2021-thesis.pdf
Description
Thesis PDF
Size
5.65 MB
Format
Adobe PDF
Checksum (MD5)
4bb455798ffbc54fe131a46bffe03baf
Author(s)
Ortiz Lopez, Anthony F.
Advisor(s)
Gore, Jeff
Date Issued
September 2021
Publisher
Massachusetts Institute of Technology
Abstract
Microbial communities play central roles in the development and maintenance of human health and in the functioning of the Earth’s ecosystems. The microbial biodiversity of many environments has been thoroughly studied in recent years, yet the dominant processes shaping microbiota assembly remain unresolved. In this thesis, I leverage a bottom-up approach to experimentally build synthetic microbial communities and to test the prevalence of different ecological and evolutionary forces. High-throughput experiments in nanoliter droplets show a wide occurrence of bacterial interactions in the form of one species or consortium affecting the abundance and yield of another species. Positive and negative interactions appear unavoidable in bacterial co-cultures when growth is permitted, with growing bacteria typically facilitating non-growing bacteria. In this thesis, I also show that bacterial interspecies interactions in the C. elegans intestine are mostly competitive and hierarchical. Interestingly, simple two-species microbiotas can predict the composition of three-species and eight-species microbiotas in this nematode. Finally, we found that the importance of interspecies interactions is robust to bacterial strains with and without previous exposure to the C. elegans gut, and to worm mutants with different immune activities. These results show that constructing and characterizing synthetic microbial communities can elucidate fundamental principles for the control of microbial communities.
MIT Department
Massachusetts Institute of Technology. Microbiology Graduate Program
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