Developing Synthetic Microbial Communities to Improve Predictions of Their Behavior
Microbial communities populate every natural environment, playing critical roles in fundamental biological and environmental processes such as food webs and carbon cycling. Members of microbial communities interact with each other both as competitors and collaborators. Understanding the complex interactions within these communities is necessary to predict and eventually manipulate their behavior for biotechnology applications. Studying natural microbial consortia is extremely challenging, so simple microbial cocultures are often used to gain insights on microbial crossfeeding and communication. However, such studies rarely represent natural systems, and, therefore, more complex synthetic microbial communities are needed to model the development and evolution of microbial populations. Researchers at Harvard and Columbia universities report the development of a system of synthetic microbial communities composed of up to 14 Escherichia coli mutants, each one incapable of synthesizing a different amino acid. Using this system, the investigators could experimentally determine the behavior of the different members of the consortium, identifying mutants that act as keystone species or that promote positive or negative interactions. After several generations, these bacterial populations tend to become enriched in mutants that cannot produce metabolically costly amino acids (those that require more energy to synthesize). The authors hypothesize that such mutants persist in the population by crossfeeding from less abundant microbes that provide needed amino acids. This hypothesis was supported by the observation that the majority of the microorganisms whose genomes have been sequenced do not have the metabolic capacity to produce costly amino acids. These results will enable development of more accurate predictive models of microbial communities and their iterative improvement by experimentation, advancing toward a more comprehensive understanding of microbial communities such as those involved in carbon cycling.
Meea, M. T., J. J. Collins, G. M. Church, and H. H. Wang. 2014. “Syntrophic Exchange in Synthetic Microbial Communities,” Proceedings of the National Academy of Sciences (USA) 111(20), E2149-56. DOI:10.1073/pnas.1405641111.