Monday, August 12, 2013
Pavilion (Sheraton San Diego)
Microbes typically live in complex, multi-species communities. New DNA sequencing technologies have allowed for the characterization of communities of microbes present in diverse environments, including in and on the human body, and have demonstrated that these communities greatly impact our health. Defining the principles that govern microbial community development and persistence will help us manipulate these communities to improve our health and perform other tasks like environmental cleanup and fuel production. However, detailed, mechanistic analyses of microbial behavior in multi-species communities require an experimentally tractable model system that is culturable, simple, and reproducible. Work done in our lab demonstrates that the microbial communities of cheese rinds exhibit these characteristics. Here, we use the cheese rind model system to track succession in a microbial community and define microbial relationships that affect succession. By 16S rDNA sequencing of time course samples taken from a natural rind cheese, we determined that a natural rind community is initially dominated by Staphylococcus sp. As the cheese ages, Staphylococcus sp. are succeeded by Brevibacterium sp., which come to dominate the rind community. We reproduced this major pattern on a cheese-like medium using a simplified, in vitro community consisting of Staphylococcus succinus and Brevibacterium linens. We determined that S. succinus stimulates growth of B. linens, and eventually, co-culture with B. linens results in death of S. succinus. We have also found that the two species specifically respond to each other’s proximity with the production of small molecules. Work defining the mechanisms and genetic pathways involved is ongoing.