Diversity, dynamics and defense in microbial communities

Cyanobacteria are an ancient group of microbes that can carry out photosynthesis and nitrogen fixation. They are important members of microbial communities in terrestrial and aquatic environments. They thrive in moderate and harsh environments where they can adapt to desiccation stress and extremes of heat or cold. For several years we have focused on extremophile communities that form stratified biofilms or microbial mats in the hot springs of Yellowstone National Park. In these communities, 16S rRNA diversity has been correlated with environmental gradients of temperature and light. The genomes of two Synechococcus isolates that dominate at different temperatures in the mats, has provided key insights into genomic and metabolic diversity within these populations. Metagenomic data in combination with deep amplicon sequencing from these communities, revealed an unexpectedly high degree of genomic micro-diversity. We have also attempted to explore the co-evolution of host and cyanophage populations in the microbial mats, by creating viromes and exploiting CRISPR spacer information. Finally, we are also interested in probing the importance of phototaxis and motility in these structured communities. I will describe our findings in the context of how these moderately complex communities are ideally suited to probing how physical forces and chemical gradients in combination with genetic diversity shape microbial community structure and organization. The future of modeling complex interactions and the ability to test hypotheses in synthetic communities will be explored.