CHARACTERIZING THE RESILIENCE AND ADAPTATION OF BIOFILM COMMUNITIES TO CLIMATE CHANGE IN GLACIER-FED STREAMS

Biofilms conform the dominant microbial lifestyle in alpine streams where they are major contributors to carbon and nutrient cycling. However, relatively little is known about their adaptive capacity to climate change as water temperature rises and hydrological conditions change. We set up a field experiment to evaluate how these changing conditions influence biofilm microbial community composition in glacier-fed streams. Biofilm bacteria were exposed to +2C and varying hydrological flows for four months in experimental flumes, and samples were collected weekly throughout the course of the experiment for16S and 18S rRNA sequencing. We additionally isolated ~400 bacteria from these biofilms and performed phenotypic and genetic characterization of over 100 of these to elucidate which traits might enable their resilience to changing environmental conditions. We found that bacterial communities shifted over the duration of the field experiment, and both higher temperature and changes in flow regime had a significant effect on community composition. Isolates characterized thus far belonged to 41 different genera including some relatively abundant in our communities such as Sphingomonas, Rhodoferax, Polaromonas and Flavobacterium. Most isolates exhibited psychrophilic growth traits and showed at least some level of desiccation tolerance. Results from this initial study will guide efforts to assemble synthetic communities that will increase our understanding of how phenotypic and genetic traits relate to community resilience in the face of environmental change.