Devan Nisson began her project as a way to develop both her advanced laboratory skills and computational experience in the field of microbial ecology while conducting research independently. Beyond the research presented here, she plans to expand her project to investigate various other means of microbial metabolic response to drought. Devan particularly enjoyed the opportunity to design the experimental setup for her project, and feels that the critical thinking skills and exposure to new experimental techniques she gained from this experience are invaluable to her growth as a biological researcher. After graduation, Devan intends to continue her studies, preparing for a career as a biological researcher.

Soil microbial communities metabolize organic matter in dead plant material by enzymatically degrading macromolecule components. The total respiration of carbon dioxide represents an integrated metric of this degradation process. This study compares the metabolic performance of microbial communities from ecosystems arrayed along a climate gradient, including desert, scrubland, grassland, pine-oak forest, and subalpine forest. Specifically, we test whether or not desert microbes display adaptations for increased metabolism relative to the other communities upon rewetting after extended periods of drought and high temperature exposure. To simulate desert conditions, we exposed microbial communities from along the gradient to moisture pulses after three, six, or nine weeks of incubation at 31 ºC on grassland leaf litter. Carbon dioxide readings were recorded every two days. We found that each type of community, regardless of its original biome, displayed both susceptibility and resilience to drought-like conditions, each exhibiting a gradual recovery to pre-treatment respiration rates. This shows that litter-inhabiting microbial communities are capable of functioning under environmental conditions vastly different from those of their original ecosystems. These results suggest that diverse microbial communities may be able to withstand drought conditions caused by climate change events.

Steven D. Allison School of Biological Sciences

The climate is getting hotter, and in places like Southern California, it’s also getting drier. Devan’s study tests how microbes like bacteria and fungi will cope. Microbes promote soil fertility and recycle nutrients, helping to maintain plant growth in natural and agriculture systems alike. After subjecting Southern California microbes to hot, dry conditions in the laboratory, Devan found that microbial communities handled stressful conditions surprisingly well, even if they came from cool, wet mountaintop environments. It is possible that the naturally variable climate in Southern California—where it can get hot even in the mountains—may prime microbes to deal with climate change. This insight would not have been possible without Devan’s creative experimental design as an undergraduate researcher.