Cultivating the unseen majority: Soil microbial response to long-term anthropogenic changes
Soil microbial communities are incredibly diverse, and different mechanisms are responsible for the maintenance of microbial biodiversity. For example, microbial biodiversity can be maintained through resource availability, such as the availability of nutrients and carbon in the environment. We hypothesize that microbes from the same species, even with all their genetic similarities, will function and process nutrients differently depending on prior nutrient and disturbance regimes. Our goal was to culture soil microorganisms and characterize their metabolic profiles after long-term nutrient and disturbance regimes. For 12 years, a 2 × 2 factorial experiment at East Carolina University’s West Research Campus has been maintained to test the effects of nutrient addition, disturbance, and their interaction on a wetland ecosystem in a randomized block design on an array of eight 20 × 30 m blocks. We collected soil samples from a long-term ecological experiment. We cultured, isolated, and sequenced bacterial isolates from each of the treatment plots. We also characterized community level physiological profiles of these isolates from each fertilization/mowing treatment to test metabolic diversity of the cultured members of the soil microbial community.
Different bacterial groups were over-represented depending on fertilization/mowing treatments (e.g., Bacillus and Anthrobacter species in fertilized only plots). In addition, carbon turnover varied across the environmental gradient as well. The identity and relationship of the microbial isolates allowed us to examine the long-term impacts of fertilization and disturbance on soil microorganism. Together with data on plant communities and soil chemical conditions, we can build on the knowledge of cultured soil microbes and how resource availability influences microbial communities and functions related to carbon and nutrient cycling.