Anthropogenic nutrient enrichment alters the culturable soil microbiome in a wetland ecosystem

Link To Share This Poster: https://cdmcd.co/dEy4zR
Live Discussion Link: https://cdmcd.co/QM8kAn

Aied Garcia, Regina Bledsoe and Ariane L. Peralta, Department of Biology, East Carolina University, Greenville, NC, Regina Bledsoe, Department of Plant Science, Pennsylvania State University

Background/Question/Methods
Human activities during this century have created non-point pollution sources of nitrogen and phosphorus that can disrupt natural ecosystems. As such, nutrient addition could change the functional roles of soil microbes. For example, plants recruit rhizosphere microbes from the soil microbiome. These microbes can promote nutrient uptake and disease suppression. In this study, we ask how does chronic nutrient enrichment of a historically low nutrient wetland alter the culturable soil microbiome? Identifying dominant taxa in unfertilized and fertilized soils and studying the phylogenetic history and biochemical traits of these taxa could provide insight into how chronic fertilization has modified bacterial function. We hypothesize that long-term nutrient enrichment modifies bacterial growth and metabolic traits. In order to test this hypothesis, we collected bulk soil samples from a coastal plain wetland located at East Carolina University’s West Research Campus. This ecological experiment was established in 2003 to examine the effects of nutrient additions (N-K-P fertilizers) and disturbance (by mowing) on plant and microbial communities. For this study, we cultured soil bacterial isolates (from different nutrient enrichment histories) on minimal media and identified bacterial taxa using 16S rRNA Sanger sequencing and we conducted various biochemical tests (e.g., carbohydrate and protein catabolism) as well.
Results/Conclusions
Results revealed differences in biochemical tests related to nutrient and carbon metabolism for a subset of bacterial isolates from mowed/fertilized soils compared to mowed/unfertilized soils. Differences in nutrient and carbon metabolism could alter nutrient exchange between plants and root-associated microbes. In addition, some bacterial isolates from fertilized bulk soils formed smaller colonies compared to related taxa cultured from unfertilized soils. This colony size trait could suggest faster growth rates and result in competitive interaction among microbes. This ongoing work indicates that the addition of nutrients at this wetland site is modifying soil microbial traits of the cultured representatives, and the modifications to these traits could affect the productivity of plants. The faster growth rates of microbes and increased bacterial diversity due to nutrient enrichment could be indicative of a competitive environment that could negatively impact plant productivity.