Nutrient Enrichment Effects on Wetland Soil Bacterial Traits

Abstract

Soil microbiomes participate in nutrient transformations that result in bioavailable nutrients for maintaining global biodiversity. However, land use change and industrialization modify environmental conditions that influence bacterial interactions, ultimately altering microbial diversity and plant-microbe relationships. For example, nutrient enrichment from atmospheric deposition onto low-nutrient but high-biodiversity ecosystems is increasing. We hypothesize that this nutrient enrichment will modify species interactions between bacterial species and between bacteria and plants from cooperative to competitive ways. We tested this hypothesis using soil bacteria isolated from a long-term wetland fertilization experiment (Greenville, North Carolina, USA). This ecological experiment (est. 2003) examines how nutrient additions (N-P-K fertilizer) and disturbance (by mowing) affect wetland plants and microbial community structure and function. We measured growth rates and compared antibiotic resistance trends for bacteria in the genera Bacillus isolated from fertilized/mowed and unfertilized/mowed plots. Results have revealed that nutrient enrichment tends to increase soil bacterial growth rates. The results from this work will help us understand how human activities that involve indirect nutrient enrichment influence wetland soil microbiomes and plant-microbe associations.