Adjacent terrestrial landscapes impact the biogeographical pattern of soil Escherichia coli in produce fields by modifying the importance of environmental selection and dispersal

High-quality habitats for wildlife (e.g., forest) provide essential ecosystem services while increasing species diversity and habitat connectivity. Unfortunately, presence of such habitats adjacent to produce fields may increase risk for contamination of fruits and vegetables by enteric bacteria, including Escherichia coli. E. coli survives in extra-host environments (e.g., soil) and could disperse across landscapes by wildlife. Understanding how terrestrial landscapes impact the distribution of soil E. coli is of importance in assessing the contamination risk of agricultural products. Here, using multi-locus sequence typing, we characterized 938 E. coli soil isolates collected from two watersheds with different landscape patterns in New York state, USA, and compared the distribution of E. coli and the influence of two ecological forces (environmental selection and dispersal) on the distribution between these two watersheds. Results showed that for the watershed with widespread produce fields, sparse forests, and limited interaction between the two land-use types, E. coli composition was significantly different between produce field sites and forest sites; this distribution was shaped by relatively strong environmental selection likely from soil phosphorus and slight dispersal limitation. For the watershed with more forested areas and stronger interaction between produce field sites and forest sites, E. coli composition between these two land-use types was relatively homogeneous; this distribution appeared to a consequence of wildlife-driven dispersal, inferred by competing models. Collectively, our results suggest that terrestrial landscape attributes could impact the biogeographic pattern of enteric bacteria by adjusting the importance of environmental selection and dispersal.