Characterization of Anthropogenic Influence and Levels of Antibiotic Resistance Gene, erm(F), in Soil at 26 Public Parks in Four Cities and Two Pristine Sites in California

The goal of this study was to characterize the soil constitution and the presence of antibiotic resistance gene (ARG) erm(F) in soils across California to investigate the relationship between the levels of anthropogenic influence and ARG erm(F) levels locally and regionally. Soil samples were collected from 26 parks in four cities, San Diego, Los Angeles, Bakersfield, Fresno, where six publicly accessible parks sites were selected in each, and two pristine sites, Yosemite National Park and Mount Baldy. DNA was extracted, normalized, and tested for the presence and quantity of genes 16S rRNA and erm(F) using quantitative polymerase chain reaction (qPCR). Erm(F) quantities were determined via two analysis approaches---on a per gram of soil basis, and relative to 16S gene abundance. Locally among 26 parks, the five quantifiably detected erm(F) sites all occurred in high-level anthropogenic influenced sites. Regionally among four cities, urban and agricultural cities shared the similar soil constitution respectively and urban cities had higher erm(F) gene levels than agricultural ones. Population and population density in each city is positively correlated with erm(F) gene levels whichever analysis approach was applied.