Environmental DNA as a Tool For Assessing Microbial Diversity & Ecological Impacts by Contaminants at a Brownfield Site in Southern California
Abstract
Brownfield sites are properties with the presence of hazardous substances, toxicpollutants, or contaminants. Based on environmental regulations, these abandoned sitesare considered non-usable due to the presence of a high level of organic and inorganictoxic chemicals. Revitalization of Brownfield sites has ecological, economical and publichealth implications for the local communities. Our designated Brownfield site is locatedon the southern California Central groundwater basin and approximately 8 miles east ofthe Los Angeles River, and was previously used as a steel mill and more recently as a gasstation. In this study, our goal is to provide a baseline for the microbial community inassociation to the presence of heavy metals and toxic volatile chemical leaks resultingfrom previous activities. We employed the environmental DNA (eDNA) metabarcodingapproach on soil samples collected from the site at different depths and transects toprovide a profile of microbial communities directly associated with toxic hazardousmaterials. The bacterial soil composition analysis shows the overall bacterial compositionof the site is altered compared to control; with the class of Acidobacteria being moreabundant in the core and depth soil samples. This class of bacteria can tolerate highlyacidic and heavy metal-containing soils. The identification of bacterial mixture can be agateway to classifying microorganisms that consume or breakdown environmentalpollutants and could be used for future bioremediation purposes.