Shifts in microbial community structure and function in surface waters impacted by unconventional oil and gas wastewater revealed by metagenomics

• Published in: The Science of the total environment 2017-02, Vol.580, p.1205-1213
• Main Authors: Fahrenfeld, N.L., Delos Reyes, Hannah, Eramo, Alessia, Akob, Denise M., Mumford, Adam C., Cozzarelli, Isabelle M.
• Format: Article
• Language: English
• Subjects: Antibiotic resistance genes; Bacteria - classification; Biocides; Dormancy and sporulation; Genes, Bacterial; Hydraulic fracturing; Metagenomics; Oil and Gas Industry; RNA, Ribosomal, 16S; Sediment; Waste Water
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2016.12.079

Unconventional oil and gas (UOG) production produces large quantities of wastewater with complex geochemistry and largely uncharacterized impacts on surface waters. In this study, we assessed shifts in microbial community structure and function in sediments and waters upstream and downstream from a UOG wastewater disposal facility. To do this, quantitative PCR for 16S rRNA and antibiotic resistance genes along with metagenomic sequencing were performed. Elevated conductivity and markers of UOG wastewater characterized sites sampled downstream from the disposal facility compared to background sites. Shifts in overall high level functions and microbial community structure were observed between background sites and downstream sediments. Increases in Deltaproteobacteria and Methanomicrobia and decreases in Thaumarchaeota were observed at downstream sites. Genes related to dormancy and sporulation and methanogenic respiration were 18–86 times higher at downstream, impacted sites. The potential for these sediments to serve as reservoirs of antimicrobial resistance was investigated given frequent reports of the use of biocides to control the growth of nuisance bacteria in UOG operations. A shift in resistance profiles downstream of the UOG facility was observed including increases in acrB and mexB genes encoding for multidrug efflux pumps, but not overall abundance of resistance genes. The observed shifts in microbial community structure and potential function indicate changes in respiration, nutrient cycling, and markers of stress in a stream impacted by UOG waste disposal operations. [Display omitted] •Microbial communities change downstream from a wastewater disposal facility.•Deltaproteobacteria and Methanomicrobia are in higher abundance in affected sediments.•Increases in genes for dormancy and sporulation were found downstream from the facility.•Select efflux pump genes increase downstream but not total antibiotic resistance genes.