Microbial communities thrive in fracking wells

Some hardy microorganisms can survive the harsh underground conditions created by the oil and natural gas extraction method known as hydraulic fracturing. New revelations about the microbes come from a team led by microbiologist Kelly C. Wrighton of Ohio State University, which has used metagenomics and metabolite analyses to characterize microbial communities deep inside the Marcellus and Utica shale formations of the northeastern U.S. (Nat. Microbiol. 2016, DOI: 10.1038/nmicrobiol.2016.146). The researchers collected samples from a week to months after initial fracking when oil and gas were flowing from the wells. From metagenomics data, they reconstructed 31 microbial genomes, finding one organism that seems to be unique to shale formations, which they have named Candidatus Frackibacter. Overall, the microbes have interdependent metabolisms. For example, some microbes make glycine betaine, a compound that protects cells against osmotic stress that results from the high salt content of the shale. Other organisms take up that glycine betaine and metabolize it to form trimethylamine, which can be used by still other organisms to produce methane. The researchers also identified microbes that are likely culprits in producing sulfides that can lead to equipment corrosion and oil and gas reservoir souring. They further observed that the microbes persisted and even thrived despite added biocides and the high temperatures of fracking wells.