Scientists have discovered an entirely new genus of bacteria living in hydraulic fracking wells, part of a thriving ecosystem of microorganisms that contains at least 31 different species.
Writing in the journal Nature Microbiology, researchers from Ohio State University describe finding nearly identical microbial communities in two fracking wells, despite the fact that the wells were located hundreds of miles from each other, and drilled by different energy companies using different techniques, into different types of shale that formed millions of years apart.
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At least part of the reason for that, they suspect, is that many of them were likely introduced via water from the ponds that were used to provide water to the wells, a suspicion reinforced by the fact that many of the microbes had been previously identified.
"We thought we might get some of the same types of bacteria, but the level of similarity was so high it was striking. That suggests that whatever's happening in these ecosystems is more influenced by the fracturing than the inherent differences in the shale," said Kelly Wrighton, assistant professor of microbiology and biophysics at Ohio State and one of the paper's authors, in a press release.
Among the discoveries were that one genus of bacterium, Halanaerobium (photographed above), dominated the communities in both wells; and the wells contain at least one species, which the scientists believe is a member of a previously-unclassified genus, that had not been seen before. They have initially dubbed this new microbe Candidatus frackibacter.
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Understanding the microbial ecosystems in fracking wells begins with understanding the fracking process itself, which involves pumping fluid at high pressure into shale to break up the rock and release oil or gas. Different companies generally use proprietary recipes for this fluid, but they all begin with water and add other chemicals. Once the fluid is inside a well, salt within the shale leaches into it, making it briny.
This salinity forces microorganisms to synthesize organic compounds called osmoprotectants to keep themselves from bursting. When the cells die, the osmoprotectants are released into the water, where other microbes can use them for protection themselves or eat them as food. In that way, salinity forced the microbes to generate a sustainable food source.
"We think that the microbes in each well may form a self-sustaining ecosystem where they provide their own food sources," Wrighton explained. "Drilling the well and pumping in fracturing fluid creates the ecosystem, but the microbes adapt to their new environment in a way to sustain the system over long periods."
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By examining the genomes of the different microbes, the researchers found that the osmoprotectants were being eaten by Halanaerobium and Candidatus Frackibacter. In turn, these bacteria provided food for other microbes called methanogens, which ultimately produced methane.
The scientists suspect that Frackibacter may have been living in the shale since long before fracking began, but research is ongoing.
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