A boon to natural gas production, hydraulic fracturing or fracking introduces surface microbes thousands of feet below the Earth's surface. How do they survive? Could they be harnessed to increase energy output? Scientists brought these microbes into the laboratory. They found that the amino acid glycine betaine protects the microbes. It also serves as an energy source for a specific community of microorganisms that become adapted to life in fractured shale.
Sixty percent of U.S. natural gas comes from hydraulically fractured shales. These shales are located primarily in Ohio, West Virginia, and Pennsylvania. As engineers inject water and chemical additives into the ground, microbes hitch a ride. The microbes can affect the efficiency of gas and oil production, increase methane formation, corrode equipment, and "sour" the field. A greater understanding of the metabolism of these microbes will help scientists develop strategies to manage them and possibly increase gas production.
The team re-created a shale microbial community in the laboratory. This allowed them to measure microbial activity and fluid chemistry under temperature and pressure conditions similar to those underground. They confirmed their results by comparing the laboratory re-created communities with more than 40 real-world samples from five fracturing wells in the Appalachian Basin. The team was from The Ohio State University; the University of New Hampshire; West Virginia University; EMSL, the Environmental Molecular Sciences Laboratory; and the Joint Genome Institute (JGI). Fusing metagenomics sequencing data from JGI with proteomic and metabolomics data from EMSL gave researchers unique insights into the chemical transformations controlled by the microorganisms. Based on these data, the team used regression-based modeling to identify key indicators of microbial activity and predict conditions underground. By scaling results from the laboratory to the field, they discovered mechanisms behind critical biogeochemical reactions, including ways to increase gas production. Scientists could harness this knowledge to increase energy yields and improve management practices in hydraulically fractured shales. They could also apply such knowledge to protein-rich microbial ecosystems like soils to predict emission of potent gases.
Biological and Environmental Research Program Manager
Department of Energy, Office of Science
The Ohio State University
This work was funded by Faye Fellowship from the Ohio State University Environmental Science Graduate Program (M.A.B); National Sciences Foundation Dimensions of Biodiversity (K.C.W., P.J.M., D.R.C., S.S., and M.J.W.); and the Department of Energy's Office of Science, Office of Biological and Environmental Research, including support of the Environmental Molecular Sciences Laboratory and the Joint Genome Institute, both DOE Office of Science user facilities. Samples for this research were provided by the Marcellus Shale Energy and Environment Laboratory funded by Department of Energy's National Energy Technology Laboratory. Metagenomic sequencing for this research was performed by the Joint Genome Institute via a large-scale sequencing award (K.C.W.).
M.A. Borton, D.W. Hoyt, S. Roux, R.A. Daly, S.A. Welch, C.D. Nicora, S. Purvine, E.K. Eder, A.J. Hanson, J.M. Sheets, D.M. Morgan, R.A. Wolfe, S. Sharma, T.R. Carr, D.R. Cole, P.J. Mouser, M.S. Lipton, M.J. Wilkins, and K.C. Wrighton, "Coupled laboratory and field investigations resolve microbial interactions that underpin persistence in hydraulically fractured shales." Proceedings of the National Academy of Sciences USA 115, E6585 (2018). [DOI: 10.1073/pnas.1800155115]
Environmental Molecular Sciences Laboratory highlight: How injected microbes persist in hydraulically fractured shale
The Ohio State University news release: Methane-producing microbial communities
These results build upon previous work K.C. Wrighton published in Nature Microbiology (2016). This work is summarized in a Joint Genome Institute highlight: Microbial metabolism impacts sustainability of fracking efforts