Deep Subterranean Microbe Thrives On Iron And Oil

April Flowers for – Your Universe Online
Able to withstand high heat, high salinity, low oxygen, utter darkness and pressures that would kill most other organisms, the bacteria Halomonas is a very hardy breed. Traits such as these enable these microbes to eke out a living in deep sandstone and have proven to be useful for hydrocarbon extraction and carbon sequestration.
The new study, published in Environmental Microbiology, gives the first unobstructed view of the microbial life of sandstone formations more than a mile below the surface.
“We are using new DNA technologies to understand the distribution of life in extreme natural environments,” said Bruce Fouke, a professor of geology and of microbiology at the University of Illinois at Urbana-Champaign.
Fouke, who is also is an investigator with the Energy Biosciences Institute and an affiliate of the Institute for Genomic Biology at Illinois, said that underground microbes are at least as diverse as their surface-dwelling counterparts. That diversity has gone largely unstudied, he says.
“Astonishingly little is known of this vast subsurface reservoir of biodiversity, despite our civilization’s regular access to and exploitation of subterranean environments,” he said.
Fouke’s team collected microbial samples from a sandstone reservoir 1.1 miles below the surface to address the gap in our knowledge. Using a probe that reduces or eliminates contamination from mud and microbes at intermediate depths, the team sampled sandstone deposits from the Illinois Basin, a vast, subterranean bowl underlying much of Illinois and parts of Indiana, Kentucky and Tennessee, and a rich source of coal and oil.
Analysis and genomic study of the microbes recovered by the team revealed “a low-diversity microbial community dominated by Halomonas sulfidaeris-like bacteria that have evolved several strategies to cope with and survive the high-pressure, high-temperature and nutrient deprived deep subsurface environment,” Fouke said.
The team found that the bacteria are able to utilize iron and nitrogen from their surroundings and recycle scarce nutrients to meet their metabolic needs. The superstructure of the sunken Titanic is being consumed by another member of the same group, named the Halomonas titanicae.
The researchers also found that the microbes living in the deep sandstone deposits of the Illinois Basin were capable of metabolizing aromatic compounds, a common component of petroleum.
“This means that these indigenous microbes would have the adaptive edge if hydrocarbon migration eventually does occur,” Fouke said.
Fouke said that a better understanding of the microbial life of the subterranean world will “enhance our ability to explore for and recover oil and gas, and to make more environmentally sound choices for subsurface gas storage.”