Discovery could unlock potential of sustainable bioenergy
Methanogens are tiny microbes, invisible to the human eye and ubiquitous in environments without oxygen around the world.
Despite their microscopic size, these single-cell organisms play a major role in the global carbon cycle. A Husker research team uncovered another dimension of how they function, painting a clearer picture of environmental carbon flow and providing key information for the sustainable development of bioenergy sources.
Nebraska geobiologists Karrie Weber and Nicole Fiore led a team in publishing one of the first studies demonstrating that methanogens propel their growth by consuming calcium carbonate, one of Earth’s most abundant minerals. They also eat hydrogen, a diet that produces methane – both a biofuel and a greenhouse gas.
The study, which culminated more than a decade of work at the university, suggests that methanogens’ metabolism may have a bigger impact on the Earth’s biogeochemistry than previously known. This is because methanogens and calcium carbonate exist side by side in many locations worldwide.
“This is local research with global significance,” said Weber, professor of biological sciences and Earth and atmospheric sciences.
The results challenge the prevailing belief that carbonate minerals – which contain roughly 80% of the Earth’s carbon – are stable at elevated pH levels. This potential instability may warrant reassessment of carbon sequestration strategies where subsurface carbonates and microbial life coexist.
This is local research with global significance.
Karrie Webber
The work may also impact the bioenergy arena. Researchers interested in using natural hydrogen as clean fuel should assess whether microbial processes affect subsurface hydrogen reservoirs. Another avenue to explore is harnessing the methane produced by methanogens as an alternative natural gas.
Nebraska’s research facilities and equipment enabled the work. The team started with a mud sample from an alkaline saline wetland soil in Lincoln, then created special culture conditions designed to weed out microorganisms not capable of using carbonate as fuel. They used Nebraska’s CARS (coherent anti-Stokes Raman scattering) microscope, part of the Laser Assisted Nano Engineering Lab, and the Holland Computing Center to visualize and identify the surviving microorganisms. The study, published in Communications Earth and Environment, received support from the National Science Foundation, a NASA Nebraska Space Grant, the Nebraska Center for Energy Sciences Research and the NSF-funded Center for Root and Rhizobiome Innovation.
Nicole Fiore (front) and Karrie Weber