Munching Microbe Rules Methane Production

Landfills produce methane—which can be valuable as an energy source. But scientists haven’t known why landfills make so much methane. The solid waste in landfills is typically at a pH that’s considered too acidic to host methanogens, methane-producing microbes.

So scientists did some digging, literally, to investigate. They found a particularly hearty methanogen called named Methanosarcina barkeri, or just M. barkeri, that can survive at low pH levels.

M. barkeri eats the acids and produces some methane. At the same time, it raises the pH level in the area around it. The less-acidic environment that results becomes a better host for other methanogens. As liquid leaches through the landfill, it carries higher pH materials and the methanogens living among them to other areas of the landfill.

M. barkeri repeats this cycle, making the landfill environment even more methanogen-friendly. The research was published in the journal Applied and Environmental Microbiology. [Bryan Staley, Francis de los Reyes III and Morton Barlaz, Effect of Spatial Differences in Microbial Activity, pH, and Substrate Levels on Methanogenesis Initiation in Refuse]

M. barkeri not only produces methane that could be harvested for fuel—the microbes also make the whole trash mound more compact. The finding could help in the development of ways to accelerate the process. Leading to more methane collection and more room for waste without more landfills.

—Cynthia Graber