Wheat straw, the dried stalks left over from grain production, is a potential source of biofuels and commodity chemicals. But before straw can be converted to useful products by biorefineries, the polymers that make it up must be broken down into their building blocks. Now, researchers reporting in ACS Sustainable Chemistry & Engineering have found that microbes from the guts of certain termite species can help break down lignin, a particularly tough polymer in straw.
In straw and other dried plant material, the three main polymers -- cellulose, hemicelluloses and lignin -- are interwoven into a complex 3D structure. The first two polymers are polysaccharides, which can be broken down into sugars and then converted to fuel in bioreactors. Lignin, on the other hand, is an aromatic polymer that can be converted to useful industrial chemicals. Enzymes from fungi can degrade lignin, which is the toughest of the three polymers to break down, but scientists are searching for bacterial enzymes that are easier to produce. In previous research, Guillermina Hernandez-Raquet and colleagues had shown that gut microbes from four termite species could degrade lignin in anaerobic bioreactors. Now, in a collaboration with Yuki Tobimatsu and Mirjam Kabel, they wanted to take a closer look at the process by which microbes from the wood-eating insects degrade lignin in wheat straw, and identify the modifications they make to this material.
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