The quick rise and depressing downward spiral of the ethanol industry proved that using food to make biofuel is both wasteful and costly. Non food-based biofuels, such as those derived from grasses, trees, or algae, are far more sustainable but harder to produce. In order to access the sugars in plant biomass that will eventually become fuel, scientists must find a way to break down lignin, a polymer that forms the thick, woody cell walls of most plants and trees. Now researchers at Brown University have identified a type of bacteria that loves to digest lignin, and it might be able to act as a tiny biorefinery for sustainable fuel production.
The bacteria is called Streptomyces and it is one of the few microorganisms known to degrade and consume lignin. But just unleashing some Strptomyces in a pile of wood won’t give you usable biofuel. As Cleantechnica points out, getting it to work on a commercial scale is “kind of like the microbial version of herding cats” and it requires a detailed understanding of the process.
Jason Sello, professor of chemistry at Brown, and Rebecca Page, professor of biology in the Department of Molecular Biology, Cell Biology, and Biochemistry have been working withgraduate students Jennifer Davis and Breann Brown to unlock the microbes‘ secret digestive process. In previous work, Sello and Davis identified a cluster of genes in Streptomyces bacteria that encode enzymes for breaking down a lignin-derived compound called protocatechuate. Under normal circumstances, those genes were inactive — essentially switched off. Only when bacteria were grown in a medium containing protocatechuate did the genes switch on and produce the appropriate enzymes.
Their current research has allowed Sello and Davis to uncover the “finger” on that genetic switch, a clue that could help them to be able to control the bacteria, effectively scaling up its production to help produce biofuels.
“Aside from the implications for biotechnology, this work is significant because it yielded fundamental insights into how bacteria control the expression of their genes,” Sello said. “Understanding how genes underlying lignin degradation are regulated could have practical importance in that we could possibly use this information to engineer bacteria that can convert this important component of plant biomass into the biofuels of high-value chemicals.”