In the hands of scientists, a list of enzymes produced by gut fungi is the first step to unlocking their biofuel-producing potential. Like monks in a monastery copying religious texts, messenger RNA molecules transcribe the genetic information needed to make proteins, including enzymes. So the DOE JGI sequenced the mRNA of several gut fungi to come up with their transcriptome, which represents all the possible proteins they could make.
O'Malley compared this effort to re-assembling a map from its pieces, only without seeing the complete picture. Since not all proteins are enzymes, the researchers needed to cross check their map with another one. Enter the EMSL, where researchers created that second map that identified enzymes the fungi actually produced. This so-called proteome acted like landmarks that matched up to JGI's map, highlighting the biomass-degrading enzymes in the transcriptome.
Together, the maps from JGI and EMSL pointed to the treasure trove of enzymes gut fungi can produce. Compared to the industrial varieties, which top out around 100 enzymes, gut fungi can produce hundreds more. Of note, the fungi produce enzymes better at breaking down a hemicellulose found in wood, called xylan. And when the scientists changed the fungi's diet from canary grass to sugar, the fungi responded by changing the enzymes it produced. In other words, the fungi can update their enzyme arsenal on the fly.
"Because gut fungi have more tools to convert biomass to fuel, they could work faster and on a larger variety of plant material. That would open up many opportunities for the biofuel industry," said O'Malley, whose study was funded by the U.S. Department of Energy Office of Science, the U.S. Department of Agriculture and the Institute for Collaborative Biotechnologies. Additionally, O'Malley was the recipient of a DOE Office of Science Early Career Award
within the Biological and Environmental Research Program.
O'Malley will present her findings at the DOE JGI's 11th Annual Genomics of Energy & Environment Meeting
in Walnut Creek, California, on March 24. Registration is still open for the meeting.Literature
Kevin V. Solomon, Charles H. Haitjema, John K. Henske, Sean P. Gilmore, Diego Borges-Rivera, Anna Lipzen, Heather M. Brewer, Samuel O. Purvine, Aaron T. Wright, Michael K. Theodorou, Igor V. Grigoriev, Aviv Regev, Dawn A. Thompson, Michelle A. O'Malley, Early-branching gut fungi possess a large, comprehensive array of biomass degrading enzymes, Science, February 18, 2016, DOI:10.1126/science.aad1431.Source