Bacterial Protein Shows Promise for Efficiently Converting Plant Biomass to Biofuels
Enzyme has the highest known activity for hydrolyzing recalcitrant crystalline cellulose found in plant cell walls.
Glycoside hydrolases are microbial enzymes that play a key role in nutrient acquisition through the breakdown of cellulose—a major component of plant cell walls. A recent study showed that a protein from the bacterial glycoside hydrolase family 12 plays an unexpectedly important role in converting the hard-to-degrade crystalline form of cellulose and that it does so through a random mechanism unlike other hydrolases.
The discovery of a glycoside hydrolase protein that is highly effective at breaking down rigid plant cell wall components could be harnessed to develop more efficient strategies for converting plant biomass to fuels and chemicals.
Microbes such as fungi and bacteria produce enzymes called glycoside hydrolases to acquire nutrients through the degradation of cellulose—carbohydrates that make up plant cell walls. Some of these enzymes are capable of breaking down the rigid, crystalline form of cellulose and, therefore, could be especially effective at efficiently converting tough plant biomass to fuels and chemicals. However, they have largely been studied in pure cultures of microorganisms, even though microorganisms break down cellulose as communities in the environment. To address this knowledge gap, a multi-institutional team of researchers led by scientists at the Department of Energy’s (DOE) Joint BioEnergy Institute (JBEI) combined comparative proteomics with biochemical measurements. They then assessed differences in glycoside hydrolases produced by diverse microbes in communities cultivated from green waste compost and grown on crystalline cellulose. The team used several mass spectrometry instruments at the Environmental Molecular Sciences Laboratory (EMSL) and high-throughput DNA sequencing technologies at the Joint Genome Institute, both of which are DOE Office of Science user facilities. Their analysis revealed that a glycoside hydrolase family 12 protein, produced by the bacterium Thermobispora bispora, plays a previously underappreciated important role in breaking down crystalline cellulose. The new findings suggest this protein could be especially effective at converting plant biomass to fuels and chemicals. More broadly, the study illustrates the power of comparative community proteomics to reveal novel insights into microbial proteins that could be harnessed for fuel production from renewable energy sources. This research represents collaboration among JBEI, Lawrence Berkeley National Laboratory, Sandia National Laboratories, Pacific Northwest National Laboratory, EMSL, and University of Applied Sciences Mannheim.
Lawrence Berkeley National Laboratory/Joint BioEnergy Institute
Errol (Robby) Robinson
Pacific Northwest National Laboratory
This work was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Biological and Environmental Research (BER). Furthermore, this work was performed under the Facilities Integrating Collaborations for User Science (FICUS) initiative and used resources at DOE’s Environmental Molecular Sciences Laboratory and Joint Genome Institute, which are DOE Office of Science user facilities sponsored by BER.
J. Hiras, Y. W. Wu, K. Deng, C. D. Nicora, J. T. Aldrich D. Frey, S. Kolinko, E. W. Robinson, J. M. Jacobs, P. D. Adams, T. R. Northen, B. A. Simmons, and S. W. Singer, “Comparative community proteomics demonstrates the unexpected importance of actinobacterial glycoside hydrolase family 12 protein for crystalline cellulose hydrolysis.” mBio 7(4), e01106-16 (2016). [DOI: 10.1128/mBio.01106-16].