07/29/2010
Compost Microbes Adapted to Produce Switchgrass-Degrading Enzymes
Summary
By incubating switchgrass with a mix of microbes isolated from compost, JBEI researchers provided the selective pressure needed to grow a new microbial community enriched with enzymes that degrade cell-wall polymers specific to switchgrass. The sample was incubated in a bioreactor for 31 days under typical composting conditions. Metagenomic sequencing of the switchgrass-adapted compost (SAC) community on day 31 was carried out to investigate the sample’s diverse pool of glycoside hydrolases-enzymes that break bonds between carbohydrate molecules. The sample contained a high proportion of genes encoding enzymes that attack the branches and backbone of a major hemicellulose in grass cell walls. Analysis of the small-subunit ribosomal RNA (rRNA) isolated from the microbial community revealed dramatic changes in the community profile with more than a 20-fold increase for some bacterial populations in the SAC. Although metagenomic DNA sequence is highly fragmented, making isolation of full genes from complex communities difficult, two full-length genes for cellulose-degrading enzymes were discovered, synthesized, expressed in Escherichia coli, and tested for enzyme activity.
References
This research was reported in Allgaier, M., et al. 2010. “Targeted Discovery of Glycoside Hydrolases from a Switchgrass-Adapted Compost Community,” PLoS One 5(1), e8812.