title: Glycoside hydrolase activities of thermophilic bacterial consortia adapted to switchgrass.
abstract: Industrial-scale biofuel production requires robust enzymatic cocktails to produce fermentable sugars from lignocellulosic biomass. Thermophilic bacterial consortia are a potential source of cellulases and hemicellulases adapted to harsher reaction conditions than commercial fungal enzymes. Compost-derived microbial consortia were adapted to switchgrass at 60°C to develop thermophilic biomass-degrading consortia for detailed studies. Microbial community analysis using small-subunit rRNA gene amplicon pyrosequencing and short-read metagenomic sequencing demonstrated that thermophilic adaptation to switchgrass resulted in low-diversity bacterial consortia with a high abundance of bacteria related to thermophilic paenibacilli, Rhodothermus marinus, and Thermus thermophilus. At lower abundance, thermophilic Chloroflexi and an uncultivated lineage of the Gemmatimonadetes phylum were observed. Supernatants isolated from these consortia had high levels of xylanase and endoglucanase activities. Compared to commercial enzyme preparations, the endoglucanase enzymes had a higher thermotolerance and were more stable in the presence of 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]), an ionic liquid used for biomass pretreatment. The supernatants were used to saccharify [C2mim][OAc]-pretreated switchgrass at elevated temperatures (up to 80°C), demonstrating that these consortia are an excellent source of enzymes for the development of enzymatic cocktails tailored to more extreme reaction conditions.
authors: Joint BioEnergy Institute, Emeryville, CA 94608, USA.
authors: John M
authors: JM
authors: Gladden
authors: Martin
authors: M
authors: Allgaier
authors: Christopher S
authors: CS
authors: Miller
authors: Terry C
authors: TC
authors: Hazen
authors: Jean S
authors: JS
authors: VanderGheynst
authors: Philip
authors: P
authors: Hugenholtz
authors: Blake A
authors: BA
authors: Simmons
authors: Steven W
authors: SW
authors: Singer
mesh_terms: D000222:Adaptation, Physiological; D001419:Bacteria / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D015373:Bacterial Typing Techniques; D001483:Base Sequence; D018533:Biomass; D004789:Enzyme Activation; D005285:Fermentation; D020459:Genes, rRNA; D006026:Glycoside Hydrolases / Q000378:metabolism*; D008031:Lignin / Q000378:metabolism; D059013:Microbial Consortia; D008969:Molecular Sequence Data; D008897:Panicum / Q000382:microbiology*; D010802:Phylogeny; D055550:Protein Stability; D017422:Sequence Analysis, DNA; D012987:Soil / Q000737:chemistry; D013696:Temperature
chemical_list: D012987:Soil; C036909:lignocellulose; D008031:Lignin; D006026:Glycoside Hydrolases