title: Thermostable hemicellulases of a bacterium, Geobacillus sp. DC3, isolated from the former Homestake gold mine in Lead, South Dakota.
abstract: A thermophilic strain, Geobacillus sp. DC3, capable of producing hemicellulolytic enzymes was isolated from the 1.5-km depth of the former Homestake gold mine in Lead, South Dakota. The DC3 strain expressed a high level of extracellular endoxylanase at 39.5 U/mg protein with additional hemicellulases including β-xylosidase (0.209 U/mg) and arabinofuranosidase (0.230 U/mg), after the bacterium was grown in xylan for 24 h. Partially purified DC3 endoxylanase exhibited a molecular mass of approximately 43 kDa according to zymography with an optimal pH of 7 and optimal temperature of 70 °C. The kinetic constants, K m and V max, were 13.8 mg/mL and 77.5 μmol xylose/min·mg xylan, respectively. The endoxylanase was highly stable and maintained 70 % of its original activity after 16 h incubation at 70 °C. The thermostable properties and presence of three different hemicellulases of Geobacillus sp. DC3 strain support its potential application for industrial hydrolysis of renewable biomass such as lignocelluloses.
authors.affiliation: Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, 501 East Saint Joseph Street, Rapid City, SD, 57701, USA.
authors.forename: Terran E
authors.initials: TE
authors.lastname: Bergdale
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Hughes
authors.forename: Sookie S
authors.initials: SS
authors.lastname: Bang
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004795:Enzyme Stability; D056506:Geobacillus / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification*; D019015:Geologic Sediments / Q000382:microbiology*; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008906:Mining; D008969:Molecular Sequence Data; D010802:Phylogeny; D013023:South Dakota
chemical_list: D001426:Bacterial Proteins; D006026:Glycoside Hydrolases; C023305:hemicellulase