title: Characterization of a novel Stenotrophomonas isolate with high keratinase activity and purification of the enzyme.
abstract: A feather-degrading bacterium was isolated from poultry decomposition feathers in China. The strain, named L1, showed significant feather-degrading activity because it grew and reproduced quickly on basal medium containing 10 g/L of native feather as the source of energy, carbon, and nitrogen. According to the phenotypic characteristics and 16S rRNA profile, the isolate belongs to Stenotrophomonas maltophilia. Keratinase activity of the isolate was determined during cultivation on raw feathers at different temperatures and initial pH. Maximum growth and feather-degrading activity of the bacterium were observed at 40 degrees C and initial pH ranging from 7.5 to 8.0. The crude enzyme was purified by ammonium sulphate precipitation, Sephadex G-100 chromatographic and ceramic hydroxyapatite (CHT) chromatographic. Its molecular mass estimated as 35.2 kDa in SDS-PAGE. The enzyme had an optimum activity at the pH was 7.8 and the temperature was 40 degrees C. The keratinase was wholly inhibited by a serine protease inhibitor, PMSF. Its activity was activated or inhibited by different metal ions. The keratinase activity of enzyme from strain L1 functioned on different keratins, such as feather, hair, wool, horn, and so on.
authors.affiliation: Key Laboratory of Science and Technology of Eco-Textile, Donghua University, Ministry of Education, 201620, Shanghai, China.
authors.forename: Zhang-Jun
authors.initials: ZJ
authors.lastname: Cao
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhang
authors.forename: Dong-Kai
authors.initials: DK
authors.lastname: Wei
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Xing-Qun
authors.initials: XQ
authors.lastname: Zhang
authors.forename: Mei-Hua
authors.initials: MH
authors.lastname: Zhou
mesh_terms: D000818:Animals; D001709:Biotechnology / Q000379:methods; D002645:Chickens / Q000378:metabolism; D002681:China; D003470:Culture Media; D004795:Enzyme Stability; D005241:Feathers / Q000378:metabolism / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D010447:Peptide Hydrolases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D013045:Species Specificity; D020615:Stenotrophomonas maltophilia / Q000145:classification* / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D003470:Culture Media; D010447:Peptide Hydrolases; C035855:keratinase