title: Keratinase production and keratin degradation by a mutant strain of Bacillus subtilis.
abstract: A new feather-degrading bacterium was isolated from a local feather waste site and identified as Bacillus subtilis based on morphological, physiochemical, and phylogenetic characteristics. Screening for mutants with elevated keratinolytic activity using N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis resulted in a mutant strain KD-N2 producing keratinolytic activity about 2.5 times that of the wild-type strain. The mutant strain produced inducible keratinase in different substrates of feathers, hair, wool and silk under submerged cultivation. Scanning electron microscopy studies showed the degradation of feathers, hair and silk by the keratinase. The optimal conditions for keratinase production include initial pH of 7.5, inoculum size of 2% (v/v), age of inoculum of 16 h, and cultivation at 23 degrees C. The maximum keratinolytic activity of KD-N2 was achieved after 30 h. Essential amino acids like threonine, valine, methionine as well as ammonia were produced when feathers were used as substrates. Strain KD-N2, therefore, shows great promise of finding potential applications in keratin hydrolysis and keratinase production.
authors.affiliation: College of Food Science and Biosystem Engineering, Zhejiang University, Hangzhou 310029, China.
authors.forename: Cheng-gang
authors.initials: CG
authors.lastname: Cai
authors.forename: Bing-gan
authors.initials: BG
authors.lastname: Lou
authors.forename: Xiao-dong
authors.initials: XD
authors.lastname: Zheng
mesh_terms: D000596:Amino Acids / Q000096:biosynthesis; D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media; D006863:Hydrogen-Ion Concentration; D007633:Keratins / Q000378:metabolism*; D009154:Mutation; D010447:Peptide Hydrolases / Q000096:biosynthesis*
chemical_list: D000596:Amino Acids; D003470:Culture Media; D007633:Keratins; D010447:Peptide Hydrolases; C035855:keratinase