Keratinase production and keratin degradation by a mutant strain of Bacillus subtilis  

作　　者：Cheng-gang CAI Bing-gan LOU Xiao-dong ZHENG 

机构地区：[1]College of Food Science and Biosystem Engineering, Zhejiang University, Hangzhou 310029, China [2]Institute of Biotechnology, Zhejiang University, Hangzhou 310029, China

出　　处：《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》2008年第1期60-67,共8页浙江大学学报（英文版）B辑（生物医学与生物技术）

基　　金：Project (No.3057130) supported by the National Natural Science Foundation of China

摘　　要：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 ℃. 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.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 in-oculum of 16 h,and cultivation at 23 °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.

关 键 词：Bacillus subtilis KERATIN Keratin degradation Keratinase production N-methyl-N＇-nitro-N-nitrosoguanidine （MNNG） mutagenesis 

分 类 号：Q81[生物学—生物工程]