Native-feather degradation by Fervidobacterium islandicum AW-1, a newly isolated keratinase-producing thermophilic anaerobe.
A native-feather-degrading thermophilic anaerobe was isolated from a geothermal hot stream in Indonesia. Isolate AW-1, identified as a member of the species Fervidobacterium islandicum, was shown to degrade native feathers (0.8%, w/v) completely at 70 degrees C and pH 7 with a maximum specific growth rate (0.14 h(-1)) in Thermotoga- Fervidobacterium(TF) medium. After 24 h of culture, feather degradation led to an increase in free amino acids such as histidine, cysteine and lysine. Moreover, nutritionally essential amino acids such as tryptophan and methionine, which are rare in feather keratin, were also produced as microbial metabolites. A homomultimeric membrane-bound keratinolytic protease (>200 kDa; 97 kDa subunits) was purified from a cell extract of F. islandicum AW-1. The enzyme exhibited activity toward casein and soluble keratin optimally at 100 degrees C and pH 9, and had a half-life of 90 min at 100 degrees C. The enzyme showed higher specific activity for the keratinous substrates than other proteases and catalyzed the cleavage of peptide bonds more rapidly following the reduction of disulfide bridges in feather keratin by 10 mM dithiothreitol. Therefore, the enzyme from F. islandicum AW-1 is a novel, thermostable keratinolytic serine protease.
Nam
Gae-Won
GW
Department of Biotechnology and Bioproducts Research Center, College of Engineering, Yonsei University, Seodaemun-Gu, Shinchon-Dong 134, Seoul 120-749, Korea.
Lee
Dong-Woo
DW
Lee
Han-Seoung
HS
Lee
Nam-Ju
NJ
Kim
Byoung-Chan
BC
Choe
Eun-Ah
EA
Hwang
Jae-Kwan
JK
Suhartono
Maggy T
MT
Pyun
Yu-Ryang
YR
D000596:Amino Acids; D000818:Animals; D001421:Bacteria, Anaerobic / Q000145:classification / Q000201:enzymology* / Q000302:isolation & purification / Q000378:metabolism; D001673:Biodegradation, Environmental; D004795:Enzyme Stability; D005241:Feathers / Q000737:chemistry / Q000378:metabolism* / Q000382:microbiology; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007633:Keratins / Q000378:metabolism*; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D010447:Peptide Hydrolases / Q000032:analysis* / Q000378:metabolism; D010802:Phylogeny; D012697:Serine Endopeptidases / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature
D000596:Amino Acids; D007633:Keratins; D010447:Peptide Hydrolases; C035855:keratinase; D012697:Serine Endopeptidases