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IDENTIFICATION OF FEATHER-DEGRADING BACTERIA AND THEIR KERATINASE PRODUCTION ผูรับผิดชอบโครงการ : Worapot Suntornsuk, Siriwat Poonthrigpun, Sorntham Jeeranaithanawat เผยแพรผลงาน : The 5th Asia-Pacific Biochemical Engineering Conference 1999 and The 11th Annual Meeting of the Thai Society for Biotechnology 15-18 November, Phuket Chicken feather is recognized as a xolid waste generated from poultry processing industry and is abundant in Thailand. It is generallly treated by high pressure and temperature to be feather meal used as an animal feed. It can be also hydrolyzed by keratinase which is a specific protease for feather degradation. The enzyme is produced by some species of Bacillus, Fervidobacterium, saprophytic and parasitic fungi and actinomycetes. Three unidentified bacterial strains isolated from soil samples were collected at the department of Microbiology, KMUTT. They had show ability of feather degradation by making a clear zone around their colonies grown on a solidified screening medium containing 5% feather meal and mineral salts. The objectives of this work were to identify feather-degrading isolates and to evaluate their keratinase activity. In this study, the isolates were identified by morphological and biochemical tests. The results were confirmed by API est kits. The strains were also examined for keratinase production by shake flask fermentation in a liquid medium consisting of a basal medium: 0.05% NH4Cl; 0.05% NaCl; 0.03% K2HPO4; 0.04% KH2PO4; 0.024% MgCl2.6H2O; 0.01% yeast extract plus 1% feather meal, pH 7.5. The fermentation was carried out at 37°C and an agitation rate of 150 rpm for 5 days. Samples were taken everyday for bacterial growth and keratinase activity measurement. the keratinase activity was determined by incubating enzyme solution with 10 mg of feather meal at 45°C for 30 min; stopping the reaction with trichloroacetic acid solution and measuring amino acids produced at absorbance of 275 nm. One unit of keratinase activity was expressed as 1 µ mol of tyrosine released per minute under the above conditions. Three strains of feathe-degrading bacteria were identified as Bacillus licheniformis, Bacillus sphearicus and Flavimonas oryzihabitans. They produced Keratinase in a range of 1.79-2.13 units/ml with maximum specific growth rate of 0.23-0.24 h-1. The results show that these bacterial strains could be used for producing keratinase applied for enzymatic hydrolysis of chicken feather into animal feed.
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