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IDENTIFICATION OF FEATHER-DEGRADING BACTERIA AND THEIR KERATINASE

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IDENTIFICATION OF FEATHER-DEGRADING BACTERIA AND THEIR KERATINASE Powered By Docstoc
					 IDENTIFICATION OF FEATHER-DEGRADING BACTERIA AND THEIR KERATINASE PRODUCTION

ผูรับผิดชอบโครงการ        : Worapot Suntornsuk, Siriwat Poonthrigpun, Sorntham Jeeranaithanawat
เผยแพรผลงาน               : 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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posted:11/29/2011
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