36B-4 |
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W. SUNTORNSUK, R. Promsiri, and P. Tuitemvong. Microbiology, King Mongkut's Univ. of Technology Thonburi, Thungkru, Bangkok, 10140, Thailand Feathers contain over 90% crude protein in a form of keratin. Generally, they become feather meal used as animal feed after undergoing physical and chemical treatments. Over the past decades, however, feather digestion by biological methods has attracted more interest because of increased environmental awareness and low cost investment. Recently, Bacillus licheniformis FK 50, a thermotolerant feather-degrading bacterium, has been isolated from a soil sample in Thailand. It could grow well on feather under solid state cultivation. The objective of this study was to investigate factors affecting feather degradation by this bacterium and to evaluate nutritional values of degraded feather compared to undigested feather. One gram of sterile chicken feather with 88% initial moisture was fermented by Bacillus licheniformis FK50 at 37o C for 5 d. Factors affecting feather digestion; feather size, initial moisture content, incubation temperature and sucrose addition, were studied. During bacterial cultivation, bacterial growth, % feather degradation and keratinase activity was determined. Pepsin digestibility and nutritional values of raw feather and fermented feather were examined. Scanning electron microscopy on feathers was also carried out. Feather was maximally degraded at 51% under an optimal condition which was 1x1 cm2 feather size, 88% initial moisture content and a temperature of 43o C for 5 d. Under this condition, maximal keratinase production was found to be 37.27 units/gram, while maximal growth of 6.84 x 108 CFU/gram was observed. Fermented feather gave much higher pepsin digestibility, fat content and ash but less crude protein and fiber than the raw feather. Most essential amino acids such as tyrosine, valine, lysine and leucine in the fermented one were higher than those in the raw one. The results suggest the bacterial strain could degrade feather by the solid state fermentation into easily digestible proteins and more nutrients potentially applied to be an animal feed at low cost.
Session 36B, Biotechnology: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |