Abstract:
A number of keratinase-producing bacteria was isolated and investigatedfor keratinase production and kather degradation. Fifty two strains of keratinaseproducingbacteria were selected on a screening medium containing 5 % feather mealand minerals. Of all strains tested, seven isolated highly produced keratinase in amedium containing 1.0% feather meal by submerged cultivation. They wereidentified as species of Bacillus and Flavimonas. The most active strain forkeratinase production was identified as Bacillus sphaericus FK 28. Its optimumconditions for keratinase production were 1.0% feather meal used as a substrate,initial pH of medium at 7.5, shaking rate of 150 rpm and at temperature of 37 OC .During five-day fermentation, the strain gave the highest keratinase activity at 2.1U/ml on the third day.It was also found that the most active strain for feather degradation wasidentified as Bacillus cereus FK 26. It degraded 99% feather at temperature of 37OC,shaking rate at 200 rpm and initial pH medium at pH 8.0 containing chicken featheras substrate. After feather fermentation with Bacillus cereus FK 26, some aminoacid contents in fermented chicken feather were slightly lower than in non-fermentedchicken feather. This possibly resulted fiom amino acid consumption by bacteria.However, the residue of fermented chicken feather had excellent percentage ofpepsin digestibility (90%) which was higher than non-fermented chicken featherresidue (23%) and feather meal (36%). Therefore, the strain of keratinase-producingbacteria could be applied for hther degradation and the feather residue afterbacterial fermentation could be served as an animal feed.