Study On Degradation Of Feather By Bacillus Cereus YSQ08 And Keratinase

This study focused on the different degradation rates caused by different adding orders of Bacillus cereus YSQ08 and keratinase,with varying Bacillus cereus YSQ08 culturing time and different keratinase adding time.Feathers degradation was compared in three ways,firstly by using Bacillus cereus YSQ08,secondly by using keratinase and thirdly by using both keratinase and Bacillus cereus YSQ08.We found that combining Bacillus cereus YSQ08 and keratinase was the most efficient way to degrade feather.The results explained that adding Bacillus cereus YSQ08 and keratinase could degrade more feathers.14 h after cultivation of the bacteria(Bacillus cereus YSQ08)the enzyme reached its highest peak of protease secretion,24 h after the bacteria was added,and keratinase was added to maintain its high activity.Based on the five test factors(pH?amount of feather?amount of keratinase?the inoculum size?fermentation time),we designed the L16(4~5)orthogonal optimization experimentation,and the results showed that when the fermentation conditions was at pH level of 9.0?the amount of feather was 3.0%?amount of keratinase was 2000 U/g?the inoculum size was 1.5%?fermentation time was 96 h,the result of the fermentation was considered best,and the contents of amino acids in fermentation liquid were 223.26 mg/L and the degradation rate of feather was 81.76%.The fermentation broth was prepared according to optimal fermentation conditions.The fermentation broth was then centrifuged at 5000 r/min for 10 min to obtain the fermentation supernatant and fermented precipitate.And freeze-dried by vacuum to get the dry matter of fermentation broth,the supernatant dry matter and sediment dry matter.The protein content,were 87.35%,41.43%,92.36%respectively.The fermentation supernatant dry matter obtained after the degradation of chicken feather by Bacillus cereus YSQ08 and keratinase was used to feed Black soldier fly,the effect of the Black soldier fly feed with the dry matter was better than those feed with pig manure,just as fermented precipitated dry matter and fermented liquid dry matter.The average weight gain was 0.2399g,the material weight ratio was 2.6341,the conversion rate was 38.19%,and the survival rate was 90.79%.In conclusion,the method of combining Bacillus cereus YSQ08 and keratinase for feather degradation would provide new insights for feather wastes industrialization.