Screening of Feather Degrading Bacteria and Optimization of Fer-mentation Conditions from Poultry

The purpose of this experiment was to isolate and screen the microorganisms from the soil where chicken feathers were piled for a long time and identify them biologically.Single-factor test and response surface methodology （RSM） analyses were used to explore the optimum conditions for the growth and fermentation of a strain.Screening of bacterial strains from the soil where feathers were piled for a long time was performed,and 12 keratinolytic bacterial strains were isolated.One of these isolates,CH-7,was found to be the most effective feather-degrading strain,which was identified as Lactococcus lactis KU568489.1.The growth situation of feather keratin degrading bacterium analysis results showed that the best degradation effect of CH-7 was found in oxygen,inoculation 5%,initial pH=6.5,fermentation temperature 30℃,speed 220 r · min^-1 and fermentation time 36 h,and CH-7 had the highest degradation rate of feather keratin.The optimization analysis of RSM showed that there was more significances of the three factors,32℃,pH 6.3 and amount of inoculum at 5.7% on the degradation of feather keratin.Based on the above results,the feather degrading bacterium,Lactococcus lactis CH-7,was obtained by screening,30℃ and pH 5.5-6.5 were the best growth conditions.The oxygen,the amount of inoculum 5.7%,the fermentation temperature,32℃,pH 6.3 and the rotational speed 220 r · min^-1 were the best fermentation conditions.Under these conditions,38.48% degradation rate was obtained after 36 h fermentation,which demonstrated the strain CH-7 was potential to the fermented feather meal for feed.