Isolation And Screening And Characteristics Of Enzyme Production Studies On Bacillus Licheniformis From Chickens

Bacillus licheniformis as probiotics is widely used in animal production can regulate the micro ecological balance of intestinal microbial community participate in the intestinal metabolism,enhance immunity and anti stress ability.So as probiotics are added to animal feed.The purpose of this study is to separat B.licheniformis with good probiotic properties and enzymatic properties of B.licheniformis,to lay the foundation for the development of animal micro ecological preparations with independent intellectual property rights.This paper included three parts: isolation and identification,characteristics of biology,enzyme producing strains.The main results are as follows:Twenty supposed strains were isolated from excrement of healthy chicken with heat and selective media.The identification of these strains was based on characteristics of B.licheniformis following the relatecd methods in the Bergry’s Manual of Determinative Bacteriology.Colonies were examined microscopically and identified by biochemistry tests,and the identification results were verified by PCR based on 16 S rRNA gene sequences species-specific primers.Finally,eight B.licheniformis strains were identified.By comparing the ability of antimicobial activity against gastrointestinal pathogens and growth ability,the optimum performance of strain HDRaBLp and HDRaBLt were selected to do further study on the biological characteristics of on tolerance to gastrointestinal conditions(acid and bile salt)and high temperature.The results demonstrated that these two strains had the resistance for stomach juice at pH 2.0,and well survived in 0.3% porcine bile salt and 90℃ for 10 min.First these two strians’ ability of producing protease,cellulase,amylase were tested and it showed that both of these two strains had the ability of producing protease,cellulase,amylase.Second,quantitative assay of these two strains in four commonly used feed culture conditions which are rapeseed,soybean meal,wheat bran and cottonseed meal was performed to detect the ability of producing protease,cellulase and amylase,and it showed that the results are good.among these results,the strain HDRaBLp in rapeseed meal culture ability to produce cellulase best,in wheat bran culture amylase producing ability was the best,in the soybean meal to produce protease best;while the strain HDRaBLt in soybean cultivation cellulase producing ability best in cottonseed meal culture amylase producing ability and protease producing the best.Finally,Further study of the digestion effect of these two strains in rapeseed,soybean meal,wheat bran and cottonseed meal four commonly used feed solid culture conditions.The study shows that after the experiment,reducing sugar content increased significantly,Incremental in 60% or more,two strains had a better effect in bran feed culture conditions,reducing sugar content increased by257.74%(HDRaBLp)、220.18%(HDRaBLt).Soluble protein content of these two strains increased obviously,reached by 160.00%(HDRaBLp)、80.00%(HDRaBLt).The research also showed that these two strains were effective in promoting protein digestion.The amino acid concentration was increased significantly.The contents of digested protein,which were discounted by increment of amino acid contents,were more than 3.52mg/g.Two strains in soybean meal and wheat bran feed culture conditions had better treatment effect which were 8.43mg/g(HDRaBLp to soybean meal)、7.42mg/g(HDRaBLp to wheat bran)、10.07mg/g(HDRaBLt to soybean meal)、7.30mg/g(HDRaBLt to wheat bran).The material loss rate were also very low,they were 1.71%(HDRaBLp)and 4.14%(HDRaBLt).These results indicated both of these two strains had a promoting effect of digestion and absorption of feed nutrition.Also,the strain HDRaBLp is more suitable to be used as feed additive than the strain HDRaBLt.