Screening And Identification Of Bacillus With High Activity From Swine Deep Litter System And The Optimization Of Protease Produce

Screening of Bacillus with high activity is an important key to swine deep litter system.The Bacillus can reach the goal of deep litter system only by possessing the property of high increase rate,high protease produce,significant inhibitory action to harmful bacteria as E.coli and Salmonella,and ability to degrade and transform the organic material in swine fecal and urine.Twenty strains of Bacillus were isolated from local swine farm.The first and final screening was based on activity of protease,cellulose and diastase produce of Bacilli.The first screening included the methods of culture on plat and staining, while the final screening based on the methods of spectrophotometer to test the enzyme activity of Bacilli.Strain Yb16 and Yb17 were chose for the higher enzyme activity,the enzyme activity of which as follows:2.509 u/ml(Yb16),2.576 u/ml (Yb17) for protease,2.000u/ml(Yb16),3.2500u/ml(Yb17) for cellulose,and 6.0643u/ml(Yb16),4.6126u/ml(Yb17) for diastase.Double plate's method was used to test the inhibitory effect of Bacillus to three common conditional pathogenic microorganisms.Strain Yb17 was selected for the best inhibitory effect.Through morphology examination,physiology and biochemistry test,and 16S rRNA array test,Yb17 was identified as Bacillus megaterium.Bacillus Yb17 has high endurable ability to acid and bile.According to the result of safe experiment to mice,Yb17 was safe and without side effect. Signal fact study was designed to test the effect of temperature,pH,and culture time and incubation amount to Yb17 producing protease.The best protease produce condition as follows:temperature 30℃,pH 7.5,fermentation time for 18 hours,and the incubation amount for 1%.