Screening Of Bacillus Strains Producing Lipase And Application In The Feeding Of Cock

A high lipase activity bacillus designated as3EA1-1, which was identified asBacillus subtilis through identification of molecular biology combining with bacterialcolony morphological and biochemical characterization after UV mutagenesis, wasisolated from greasy soils. Its lipase activity reached50.5U/mL, named EA-300-A.The tolerance in artificial gastric intestinal juice of the strain were further studied.Tolerence test manifested that strain EA-300-A had strong resistance to artificialintestinal fluid, gastric juice and bile salts medium. Meanwhile, safety test basiclyproved that it was non-toxic to animals.The study above indicated that the strain Bacillus subtilis EA-300-A had higheractivity than others, and had resistance to artificial gastrointestinal fluids and creatureswere safe. The results demonstrated that this strain had potential application of furtherlarge-scale. In order to produce microbial inoculants later, spore formationoptimization of the strain was studied. Through single factor and orthogonalexperiments, we found that the best conditions of spore formation were2.0%cornflour,1.0%soybean powder,0.3%CaCl2·2H2O，Na2HPO4·12H2O0.4%，NaH2PO4·2H2O0.2%，initial pH8.0, culture time12h, inoculums volume10%, and bottlefilling capacity50mL/250mL.In order to verify the effect of strain EA-300-A on feeding, we chose cock as theobject of study and detected the effects of microbial inoculants on cock body weightgain, feed/gain, various digestive enzymes’ activities and number of microorganisms.First, we produced microbial inoculants refering to the result of spore productionoptimization of the strain.150healthy1-d Jingbai939blue ash cocks were dividedinto3groups,50cocks per group. Birds in the control group were fed with basal dietwhich was added1%soybean oil. On the basis of basal diet,0.5%microbial inoculants(5×108CFU/g) were added to test group1,1%microbial inoculants (5×108CFU/g) were added to test group2. Feeding test lasted42d. After7d preliminary feeding, the test began. During the test, the number of E.coli, Lactic acid bacteria and Bifidobacterium were counted, the variation of protease,amylase and lipase in the duodenum were determined, and the crude proteindigestibility and the content of crude fat and ash were calculated using the nationalstandard methods. The result of feeding test revealed that adding enzyme bacteriaagent to fodder increased cocks’ average body weight gain by23.06%, and reduced feed/gain by19.60%. Meanwhile, it could outstandingly improve lipase activity in theduodenum and the number of Lactic acid bacteria and Bifidobacterium in the cecum,and reduce the residual of nutrients in the faeces and the number of E. coli in thececum. The feed test in the cocks achived desired effect.The results of the test above demonstrated that adding bacillus EA-300-A tofodder had the effects of increasing feed conversion ration, improving cocks’ growthperformance, adjusting gut microbiota and reducing feed/gain. It provided goodtheoretical and practical basis for reducing the production cost of breeding andimproving economic returns.