Preparation Of The Bacillus Subtilis Microecological Probiotics

As a new kind of additives, probiotics can promote balance of intestinal microflora. Bacillus subitilis can secrete rich enzyme system, such as protease, lipase, amylase and so on. So it can be used as probiotics applied in animal feed additives.In this study, a Bacillus subitilis HS-A38was used as a probiotic strain which was isolated from the intestine of wild sea cucumbers in Dalian sea area. This study focused on optimization of Bacillus subitilis fermentation conditions and preparation of its microecological probiotics. With both single factor trial and orthogonal experiment, the optimal fermentation liquid media were determined as glucose1.0%, beef extract1.5%and K2HPO40.5%. The optimal fermentation process conditions were obtained as the fermenting temperature30℃, the initial pH7.2inoculating quantity4%and fermenting time36-38h. Under the optimal conditions, the maximum live cell concentration reached3.98×109cfu/mL (colony-forming units per milliliter).The preparation of the strain HS-A38microecological probiotics was done by microencapsulation using1%sodium alginate and4%CaCl2. The live cell counting method was used to inspect the stability of the microecological probiotics. Stability tests showed that, under the liquid preservation condition4℃, the survival rates of the microecological probiotics prepared by emulsification and extrusion were95.4%and97.5%for30days,53.4%and56.9%for60days,28.7%and30.5%for90days, respectively; under the freeze-dried preservation condition at4℃, the survival rates of the microecological probiotics prepared by emulsification and extrusion were92.4%and93.7%for30days,57.1%and60.8%for60days,31.4%and32.9%for90days, respectively. Both of their survival rates were much higher than unmicroencapsulation probiotics, and the methods used in the study can improve the survival period of probiotics. Compared with the extrusion method, the emulsification method will be more suitable for large-scale industrial production. This study could provide a basis on the industrial production of the probiotic strain HS-A38in the future.