In Vitro Study On A Strain Of Bacillus Subtilis For Feeding

The antimicrobial activity and probiotic properties of Bacillus subtilis K12,isolated from local soil,were investigated.The cell-free supernatant(CFS)exhibited inhibitory effects on Gram-positive bacteria and fungi.The antibacterial activity of the CFS remained even after treatment at 60? and 100? for 30 minutes,at pH 4 and 10,with proteolytic enzymes and detergents.Three active ingredients with bacteriostatic action were identified as the lipopeptides by LC-MS after separation and purification of the CFS.The inhibitory activity of CFS on fungi was due to its excellent chitinase and chitosanase activity,which could lyse the cell wall of the fungus.B.subtilis K12 showed an excellent acid and bile salts tolerance.Also it excreted plentiful protease,cellulase and amylase during the cultivation which were used as additives in the animal husbandry.This study also optimized the fermentation conditions for the enzyme production and bacteriostatic performance of Bacillus subtilis K12 strain,in order to achieve the best use effect in different application environments.The characteristics of the isolated Bacillus subtilis suggested that it has potiential application as feed additives and substitute for antibiotics in animal industry.