Study On The Fermentation Conditions And Stability Of Antibacterial Materials Produced By Bacillus Amyloliquefaciens HRH₃₁₇

In this experiment, the major study were fermentation conditions and physicochemical stability for antibacterial substances produced by Bacillus amyloliquefaciens HRH317.Through single factor tests and an orthogonal design the liquid fermentation medium of HRH317strain with antibacterial substances was optimized; Getting the optimum fermentation medium, with this basis it was studied influence of broth antibacterial activity on fermentation time, fermentation temperature, initial pH, inoculation volume, inoculation age, liquid volume, rotation speed of by single factor tests, Then through response surface methodology it systematically determined the optimum fermentation conditions of HRH317strains’broth; using the dilution method determined the titer of antimicrobial active substances of broth; inhibitory substances of Bacillus amyloliquefaciens of HRH317would be preliminarily identified and would be studied on storage stability, sensitivity to different proteases and stability of metal ions by the stability of the physical and chemical. The main findings are as follows:1. Though single factor tests and an orthogonal design the results showed that the optimum fermentation medium was glucose1g, yeast extract1g, NaCl0.5g, Tween200.1g, MgSO40.075g, water100mL.2. By response surface design the optimal fermentation conditions were inoculation age21h, inoculation size of3.8%, fermentation time25h, fermentation temperature37℃, fermentation initial pH7.0,100mL flask installed with volume30mL broth, shaking speed150r/min.3. Using dilution method determined the broth antibacterial active substances’titer was2560AU/mL in optimized fermentation conditions, increased by100%than the original fermentation conditions.4. Through preliminarily researching strains HRH317produced the antibacterial substances, showed that the antibacterial substance were catalase and substances of a protein or peptide class. Studying physicochemical properties of the strains fermentation supernatant showed that the inhibitory substances had good thermal stability and pH stability, and antibacterial activity could still be maintained at88.65%of the original broth stored at4℃for60d; fermentation supernatant was sensitive to pepsin and trypsin, had a tolerance to proteinase K and papain; K+, Mg2+, Mn2+could enhance the antibacterial activity, while Zn2+, Cu2+, Al3+, Fe2+, Na+were partially inhibited its antibacterial activity, and Ca2+had no significant effect on the antimicrobial activity; polyethylene glycol, polysorbate20, polysorbate80these surface-active agents had little effect on its antibacterial activity. The above results showed that the antibacterial substances not only had good antibacterial activity, but also had good stability, could be used to develop a new biological preservative.