Optimization Of Technologies For Culturing Bacillus Marinus B-9987and Its Wettable Powder Formulation

The new lipopeptides--BM produced by Bacillus marinus B-9987which is the biocontrol bacteria of the first marine microbial pesticide at home and abroad showed great agricultural bacteriostatic activity. To solve the problems in BM large-scale application, two key problems, including controlling foam during fermentation process and improving the yields of BM, were studied in this paper. To better demonstrate and industrialize Bacillus marinus B-9987wettable powder, further optimization of Bacillus marinus B-9987wettable powder formulation was also studied in this paper.To solve the foam problem, different defoamers were screened by shake flasks. Polyether modified silicone defoamer THIX-298was the best defoamer, and the result was verified in5L fermenter. Due to the low instantaneous defoaming ability of THIX-298, the compound defoamer TC-2was created, which was compounded by THIX-298and silicone defoamer Antifoam that can defoam instantaneously and persistently. And the optimized defoamer TC-2was used in the process of culturing finally.The fermentation conditions of producing BM were optimized through the single factor experiment and orthogonal experiment. The results showed that optimized conditions were better than the original in500mL shake flask. The yields of BM using optimized conditions was224.02mg/L, improved by55.43%compared with the original144.13mg/L. Then we investigated5L,50L, and5000L fermenters using optimized conditions, the yields of BM had held steady above210mg/L. At last, the defoaming effect of Antifoam, THIX-298and TC-2were compared in5000L fermenters, and the results similarly indicated TC-2was the best.The formulation of Bacillus marinus B-9987wettable powder was optimized by additives screening and mixture design. And results showed that sodium dodecyl sulfate (SDS) was appropriate to be used as the additive of Bacillus marinus wettable powder. Mixture design was used to determine the optimal mixture proportion of light calcium carbonate(LCC), kaolinite and SDS. It was proved that the suitable contents of SDS, LCC, and kaolinite in Bacillus marinus B-9987wettable powder were9.54%,83.74%, and6.72%, respectively. Under these conditions, predicted suspensibility, pH and wetting time of Bacillus marinus wettable powder was75.15%,8.62and89.40s, respectively. Furthermore, the experimental results were in good agreement with those predicted. The optimized Bacillus marinus B-9987wettable powder without milling even can meet the standards of wettable powder. With the scale up of manufacture, the suspensibility and wettability was both worse than those in the small scale test but better than those before optimized.The research results of this paper establish established good foundations for the industrialization of Bacillus marinus B-9987wettable powde and BM...