Selection Of New Strains166-2051and Optimization Of Fermentation Conditions In Vitamin C Fermentation

Two-step fermentation is the main technology of vitamin C producton in China, and its second step is mixed fermentation of two kinds of bacterium. The complexity of the mixed bacteria fermenting influenced total yield of second step. Mutants screening of the second step strain and fermentation condition optimizing are the useful ways to improve the efficiency of conversion of the second step fermentation.In this paper, taking production strains25b-0of Northeast Pharmaceuticals Group CO.,LTD as the research objects, new effective mutation breeding strains166-2051was selected by space mutation through Shenzhou7Space Shuttle and new strains fermentation conditions are optimized by Response Surface Method (RSM).After space mutation breeding, several rounds of selection were conducted.Ultimately, new combination mutagenesis strains166-2051was obtained from1020associated bacteria and3030acid producing bacteria.By examining the characteristics of seed production prosess for the new strains, the best seed production conditions were obtained:pack quantity20mL/250mL,180rpm,29℃,18-15h. The RSM was used to optimize the fermentation conditions of new mutation strains and it was found that significant influence composition in2-KGA production was corn syrup, urea and KH2PO4.The best medium was L-sorbic9%, corn syrup1.95%, urea1%, KH2PO40.03%, MgSO40.01%and CaCO30.05%, and the initial pH value was6.7-7.0. In the optimized fermentation conditions, delay period of new strains was shortened, and its production of2-KGA increase5%at35h, and the end production of2-KGA was improved by7.67%contrast to those of before optimization. Comparing the cultivation of bacteria growth curve with production of2-KGA curve, it was confirmed that the production process of2-KGA is coupling with bacterial growth phase. In the fast process of production of2-KGA in fermentation, the OD value of associated bacteria, the OD value of acid production bacteria and2-KGA production was anlyzed by correlation analysis, and the results showed that there were singnificant positive correlations between the OD value of acid production bacteria and that of2-KGA production. Research results further confirmed that the growth of acid production bacteria has vital role in fermenting synthesis of2-KGA.