Analysis Of The Essential Metabolites Of The Mixed Bacteria In The Second Step Of VC Fermentation

The second fermentation of Vitamin C is a process of oxidizing sorbinose to2-KLG and it is accomplished by two interworked bacteria. One is Ketogulonigenium vulgare, and its function is oxidizing sorbinose. The other one is Bacil1us megaterium, it is used as a companion bacterium to help Ketogulonigenium vulgare grow and produce acid.To clarify the second fermentation of Vitamin C in the interaction between the two strains to provide parameters for the fermentation process optimization, the experiment using GC-TOF-MS means, do some research on the processes of two strains alone and the mixed fermentation with different inoculative states and analysis the metabolite data. It compares the different metabolite data in order to describe the interaction mechanism between the two strains. The major findings are: (1)the experiment determined the types and levels of metabolites in two separate bacteria fermentation, and suggested the pathway of each bacterium; (2) it drew growth curves of the two bacteria in the mixed fermentation process, and found with the inoculum increasing of Ketogulonigenium vulgare, the growth rate of Bacillus megateriumsignificantly increased when the inoculation of Bacillus megaterium got 106CFU/ml. Besides, the final situation depends on the initial inoculative states of Ketogulonigenium vulgare ; (3) it determined the types and levels of metabolites in the mixed fermentation process and found the ammonia molecular dissimilation process based on amino acid and keto acid change in amount. We also found the nucleotide degradation pathway according to the changes of the substances like nucleotide; (4) it determined the extracellular accumulation of metabolic products and found the accumulation of the erythrose and 2-KLG increased with the inoculum size of the Ketogulonigenium vulgare. Besides, the change rule of extracellular cysteineimplies that the function of acid production by Ketogulonigenium vulgare may relate to redox.The results of these studies provides a new method to explore the material basisin the interaction between the two strains in the Vitamin C fermentation process, and provides a theoretic basis for the optimization of Vitamin C fermentation.