The Proteomic And Metabolomic Analyses Of The Consortia For Vitamin C Fermentation

The microbial consortium consisted of Ketogulonicigenium vulgare and Bacillus plays an important role in the industrial two-step fermentation of vitamin C. How to resolve the interaction between the two strains, finding the critical controlling points, thereby increasing productivity of K. vulgare, and how to realize one-step fermentation, not only can reduce the production cost and improve the productivity gains of vitamin C, but also can give significant clues for the study of complex microbial consortia. In this study, proteomic analysis of the K. vulgare-B. endophyticus consortium was performed to clarify their interaction mode on protein level. A consortium of G. oxydans-K. vulgare-Bacillus was constructed, and the metabolomic and proteomic analyses of the three-bacteria mixed fermentation were conducted to clarify their interaction mode.The approach of iTRAQ-based quantitation was applied to investigate the influence of glutathione on the proteome of K. vulgare. The results suggested that glutathione could promote the transport of thiamin/TPP, enhance the TCA and PPP metabolism, and produce more ATP and NADPH for the cells to resist ROS. In this way, the growth and 2-KGA production of K. vulgare were increased. The approach of 2-DE based proteomics was applied to the time-series study of industrial production process of vitamin C. The sporulation and cell lysis of Bacillus were found to stimulate the expressions of proteins related with ROS resistance, PPP pathyway, sorbose conversion, and cell division(FtsZ). The integration of metabolome and proteome results suggested the sporulation and cell lysis of Bacillus could provide purines for K. vulgare. The proteomic analysis of the experimental evolution of B. cereus-K. vulgare suggested the two strains acquired more power in their respective growth.A consortium consisting of G. oxydans, K. vulgare and B. endophyticus was constructed for the one-step fermentation of 2-KGA from D-sorbitol. The fermentation period was about 30 h, with a yield above 80%, which had the potential to compete with the current two-step fermentation. Metabolomic and proteomic analyses were performed to the three-bacteria consortium. The mix culture could promote the PPP in K. vulgare, and increase the expression of SSDH for sorbose conversion. The consumption of sorbose in G. oxydans for growth was reduced, which could save more sorbose for the conversion of 2-KGA. At the later stage of fermentation, the carbon metabolism pathways including EMP, TCA and PPP were weakened in B. endophyticus. Meanwhile, the sporulation of B. endophyticus was gradually enhanced, which could provide purines for K. vulgare. By the cooperation of these bacteria, the bypass consumption of sorbose was reduced, on the contrary, the production ability of K. vulgare was enhanced, thereby improving the production efficiency from D-sorbitol to 2-keto-gulonic acid(2-KGA).