Production of Mannatide by a-hemolytic Streptococcus Using Batch Fermentation with pH-shift Control

摘要

Mannatide was a glycopeptide with a variety of bioactive compounds and isolated from fermentation broth of cultured alpha-hemolytic streptococci strain H1S-33. The influence of pH value on production of mannatide in batch fermentations was studied. The optimal values for biomass and mannatide production occurred at pH 7.5 and 7.0, reaching 17.91 g/L and 0.77 g/L, respectively, at constant pH in 5-L stirred fermenters. As a result, an effective pH-shift control strategy was established for the fermentation of mannatide in 5-L stirred fermenters. In this strategy, pH was controlled to 7.5 for the first 8 h of fermentation, and then subsequently shifted to 7.0 and maintained until the end of the process. The maximal mannatide production (0.98 g/L) was 27.6, 37.6 and 51.5% higher than that of the fermentation at constant pH 7.0 and 7.5 in 5-L stirred fermenters and initial pH 7.5 in shake flasks by taking the pH-shift control strategy. These findings suggested that pH-shift control in batch fermentations of a-hemolytic Streptococcus H1S-33 could enhance production of mannatide in 5-L stirred fermenters. This study would be helpful for the design of a highly efficient mannatide biosynthesis process.