Research On Effects Of Carbon And Nitrogen Resource And Other Components Of Medium On VB₁₂ Production

In this work, we studied the effect of carbon resource, nitrogen resource, temperature, pH and other factors on fermentation and researched the influence of supplemented A, ammonia and propionic acid on VB12 production.1. Screening of carbon resourceThe result showed that carbon resource A was the best for VB12 fermentation.2. The effect of initial concentration of A on fermentationThe results showed that initial concentration of A drastically influenced the biomass and biosynthesis of VB12. Wjth the increase of initial concentration of A, the growth rate decreased during exponent phase, and the biomass changed from lower to higher and to lower again. And the same change to the biosynthesis of VB12. 'When initial concentration of A was 7% or beyond, the biomass and VBn production was repressed.3. The influence of supplemented A on VB12 productionThe experiment results showed that supplemented A could promote VB12 production, and the promotion effect may be caused by the increase of biomass or the elimination of feedback inhibition to VB12 biosynthesis. When concentration of A was sustained about 4% and was maintained about 20-30h, fermentation titer was improved largely.4. Screening of nitrogen resourceThe results showed that nitrogen resource B was the best for VB12 fermentation.5. The influence of supplemented ammonia on VB12 productionThe result showed that supplemented ammonia was beneficial to improve the biomass and fermentation titer of VB12. But if the feeding time was beyond 90h and last the whole period of fermentation, the fermentation titer fell.6. Analysis of the components of nitrogen resource BNitrogen resource B from different firm had different effect on VB12 fermentation. We analyzed the content of protein and the kinds and the content of amino acids of B in order to find the cause that led to the difference. But the resultsdid not tell the difference.7. The change of amino nitrogen vs. timeWe studied the change of amino nitrogen vs. time. The results showed that initial concentration of A and inoculums quantity both had influence on the change of amino nitrogen.8. We also researched the influence of temperature and pH on the growth and the change of A. And the effect of VBn precursor on the VB12 fermentation9. Other additional components on the VB12 fermentation was studied too.10. propionic acid on the VB12 fermentationThe results showed that propionic acid had bad effect on VB12 fermentation.