Study On The One-step Fermentation System Of Vitamin C

The two-step fermentation is the main method for the production of vitamin C in China.Due to the high production efficiency of the two-step fermentation,there are difficulties in the further improvement of production.At the same time,the process is tedious and energy consumption is high.If we can develop the one-step fermentation instead,it can significantly save energy consumption,reduce pollution,and improve economic efficiency.In the present research,we try to construct and optimize the one-step fermentation system by adding glutathione(GSH)into one-step fermentation of Ketogulonicigenium vulgare-Gluconobacter oxydans,constructing the one-step fermentation of K.vulgare-G.oxydans-Bacillus endophyticus,and constructing the lysis and knowdown modules in B.endophyticus for one-step fermentation improvement.Firstly,this research aims to find the effect of GSH on the two bacteria K.vulgare and G.oxydans in vitamin C one-step fermentation process.It was found that addition of 1 mg/ml glutathione to the 5 L fermentation by K.vulgare-G.oxydans consortium significantly enhanced the production of 2-KGA by 22.8 %.According to the 16 S rDNA realtime fluorescence quantitative PCR analysis,the final biomass of K.vulgare increased to 148 % and G.oxydans decreased to 61 % relative to the control strain.Using the metabolomics methods,we found that GSH could promote pentose phosphate pathway,citric acid cycle,the sulfate and other metabolic pathways of K.vulgare,and it can at the same time slow down the consumption of L-sorbose by G.oxydans to improve fermentation efficiency of the consortium.Secondly,the one-step fermentation including K.vulgare,G.oxydans and B.endophyticus was constructed and improved by optimizing the fermentation conditions.The alcohol conversion rate had reached 81.89 % in the fed-batch fermentation process while it had reached 87.90 % in the batch fermentation.And they could grow fast under D-sorbitol,and 10 hours later of the fermentation process,B.endophyticus could consume D-sorbitol constantly.The knockdown of sorbitol dehydrogenase gene was done and we found the waste of sorbitol decreased;And it worked when the sorbitol dehydrogenase gene from G.oxydans was imported to Bacillus sp;And the lysis module could work in specific time periods,while cell biomass was reduced by about 18-27 %.The research laid a foundation for further optimization of the one-step fermentation of three trains.