Study On Fermentation Process Of Bacillus Subtilis 24A1/pMX45 Producing Riboflavin

The Bacillus subtilis 24A1/pMX45 is a strain whose ccpA gene is knockouted. So when CcpA is deleted, the Carbon catabolite repression (CCR) is destroyed. So fermentation can fit the higher concentration of glucose. This work mainly investigates the effects of inoculum size, several organic nitrogen source and inorganic nitrogen source, dissolve of oxygen, ion on riboflavin fermentation.Riboflavin production is importantly influenced by inoculum size. The lower inoculum size let biomass and riboflavin production increase lower. Increasing inoculum size can short the cycle of fermentation. The standard of seed culture is that OD₆₀₀ should 6.0.when inoculation is 7 %, the yield of riboflavin is the most.Under the basic fermentation culture medium using 2.5% yeast powder as nitrogen source condition, adding urea and ammonium dibasic phosphate can increase riboflavin production and meet the need of nitrogen source. Adding 0.2% urea and 0.4% ammonium dibasic phosphate together can make the riboflavin production as high as 4.0g/L.This work investigates the effects of several organic nitrogen source on riboflavin fermentation and finds yeast power is the optimal nitrogen source. The cottonseed protein is also a good nitrogen source and the other organic nitrogen source is bad. When using yeast power and cottonseed protein together, riboflavin yield is 4.7g/L.By alter cultural medium quantity , this work investigates the effects of dissolve of oxygen on riboflavin fermentation and finds that during 24^th hour dissolve of oxygen is a limit factor. Reducing cultural medium quantity can noticeable increase riboflavin production. When cultural medium quantity is 30ml, riboflavin production is 5.1g/L.Adding calcium chloride to culture medium is of benefit to riboflavin production, but Adding ammiaonia sulfate to culture medium is of disbenefit to riboflavin production.