Study On The Mutation Screening And Fermentation Process Optimizationof Rhodopseudomonas Palustris

Co-enzyme Q10(CoQ10)is known as a kind of natural antioxidant,which can eliminate free radical,improves immunity and anti-aging.It is widely used in the field of medical treatment,food,healthcare,and cosmetics industry.In this paper,the Rhodopseudomonas palustris FM-01-12 is used as the original strain for the fermentation of CoQ10.A higher fermentation level mutant strain was obtained by compound mutagenesis and breeding technology and the fermentation process was optimized,and feeding process and operation process were finally optimized in a 50 L fermentor.The main results of the research are as follows:(1)Fistly,Rhodopseudomonas palustris FM-01-12 was mutated by UV-LiCl to improve the tolerance of PHB and roxithromycin.And a higher fermentation level mutant strain of 393 ?g/mL was obtained,which was improved by 26.5%.And the results showed that the strain has good genetic stability after five generations,and it can be used for industrial production.(2)Secondly,the seed flask culture time,rotation speed,volume of liquid,culture temperature and pH were optimized in shake flask culture process,as well as the effect of carbon source,nitrogen source,andinorganic salt concentration on the fermentation of CoQ10.The results showed that the culture time for seed was 23 h,with rotation rate of 218 rpm,temperature 33?,pH 7.0,filling quantity 30 mL/250 mL,inoculation amount 10%,and the fermentation medium concentration was: 0.15% yeast extract,0.5% glucose,1% corn starch powder,0.25% ammonium sulfate,0.25% potassium dihydrogen phosphate,0.2% sodium chloride,0.25%magnesium sulfate,0.8% monosodium glutamate and 0.5% calcium carbonate,0.01% ferrous sulfate,and the fermentation production of CoQ10 can reach to 423 ?g/mL.(3)Finally,the effect of ventilation and stirring speed on the fermentation of CoQ10 was investigated in the 50 L fermentation tank.The fermentation production of CoQ10 was significantly increased when the ventilation volume was 2 vvm and the stirring speed was 300 rpm.In the following fed-batch fermentation process studies,the fermentation period of CoQ10 was extended to 120 h by controlling the concentration of glucose and potassium dihydrogen phosphate and adding fresh medium in the batch fermentation process.The final fermentation conditions were determined as follows: using the optimized medium and the medium filling quantity 30 L,seed culture time 23 h,inoculum concentration 10%,ventilation 2 vvm,mixing speed 300 rpm,glucose concentration 5-10 g/L,potassium dihydrogen phosphate concentration 50-150?g/mL,and the fresh culture medium and fermentation culture medium was added with the ratio of 5:5.The differential inoculation and continuous sterilization process were used in the fermentation process,the fermentation period was 120 h,and the CoQ10 titer could reach to 3158 ?g/mL,which was significantly increased.