Screening And Fermentation Optimization Of Microorganisms Transforming Ginsenosides

Ginsenosides are the main active substances of traditional Chinese medicine ginseng.Compared with ginsenosides,rare ginsenosides have better biological activity and are more conducive to body absorption.They have sedative and hypnotic properties,promote cell differentiation and proliferation,anti-tumor,lower blood sugar,and enhance immunity.Force and other effects.However,the structure of rare ginsenosides is complex and the content in ginseng is extremely low,which limits its development and utilization.With the development of biotechnology,the use of biotransformation to synthesize rare ginsenosides has become a research hotspot in this field.In order to solve the problem of producing rare ginsenosides from the perspective of biotransformation,soil was collected from the Jilin ginseng breeding base to screen strains that can transform ginsenosides.116 strains of bacteria were screened through the medium,including 47 strains of fungi and 69 strains of bacteria.With the help of E-R2 A screening medium,62 strains of glycosidase-producing strains(fungi 34,bacteria 28)were screened.The p NPG method was used to determine the enzyme activity of 62 strains,20 strains with higher enzyme activity were selected for transformation experiments,and the three ginsenosides Rb1,Rg1 and Re with higher content in ginseng were used as substrates for transformation experiments.The strain can transform ginsenoside Rb1 into rare ginsenoside PPD strain LD47,the transformation path: Rb1→Rd→F2→CK→PPD.The 16 S r DNA strain development tree identified the strain LD47 as Bacillus tequilensis LD47 with an enzyme activity of 1.28 U/m L.It is a type I glycosidase,which can hydrolyze the glucoside of the glycosidic bond connected to the C3 and C20 positions of ginsenoside.In the conversion experiment,the conversion rate of Rb1 to PPD was 31.21%when the temperature was 30℃,the rotation speed was 180 rpm,and the p H was 7.Through response surface analysis,the Plackett-Burman test was designed to screen out the four key factors of p H,nitrogen source addition,temperature and carbon source addition from the six factors.The Box-Behnken test design was used to optimize the transformation experiment with four factors and three levels,and the best conditions were obtained: temperature 30℃,p H 8,carbon source addition amount of5 g/L,nitrogen source addition amount of 16 g/L,The rotation speed is 210 rpm and the addition amount of sodium chloride is 10 g/L.Under these conditions,the predicted maximum theoretical value of the enzyme activity is 1.50 U/m L,and the conversion rate is 39.40%.After fermentation verification,the enzyme activity is 1.49U/m L,the conversion rate is 38.45%,the relative error of the enzyme activity is2.56%,and the relative error of the conversion rate is 2.47%,and the difference is not significant.