Study On The Transformation Of Phytosterol To 9?-hydroxy-4-androstene-3,17-dione By Mycobacterium Sp.BFZ304

The transformation of sterol to 9a-hydroxy-4-androstene-3,17-dione(9?-OH-AD)by microorganism,such as Mycobacteria,is one of the important technological rotute to produce steroidal medicines in the pharmaceutical industry.The influence of different carbon sources,nitrogen source,phosphate on 9?-OH-AD producted by Mycobacterium sp.BFZ304 was studied.On the base of single factors experiments,using 9a-OH-AD production as index response surface analysis was applied to optimize the fermentation medium composition.The quadratic regression analysis was applied to get the optimal level of main factors(corn steep liquor,glucose,NaNO3?(NH4)2HPO4).Finally determined the optimal medium as follows:corn steep liquor 40g/L,glucose 10g/L,NaN036g/L,(NH4)2HPO40.7g/L.Under these optimal conditions,the production of the 9?-OH-AD was high up to 4.86g/L when the concentration of the feeding was 10g/L,increased by 40%compared with the original medium.Then screening using the optimal medium for fermentation conditions such as initial pH,inoculum size,shake bottled liquid vol-ume,feeding methods,Optimization results are as follows:pH was adjusted to 7.0 before sterilization,inoculation amount to 4%of the inoculation,liquid volume in flask was 50mL and the incubation temperature was 30 ?.Then take advantage of the optimized medium composition and transformation conditions on the ability to verify the strain transformed,the result is:the feeding concen tration of 10 g/L under the circumstances,the substrate conversion rate can be as high as 80%;Finally,By adding accelerator,10 g/L feed con-centration conversion rate of 95%.