双相系统中硅藻土固定分枝杆菌转化甾醇的初步研究

Conversion of Sterols into Androst-4-ene-3,17-dione (AD) by Fermentation of Mycobacterium sp. Immobilized on Diatomite in Organic-aqueous System

在双相发酵系统中,将分枝杆菌BD696-6细胞固定在不同载体上,进行降解植物甾醇侧链生成雄烯二酮(AD)效果的研究。结果表明:相对丝瓜布、棉纱布及泡沫,硅藻土有更好的固定化效果。在硅藻土用量7g/L,接种量18%(V/V),甾醇添加量3g/L的实验条件下发酵7d,AD得率达到81.47%,比游离细胞发酵AD得率提高了19.52%。

The microbial fermentation in organic-aqueous system is an effective method for the conservation of sterols into AD, but some related problems such as integrity of bacterial membrane and mass transfer resistance still have not been solved. In the present study, the Mycobacterium sp. BD696-6 immobilized on different carriers was used to convert sterols into AD. Compared to the strains immobilized on vegetable sponge, cotton yarn and bubble, the diatomite-immobilized strain resulted in the highest AD yield. Furthermore the conversion conditions of sterols by the fermentation of the diatomite-immobilized strain were optimized by orthogonal test design. The results showed that the optimal conditions were as follows： addition amount of diatomite to seed culture medium 7 g/L, inoculation amount 18% （V/V）, concentration of sterols in fermentation medium 3 g/L, and fermentation time 7 d; under these conditions, the AD yield was up to 81.47%, which was 19.52% higher than that by the fermentation of the free strain.