2-Keto-L-gulonic acid is prepared directly from D-glucose by microbial conversion utilizing mixed culturing on or mixed contacting with a medium containing D-glucose, employing at least two kind of microorganisms; 2,5-diketo-D-gluconic acid producing strains which belong to the genera of Acetobacter, Acetomonas and Gluconobacter and strains capable of converting the 2,5-diketo-D-gluconic acid into 2-keto-L-gulonic acid which belong to the general of Brevibacterium and Corynebacterium. Both the incubation of the microorganisms in a medium containing D-glucose and the direct contact of any products obtained from the cells of the microorganisms with the substrate may be used in the disclosed process. By-production of the undesired optical isomer, 2-keto-D-gluconic acid, of the intended product is effectively prevented by employing the mixed culturing or contacting because of the presence of the 2,5-diketo-D-gluconic acid producing strain or any products thereof in the medium during at least part of the entire process.
2-酮-L-古洛酸是通过利用混合培养或混合接触含有
D-葡萄糖的
培养基,利用至少两种微
生物进行微
生物转化直接从
D-葡萄糖制备而成的;这两种微
生物分别为能够产生2,5-二酮-
D-葡萄糖酸的Acetobacter、Acetomonas和Gluconobacter属的菌株,以及能够将2,5-二酮-
D-葡萄糖酸转化为2-酮-L-古洛酸的Brevibacterium和Corynebacterium属的菌株。在所披露的过程中,可以使用微
生物在含有
D-葡萄糖的
培养基中的孵育,也可以使用从微
生物细胞中获得的任何产物与底物直接接触。通过采用混合培养或接触,由于2,5-二酮-
D-葡萄糖酸产生菌株或其任何产物在整个过程的至少一部分时间内存在于
培养基中,因此可以有效地防止所期望的产物的非期望光学异构体2-酮-
D-葡萄糖酸的副产生。