Abstract
In this review, the transformation of vitamin B_6,the formation of pyridoxine glucoside, and the extracellular formation of vitamin B_6 in microorganisms are described. Pyridoxine (PIN) was oxidized to pyridoxal (PAL) by baker's yeast in the presence of semicarbazide. The yield of PAL semicarbozone formed from PIN was about 80%. A new phosphorylating reaction of vitamin B_6 which phosphorylated PIN through the transfer of a phosphoryl group from ρ-nitrophenylphosphate and other phosphate donors was found in various kinds of microorganisms. The enzyme catalyzing the transphosphorylation was purified to a crystalline from the cell extract of Escherichia freundii. It was recognized that the transphosphorylation might be catalyzed by the acid phosphatase. Pyridoxine phosphate (PINP) oxidase was purified from Alkaligenes faecalis and Azotobacter agilis and it was confirmed that PINP and pyridoxamine phosphate (PAMP) were oxidized to pyridoxal phosphate (PALP) by the same enzyme, requiring FMN as a coenzyme. It was suggested that the PINP oxidase might be used in the industrial production of PALP from PINP in the presence of some amino acids forming Schiff's compound of PALP. In some anaerobic bacteria, it was found that a new enzyme, PAMP-α-KGA aminotransferase, catalyzed the transamination between PAMP and α-KGA. The enzyme was purified from Clostridium kainantoi. Different enzyme systems in aerobic and anaerobic bacteria were suggested with regard to the formation of PALP. The formation of pyridoxine glucoside (PING) was found in the culture broth of Sarcina and Micrococcus, grown on medium containing sucrose and PIN. The enzyme which catalyzed the transglucosidation to form PING was purified from Micrococcus sp. and characterized. The extracellular formation of vitamin B_6 was searched in marine and terrestrial microorganisms. Marine microorganisms showed considerable formation of vitamin B_6 and the presence of vitamin B_6 in sea water was recognized.
