Abstract
In the preceding paper, transformation of exogenously added cyanocobalamin to DBCC was observed during thermophilic methane fermentation and the yield of DBCC in the bacterial cells was about 20% of the amount of cyanocobalamin supplied. This paper deals with vitamin B_<12> and related compounds in the cultural filtrate. Vitamin B_<12>-active substances in the filtrate were adsorbed on active charcoal, eluted with 80% ethanol and fractionated by DEAE-cellulose column chromatography after usual phenol treatment. The fractions were eluted successively with water (tentatively named DS-1), 0.1 N acetate buffer (pH 4.7)(DS-2), and 0.1 M NaCl-acetone mixture and studied by paper ionophoresis, absoprtion spectroscopy and coenzyme activity in Abeles・Lee's system. In fraction DS-1,the presence of small amount of DBCC together with hydroxocobalamin and cyanocobalamin was observed. In addition to these known forms of vitamin B_<12>, an unidentified yellow substance was detected, but detailed studies were not performed. In fraction DS-2,another unidentified yellow substance, slightly moved to cathode side in paper ionophoresis in 0.5 N acetic acid, was detected. Its yellow color changed to red by light irradiation. Though the lability in light is analogous to cobamide coenzyme, fraction DS-2 did not show coenzyme activity in Abeles・Lee's system.
