Abstract
The present study was undertaken in order to obtain exact information about activity of hydroxocobalamin for Ochromonas malhamensis. When autoclaved together with Ford's assay medium in which cyanide was absent, hydroxocobalamin gave only approximately 20% of the response of cyanocobalamin. However, when autoclaving was conducted in the presence of ascorbate, difference was not observed in activities between hydroxocobalamin and cyanocobalamin. Also, the loss of activity in case of hydroxocobalamin could be avoided by employing the aseptic addition procedure. It is concluded from these results that hydroxocobalamin is as effective as cyanocobalamin on Ochromonas malhamensis.
