Abstract
Various extraction procedures have been employed for the microbiological determination of vitamin B_<12> in the past. In view of the toxicity of sodium acetate to Ochromonas malhamensis, comparative investigations were made on the liberating procedures of vitamin B_<12> from natural materials using Escherichia coli, Lactobacillus leichmannii and Ochromonas malhamensis as test organisms. The results indicate that KCN method seems to be most suitable for the extraction of vitamin B_<12>, since the highest vitamin B_<12> values were obtained in the determination with any test organism used.
