Abstract
Studies on the manufacture of crystalline vitamin B_<12> from activated sludge are now in progress in our laboratory. On the other hand, a search is made for vitamin B_<12> resources in Japan other than the activated sludge. The supernatant liquor running from the night soil digestion plant was found to be a superior raw material for the preparation of vitamin B_<12> to the activated sludge. The vitamin content of the solid portion obtained by centrifugation of the former (composed chiefly of bacterial cells) was 30-40 μg/g on dry basis, while that of activated sludge was 4-8 μg/g.
