クロレラによるビタミンB12の取り込みについて〔英文〕

概要

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The development of the capacity to store vitamin B12 is necessary for improvement in the dietary value of Chlorella as a food for mass production of the rotifer Brachionus plicatilis. In the present study, the uptake of vitamin B12 by fresh-water Chlorella was investigated under controlled culture conditions.The vitamin B12 content of nine Chlorella strains grown in a medium without enrichment of vitamin B12 were at less than 0.26μg/100g, regardless of the culture methods of autotrophy, mixotrophy and heterotrophy. The test of vitamin B12 uptake from the medium clarified that the strains were divided into two groups. The first group was composed of 5 strains and has the ability to take up more than 81% of the vitamin B12 which had been added to the medium. The other group of 4 strains took up less than 19% of the vitamin B12 supplied. The former group has no ability to produce secondary carotenoids, which are related to the structure and composition of cell walls, while the latter group has the ability.The addition of vitamin B12 at various concentrations into the culture medium makes it possible for Chlorella vulgaris K-22 to store vitamin B12 in the cells at various levels from 0.2 to 1100μg/100g. The vitamin B12 content of cells remained virtually unchanged during a thirty-day cold storage and during a three-day suspension in artificial sea water.