Function of Bacteria as Vitamin B12 Producers during Mass Culture of the Rotifer Brachionus plicatilis

Abstract

The balance of vitamin B12in massculture of the rotifer Brachionus plicatilis was calculated for both batch and semicontinuous cultures after the evaluation of B12concentrations in Nannochloropsis, yeast, rotifer and culture water. The B12output, which is taken as the total of B12 harvested and left remaining in a tank, was 1.6-2.2 times larger than the B12 introduced with food, water and inoculutn. On the other hand, among 100 bacterial strains isolated from rotifer tanks, 35 had B12 productivity and 19 of them promoted the growth of the rotifer effectively when supplied with yeast. Calculated from the feeding rate, the B12content of bacteria and the B12 demand of the rotifer, it is proved that the greater part of B12, the essential vitamin to the rotifer is produced by bacteria existing in water, and excess amount was transferred to the rotifer automatically by grazing. © 1989, The Japanese Society of Fisheries Science. All rights reserved.