RT Journal Article SR Electronic(1) A1 Cuthbertson, W. F. J. A1 Lloyd, Joan T.YR 1951 T1 The Assay of Vitamin B12: I. Factors affecting the Response of Lactobacillus lactis Dorner ATCC 8000 to Vitamin B12 JF Microbiology, VO 5 IS 2 SP 416 OP 420 DO https://doi.org/10.1099/00221287-5-2-416 PB Microbiology Society, SN 1465-2080, AB SUMMARY: For maximal zones of ‘exhibition’ in the plate test for vitamin B12 with Lactobacillus laclis Dorner ATCC 8000, using the media described, the presence of both oxygen and vitamin B12 is necessary. Under anaerobic conditions the vitamin is not an essential growth factor and under highly aerobic conditions growth does not occur even in its presence. Under the conditions of maintenance used variant strains were not detected. When grown in the presence of vitamin B12 the bacteria may store sufficient of the vitamin to render measurements of growth useless for assay purposes: when grown under anaerobic conditions the culture obtained is unsuitable for use as an inoculum. A technique for preparing satisfactory inocula of the test organisms and the conditions necessary for well-defined responses to vitamin B12 are described., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-5-2-416