Influence of the amino acids of synthetic media upon the response of Lactobacillus leichmannii to vitamin B12.

The use of potassium cyanide in the lactobacillus leichmannii assay for vitamin B12.

Studies by several investigators (Stokstad, Dornbush, Franklin, Hoffmann, Hutchings, and Jukes, 1949; Skeggs, Nepple, Valentik, Huff, and Wright, 1950) have indicated that an increased growth response was obtained to liver concentrates with thioglycolic or thiomalic acids when vitamin B12 activity was determined with Lactobacillus leichmannii. This was attributed to the prevention, by such redu...

Extraction of serum vitamin B12 for radio-isotopic and Lactobacillus leichmannii assay.

The protein precipitates discarded during the extraction process of the Lactobacillus leichmannii vitamin B12 assay have been shown to contain significant amounts of vitamin B12. This loss of vitamin B12 provide a satisfactory explanation for many of the descrepancies between the serum vitamin B12 values obtained by the L. leichmannii method and the radio-isotopic method of Raven et al (1969). ...

Relationship between vitamin B12 oxidation product and sodium chloride toxicity for lactobacilli.

Beiler et al. (1951) reported that oxidation of vitamin B12 by hydrogen peroxide under strongly acid conditions resulted in the production of a colorless product which inhibited the vitamin B12 requiring microorganism, Lactobacillus leichmannii (ATCC 4797). Such inhibition was antagonized competitively by vitamin B12. Since we had observed that hydrogen peroxide itself competitively inhibited g...

The role of vitamin B12 in thymine biosynthesis by Lactobacillus leichmannii.

The biochemistry of vitamin Biz has been the subject of several recent reviews (1, 2, 3). Evidence currently available indicates that the vitamin is required for the reduction of formate to methionine and choline methyl. Indirect evidence implicates vitamin Biz in thymine biosynthesis. Thymine will replace the Blz requirements in certain microorganisms (3) and will induce a reticulocyte respons...

The microbiological assay of vitamin B12 with Lactobacillus leichmannii.