Determination of Vitamin B12 With an Escherichia Coli Mutant

1 February 1958

journal article
research article
Published by Oxford University Press (OUP) in Clinical Chemistry

Vol. 4 (1) , 22-26
https://doi.org/10.1093/clinchem/4.1.22

Abstract

An improved method for the determination of vitamin B₁₂, using a more sensitive mutant of Escherichia coli, which enables determination of 4-20 µµg./ml. of the vitamin, has been described. Comparative determinations of vitamin B₁₂ content of human sera and of animal tissue extracts gave similar values when assayed with both E. coli and O. malhamensis. Although O. malhamensis is more specific in its response to cyanocobalamin than E. coli, the latter organism seems just as reliable for determination of vitamin B₁₂ in serum and in tissue of human and animal origin. The simplicity, rapidity, and sensitivity of the improved E. coli assay make it very suitable for clinical use.

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