Microbiological analysis of 5-formyltetrahydrofolic acid and other folates using an automatic 96-well plate reader

Anal Biochem. 1986 May 1;154(2):509-15. doi: 10.1016/0003-2697(86)90023-0.


The growth of auxotrophic bacteria remains the method of choice for the determination of biologically active folate metabolites in plasma. This report describes a microbiological assay for folates adapted to use disposable 96-well plates and an automatic plate reader. The modifications in the assay decreased reagent costs and made the analysis of hundreds of samples per day possible with a sensitivity limit of 10 fmol of (6S)-5-formyltetrahydrofolic acid. This limit compares favorably with that of previously reported, more laborious methods. The unnatural 6R diastereomer of 5-formyltetrahydrofolic acid did not interfere with the microbiological assay of the natural 6S diastereomer.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Autoanalysis
  • Biological Assay
  • Folic Acid / blood*
  • Humans
  • Lactobacillus casei / drug effects*
  • Lactobacillus casei / growth & development
  • Leucovorin / blood*
  • Pediococcus / drug effects*
  • Pediococcus / growth & development
  • Stereoisomerism


  • Folic Acid
  • Leucovorin