Continuous-flow automation of the Lactobacillus casei serum folate assay

A method is described for the continuous-flow automation of the serum folate assay using Lactobacillus casei. The total incubation period is approximately four hours. The growth response of the organism to folate is estimated by measuring the rate of reduction of 2,3,5-triphenyl tetrazolium chloride (TTC). A simple continuous culture apparatus is used to grow the inoculum. Supplementation of the assay medium is necessary to obtain parallel results. A statistical assessment shows a favourable comparison with the whole-serum tube assay using a chloramphenicol resistant strain of L. casei. The method is less sensitive to inhibitory substances than the tube assay.