LAUSR

This study investigated the effect of various concentrations of pteroyl-mono-γ-glutamate (PteGlu1) and pteroyl-di-γ-glutamate (PteGlu2) on the growth of Lactobacillus rhamnosus strains ATCC 7469 (wild-type strain) and ATCC 27773 (chloramphenicol-resistant strain) used for folate microbiological assays. At concentrations of 0.025-0.20 nmol/L, the growth of the chloramphenicol-resistant strain was stimulated to a greater extent by PteGlu1 than by PteGlu2, but the wild-type strain did not show such phenomena. L. rhamnosus ATCC 27773 bioassays were used to determine the total folate content of various foods treated with a chicken pancreas folate conjugase. This showed a significantly lower value when PteGlu1 was used as a calibrator than with PteGlu2. These results indicated that PteGlu2 should be the standard folate compound when chicken pancreas folate conjugase is used in preparing samples for L. rhamnosus ATCC 27773 bioassay.