Abstract
The content of vitamin B6 in breast milk measured by the microbiological method has been reported to be 1/2 of the value measured by the HPLC method. In order to confirm this discrepancy, the present experiment was performed. Saccharomyces carlsbergensis is a vitamin B6 auxotrophic yeast that cannot respond to the bound type of vitamin B6, such as pyridoxal 5´-phosphate, but only to the free form of vitamin B6. This discrepancy was found to be due to the fact that pyridoxal 5´-phosphate in breast milk had not been completely converted into the free type by the recommended acid hydrolysis.
