Determination of Biotin with Lactobacillus arabinosus

The microbiological determination of biotin, using Lactobacillus arabinosus as the test organism, was studied. The existence of a water-soluble, avidin-combinable, form of biotin in certain enzymatically prepared materials which is available to L. casei, but not to L. arabinosus, was demonstrated. When natural materials are autoclaved with 6 N H2SO4, prior to determination of their biotin content, comparable results are obtained with the L. arabinosus method and with a method using L. casei.