The tubercle bacillus discrimination manner null which uses the nutrient medium, and this nutrient medium for niacin test

摘要

PURPOSE:To contrive speeding up and simplifying of niacin tests, by bioassay using a microorganism requiring niacin and a pH indicator. CONSTITUTION:A gelling agent and pH indicator are added to a culture medium for determining niacin and a microorganism requiring the niacin is added thereto at the same time. An acid-fast bacteria to be tested is added to the culture medium and cultivated to observe the change in color of the culture medium. When Lactobacillus fermentum (hereinafter referred to as Lf is cultivated in a liquid culture medium, the relationship between the niacin concentration and the culture medium pH is as follows. The culture medium pH is reduced by growth of Lf according to the amount of the niacin added to the culture medium as shown in the figure and the pH attains an almost constant value at =0.6mug/ml niacin concentration. Thereby the difference in amount of niacin contained in microbial cells in a given amount of tubercle bacillus and atypical acid-fast bacterium is set within the range and a suitable pH indicator can be used to differentiate both.