An attempt to classify the growth responses in bacteria to various B vitamins.

Abstract

The growth responses of bacteria to various B vitamins were found to be classified into four groups. In Type I the growth is affected only in shortening the lag phase of cultural development, in Type II the rate of logarithmic growth and the yield of final population are promoted, and in Type III only the final yield is enhanced leaving other phases of growth unaffected. These types of growth promotion seemed not to be a fixed character of a vitamin. Several examples showing the variability of the type for a vitamin according to the cultural conditions were presented. Physiological interpretation of these types of growth promotion was discussed. Finally, importance of the choice of test system for the turbidimetric bioassay of vitamin was suggested from the view-point of the proposed types of growth promotion.