Food accessory substances in bacterial growth. I. The influence of initial hydrogen ion concentration of media on the growth promoting effect of tomato extract.

Abstract

It seems from a review of the literature bearing on the question of the role of vitamins in bacterial growth that nobody has investigated the influence of Hydrogen ion concentration of media on the growth promoting effect of these factors. The purpose of the present work was to study this relationship.As tomatoes have been shown by Thjotta and Avery1 to contain food accessory substances for bacteria, the growth promoting effect of tomato extract adjusted to pH 7.0 upon the growth of B. Shiga in media of pH range 5.4-9.0 was investigated.It was found2 that this extract is not able to promote the growth of B. Shiga in broth at initial pH 5.2-6.2, that it has a moderate growth accelerating effect on this microorganism at initial pH 6.6-7.8 and has the best effect when added to broth having a pH 8.2-8.6. Furthermore it may be pointed out that the best growth of B. Shiga, in the presence of tomato extract, occurs at a pH (8.2-8.6) which is by itself an unfavorable one for the multiplication of this microorgani...