Growth accessory substances in the nutrition of bacteria

Abstract

In studying the growth characteristics of mucoid bacilli Thjotta observed that B. influenzœ will grow in blood-free broth containing the mucoid material from cultures of Friedlander's bacillus and other closely allied organisms. The growth accessory substance or substances which can replace blood and blood derivatives in the cultivation of Pfeiffer's bacillus Thjotta found in both the saline suspensions and watery extracts of the heat killed bacillary material. Furthermore, these bacterial emulsions and extracts can be boiled for ten minutes and filtered through Berkefeld candles without losing their growth-inducing properties. It was thought not unlikely that the growth-stimulating effect of these bacterial extracts might be due to substances belonging to the class of the so-called vitamines. To test this assumption, similar extracts were prepared from yeast cells which are known to be rich in growth accessory substances. These extracts, even in minute amounts, were found capable of promoting growth. Extraction of the growth accessory substances from another source, namely, green vegetables, was tried; extracts of fresh tomatoes, green peas and string beans were found remarkably active in stimulating growth. These active yeast or vegetable extracts when added to broth greatly accelerate growth of organisms such as Bacillus influenzœ and pneumococci, so that within five hours abundant growth is evident. In the case of pneumococcus, a seeding too minute to initiate growth in plain broth alone will amply suffice to induce abundant growth in the same medium if a small amount of extract containing these growth accessory substances is added. In the case of Bacillus influenzœ, when seeded from blood media, luxuriant growth occurs in plain broth containing yeast extract, while no growth takes place in the same broth without the addition of extract.