A Study of the so-called Implantation of the Bacillus Bulgaricus

Abstract

ing bacilli found in the fermented milk Yahourth were able to check the growth of putrefactive bacteria in the intestines, in all the articles published in attempted confirmation of his claims, the methods used to identify the bacillus are inadequately described. This work was undertaken with the purpose of determining, in the light of a better understanding of the cultural peculiarities of the bacillus bulgaricus, whether or not a true implantation took place. In the human intestine there occur normally bacilli that culturally and morphologically resemble this bacillus very closely. The group of organisms, which includes the bacillus bulgaricus, is distinguished from other groups of bacteria by the ability of its members to grow in media containing considerable amounts of acid; because of this characteristic, these bacilli are called aciduric or acid-tolerant organisms. In a previous paper1 the writer was able to show that, contrary to the usual statement, these bacteria grow luxuriantly in an ordinary laboratory medium, viz., unneutralized meat-peptone broth containing glucose or other suitable carbohydrate, and that agar prepared from this broth, with or without the addition of 0.2 percent of sodium oleate, is an excellent solid medium. It was also shown that while the bacillus bulgaricus, from its cultural and perhaps biochemical properties, also belongs to this group of sugar fermenting, acid-tolerating organisms, it differs from the bacteria of the type of the bacillus acidophilus in failing to ferment maltose. Some strains do not attack saccharose.