SOME CULTURAL CHARACTERS OF BACILLUS ABORTUS (BANG) WITH SPECIAL REFERENCE TO CO2 REQUIREMENTS

Abstract

The relative absence of saprophytism in freshly isolated strains of Bacillus abortus is conveniently measured by inoculating a series of agar tubes with. successive dilutions of culture and sealing the tubes. The appearance of films of growth is delayed from 3 to 17 days and suppressed with the increase in the dilutions. As many as 100,000 bacteria per sq. cm. of agar surface are suppressed. When the confined air contains CO2 in a concentration as low as ¼ per cent and up to 10 per cent, the inhibition and suppression do not occur. Concentrations down to 0.1 per cent are still capable, even though in a slightly retarded manner, of bringing high dilutions into growth. In all cases the resulting growth was remarkably vigorous when compared with that in sealed tubes.