FURTHER STUDIES OF BACTERIUM GLOBIFORME AND THE INCIDENCE OF THIS TYPE OF ORGANISM IN CANADIAN SOILS

Abstract

Of 90 soils examined, selected from widely separated parts of Canada, 89 showed the presence of Bact. globiforme. In soils more alkaline than pH 5 this organism occurs in large numbers in both fertile and infertile soils. Any increase in numbers in fertile soils is proportional to the increase in total count. In soils more acid than pH 5 Bact. globiforme is severely repressed; application of lime to such soils increases numbers of this organism in preference to other types. Certain pleomorphic forms of Bact. globiforme, commonly observed on artificial media, were not found in soil. On the basis of their N requirements, strains of Bact. globiforme may be divided into 2 types[long dash](1) capable of utilizing nitrates, certain amino acids and urea as N sources, and (2) capable of utilizing only complex N-compounds; the latter type is more prevalent. In soil the organism shows a marked resistance to low temps. and air drying but is destroyed at 45[degree]C in 24 hours.