The Viability of B. Coli and B. Aerogenes in Soil

Abstract

Very large numbers of Bacterium are introduced into the soil in the process of manuring. Little is known as to the viability of these bacteria in soils. We know something of their viability in water, and Murray 1 has shown that in manure piles they are rapidly crowded out by other organisms. If the soil harbors for long periods of time, it is evident that bacteria in soils will be found in surface water draining from those soils. If, on the othei hand, rapidly disappears from soils, the presence of this organism in water is a better index of human fecal pollution. It is now well established that the so-called which are found in the feces of warm blooded animals and most of those found in soil differ in certain cultural characteristics.2 The fecal colon bacilli are largely Bacterium coli, the methyl red positive and Voges-Proskauer negative organism, while in the soil most of the organisms of this group are found to be Bacterium aerogenes, an organism showing opposite methyl red and Voges-Proskauer characters. Possibly neither of these organisms is a single species, but, following Levine,2 they will be grouped as single species. According to Koser,3 the relatively few that are found in soil differ from the fecal strains in that they possess the ability of using citrates as a source of energy. That aerogenes in soil may in some cases be the B. coli found in routine water analysis has been known for some time. aerogenes is present in most soils,2 but not in very large numbers. Their function there is known, although Pillai 4 has demonstrated significant nitrogen fixation by Bacterium pneumoniae, which he considers identical or closely allied to aerogenes. did not fix nitrogen.