[Dynamics of populations of microbial antagonists in nonsterile soil]

The interaction between populations was studied with Arthrobacter crystallopoietes and Streptomyces olivocinereus, an actinomycete producing the antibiotic heliomycin active against Gram-positive microorganisms. The two organisms were either cultivated together in a growth medium or the two populations were introduced simultaneously into nonsterile soil at different levels of population density. The antagonism was found in both cases: A. crystallopoietes cells died off when a population of the potential antagonist was added. The density of a population producing the antibiotic had to be sufficiently high for the antagonism to be manifested. The antagonism influenced the dynamics of a population of the antibiotic-sensitive microorganism. The results have confirmed earlier data to the effect that antibiotic synthesis is possible in nonsterile soil.