The production and role of antibiotics in soil.

properties, structure, mechanism of action and biosynthesis. During a relatively short period in the late 1940's and early fifties there was a flush of activity on the question of the role of antibiotics in nature. This interest stemmed in the main from investigators who were seeking to understand the mechanism of microbial antagonisms in soil and its relationship to soil-borne plant diseases. At present there is a renewed interest in the role that antibiotics play in their ecology of soil and in the life of the microbes that produce them. Most soils, whether cultivated, grazed or forested contain large numbers of microbes70). BRIAN') has estimated that one gram of surface soil contains the following populations: Bacteria I to 100 million Fungi 50 thousand to a million Actinomycetes 1 to 10 million Algae 10 thousand to 50 thousand Protozoa 100 thousand to a million Their numbers vary a great deal depending on soil type, depth of the soil, season of the year, rainfall and temperature97.T0). Under extreme conditions, such as in tundra, salt flats, and barren soil due to high or low temperatures, or moisture, the population of the soil is relatively homogeneous and their numbers greatly reduced.