| Abstract: | A methodical system for directed screening of cultures producing broad-spectrum antibiotics among soil saprophytic coryneform bacteria was developed. To isolate such cultures, it was recommended to use the glucose-yeast medium supplemented with malt extract (No. 18/3) and soybean-glucose medium with sodium sulfate and cobalt chloride (No. 20/3). The preliminary alkaline treatment of the soil substrates and the use of acidic soil samples were found to favour isolation of the Mycobacterium type cultures. It was recommended to use gram-negative tests microbes with relatively low antibiotic resistance for screening cultures producing broad spectrum antibiotics. Various agarized and liquid fermentation media were compared in regard to detection of antibiotic activity in the soil coryneform bacteria. The corn medium supplemented with protein-vitamin concentrate, glucose, lactose and starch (No. 116) proved to be the most efficient. |
