SUMMARY: The production of licheniformin-like antibacterial activity in culture by a single strain of required neutral or alkaline conditions, conveniently attained by the use of lactate rather than glucose as a source of carbon in a chemically defined medium.

When the medium contained initially about 0.04-0.10% nitrogen, supplied as asparagine or as ammonium lactate, and the cultures, harvested after 4-9 days at 37°, were sterilized by bringing to pH 2.5 and autoclaving, the inhibitory dilution against a test strain of was 1/160 or greater.

Fluid from cultures in a chemically defined medium, containing 0.06 m ammonium lactate and 0.05 m sodium lactate, inhibited the test organism at a dilution of 1/200-1200 (geometric mean, 530) in 44 consecutive batches of 100-200 1. culture fluid produced by incubation of cultures in shallow layers. The pH value of the harvested fluid was about 9 and the antibiotic material was partly bound by the cells. It was largely freed by adjustment to pH 2.5.

When amino-acids were added to the medium either as a mixture of known amino-acids, or as a casein hydrolysate. the maximum titre was attained earlier, but with no significant change in its value. A similar result was obtained with yeast extract added alone or with casein hydrolysate.


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