Primycin, a New Antibiotic

Abstract

FROM the intestinal tract and the fæces of a strain of the larvæ of the wax moth (Galeria melonella), a micro-organism producing an antibiotic has been isolated. Morphologically, it belongs to the Actinomycetes, grows readily and spores abundantly on slightly alkaline nutrient agar, potato agar and asparagine agar, with an optimal yield of the antibiotic in a liquid medium containing 2–4 per cent corn-steep liquor and 1 per cent glucose. At 37° C. a surface culture on the latter medium begins to produce the antibiotic on the third day, with a maximal yield from the sixth to the ninth days. During growth the initial pH 7.4–7.6 of the medium rises to 8–8.5, accompanied by a steady decrease of carbohydrate and nitrogen concentration. At the peak of production a rapid lysis of mycelium takes place; but on further incubation the antibiotic concentration of the medium is not reduced.