GB715362A - Improvements in or relating to antimicrobial agent - Google Patents

Abstract

An antibiotic P.A.94 is produced by cultivating a strain of Streptomyces lavendulae, No. 8197-20, which is described, in an aqueous nutrient-containing solution under submerged aerobic conditions at a temperature of 25-30 DEG C. for 2 to 4 days and then recovering the antibiotic from the fermentation broth. Specified nutrients are carbohydrates such as sugars, starch and glycerol; organic nitrogen such as soyabean meal, cottonseed meal, alfalfa meal, corn steep liquor, hydrolyzates of casein and other proteins; growth substances such as distillers' solubles, yeast extract and Vitamin B concentrates; mineral salts such as sodium chloride, potassium phosphate, sodium nitrate and calcium carbonate. After the removal of the mycelium by filtration and, if desired, a preliminary treatment with activated carbon at an acid, e.g. pH 2.0, or alkaline, e.g. pH 10.0, pH the antibiotic is isolated from the culture liquid by (a) adsorption on acidic cationic exchange resins, preferably at a pH 3.0-7.0; or (b) solvent extraction by water-immiscible alcohols, e.g. butanol and benzyl alcohol after the addition to the culture liquid of a strong organic acid such as p-toluenesulphonic acid. The resins used in the adsorption step are phenol formaldehyde resins containing sulphonic acid groups introduced by adding a sulphite during formation of the resin, e.g. Amberlite IR 120 (Registered Trade Mark); or they are sulphonated hydrocarbon polymers or polymers prepared from sulphonated phenols and formaldehyde. The antibiotic is eluted from the resin by means of dilute aqueous alkali, e.g. 0.5-3 per cent aqueous ammonia; sodium hydroxide, potassium hydroxide and strong organic bases. The antibiotic recovered from the eluate may be further purified by dissolving in water or aqueous methanol and passing down a column of a basic anion-exchange resin, alumina, silica gel or other metallic oxide. As a further purification step (a) acetone may be added to a methanol solution to precipitate impurities; (b) antibiotic may be precipitated by the addition of ethanol to aqueous solution; and (c) a carbon treatment may be given at any stage. The antibiotic P.A.94 is an amphoteric substance effective in inhibiting the growth of mycobacteria. It is soluble in water and methanol. It contains C, H, O, N in the proportions C = 34.8 per cent, H = 5.8 per cent, N = 26.9 per cent and 0 = 32.5 per cent. [a ]D25 = 640 (methanol). It exhibits a characteristic infrared absorption spectrum.