<PICT:0815518/IV (b)/1> <PICT:0815518/IV (b)/2> <PICT:0815518/IV (b)/3> Novobiocin, also known as streptonivicin, a substance effective against Gram-positive and Gram-negative bacteria, is produced by growing a streptonivicin-producing strain of Streptomyces nivens, especially S. nivens NRLL2466, in an aqueous nutrient medium containing assimilable carbon and nitrogen under aerobic conditions of surface or submerged culture. The pH of the medium is adjusted to pH 7.5 to 8.5 and preferably 8.0, inoculation is with a vegetative inoculum, the temperature of cultivation is 24 DEG to 32 DEG C. and preferably 28 DEG C. and the duration is 2 to 6 days. Carbon sources are carbohydrates such as glucose, sucrose, dextrin, a mixture of glucose and starch, molasses, maltose, fructose, insulin, raffinose, lactose and glycerol. Nitrogen sources are distillers' solubles, cottonseed meal, egg products, e.g. whole egg, brewers' yeast, peanut meal, soybean meal, corn gluten meal, beef extract, meal and bone scraps, animal stick liquor, guar seed meal protein, corn steep liquor, fish meal, linseed meal, dried sewage, liver meal, yeast extract and milk proteins. Nutrient inorganic salts are such as yield ions of sodium, potassium, calcium, phosphate and sulphate; nitrates and ammonium salts. Trace elements may be present. Novobiocin is recovered from the broth by (a) acidification to e.g. pH 2.0 with e.g. H2SO4 to produce a precipitate, (b) extraction with a water-immiscible solvent, or (c) adsorption. For extraction the broth may be clarified at a pH of 7 to 10 and preferably 8.0 the pH then adjusted to 2 to 7 and preferably 6.0, the antibiotic extracted into a water immiscible alkanol, e.g. n-butanol, alkyl acetate, e.g. amyl acetate, ketone, e.g. methyl isobutyl ketone, the extract concentrated and the antibiotic precipitated by means of a non-solvent such as hexane or heptane; (c) adsorption on an anion exchange resin and elution with e.g. aqueous alcohol. Novobiocin forms acid and neutral salts with inorganic and organic bases. These are formed by reacting novobiocin with the base, or a salt of novobiocin with a salt of the base. Alternatively, novobiocin may be reacted with (a) an alkoxide such as sodium methoxide, or (b) a salt of a weak acid, e.g. alkali metal carbonate, bicarbonate or acetate. Specified salts are the alkali metal such as sodium or potassium, alkaline earth metal such as calcium and barium, ammonium, and salts with mono-, di- and tri-methyl (ethyl or propyl) amines, ethyldimethylamine, benzyldiethylamine, cyclohexylamine, benzylamine, dibenzylamine, N,N1 dibenzylethylene diamine, bis (ortho methoxyphenyl isopropyl) amine; piperidine, morpholine, pyrrolidine, piperazine, 1-methylpiperidine, 4 - ethylmorpholine, 1 - isopropylpyrrolidine, 1,4 - dimethylpiperidine, 1 - ethyl-2 - methylpiperidine; mono -, di -, tri - ethanolamines, ethyldiethanolamine, n-butylmonoethanolamine, 2 - amino - 1 - butanol, 2-animo - 2 - ethyl - 1,3 propanediol, 2 - amino-2 - methyl - 1 - propanol, tris - (hydroxymethyl) - aminomethane, phenylmonoethanolamine, p - tertiaryamylphenyldiethanolamine; galactamine, N - methylglucamine, N - methylglucosamine, ephedrine, phenylephedrine, adrenaline, procaine, guanidine and tetraethylammonium hydroxide. Novobiocin forms (a) salts with the antibiotics neomycin, erythromycin and the tetracyclines (b) alkyl derivatives with diazoalkanes such as diazomethane and (c) acyl derivatives with acid anhydrides such as acetic anhydride or acid chlorides. Novobiocin is used medicinally (see Group VI) as an animal feed supplement (see Group I) in the sugar industry and in agriculture. Novobiocin has the following structure <FORM:0815518/IV (b)/1> where R is <FORM:0815518/IV (b)/2> It is effective against Gram positive and Gram negative bacteria; has an optical rotation <FORM:0815518/IV (b)/3> (1 per cent ethanol) is soluble in alkanols, alkyl acetates, methyl ethyl ketone and acetone and in water of pH above 7.5 the solubility decreasing from pH 90-5.0; contains C = 59.69 per cent, H = 6.66 per cent, N = 4.48 per cent, O = 29.17 per cent; empirical formula C30-32 H38-22O11-12N2; molecular weight 618; has two acidic groups pKa, 5.7 and pKa, 11.9, in dimethylformamide; exists in two crystal forms; Form 1 melting between 174 DEG and 178 DEG C. and having the infra-red absorption spectrum shown in Fig. 3, and Form 2 of melting point 152 DEG to 156 DEG C. and having the absorption spectrum shown in Fig. 2. Vitamin B12 is obtained by fermenting Streptomyces nivens NRLL2466 in a nutrient medium containing cobalt ions, e.g. cobalt nitrate. A steroid such as progesterone or Reichstein's Compound S or S acetate may be oxidized in the 11 position in a medium containing S. nivens NRLL2466. Novobiocin treated with acetic anhydride is cleared into (a) a neutral compound and (b) 3-(2-isopentenyl)-4-acetoxybenzoic acid which may be catalytically hydrogenated to 3-isoamyl-4-acetoxybenzoic acid or treated with alcoholic sodium hydroxide to produce 3-(2-isopentenyl)-4-hydroxybenzoic acid. Reaction of 3-(2-isopentenyl)4-acetoxybenzoic acid with ethanolic hydrochloric acid produces 2,2-dimethyl-6-chromancarboxylic acid. Acid hydrolysis of novobiocin produces an acid which on treatment with acetic anhydride yields a neutral compound and 2,2-dimethyl-6-chromancarboxylic acid. Specification 695,273 is referred to.ALSO:Novobiocin (also known as streptonivicin), a broad spectrum antibiotic produced by the fermentation of Streptomyces niveus (see Group IV(b)), as such, or in the form of a salt with an inorganic or organic base, or an alkyl or acyl derivative thereof, is used as a feed supplement in promoting the growth of animals and poultry either alone or in combination with other antibiotics. Specification 695,273 is referred to.ALSO:Novobiocin, a broad spectrum antibiotic also known as streptonivicin and obtained by the fermentation of Streptomyces vivens (see Group IV (b)), as such, or in the form of a salt with an inorganic or organic base, or an alkyl or acyl derivative thereof, is incorporated in pharmaceutical preparations for topical, oral or parenteral use in the treatment of humans and animals. Such preparations contain at least 25 mg., and may be 50 to 1000 mg. of the antibiotic per dose. The preparations may be in the form of aerosols, ointments, nosedrops, sprays, suppositories, creams, lotions, aqueous and oily suspensions (e.g. in a fixed oil containing aluminium monostearate), powders, tablets, capsules, granules or injections. The antibiotic may be used in combination with (a) sulpha drugs such as suphadiazine sulphamerazine and sulphamethazine, especially a mixture of these three; one part of antibiotic being admixed with two parts of the sulpha drug, (b) antibiotics such as chloramphenicol, endomycin, fumagillin, erythromycin streptomycin dihydrostreptomycin, bacitracin, polymyscin, tetracycline, oxytetracycline and chlortetracycline, (c) vitamins such as thiamine, riboflavin, ascorbic acid, niacinamide, pyridoxine, pantothenic acid or a salt thereof, Vitamin B12 and folic acid, (d) corticoids such as cortisone, hydrocortisone and esters thereof; prednisone and prednisolene and esters thereof in the 21 position, e.g. acetate and cyclopentylpropionate; 2-methylhydrocortisone and esters thereof; and (e) other drugs. Examples relate to (A) tablets containing mono- or di-sodium or calcium novobiocin; (B) similar tablets containing sulpha drugs; (C) capsules containing mono- or di-sodium novobiacin, as such, or with the further addition of any of the substances (a), (b), (c) and (d) above; (D) a sterile aqueous suspension containing novobiocin, sodium carboxymethylcellulose, polyoxyethylene sorbitan monooleate and preservative, as such, or with the further addition of a corticoid; (E) ointment containing monosodium novobiscin in a base of mineral oil, wool fat and petrolatum, as such, or with the further addition of a corticoid, or an antibiotic; (F) aqueous suspension containing mono-calcium novobiocin and tetracycline, which mixture is synergistic. 5 to 95 parts of novobiocin is admixed with 95 to 5 parts of tetracycline. The tetracycline may be replaced by oxytetracycline, chlortetracycline or chloramphenicol. (G) Capsules containing monosodium novobiocin or other alkali metal or alkaline earth metal or amine salt of novobiocin and tetracycline hydrochloride, or other antibiotic as in (F) above. Specification 695,273 is referred to.