%0 Journal Article %A Brian, P. W. %A Curtis, P. J. %A Hemming, H. G. %A Jefferys, E. G. %A Unwin, C. H. %A Wright, Joyce M. %T Alternaric Acid; a Biologically Active Metabolic Product of Alternaria solani (Ell. & Mart.) Jones & Grout; its Production, Isolation and Antifungal Properties %D 1951 %J Microbiology, %V 5 %N 4 %P 619-632 %@ 1465-2080 %R https://doi.org/10.1099/00221287-5-4-619 %I Microbiology Society, %X When Alternaria solani is grown on any one of a variety of defined culture media, an antibiotic metabolic product, alternaric acid, accumulates in the medium. The quantity of alternaric acid produced is directly related to the amount of mycelium formed; good yields of alternaric acid are obtained on any medium which supports good growth. Optimal media contain high concentrations (7·5% (w/v) or more) of sucrose, which is better than any other carbon source tested. Nitrogen may be supplied as nitrate or casein hydrolysate; ammonia as nitrogen source is equally good when supplied in conjunction with a suitable organic acid, 0·25% (w/v) acetic acid being particularly favourable. The antibiotic is isolated from optimal media by extraction with chloroform after adjustment to pH 3·5; the solvent is then evaporated and the residue recrystallized from benzene. Yields of the order of 150 mg./l′ are obtained. Alternaric acid is not antibacterial. Germination of spores of some fungi (e.g. Absidia glauca, Myrothecium verrucaria) is prevented by 1μg./ml. or less of alternaric acid. Germination of spores of other fungi (e.g. Botrytis allii) is unaffected by concentrations as high as 100 μg./ml., but extension of the germ-tubes is markedly retarded shortly after germination. This secondary retarding effect may be produced by very low concentrations; 0·1 μg./ml. produced an obvious effect with B. allii. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-5-4-619