Metabolic products of microorganisms, 170. On the antibiotic activity of cladosporin [genus Eurotium]

Cladosporin was isolated from the cultures of three species of the genus Eurotium. Cladosporin inhibited the growth of several fungi and at very low concentrations the growth of Bacillus brevis and Clostridium pasteurianum. Bacillus subtilis and most other Gram-positive bacteria were not sensitive. Gram-negative bacteria and yeasts were not affected by concentrations up to 100 microgram/ml. Dimethyl cladosporin showed only week activity against Bacillus brevis with the minimal inhibitory concentrations being a 100 times higher than of cladosporin. The incorporation of leucine and uracil into acid insoluble material in Bacillus brevis cells was completely inhibited by concentration of 0.5 microgram/ml cladosporin. The incorporation of thymidine was not affected at this concentration.