Influence of antimicrobial agents on contamination and chlortetracycline production

The possibility of shortening the thermal sterilization time for cultivating media was demonstrated in chlortetracycline fermentation with an industrial strain of Streptomyces aureofaciens. The medium was artificially contaminated with a mixture of eight strains of G+ and G- bacteria isolated from contaminated industrial fermentors, and the following chemical agents, either alone or in combination, were added: formaldehyde, phenol. dimethylformamide, p-aminosalicylic acid and nitrofurazone. Dimethylformamide was inhibitory even at 0.08%. formaldehyde concentrations higher than 0.05%, Nitrofurazone stimulated chlortetracycline production. The best combination was 0.01% formaldehyde added before, and 2.10-3% nitrofurazone added after short sterilization at 120 degrees C.