Effect of pH on the production of the antitumor antibiotic retamycin by Streptomyces olindensis

The effect of pH on cell growth and retamycin production in batch bioreactor cultures of Streptomyces olindensis ICB20 was investigated. In fermentations pH-controlled over the range 6.0–8.0, the highest retamycin production was achieved at pH 7.0, and the maximum concentration of retamycin, about 1.36 A (absorbance) units, was about 43, 58 and 232% higher than the values obtained at pH 7.5, 6.0 and 8.0 respectively.