Oxytetracycline production byStreptomyces rimosus in solid state fermentation of sweet potato residue.

Sweet potato residue, a starchy agricultural waste, was used as a substrate to produce oxytetracycline byStreptomyces rimosus TM-55 in a solid-state fermentation. Oxytetracycline was detected on the third day, reached its maximum value on the sixth day and remained constant to the twentieth day. Optimal conditions for oxytetracycline production were an initial pH of 5.5 to 6.5, supplemented with 20% (w/v) defatted roasted peanut meal, as the sole nitrogen source, 1.0% (w/v) CaCO3 and 2.0% (w/v) MgSO4·7H2O, being incubated at 26 to 35°C for 6 to 7 days. Oxytetracycline reached 12.1 mg/g substrate.