Abstract
This study was focused on the investigation of the kinetics of cell growth and oxytetracycline (OTC) production during the cultivation of Streptomyces rimosus in submerged culture in different scales using semi-defined cultivation medium. In shake flask cultures, the volumetric and specific antibiotic production, reachedafter 108 h, were 170 mg/L and 37.9 mg/g, respectively. Further increases in volumetric and specific OTC productions was achieved upon transferring the process to stirred tank bioreactor and studying the effect of agitation speed on the kinetics of cell growth and antibiotic production. Of different agitation speeds applied ranging between 250 and 750 rpm, the maximal cell growth of 8.15 g/L and volumetric OTC production of 410 mg/L were obtained in 500 rpm agitated culture. Further increase in agitation speed, up to 750 rpm, decreased the biomass by about 40% and the volumetric OTC production by 29%.