Improvement of tylosin production from Streptomyces fradiae culture by decreasing the apparent viscosity in an air-lift bioreactor

Tylosin production in the culture of Streptomyces fradiae T1558 was improved by decreasing the apparent viscosity by means of a newly designed medium. When a medium containing 15 g/l Pharmamedia (a proprietary nutrient derived from cotton seed) and 25 g/l gluten meal was used in a 3-l air-lift bioreactor, the tylosin concentration and apparent viscosity of the broth were 2.1 g/l and 190 cP, on day 10 with preferential filamentous growth, while the DO level could hardly be controlled at an appropriate level during fermentation because of the high apparent viscosity. However, when a newly designed medium containing 10 g/l Pharmamedia and 10 g/l gluten meal was used, the tylosin production and apparent viscosity of the broth were 7.4 g/l and 50 cP, on day 10,vith preferential pellet growth and appropriate control of DO level. The decrease in the apparent viscosity which was dependent on morphological change, was effective in increasing the tylosin productivity in an air-lift bioreactor through the improvement of mass transfer.