Enhancing the sporulation of Streptomyces kasugaensis by culture optimization

Abstract

To be an effective microbial biocide, Streptomyces kasugaensis should be converted into spore during cultivation process for successful long-term storage. By statistical design methods, culture conditions including medium components and operating parameters were optimized and more than 100 times increase in spore yield was achieved. Addition of spent culture fluid (100 ppm), EDTA (30 ppm), mycophenolic acid (32 ppm) with combination of pH up-shock (5.5 to 8.5) increased total viable cell and spore conversion rate, resulting in 1.6×107 (spore/mL) in 5 days of culture in a fermenter. This result provides a practical method for obtaining high spore number for commercial production of Streptomyces kasugaensis as a microbial pesticide.