Effects of nutrients on production of fungichromin by Streptomyces padanus PMS-702 and efficacy of control of Phytophthora infestans

Abstract

The effects of carbon and nitrogen source on inhibitory activity of Streptomyces padanus PMS-702 culture filtrates were investigated using 12 saccharides, 12 nitrogen sources, and 7 organic compounds. Results showed that the carbon sources cellobiose, galactose, glucose, mannose and xylose; the organic compound peanut meal; and the nitrogen source glutamic acid were the most effective components for production of inhibitory substances by S. padanus and suppression of zoospore release of Phytophthora infestans. Production of the antibiotic fungichromin by S. padanus PMS-702 was high (145.5 ppm) in cultures grown in the liquid medium of peanut meal – glucose – glutamic acid (PMGG) containing 1.5% (w/v) peanut meal, 0.5% (w/v) glucose, and 0.5% (w/v) glutamic acid for 7 days. Spraying tomato plants with culture filtrates of S. padanus PMS-702 from the PMGG broth culture at a rate of 100-fold dilution significantly reduced severity of late blight of tomato (Lycopersicon esculentum) foliage caused by P. infestans both under controlled environment and field conditions.