Induction of chlamydospores in Trichoderma harzianum and Gliocladium roseum by antifungal compounds produced by Bacillus subtilis C2

One bacterial strain was isolated from a Panax notoginseng field and identified as Bacillus subtilis C2 by its physiological and biochemical characteristics. The culture filtrate of the bacterium showed strong antifungal activity against Trichoderma harzianum and Gliocladium roseum. The antifungal compound termed 10M was purified from the culture filtrates of B. subtilis C2 through organic solvent extraction, silica gel H and Sephadex LH-20 column chromatography. Chlamydospores were formed either inside the conidia or from hyphae, when the conidia of T. harzianum and G. roseum were cultured on the surface of the potato dextrose agar (PDA) containing relatively low concentrations of 10M for 48 h. While they were cultured on the surface of PDA containing relatively high concentrations of 10M for 48 h the cells were swollen and then lysed. The 10M had high similarity to iturin A as showed by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry. This is the first report that antifungal compounds produced by B. subtilis can induce chlamydospore formation in biocontrol fungi at relatively low concentrations.