Antifungal activity of a novel compound from Burkholderia cepacia against plant pathogenic fungi

Aims: To investigate antifungal activity of a novel compound (named as CF66I provisionally) against plant pathogenic fungi, mainly including Fusarium sp., Colletotrichum lindemuthianum, Rhizoctonia solani, etc. Methods and Results: Minimal inhibition concentrations (MIC) and minimal fungicidal concentrations (MFC) of CF66I for each fungi were determined using serial broth dilution method. The data demonstrated MIC ranged from 2.5 to 20.0 mu g ml(-1) and MFC were shown at levels of <= 7.5 mu g ml(-1) except Fusarium sp. With reverse microscopy, profound morphological alterations of fungal cells were observed after exposure to CF66I. Conidiospores were completely inhibited, and protoplasm aggregated to form chalamydospores because of the changes of cell permeability. Some chalamydospores were broken, suggesting the compound probably possessed strong ability of damaging the cell wall. In addition, CF66I was investigated for its antifungal stability against Curvularia lunata. The results showed CF66I kept strong fungi-static activity over-wide pH range (pH 4-9) and temperature range (from) 70 to 120 degrees C). Conclusions: The compound CF66I exhibited strong and stable broad-spectrum antifungal activity, and had a significant fungicidal effect on fungal cells. Significance and Impact of the Study: Results from prebiocontrol evaluations performed to date are probably useful in the search for alternative approaches to controlling serious plant pathogens.