Screening and characterization of antimicrobial substances originated from entomopathogenic fungi

• Diversity of antimicrobial substances derived from entomopathogenic fungi
• Antimicrobial activity against bacterium Bacillus cereus and fungus Botrytis cinerea
• Different types of antimicrobial substances with different characteristics

To illustrate the presence of different types of antimicrobial substances derived from entomopathogenic fungi, the antimicrobial activities of 342 fungi were evaluated, and their antimicrobial substances were analyzed. The antimicrobial activities of 342 fungi isolated under various conditions from different regions of Korea were evaluated against the bacterium Bacillus cereus and the fungus Botrytis cinerea using a dual culture technique on agar plates. The results showed that 170 isolates (49.7%) and 186 isolates (54.4%) inhibited the growth of B. cereus and B. cinerea, respectively. The culture filtrates of selected fungi completely suppressed the growth of the microorganisms, indicating the presence of antimicrobial substances. Characteristics of the antimicrobial substances such as thermostability, polarity, susceptibility to proteases and molecular weight varied not only within a culture filtrate but also with the fungal isolate. Different types of antimicrobial substances with different characteristics were present in the fungal culture filtrates. These substances may be useful not only as biocontrol agents against plant diseases but also in other industrial fields. This is the first study to demonstrate various kinds of antimicrobial substances from a large number of entomopathogenic fungi. This study suggests that novel antimicrobial substances could be isolated from entomopathogenic fungi.

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