Production of mutagenic metabolites by Metarhizium anisopliae

Area of Science:

• Mycology
• Toxicology
• Biotechnology

Background:

• NG-391 and NG-393 were initially identified as nerve-cell growth stimulants from unknown Fusarium species.
• These compounds are structurally related to fusarin C and (8Z)-fusarin C, known mutagenic toxins found in contaminated corn.
• Entomopathogenic fungi are increasingly explored for biocontrol applications.

Purpose of the Study:

• To identify the source of NG-391 and NG-393.
• To characterize the production and properties of these compounds in Metarhizium anisopliae.
• To assess the potential risks associated with these mycotoxins in biocontrol agents.

Main Methods:

• Fermentation of Metarhizium anisopliae strains (wild-type ARSEF 2575 and mutant KOB1-3).
• Chemical identification and characterization of isolated compounds.
• Antimicrobial disk diffusion assays.
• Mosquitocidal assays.
• Salmonella mutagenicity testing (Ames test) with S9 activation.

Main Results:

• NG-391 and NG-393 were identified in fermentation extracts of M. anisopliae.
• A mutant strain (KOB1-3) showed a 10-fold increase in production of NG-391 and NG-393, causing yellow pigmentation.
• The compounds were inactive against microbes and mosquitoes but demonstrated potent mutagenicity in the Salmonella assay.
• These mycotoxins are 7-desmethyl analogues of fusarin C.

Conclusions:

• Metarhizium anisopliae produces highly mutagenic mycotoxins NG-391 and NG-393.
• Screening M. anisopliae strains used as biocontrol agents for these mycotoxins is recommended.
• The implications of these findings for the safety and efficacy of M. anisopliae as a biocontrol agent require further investigation.