Chemical composition and bioherbicidal activity of metabolites of Mycoleptodiscus indicus produced in three culture media

Fungi produce phytotoxic metabolites that can be used in bioherbicide development. Hence, this study aimed to investigate the chemical composition of the extracts produced by the endophytic fungus Mycoleptodiscus indicus (UFSM 54) in three culture media and to evaluate their bioherbicidal potential in plants of Cucumis sativus. To this end, the fungus was cultured in submerged fermentation in a culture medium based on sugarcane bagasse (SB) and solid-state fermentation in media based on oat bran + rice (OR) or just rice (RI). For chemical composition analysis, the extracts were obtained from the culture media by ethanol extraction and subjected to derivatization with acetic anhydride/pyridine and methanolic hydrochloric acid. Metabolite identification was conducted using chromatography and mass spectrometry. These extracts were applied to seeds, detached leaves, and live plants of C. sativus to assess phytotoxicity effects. Six metabolites were identified in the three extracts: methyl-lathodoratine (1), palmitic acid (2), elaidic acid (3), glycerol (4), benzyl benzoate (5), and iditol (6). Linoleic acid (7) was identified in the OR and RI extracts, while 4-acetyl-2-carene (8) was detected in the SB extract. Sterric acid (9) was identified in the SB and RI extracts. In the phytotoxicity tests, the metabolites present in the SB and OR extracts caused greater damage to the detached leaves and live plants, although only the SB extract inhibited the germination of C. sativus. The profile of metabolites produced by M. indicus varies with the cultivation conditions, and this determines the bioherbicidal efficiency.