Otimização da Produção de Metabólitos Antibacterianos pelo Fungo Endofítico Fusarium pseudocircinatum 12IP3F4-1 Isolado de Langsdorffia hypogaea Mart. (Balanophoraceae)

Abstract

Brazil is one of the countries with the greatest biodiversity in the world, although its microbial diversity remains little explored. In this context, endophytic fungi stand out for their ability to produce bioactive secondary metabolites with biotechnological potential, including antibacterial compounds. In this context, this study investigated the potential of the endophytic fungus Fusarium pseudocircinatum 12IP3F4-1, isolated from Langsdorffia hypogaea Mart., to produce metabolites with antibacterial activity, applying the One Strain Many Compounds (OSMAC) strategy to modulate and optimize its secondary metabolism. Antibacterial activity was evaluated using a broth microdilution assay, and the chemical characterization of the extracts was performed by HPLC-DADMS and GC-MS. Variations in culture conditions directly influenced the chemical diversity of the metabolites produced. PDB medium showed greater compound diversity, including the dipeptide cyclo (Pro-Tyr) and fusaric acid, while MEB medium promoted higher intensity of metabolites at elevated retention times, associated with secondary metabolism. The apolar fraction (hexane) of the mycelial extract cultured in MEB revealed a predominance of fatty acid esters, such as ethyl linoleate and ethyl oleate, which was similar to that observed for PDB medium but differed from YPD medium, in which free fatty acids were predominantly detected. In the antibacterial assays, the methanolic fraction of the mycelial extract from MEB medium (EBmic-MEB-Me) showed the highest inhibition of Staphylococcus aureus ATCC 25904, revealing more than 93% inhibition of bacterial growth at the concentrations tested (1–0.25 mg/mL), while the supernatant extract (EBsob-MEB-Me) also exhibited significant activity, with 90.5% inhibition. For Escherichia coli (ATCC 14458), only the EBsob-MEB-Me extract showed bacterial growth inhibition, reaching 95.4% at the highest concentration tested. The results demonstrate the effectiveness of the OSMAC strategy in modulating the secondary metabolism of F. pseudocircinatum 12IP3F4-1 and highlight cultivation in MEB medium as a promising condition for producing antibacterial compounds against both Gram-positive and Gram-negative bacteria, such as S. aureus and E. coli.