Introduction: The increasing resistance of microorganisms to antibiotics has highlighted the urgent need for new antimicrobial agents. Filamentous fungi, commonly found in soil, are known producers of bioactive compounds, including antimicrobial agents. This study aimed to isolate and evaluate the antimicrobial activity of filamentous fungi found in soil samples, with the objective of identifying potential new sources of antimicrobial compounds that may offer alternatives to conventional antibiotics.
Methods: Soil samples were collected from a biological garden on the University Lusófona campus to isolate filamentous fungi using selective media. The isolated fungi were then subjected to antimicrobial activity tests using the agar well diffusion method against two pathogenic bacterial strains: Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). The fungi that exhibited the most promising results were selected for DNA analysis. To accurately identify the fungal species, DNA extraction and polymerase chain reaction (PCR) amplification were performed. Sequencing data were analysed using the BLAST algorithm to confirm the identities of the isolated fungi.
Results: Several filamentous fungi were successfully isolated from the soil samples, including Penicillium pimiteouiense and Aspergillus niger. Both fungi exhibited significant antimicrobial activity, as demonstrated by the formation of inhibition halos in the presence of E. coli and S. aureus. These results indicate these fungi's potential to produce antimicrobial compounds effective against S. aureus and E. coli, two of the most representative pathogenic bacteria.
Conclusion: This study supports the potential of soil microbiota, particularly filamentous fungi, as a rich resource for discovering new antimicrobial compounds. The findings highlight the importance of further research to explore the mechanisms of action of these compounds and to develop them for clinical applications. The isolated fungi, namely P. pimiteouiense and A. niger, show promise as sources of new antimicrobial agents that could help combat antibiotic resistance and pathogenic bacteria.
