Antifungal effect of soil Bacillus bacteria on pathogenic species of the fungal genera Aspergillus and Trichophyton

Mahnour Alsadat  Taghavi; Maryam  Ahmadi; Davoud  Dehghan-Nayeri; Zahra  Salehi; Masoomeh  Shams-Ghahfarokhi; Fatemehsadat  Jamzivar; Mehdi  Razzaghi-Abyaneh

doi:10.18502/ijm.v17i2.18397

Mahnour Alsadat Taghavi Department of Microbiology, Faculty of Pharmacy, Islamic Azad University, Tehran, Iran
Maryam Ahmadi Department of Microbiology, Faculty of Pharmacy, Islamic Azad University, Tehran, Iran
Davoud Dehghan-Nayeri Department of Microbiology, Faculty of Pharmacy, Islamic Azad University, Tehran, Iran
Zahra Salehi Department of Mycology, Pasteur Institute of Iran, Tehran, Iran
Masoomeh Shams-Ghahfarokhi Departmentt of Mycology, Faculty of Medical Science, Tarbiat Modares University, Tehran, Iran
Fatemehsadat Jamzivar Department of Mycology, Pasteur Institute of Iran, Tehran, Iran
Mehdi Razzaghi-Abyaneh Department of Mycology, Pasteur Institute of Iran, Tehran, Iran

DOI: https://doi.org/10.18502/ijm.v17i2.18397

Keywords: Antifungal activity; Aspergillus; Trichophyton; Bacillus; Molecular identification; Soil bacteria

Abstract

Background and Objectives: The increasing prevalence of fungal infections due to antifungal resistance underscores the need for novel treatment strategies. The present study aimed to investigate the inhibitory effects of soil-originated antagonis- tic bacteria against Aspergillus and Trichophyton species.

Materials and Methods: Fifty soil samples collected from Isfahan and Khuzestan provinces by using the Zig-Zag method were cultured on glucose-yeast extract (GY) agar around fungal colonies to isolate antagonistic bacteria. Antifungal activity was assessed by measuring clear zones around the colonies of A. niger, A. fumigatus, T. rubrum, and T. mentagrophytes by co-culture linear method. Potent antagonistic bacteria were identified by 16S rRNA sequencing, and evaluated for antifungal activity using disk diffusion assays compared with amphotericin B and ketoconazole.

Results: Among 50 samples, fifteen showed antifungal effects, yielding 55 bacterial strains. Four isolates with strong anti- fungal activity against all tested fungi were identified as Bacillus subtilis, B. licheniformis, B. axarquiensis, and Bacillus sp. These bacteria were distributed in distinct clusters phylogenitically and showed diverse antifungal activity.

Conclusion: The results suggest the potential of soil-derived Bacillus species as promising antifungal agents. Further studies are recommended to identify their inhibitory metabolites, their ability as biocontrol agents against soil habitated fungi and to explore their mechanism of action and spectrum of activity.