Isolation and Antibacterial Activity of Antibiotic-producing Fungi from Selected Soils in Akure, Nigeria
Titilayo Iyanuoluwa Aliu *
Department of Microbiology, Federal University of Technology, Akure, Ondo State, Nigeria.
Muftau Kolawole Oladunmoye
Department of Microbiology, Federal University of Technology, Akure, Ondo State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: Soil fungi from diverse and understudied environments such as Akure, Nigeria, represent a promising yet underexplored source of novel antibiotic-producing microorganisms with potential applications against antimicrobial resistance.
Aim: The emergence and spread of antimicrobial resistance have intensified the global search for novel antibiotics, particularly from natural microbial sources like soil. This study aimed to isolate and identify potent fungal strains with antibacterial activity.
Study Design: An experimental laboratory-based study.
Place and Duration of Study: Soil samples were collected from six distinct locations within Akure, Ondo State, including waste dumping sites, compost heaps, animal sheds, parks, and stream-side area.
Methodology: Soil samples were analyzed for physicochemical properties, revealing significant variation in pH, organic matter content, and nutrient composition. Using serial dilution and pour plate methods, a total of 11 fungal isolates were obtained and identified through cultural, morphological, and microscopic techniques as belonging to seven genera: Aspergillus (4 isolates), Penicillium (2), Fusarium (1), Trichoderma (1), Rhizopus (1), Chrysosporium (1), and Eurotium (1). Total fungal colony counts ranged from 2 × 10³ to 63 × 10⁴. Preliminary screening via agar well diffusion assessed antibacterial activity against seven clinical bacterial isolates: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus, Klebsiella pneumoniae, Citrobacter freundii, and Enterobacter cloacae.
Results: The fungal isolates exhibited inhibitory activity against at least one of the tested bacteria. Zones of inhibition ranged from 4 mm to 14 mm, with four isolates: Aspergillus niger, Trichoderma harzianum, Penicillium allii, and Aspergillus oryzae, demonstrating superior activity compared to others.
Conclusion: The findings show the prevalence of antibiotic-producing fungal strains in soils within Akure, highlighting their potential as sources of novel pharmaceutical compounds.
Keywords: Fungi, antibiotic-producing, soil, secondary metabolites, Akure