Antibiotic Properties of Aspergillus Fumigatus Isolated from Bread Mold Against Escherichia Coli

ABSTRACT
This study investigates the antibiotic properties of Aspergillus fumigatus isolated from spoilt bread against Escherichia coli at Sharada GRA, Kano State. Fungal isolation was conducted by inoculating samples from three different parts of spoilt bread onto Sabouraud dextrose agar. Observations of surface texture, topography, and pigmentation revealed distinct characteristics among the samples, with A. fumigatus identified by its smooth, colorless conidiophores and round, columnar heads after lactophenol blue staining. The fungal load, determined using serial dilution, revealed colony counts of 132, 172, and 320 for dilutions 10⁻⁴, 10⁻³, and 10⁻², respectively, with an average load of 624. The antimicrobial activity of ethyl acetate extracts of A. fumigatus was assessed using the agar dilution method. The results showed that higher extract concentrations demonstrated significant inhibition of E. coli, with the highest activity observed at 100 mg/mL, producing the largest zones of inhibition. Activity diminished at lower concentrations (50 mg/mL and 25 mg/mL) and was absent at 12.5 mg/mL. Comparatively, amoxicillin-clavulanate, used as a positive control, exhibited sensitivity at ≥18 mm, intermediate activity at 14–17 mm, and resistance at ≤13 mm, per CLSI 2024 standards. Notably, A. fumigatus extract samples (A1, A2, and A3) showed sensitivity at 100 mg/mL, intermediate activity for sample A2, and resistance at lower concentrations.