Influence of pH on the Fungitoxic Activity of Naturally Occurring Compounds

Area of Science:

• Mycology
• Food Science
• Natural Product Chemistry

Background:

• Toxigenic Aspergillus species are significant food contaminants.
• Understanding their growth conditions and inhibition is crucial for food safety.
• Natural compounds like thymol and carvacrol are explored for antimicrobial properties.

Purpose of the Study:

• To determine the optimal pH for the growth of toxigenic Aspergillus strains.
• To evaluate the inhibitory effects of thymol and carvacrol on fungal mycelial growth across different pH levels.

Main Methods:

• Eight toxigenic Aspergillus strains were cultured in potato dextrose broth.
• Mycelial growth was measured at various pH levels (4, 6, and 8).
• The impact of thymol and carvacrol at different concentrations (0.1, 0.5, and 1.0 mM) on fungal growth was assessed.

Main Results:

• Optimal Aspergillus growth occurred at pH 6, with reduced growth at pH 4 and 8.
• 1.0 mM thymol completely inhibited fungal growth at all tested pH levels.
• 1.0 mM carvacrol inhibited growth at pH 4 and 8, but not pH 6.
• Lower concentrations of both compounds caused partial inhibition, most pronounced at pH 4 and 8.

Conclusions:

• pH significantly influences the growth of toxigenic Aspergillus.
• Thymol demonstrates potent antifungal activity against Aspergillus across a range of pH values.
• Carvacrol shows pH-dependent antifungal activity, with greater efficacy at extreme pH.