Quantitative Determination of the Antifungal Activity of Polymyxin against Mold Fungi by Agar Infusion Method
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Abstract:
The quantitative determination method of antimicrobial peptides against mold fungi was studied in this paper. The antifungal activity of polymyxin B against Penicillium chrysogenum was determined by agar infusion method, and the determination conditions of indicator concentration, peptide addition amount and culture time were then optimized. Furthermore, the quantitative determination method was verified with Aspergillus niger. The antifungal activity was calculated by establishing a linear equation between the antimicrobial peptide concentration and inhibition zone diameter. The results showed that the optimal conditions for quantitatively testing the activities of polymyxin B against mold fungi were as follows: The amount of PDA in 90 mm petri dish was 15 mL, the spore concentration was (1~5)×106 spores/mL, the addition of polymyxin B was 100 μL, the pre-diffusion time was 6~10 h at 4 ℃ and the culture time was 24 h at 28 ℃. The quantitative determination method was verified with Aspergillus niger, and the results indicated that this determination method had good repeatability and high precision. Under these conditions, the antifungal activities of polymyxin B against Penicillium chrysogenum and Aspergillus niger were 524.81 U/mg and 605.76 U/mg, respectively. This study could provide a reference and basis for the activity determination of antimicrobial peptides in the process of research and production.
