Abstract:

Objective: To study the antibacterial effects and mechanism in vitro of the ethanol extracts and ultrasonic extracts of
Opuntic monacantha in Dali. Methods: Ethanol extraction and ultrasonic extraction were respectively applied to the preparation of primary extracts of Opuntia monacantha, and antibacterial effects on experimental strains Staphylococcus aureus, Escherichia coli and Candida albicans were detected by using K-B method. The minimum inhibitory concentrations (MIC) were measured by the macro dilution method, and the antibacterial mechanism was preliminarily explored by the antibacterial curve. Results: There are inhibitory effects in two kinds of primary extracts on experimental strains. The MIC of ethanol extracts were lower than that of ultrasonic extracts. Antibacterial curve demonstrated that the ethanol extracts of Opuntic monacantha had antibacterial effects on Staphylococcus aureus
within 9 hours of growth. Conclusion: Two kinds of extracts of Opuntic monacantha in Dali were able to inhibit the growth of experimental strains including gram-negative and gram-positive bacteria and fungi; antimicrobial effects of ethanol extracts were better than those of ultrasonic extracts. This study could provide a theoretic basis for further research on and application of the extracts of Opuntia monacantha.

Key words: Opuntia monacantha extracts, K-B method, minimum inhibition concentration (MIC), antibacterial curve, antimicrobial
effect, antibacterial mechanism