合浦珍珠提取物对金黄色葡萄球菌的体外抑菌活性及稳定性研究

Antibacterial Activity and Stability of Hepu Pearl Extracts on the Staphylococcus aureusin in Vitro

目的:研究合浦珍珠提取物对金黄色葡萄球菌的体外抑菌活性及稳定性。方法:采用牛津杯法及96孔法测定合浦珍珠提取物对金黄色葡萄球菌的抑菌活性及最小抑菌浓度,并探讨温度、反复冻融、酸碱、紫外线、金属离子、胰蛋白酶和胃蛋白酶对合浦珍珠提取物抑菌活性的影响。结果:合浦珍珠提取物对金黄色葡萄球菌具有显著的抑菌活性,最小抑菌浓度为0.94 mg·mL^-1,且抑菌活性呈一定的剂量依赖效应。以8×MIC合浦珍珠提取物进行抑菌稳定性实验,以金黄色葡萄球菌的OD600值为指标进行探讨,结果显示,合浦珍珠提取物在pH3.0~9.0抑菌活性保持稳定,但在pH11.0相比pH7.0抑菌活性,保留约70%;在-80~80℃抑菌活性保持稳定,但在100℃相比4℃处理30 min抑菌活性保留约68%;在-20℃反复冻融及20 W紫外灯照射条件下,提取物抑菌活性保持良好的稳定性;在25~200 mmol·L^-1的NaCl、KCl、CaCl2条件下,提取物抑菌活性稳定,但在25~200 mmol·L^-1MgCl2条件下,抑菌活性逐渐降低,在200 mmol·L^-1 MgCl2时,抑菌活性相比未添加金属离子组保留约40%;提取物对胰蛋白酶处理保持良好的抑菌稳定性,但在胃蛋白酶处理下,抑菌活性消失,说明对胃蛋白酶敏感。结论:合浦珍珠提取物对金黄色葡萄球菌具有稳定的体外抑制活性,为其今后在食品工业上的应用和开发提供一定的理论基础。

Objective:To study the antibacterial activity and stability of Hepu pearl extracts against standard strains of Staphylococcus aureus(S. aureus)in vitro. Method:The bacteriostatic zone size and minimum inhibitory concentration(MIC)of Hepu pearl extracts on S. aureus were determined by Oxford cup method and 96-well method. The effects of temperature,repeated freezing and thawing,acid-base,ultraviolet,metal ion,trypsin and pepsin on the antibacterial activity of Hepu pearl extracts were studied. Results:The Hepu pearl extracts had significant antibacterial activity against S. aureus,and the minimum inhibitory concentration was 0.94 mg·mL-1,and the antibacterial activity showed a dose-dependent effect. The bacteriostatic stability experiment of 8×MIC Hepu pearl extracts was carried out,and the OD600 value of S. aureus was used as an index. The results showed that the antibacterial activity of Hepu pearl extracts remained stable in pH3.0~9.0,but about 70% in pH11.0 retained compared with pH7.0. The antibacterial activity remained stable at-80 ℃,but about 68% retained at 100 ℃ compared with 4 ℃. Under the condition of repeated freezing and thawing at-20 ℃ and irradiated by 20 W UV lamp,the antibacterial activity of the extracts remained good stability. Under the conditions of NaCl,KCl and CaCl2 of 25~200 mmol·L-1,the antibacterial activity of the extracts was stable. While under the condition of 25~200 mmol·L-1 MgCl2,the antibacterial activity decreased gradually,and the antibacterial activity was retained by about 40% compared with the non-added group at 200 mmol·L-1 MgCl2. The extracts maintained good bacteriostatic stability to trypsin treatment,but the antibacterial activity disappeared under pepsin treatment,indicating that it was sensitive to pepsin. Conclusion:Hepu pearl extracts had stable inhibitory activity against S. aureusin in vitro,which would provide a theoretical basis for its application and development in food industry in the future.