| 摘要: |
| 【目的】探究魔芋飞粉生物碱(Alkaloid from konjac powder，AKP)的抑菌作用及其对大肠杆菌和金黄色葡萄球菌的抑菌机理，为新型天然抑菌剂和防腐剂的开发提供理论依据。【方法】采用液体倍比稀释法,确定AKP对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、鼠伤寒沙门氏菌4株供试菌的最小抑菌质量浓度（Minimum inhibitory concentration，MIC），并采用牛津杯法测定AKP对上述4株供试菌的抑菌圈大小；通过测定在AKP作用下，大肠杆菌和金黄色葡萄球菌的生长曲线、菌体培养液电导率及观察细胞膜完整性、细胞形态等，对AKP的抑菌作用及其机理进行分析。【结果】AKP对4株供试菌均有明显的抑制作用，对金黄色葡萄球菌的抑菌作用最强(MIC为10 mg/mL)，大肠杆菌次之（MIC为20 mg/mL）。AKP对供试菌的抑菌圈直径依次为金黄色葡萄球菌＞大肠杆菌＞枯草芽孢杆菌＞鼠伤寒沙门氏菌。菌体生长曲线显示，AKP对大肠杆菌和金黄色葡萄球菌的生长有明显的抑制效果。AKP作用后，大肠杆菌和金黄色葡萄球菌细胞膜受损，存活率显著降低，菌体培养液电导率显著上升。电镜观察发现，AKP使菌体细胞膜出现破损，部分菌体出现空腔。【结论】AKP具有抑菌作用，其可能通过破坏细菌细胞膜结构而导致内容物外泄，进而影响细胞的生长代谢或造成细胞死亡，从而抑制其生长。 |
| 关键词: 魔芋飞粉 生物碱 抑菌活性 抑菌机理 |
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| 基金项目:陕西师范大学中央高校基本科研业务费创新团队项目（GK201601007）；陕西省科技统筹创新工程计划项目（2016KTCL02-33）；陕西省农业科技创新与攻关项目（2015NY009） |
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| Antimicrobial activity and mechanism of alkaloid from konjac powder |
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ZHOU Qi,ZHANG Baoshan,WEI Lusha,et al
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| Abstract: |
| 【Objective】In this study,the antibacterial effect of alkaloid extraction isolated from konjac powder (AKP) and its antibacterial mechanism against Escherichia coli and Staphylococcus aureus were investigated to provide theoretical basis for production of new natural bacteriostatic and preservative agent.【Method】The minimum inhibitory concentrations (MIC) of AKP to Escherichia coli,Staphylococcus aureus,Bacillus subtilis and Salmonella typhimurium were determinedby liquid ratio dilution method,and the susceptibility tests of AKP to these four bacteria were studied by the Oxford Cup method.The growth curve,electrical conductivity of bacteria culture,cytomembrane integrity and mophologies of tested bacteria were investigated to understand the antibacterial mechanism of AKP.【Result】AKP had the strongest antibacterial effect on all test strains.Staphylococcus aureus was the most inhibited strain (MIC 10 mg/mL),followed by Escherichia coli (MIC 20 mg/mL).The inhibition zone diameters were in the order of Staphylococcus aureus＞Escherichia coli＞Bacillus subtilis＞Salmonella typhimurium.Growth curves showed that AKP had significant inhibitory effect on growth of Escherichia coli and Staphylococcus aureus.When exposed to AKP,cell membrane was destroyed,bacteria survival was decreased and the conductivity of the bacteria culture was increased.Besides,cell morphology was changed,some cells even had cavities after exposure to AKP.【Conclusion】AKP showed antibacterial activities by destroying cell membrane and causing cytoplasm leakage to inhibit cell growth and cause cell death. |
| Key words: konjac powder alkaloid antibacterial activity antibacterial mechanism |
