Antimicrobial activity of Musca domestica cecropin-4(mdCec4) against Acinetobacter baumannii
Antimicrobial activity of Musca domestica cecropin-4(mdCec4) against Acinetobacter baumannii
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DOI：
10.3760/cma.j.issn.0254-5101.2017.12.002
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发表时间：
2017-12
期刊：
影响因子：
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通讯作者：
Huiling Long;Juhao Yang;Jian Peng;Jian-wei Wu
中科院分区：
文献类型：
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作者：
Huiling Long;Juhao Yang;Jian Peng;Jian-wei Wu
目的研究化学合成家蝇天蚕素-4 （mdCec4）对鲍曼不动杆菌的抑菌活性。方法采用微量稀释法检测mdCec4对鲍曼不动杆菌的最低抑菌浓度（MIC）和最低杀菌浓度（MBC）。用微孔板阅读器监测动态时间杀伤曲线。考察了NaCl、胰蛋白酶和pH值等不同影响因素对mdCec4抑菌活性的影响。用扫描电镜观察了mcec4对鲍曼不动杆菌的超微结构影响。结果mdCec4对鲍曼不动杆菌的MIC和MBC分别为4 μg/ml和8 μg/ml。动态时间杀伤曲线显示mdCec4在24 h内具有较高的抗菌活性。在0 ~ 200 mmol/L NaCl浓度范围内，mdCec4的抑菌活性不受影响，但1.0 mg/ml的胰蛋白酶可抑制其抑菌活性。在不同pH值（6.5、7.5、8.8）的Tris-HCl缓冲液中，mdCec4的最佳条件为pH8.8。扫描电镜结果显示，细菌细胞损伤程度与暴露时间呈正相关。结论新发现的mdCec4对鲍曼不动杆菌具有较好的抑菌活性，可在短时间内杀灭鲍曼不动杆菌，且其抑菌能力可达24小时以上。此外，mdCec4在不同浓度的NaCl和胰蛋白酶以及不同的pH值条件下都具有良好的稳定性。SEM观察表明，mdCec4的MIC可破坏菌膜的完整性，导致大量细胞内容物释放，最终导致鲍曼不动杆菌死亡。本研究为进一步研究mdCec4对鲍曼不动杆菌的抑菌机制提供了参考。关键词：家蝇；抗菌肽Cec4；鲍曼不动杆菌;抗菌活性;影响因素
Objective To study the antimicrobial activity of chemically synthesized Musca domestica cecropin-4 (mdCec4) against Acinetobacter baumannii. Methods Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of mdCec4 against Acinetobacter baumannii were detected by microdilution method. Dynamic time-kill curve was monitored by microplate reader. Effects of different influencing factors, such as NaCl, trypsin and pH value, on the antimicrobial activity of mdCec4 were assessed. The ultrastructure of Acinetobacter baumannii exposed to the MIC of mdCec4 was observed under scanning electron microscope (SEM). Results The MIC and MBC of mdCec4 against Acinetobacter baumannii were 4 μg/ml and 8 μg/ml, respectively. The dynamic time-kill curve revealed that mdCec4 had a high antimicrobial activity within 24 hours. The antimicrobial activity of mdCec4 was not affected by NaCl concentration ranged from 0 to 200 mmol/L, but could be inhibited by trypsin at a concentration of 1.0 mg/ml. Among Tris-HCl buffers with different pH values (6.5, 7.5, 8.8), the optimum condition for mdCec4 was pH8.8. Results of SEM showed that the degree of bacterial cell injury was positively correlated with exposing time. Conclusion This study shows that the newly discovered mdCec4 has a better antimicrobial activity against Acinetobacter baumannii as it can eliminate Acinetobacter baumannii within a short period of time and its antimicrobial ability can last more than 24 hours. Moreover, mdCec4 has the characteristic of good stability in conditions of different concentrations of NaCl and Trypsin as well as various pH values. SEM observation shows that the MIC of mdCec4 can destroy the integrity of bacterial membrane resulting in a release of a large number of cell contents, which finally lead to the death of Acinetobacter baumannii. This study provides references for further study of the antimicrobial mechanism of mdCec4 against Acinetobacter baumannii. Key words: Musca domestica; Antimicrobial peptide Cec4; Acinetobacter baumannii; Antimicrobial activity; Influencing factor