SobhZahedi Mahdieh, Zamani Hojjatollah, YektaKooshali Mohammad Hossein
Department of Biology, Faculty of Science, University of Guilan, Rasht, Iran.
Razi Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
Galen Med J. 2023 Dec 17;12:e3038. doi: 10.31661/gmj.v12i.3038. eCollection 2023.
Aeromonas hydrophila is a pathogenic bacterium responsible for various infections in humans and animals. Bacterial exoproteases are considered an important determinant in the pathogenicity of A. hydrophila. Serine protease and metalloprotease, that are regulated by the bacterial Quorum sensing (QS) system are important virulent factors in the pathogenicity of A. hydrophila. Anti-QS potential of curcumin has been reported, previously. In this work, we characterized the effect of curcumin on the expression of the metalloprotease and serine protease genes in A. hydrophila.
The minimum inhibitory concentration (MIC) of curcumin was measured by the agar macro-dilution method and a sub-inhibitory concentration (1/2 MIC) was used in subsequent experiments. The expression level of the metalloprotease and serine protease genes among the treated and control bacteria was evaluated using quantitative PCR (qPCR) assay. Bacterial proteolytic activity was also measured by skim milk agar plate assay.
MIC of curcumin for bacterial strain was 1024 μg/ml curcumin, and at 512 µg/mL (1/2 MIC) it remarkably attenuated the expression of the metalloprotease and serine protease genes up to 66 and 77%, respectively. Also, the proteolytic activity of A. hydrophila was considerably reduced by curcumin.
Due to the promising inhibitory effect on bacterial proteolysis, curcumin could be considered an anti-virulence agent against A. hydrophila.
嗜水气单胞菌是一种致病性细菌，可导致人类和动物发生各种感染。细菌外蛋白酶被认为是嗜水气单胞菌致病性的重要决定因素。受细菌群体感应（QS）系统调控的丝氨酸蛋白酶和金属蛋白酶是嗜水气单胞菌致病性中的重要毒力因子。此前已有报道姜黄素具有抗群体感应的潜力。在本研究中，我们表征了姜黄素对嗜水气单胞菌中金属蛋白酶和丝氨酸蛋白酶基因表达的影响。
采用琼脂大稀释法测定姜黄素的最低抑菌浓度（MIC），并在后续实验中使用亚抑菌浓度（1/2 MIC）。使用定量PCR（qPCR）测定法评估处理组和对照组细菌中金属蛋白酶和丝氨酸蛋白酶基因的表达水平。还通过脱脂乳琼脂平板测定法测量细菌的蛋白水解活性。
姜黄素对该菌株的MIC为1024μg/ml，在512μg/mL（1/2 MIC）时，它分别使金属蛋白酶和丝氨酸蛋白酶基因的表达显著降低了66%和77%。此外，姜黄素还显著降低了嗜水气单胞菌的蛋白水解活性。
由于对细菌蛋白水解具有良好的抑制作用，姜黄素可被视为一种抗嗜水气单胞菌的抗毒力剂。
