Evaluation of the Effect of Curcumin on the expression of hcp and vgrG genes in Aeromonas hydrophila

Background and Aim : Aeromonas hydrophila is an oxidase-positive,gram-negative rod.Curcumin, a polyphenolic compound derived from dietary spice turmeric, possessesdiverse pharmacologic effects including anti-inflammatory, antioxidant, antiproliferative and antian-giogenic activities.The genes hcp and vgrG are expressed in aeromons hydrophila. The type VI secretion system (T۶SS) is a recently discovered mechanism in gram-negative bacteria that targets proteins to both prokaryotic and eukaryotic cells.T۶SS occur in many pathogenic bacteria and are implicated in virulence in important pathogens. The type VI secretion system (T۶SS) functions analogously to a phage tail, allowing injection of virulence factors into host cells via valine glycine repeat G (VrgG) proteins and hemolysincoregulated protein (Hcp), which functions as an antimicrobial pore-forming protein when secreted or as a structural protein. Hcp and Vgr are unable to be secreted which results in decreased biofilm formation. Methods : A. hydrophila strain and cultured in Muller Hinton Agar. Then, antibacterial effect of curcumin was investigated using the well diffusion agar method. The minimum inhibitory concentration (MIC) of Curcumin against A. hydrophila strain was determined using broth microdilution method and sub-mic of curcumin was selected. A. hydrophila grown in Muller Hinton Agar containing sub-mic of curcumin were subjected to RNA extraction and cDNA synthesis.Expression of hcp and vgrG genes will be checked using quantitative polymerase chain reaction (qPCR) with gene specific primers. The relative gene expression will be determined by the expression of ۱۶s rRNA gene and then the results will be compered with control cells.Results : The aim of current study was to Evaluation of the Effect of Curcumin against Aeromonas hydrophila, a bacterial fish pathogen causing hemorrhagic septicemia, by evaluating expression of hcp and vgrG gene. At first, bacterial strains were identified using biochemical and molecular assays. Then, the minimum inhibitory concentration (MIC) of curcumin against bacteria was determined using broth microdilution method. Expression of quorum sensing genes Hcp and VgrG among the bacteria exposed to curcumin at sub-MIC ( ½ MIC) was determined using real-time PCR method and compared to the control.Conclusion : curcumin significantly reduced expression of both Hcp and VgrG among bacterial strain. In conclusion, curcumin showed a promising potential to be used as antiquorum sensing, T۶SS and antibiofilm agent against A. hydrophila.

کلیدواژه ها:

Aeromonas hydrophila ، Curcumin ، type VI secretion system ، hcp and vgrG genes.