ABSTRACT
Following the increasing antibiotic resistance of pathogenic bacteria, the use of medicinal herbs as antibacterial agents has attracted growing attention. Pseudomonas aeruginosa is a human opportunistic pathogen that uses quorum sensing for regulating virulence gene expression [pyocyanin, protease, and elastase production and biofilm formation]. This study examined the anti-quorum sensing activity of Quercus infectoria, Zataria multiflora and Trachyspermum copticum extracts on standard P. aeruginosa strain. The minimum inhibitory concentration [MIC] of Q. infectoria, Z. multiflora and T. copticum extracts for standard P. aeruginosa strain was determined through micro dilution. Microtiter plates were used to evaluate the anti-quorum sensing effects of the three extracts [at a sub-MIC concentration] on pyocyanin, protease, and elastase production and biofilm formation. The acetone extract of Q. infectoria showed the highest anti-quorum sensing activity and reduced the pyocyanin, protease, and elastase production and biofilm formation by 89.1%, 78%, 73.3%, and 70.1%, respectively. The corresponding values were 88.2%, 72.1%, 69%, and 61.1% for the methanol extract of Z. multiflora and 70.6%, 63.42%, 60.1%, and 59.1% for the methanol extract of T. copticum. Considering the high anti-quorum sensing activity of the studied extracts, especially the acetone extract of Q. infectoria, these herbs can be used as antipathogenic drugs
ABSTRACT
Bacillus cereus is one of the most common causes of food spoilage, keratitis, endophthalmitis, and panophthalmitis. These bacteria produce spores which are resistant to chemical and physical agents. Nowadays, the sporicidal properties of plants have been considered as alternatives to chemical sporicidal agents. In this empirical-experimental study the effect of ethanol extract of edible burdock [Arctium lappa] root has been studied on Bacillus cereus spores. In this investigation, the suspensions of tested microorganisms were cultured in sporulating agar. Sporulation process was assessed by optical microscopy following the staining of spores. Then the produced spores were exposed to various concentrations [100, 150, 200, 250, 300 mg/mL] of ethanol extract of edible burdock [Arctium lappa] root and finally the remaining spores were counted. With increasing concentrations of ethanol extract, the number of spores declined. Pearson correlation showed inverse relation between the spores count and concentration of ethanol extract of edible burdock [Arctium lappa] root [r=-0.765, p<0.001]. The most effective extract concentration was 300 mg /mL. Ethanol extract of edible burdock [Arctium lappa] root, has sporicidal activity. Only, the sporicidal nature of ethanol extract has been evaluated by this study; therefore, the assessment of other extracts and essences is necessary