Evaluation of the effect of treated wastewater and well water irrigation on the quality, quantity and antibacterial/antifungal activities of Rosa × damascena Herrm. essential oil

Water is one of the important environmental factors affecting the quality and quantity of Rosa × damascena Herrm. essential oil. This study aimed to evaluate and compare the quality, quantity, and antibacterial/antifungal activity of R. × Damascena essential oil in fields under irrigation treatments such as treated wastewater and well water at the University of Kashan, Kashan, Iran. In each field, flowers (sepals and petals) were collected from different bushes in May 2019, coinciding with the beginning of buds opening. After extracting the essential oil by water distillation using the Clevenger apparatus, the analysis and identification of the compounds were performed by a gas chromatograph coupled to a mass spectrometer (GC/MS). The antibacterial/antifungal activity of the essential oils was evaluated by determining the diameter of the inhibition zone by the agar diffusion method and determining the minimum concentration of growth inhibitor and bactericidal/fungal lethality. The results of quantitative analysis of essential oil showed that the highest yield belonged to R. × damascena irrigated with treated wastewater with a value of 0.1527 ± 0.0045%. Based on the results of the analysis of chemical compounds, citronellol (32.38%), geraniol (12.86%), nonadecane (10.14%), and heneicosane (6.16%) were the predominant compounds of R. × damascena essential oil under irrigation with treated wastewater and geraniol (17.81%), citronellol (17.67%), nonadecane (12.87%), heptadecane (5.60%), and heneicosane (5.44%) were the predominant compounds of R. × damascena essential oil under irrigation with well water. The strongest inhibitory and lethal activity of R. × damascena essential oil under treated wastewater irrigation was against Gram-negatives Pseudomonas aeruginosa (MIC<15.63 μg/mL) and Candida albicans (MIC=62.50 μg/mL) which were twice as strong as control antibiotics such as rifampin and nystatin. Therefore, it can be found that irrigation with treated wastewater increases the quantity and quality, and antimicrobial activity of R. × damascena essential oil against many microbial strains, which can be a possible option to produce high-quality essential oil for treating infectious diseases.