In vitro growth-inhibitory effect of essential oils against plant pathogenic bacteria and fungi in vapour phase

Abstract

Diseases caused by plant pathogens lead to significant losses to food crops in agricultural storages and greenhouses. In closed environment, plant diseases are currently controlled with fungicides, however, reliance on this single strategy leads to problems such as harmful residues and health issues of workers. Therefore, there is an increasing pressure to find more natural methods of disease control in special environment. One of the prospective methods could be the use of essential oil (EO) vapours [1]. EOs have previously demonstrated antimicrobial activity against number of plant pathogens. Despite the great antimicrobial potential of EOs, growth-inhibitory effects of their vapours have poorly been investigated against microorganisms causing plant diseases in closed environment [1]. In this study we determined chemical composition and antimicrobial activity of EOs and their vapours against plant pathogens such as Aspergillus niger, Fusarium oxysporum and Pectobacterium carotovorum. EOs of Allium sativum, Cinnamomum zeylanicum, Citrus sinensis, Syzygium aromaticum and Thymus vulgaris were obtained using hydrodistilation. Subsequently, minimum inhibitory concentrations (MICs) were identified using broth microdilution volatilization method [2], [3]. The chemical composition of the most effective EOs have been determined using GC/MS. The results showed that the C. zeylanicum, T. vulgaris and S. aromaticum EOs produced the highest antimicrobial activity in vapor or liquid phase (MICs 256 – 1024 µg/mL). The major components were E-cinnamaldehyde (cinnamon), thymol (thyme) and eugenol (clove). In conclusion, above-mentioned EOs could be used for the development of new products for control of pathogenic microorganisms causing spoilage of agricultural products or plant diseases e.g., controlled atmosphere.