Chemical Composition and Antibacterial Activity of Essential Oils ofTagetes minuta(Asteraceae) against Selected Plant Pathogenic Bacteria

Abstract

The objective of this study was to determine the chemical composition and antibacterial activity of essential oils (EOs) ofTagetes minutaagainst three phytopathogenic bacteriaPseudomonas savastanoipv.phaseolicola,Xanthomonas axonopodispv.phaseoli, andXanthomonas axonopodispv.manihotis. The essential oils were extracted using steam distillation method in a modified Clevenger-type apparatus while antibacterial activity of the EOs was evaluated by disc diffusion method. Gas chromatography coupled to mass spectrometry (GC/MS) was used for analysis of the chemical profile of the EOs. Twenty compounds corresponding to 96% of the total essential oils were identified with 70% and 30% of the identified components being monoterpenes and sesquiterpenes, respectively. The essential oils ofT. minutarevealed promising antibacterial activities against the test pathogens withPseudomonas savastanoipv.phaseolicolabeing the most susceptible with mean inhibition zone diameters of 41.83 and 44.83 mm after 24 and 48 hours, respectively.The minimum inhibitory concentrations and minimum bactericidal concentrations of the EOs on the test bacteria were in the ranges of 24–48 mg/mL and 95–190 mg/mL, respectively. These findings provide a scientific basis for the use ofT. minutaessential oils as a botanical pesticide for management of phytopathogenic bacteria.