Efecto de los aceites esenciales de cymbopogon citratus (Dc.) stapf (limonaria) y lippia alba (mill.) n.e.br. ex britton & p. wilson (pronto alivio) sobre xanthomonas axonopodis y ralstonia sp.

Introduction: The essential oils of Cymbopogon citratus (DC.) Stapf (lemon grass) and Lippia alba (Mill.) N. E. Br. ex Britton & P. Wilson (bushy matgrass) have shown to inhibit the growth of various microorganisms, among them phytopathogenic bacteria causing great damage to economically important crops. Objective: Evaluate the effect of essential oils of C. citratus and Lippia alba on the phytopathogenic bacteria Xanthomonas axonopodis and Ralstonia sp. Methods: The plants C. citratus (DC.) and L. alba were obtained from Samper Mendoza collection center in Bogotá, Colombia. The essential oils were extracted from the leaves by steam entrainment. Yield was estimated by gravimetry and relative composition by gas chromatography/mass spectrometry. Determination was made of the density and refractive index. The growth curves for the bacteria X. axonopodis and Ralstonia sp. were based on estimation of the optical densities on the Bioscreen C at 25ºC for 84 hours versus the two essential oils at a concentration of 28 mg/ml. Results: The yields obtained were 0.13% for C. citratus and 0.62% for L. alba. The most abundant compounds were geranial in lemon grass (41.88%) and limonene in bushy matgrass (49.91%). The growth curves show significant differences in the effect of each oil on the bacteria evaluated, with L. alba as the one displaying the greatest growth inhibition. Conclusions: According to the data obtained by the study, the compounds in the essential oils may be combined in different ways to produce biopesticides or antimicrobials against the microorganisms evaluated herein or others that cause damage to the agricultural sector, thus reducing the use of synthetic pesticides.