RESUMO

Chemical products are applied during horticulture to increase food production, but the environmental problems resulting from these applications have led to a search for more sustainable products. Volatile organic compounds (VOCs) demonstrating plant growth promoter (PGP) activity released by bacterial species have emerged as alternatives, but their effects on Lactuca sativa growth are unknown. In this study, VOCs released by Bacillus sp. BCT9 cultures grown in different media (Methyl Red & Voges Proskauer, Murashige & Skoog and nutrient media) at concentrations of 0.1, 0.2, 0.5 and 0.7 (measured as the absorbance, λ=600nm) were tested to evaluate their activity as growth inducers of L. sativa after 10days of exposure. Lower concentrations of BCT9 increased root length, and higher concentrations induced shoot length and lateral root length. The dry weight and number of lateral roots increased similarly, independent of concentration, for VOCs produced in all culture media. BCT9 cultures grown in Methyl Red & Voges Proskauer medium as bioactive compounds with or without lanolin. These VOCs increased shoot length, root length and dry weight at low concentrations, independent of the presence of lanolin. Lateral root length increased with the application of 2-nonanone (50ppm) and 2-undecanone (0.05ppm). Based on these results, the use of bioactive volatiles as growth inducers of horticultural species represents an alternative or complementary strategy.

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RESUMO

Laureliopsis philippiana (Looser) is native evergreen specie from Chile and Argentina used in traditional medicine. In this study, chemical composition as well as its in vitro antibacterial activity against Escherichia coli, Enterobacter aerogenes, Staphylococcus epidermidis and Staphylococcus aureus of essential oil from leaves of this species was determinated. Chemical analysis by GC-MS resulted in the identification of 19 compounds representing 98.8 percent onoterpenes; linalool (32.3 percent) and eucalyptol (37.4 percent) were the main constituents. To evaluate the antibacterial activity disc diffusion method and broth dilution method were used. The essential oil exhibited inhibitory activity against Gram (-) and Gram (+) bacteria, whereas similar activity to essential oil was showed for linalool against E. aerogenes and S. epidermidis whereas linalool alone, achieves an inhibitory effect against E. aerogenes and S. epidermidis comparable to the essential oil.

Laureliopsis philippiana (Looser) es una especie siempre verde nativa de Chile y Argentina usado en medicina tradicional. En este estudio se determinó tanto la composición química del aceite esencial obtenido a partir de hojas de esta especie, así como su actividad antibacterial in vitro contra Escherichia coli, Enterobacter aerogenes, Staphylococcus epidermidis and Staphylococcus aureus. El análisis químico por GC-MS permitió la identificación de 19 compuestos, representando el 98,8 por ciento de la composición del aceite. Monoterpenos oxigenados, eucaliptol y linalol fueron los mayores constituyentes del aceite con un 37,4 por ciento y 32,3 por ciento respectivamente. Para evaluar la actividad antibacteriana se utilizaron los métodos de difusión en agar y dilución en caldo. El aceite esencial muestra actividad inhibitoria contra las bacterias Gram (-) y Gram (+) evaluadas, mientras que linalol por si solo logra un efecto inhibitorio comparable con el aceite esencial contra E. aerogenes y S. epidermidis mientras que el linalol por si solo, logra un efecto inhibitorio contra E. aerogenes y S. epidermidis comparable al del aceite esencial.

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