Examinando por Materia "Virulence"

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    Evaluación de la patogenicidad de Xenorhabdus spp. nativos en Colombia
    (2014-07) Guerra-Sierra, Beatriz Elena; Chacón, Julie Giovanna; Muñoz Flórez, Jaime Eduardo; Caicedo, Ana Milena
    Xenorhabdus and Photorhabdus bacteria are symbiotically associated with nematodes of the Steinernematidae and Heterorhabditidae families respectively. They are characterized by producing a complex of substances such as toxins, antibiotics and extracellular enzymes that kill insects. In order to select the most pathogenic nematodes and antibiotic production level, it was propose to evaluate the pathogenicity of 13 native isolates. Bacteria were isolated from infective juveniles (JIS) by direct macerated, cultured on selective media (NBTA and MacConkey) and described phenotypic and biochemically. The pathogenicity was evaluated on the last instar larvae of G. mellonella, using serial dilutions of the bacterial inoculum with a concentration of 104cel/ml. The mortality rate was registered at 12, 24 and 48 hours and the colony forming units (CFU) in NBTA agar in the same intervals of time. The data were analyzed by variance analysis and mean comparison by Duncan test. Biochemical and enzymatic tests were positive for the genus Xenorhabdus. The results showed that the isolates UNPX04, UNPX15 from agricultural soils of Florida -Risaralda and Llano Bajo- Valle del Cauca respectively, caused 100% of mortality at 12 and 24 hours in contrast with seven isolations that caused only 70% of mortality.