Examinando por Materia "Bioinsecticida"

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  • Publicación
    Acceso abierto
    Caracterizaci ón molecular de genes cry1, cry2, cry3 y cry4 en aislados de Bacillus thuringiensis y determinación de su actividad bioinsecticida en larvas de Aedes aegypti
    (2013-02-20) Galvis Serrano, Nestor Fabián
    Chemical insecticides can be toxic and cause environmental degradation. Therefore, biological control of insects represents an alternative of low ecological impact. Bacillus thuringiensis is a spore-forming Gram-positive bacterium that produces parasporal crystals of a proteic nature, formed by delta endotoxins that are toxic to a large number of insects and are biodegradable and innocuous to other species. In the present work 13 native strains of B. thuringiensis were isolated from soil samples and identified by selective methods and the BBL CRYSTAL method. In the molecular characterization utilizing specific primers for the identification of cry1, cry2, cry3 y cry4 genes, eight isolates presented the cry3 gene and two presented the cry2 gene. These two latter isolates were used in a bioassay on Aedes aegypti larvae to determine their toxic effect, showing that the preliminary toxicity essay of the BtUDES2 isolate presented a lethality of 56.67%. When determining the lethal concentration of this same isolate, an average lethal concentration of 11.4333ng·ml-1 and a total lethal concentration of 17.1542ng·ml-1 were found.
  • Publicación
    Acceso abierto
    Caracterización molecular mediante REP-PCR de aislados nativos de bacillus thuringiensis, obtenidos de muestras de suelo
    (2014) Galvis Serrano, Nestor Fabián; Moreno, Laura Yolima
    Molecular characterization using rep-PCR of native isolates of Bacillus thuringiensis, obtained from soil samples. Bacillus thuringiensis is a Gram-positive bacteria forming spores, which produces parasporal crystals of a proteic nature, toxic against various orders of insects and biodegradable and harmless to other species. This research use the experimental model, allowing, through observation techniques, microbiological and biochemical identification of B. thuringiensisfrom soil samples from municipalities of Cúcuta, El Zulia, Los Patios, San Cayetano and Villa del Rosario, Norte de Santander, Colombia, and its subsequent characterization with molecular markers Bc-Rep and MB1. Microbiological and biochemical tests identified 10 isolates as B. thuringiensis; the results of phylogenetic analysis showed significant differences in the clusters obtained with Bc-Rep and MB1 markers. With Bc-Rep a low index of similarity (18%) was recorded, while with the marker MB1 a higher similarity index, 58%, was obtained. This work indicated a great genetic variability among isolates, showing that markers Bc-Rep and MB1 are highly effective to differentiate closely related strains, thus becoming a genetic tool of great value for studies of identification and diversity in B. thuringiensis.