8 research outputs found
Efeitos toxicológicos de ?-endotoxinas e ?-exotoxinas de Bacillus thuringiensis em ratos Wistar
Bacillus thuringiensis is an entomopathogen consisting of toxic proteins, such as the ?- endotoxins specific to insects. However, some subspecies can produce ?-exotoxins that are nonspecifi c and toxic to the vertebrates. So, in this research the toxicology effect of two isolates of B. thuringiensis in Wistar rats have been assessed. In the in vivo assays the animals have been given 3.1010UFC/mL of B. thuringiensis thuringiensis and B. thuringiensis aizawai and supernatant bacterial suspensions orally. The excrements and the stomachic content of the animals have been collected and analyzed in SDS-PAGE (10%). The analyzed data show protein fragments between 151 kDa and 28 kDa, seeing that the fecal samples show only one track of peptides in the treatments when compared with the control group. The assessments of the stomach of the treated rats carried out under stereomicroscope have not shown alterations when compared with the control. These results indicate that the toxins which can be found in both B. thuringiensis species used in these assays can be degraded by the gastrointestinal conditions of the animals and have not presented oral toxic effect to this mammalian species under the conditions which the experiments had been carried out. Key words: bacterium, toxins, mammalian, toxicity.Bacillus thuringiensis é um entomopatógeno constituído de proteínas tóxicas, como as ?-endotoxinas específicas a insetos. Porém algumas subespécies podem produzir ?-exotoxinas inespecíficas e tóxicas aos vertebrados. Sendo assim, nessa pesquisa foram avaliados os efeitos toxicológicos de dois isolados de B. thuringiensis em ratos Wistar. Nos ensaios in vivo os animais foram tratados via oral com suspensões de 3.1010UFC/mL de B. thuringiensis aizawai e B. thuringiensis thuringiensis e sobrenadante. As fezes e o conteúdo estomacal dos animais foram coletados e analisados em SDS-PAGE (10%). Os dados das análises do conteúdo estomacal mostram fragmentos protéicos entre 151 e 28 kDa, sendo que as amostras fecais mostram apenas um rastro de peptídeos nos tratamentos, quando comparados à testemunha. As avaliações, realizadas sob estereomicroscópio, do estômago dos ratos tratados não mostraram alterações quando comparados com a testemunha. Esses resultados indicam que as toxinas, presentes nas duas subespécies de B. thuringiensis utilizadas nestes ensaios, podem ser degradadas pelas condições gastrointestinais dos animais e não apresentaram efeito tóxico, via oral, a essa espécie de mamífero, nas condições em que foram realizados os experimentos. Palavras-chave: bactéria, toxinas, mamífero, toxocidade
Mortality of Oryzophagus oryzae (Costa Lima, 1936) (Coleoptera: Curculionidae) and Spodoptera frugiperda (J E Smith, 1797) (Lepidoptera: Noctuidae) Larvae Exposed to Bacillus thuringiensis and Extracts of Melia azedarach
Efeitos toxicológicos de ?-endotoxinas e ?-exotoxinas de Bacillus thuringiensis em ratos Wistar
Bacillus thuringiensis is an entomopathogen consisting of toxic proteins, such as the ?- endotoxins specific to insects. However, some subspecies can produce ?-exotoxins that are nonspecifi c and toxic to the vertebrates. So, in this research the toxicology effect of two isolates of B. thuringiensis in Wistar rats have been assessed. In the in vivo assays the animals have been given 3.1010UFC/mL of B. thuringiensis thuringiensis and B. thuringiensis aizawai and supernatant bacterial suspensions orally. The excrements and the stomachic content of the animals have been collected and analyzed in SDS-PAGE (10%). The analyzed data show protein fragments between 151 kDa and 28 kDa, seeing that the fecal samples show only one track of peptides in the treatments when compared with the control group. The assessments of the stomach of the treated rats carried out under stereomicroscope have not shown alterations when compared with the control. These results indicate that the toxins which can be found in both B. thuringiensis species used in these assays can be degraded by the gastrointestinal conditions of the animals and have not presented oral toxic effect to this mammalian species under the conditions which the experiments had been carried out. Key words: bacterium, toxins, mammalian, toxicity.Bacillus thuringiensis é um entomopatógeno constituído de proteínas tóxicas, como as ?-endotoxinas específicas a insetos. Porém algumas subespécies podem produzir ?-exotoxinas inespecíficas e tóxicas aos vertebrados. Sendo assim, nessa pesquisa foram avaliados os efeitos toxicológicos de dois isolados de B. thuringiensis em ratos Wistar. Nos ensaios in vivo os animais foram tratados via oral com suspensões de 3.1010UFC/mL de B. thuringiensis aizawai e B. thuringiensis thuringiensis e sobrenadante. As fezes e o conteúdo estomacal dos animais foram coletados e analisados em SDS-PAGE (10%). Os dados das análises do conteúdo estomacal mostram fragmentos protéicos entre 151 e 28 kDa, sendo que as amostras fecais mostram apenas um rastro de peptídeos nos tratamentos, quando comparados à testemunha. As avaliações, realizadas sob estereomicroscópio, do estômago dos ratos tratados não mostraram alterações quando comparados com a testemunha. Esses resultados indicam que as toxinas, presentes nas duas subespécies de B. thuringiensis utilizadas nestes ensaios, podem ser degradadas pelas condições gastrointestinais dos animais e não apresentaram efeito tóxico, via oral, a essa espécie de mamífero, nas condições em que foram realizados os experimentos. Palavras-chave: bactéria, toxinas, mamífero, toxocidade
Benefits Associated with the Interaction of Endophytic Bacteria and Plants
ABSTRACT The endophytic bacteria belong to a larger group of microorganisms that have their life-cycle partly or entirely inside the plant and are located in intra and inter-cellular spaces or in the vascular tissue. These bacteria can be found colonizing aerial parts or roots. This review aims to analyze the colonization strategies of endophytic bacteria through interaction with plants, as well as to highlight the metabolic influence of these organisms in plant tissues, which result in physiological and biochemical changes. Depending on the different mechanisms used internally to colonize a plant, these microorganisms are called obligate, facultative, or passive endophytes. Phytostimulation, biofertilization and biological control are mechanisms that result in the development of the plant through the production of plant hormones, bioavailability of nutrients and antagonistic action to phytopathogens, respectively. The association between endophytic bacteria and plants features important benefits such as significant increases in growth, plant biomass, length of roots, dry matter production, and grain yield. Studies show that there is a great diversity of endophytic bacteria colonizing plant structures that result in several benefits to the host plant