Characterization of Cry toxins from autochthonous Bacillus thuringiensis isolates from Mexico

Background: Chemical pesticides, widely used in agriculture and vector-borne disease control, have shown toxic effects on the environment and the people in contact with them. Bacillus thuringiensis is a widely used bacterium for alternative and safer control of insect pests. Its toxins are specific for insects but innocuous for mammals and may be used as powerful adjuvants when applied with vaccines. The objective of this work was to characterize some autochthonous B. thuringiensis strains, which could be used for the control of a local pest (Diatraea considerata Heinrich) that affects sugar cane crops in Sinaloa, Mexico. Also, to evaluate these strains as a source of Cry toxins, which may be used in the future as adjuvants for some vaccines. Methods: Eight strains from field-collected dead insects were isolated. These were microbiologically identified as B. thuringiensis and confirmed by amplification and sequencing of 16S rDNA. Bioassays were performed to evaluate their pathogenicity against D. considerata, and Cry toxins were identified by proteomic analyses. Results: An increased mortality among larvae infected with strain Bt-D was observed, and its toxin was identified as Cry1Ac. Conclusions: The observed data showed that the selected strain was pathogenic to D. considerata and seemed to produce Cry1Ac protein, which has been reported as an adjuvant in different types of immunization

Eficacia de formulaciones y dosis de calcio en el rendimiento de pimiento morrón

In order to know the effectiveness of formulations (CaNO3)2 líq, (CaNO3)2 sol-1, (CaNO3)2 sol-2 and (CaNO3)2 sol-3 as well as the most appropriate dose of each formulation, to induce greater fruit yield in bell pepper (Capsicum annuum L.), research was conducted in a chapel-type greenhouse, transplanting a plant plastic pot with a capacity of12 L, in which doses were applied of 21, 20 , 19, 18, 17, 16 and 15 L ha-1 with each formulation solution. The experimental design was randomized complete block with three replicates per treatment. The most appropriate formulations were of (CaNO3)2 líq and (CaNO3)2 sol-1, since the first caused the dry weight of fruits was increased 24.5, 31.9 and 44.4% compared to that obtained with formulations (CaNO3)2 sol-1, (CaNO3)2 sol-2 and (CaNO3)2 sol-3, respectively. While the (CaNO3)2 sol-1 increases were 5.9% compared to that achieved with (CaNO3)2 sol-2 and 15.9% compared to that obtained with (CaNO3)2 sol-3. So that the yield of plants with (CaNO3)2 líq exceeded the respective 11.2, 26.8 and 60.8% at the averages were obtained (CaNO3)2 sol-1, (CaNO3)2 sol-2 and (CaNO3)2 sol-3, respectively. Based on the dry weight of fruit, the most appropriate doses were 17, 15, 18 and 19 L ha-1, in the order of the formulations of calcium above, but with 15 and 17 L ha-1 more influence had in agricultural sustainability. Keywords: chlorophyll; dry matter of plants and fruits; plant heightCon el objetivo de conocer la eficacia de formulaciones de (CaNO3)2 líq, (CaNO3)2 sol-1, (CaNO3)2 sol-2 y (CaNO3)2 sol-3, así como la dosis más adecuada de cada formulación, para inducir mayor rendimiento de frutos en pimiento morrón (Capsicum annuum L.), se realizó la investigación en un invernadero tipo capilla, al trasplantar una planta por maceta de plástico con capacidad de 12 L, en las cuales se aplicaron dosis de 21, 20, 19, 18, 17, 16 y 15 L ha-1 de solución con cada formulación. El diseño experimental fue bloques completos al azar con tres repeticiones por tratamiento. Las formulaciones más adecuadas fueron la de (CaNO3)2 líq y (CaNO3)2 sol-1, ya que la primera ocasionó que el peso seco de frutos se incrementara 24.5, 31.9 y 44.4% en relación al que se obtuvo con las formulaciones de (CaNO3)2 sol-1, (CaNO3)2 sol-2 y (CaNO3)2 sol-3, respectivamente. Mientras que con el (CaNO3)2 sol-1 los incrementos fueron de 5.9% en comparación al que se logró con (CaNO3)2 sol-2 y 15.9% con respecto al obtenido con (CaNO3)2 sol-3. De tal manera que el rendimiento de las plantas con (CaNO3)2 líq superó en los respectivos 11.2, 26.8 y 60.8% a los promedios que se obtuvieron con (CaNO3)2 sol-1, (CaNO3)2 sol-2 y (CaNO3)2 sol-3, respectivamente. Con base al peso seco de frutos, las dosis más adecuadas fueron 17, 15, 18 y19 Lha-1, en el mismo orden de las formulaciones de calcio mencionadas, pero con 15 y 17 L ha-1 se tuvo más influencia en la sustentabilidad agrícola. Palabras clave: altura de plantas; clorofila; materia seca de plantas y fruto