Isolation of Bacillus thuringiensis strains that contain Dipteran-specific cry genes from Ilha Bela (São Paulo, Brazil) soil samples
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Data
2012-05-01
Autores
Campanini, E. B. [UNESP]
Davolos, C. C. [UNESP]
Alves, E. C. C. [UNESP]
Lemos, M. V. F. [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Instituto Internacional de Ecologia
Resumo
Bacillus thuringiensis é entomopatogênica, por produzir proteínas cristais, denominadas proteínas Cry, as quais são codificadas pelos genes cry. Essa bactéria atua no controle biológico de insetos-praga de culturas economicamente importantes, bem como no controle de insetos vetores causadores de doenças, como o Aedes aegypti, mosquito transmissor do vírus da dengue. Os isolados dessa bactéria podem ser caracterizados pelo conteúdo de genes cry que possuem e, assim, predizer o alvo de controle dos mesmos às diferentes ordens de insetos. Com o objetivo de encontrar isolados eficientes no controle do vetor A. aegypti, o presente trabalho isolou 76 colônias de B. thuringiensis a partir de 30 amostras de solo oriundas de Ilhabela-SP, município que se caracteriza por realizar controle biológico de simulídeos com essa bactéria. Os 76 isolados foram sequenciados na região da subunidade ribossomal 16S e caracterizados molecularmente quanto ao conteúdo de genes cry díptero-específicos. No total, oito isolados (10,52% do total) apresentaram bandas para os genes cry4Aa, cry4Ba e cry10Aa, sendo os mesmos testados contra larvas de A. aegypti por meio de bioensaios. A presença e/ou ausência dos genes cry foi associada à mortalidade média de larvas. Dentre os isolados estudados, sete (9,2% do total) apresentaram elevado potencial de controle às larvas de A. aegypti, sendo assim considerados como promissores para o manejo do controle biológico de larvas de A. aegypti com a bactéria B. thuringiensis.
The entomophatogenic bacterium Bacillus thuringiensis produces crystal proteins, named Cry proteins which are encoded by the cry genes. This bacterium is used on biological control of important economical pests, as well as in the control of disease´s vectors, such as Aedes aegypti, a mosquito that transmits the dengue viruses. Isolates of this bacterium can be characterized by the content of cry genes and this prediction helps target different insect orders. In this research, we isolated 76 colonies of B. thuringiensis from 30 soil samples that were taken from Ilha Bela (SP, Brazil), a place where simulids are already biologically controlled by B. thuringiensis, to find bacterial isolates that were capable of controlling A. aegypti. The 16S ribosomal subunit genes of the selected isolates were sequenced, and the isolates were molecularly characterized based on their Dipteran-specific cry gene contents. Eight of the 76 isolates (10.52%) contained the cry4Aa, cry4Ba or cry10Aa genes, these isolates were carried out against A. aegypti larvae on bioassay. The presence or absence of specific cry genes was associated with the observed average larval mortalities. From the 76 isolates, seven (9.2%) were potentially able to control A. aegypti larvae. Therefore these are promising isolates for the biological control of A. aegypti larvae.
The entomophatogenic bacterium Bacillus thuringiensis produces crystal proteins, named Cry proteins which are encoded by the cry genes. This bacterium is used on biological control of important economical pests, as well as in the control of disease´s vectors, such as Aedes aegypti, a mosquito that transmits the dengue viruses. Isolates of this bacterium can be characterized by the content of cry genes and this prediction helps target different insect orders. In this research, we isolated 76 colonies of B. thuringiensis from 30 soil samples that were taken from Ilha Bela (SP, Brazil), a place where simulids are already biologically controlled by B. thuringiensis, to find bacterial isolates that were capable of controlling A. aegypti. The 16S ribosomal subunit genes of the selected isolates were sequenced, and the isolates were molecularly characterized based on their Dipteran-specific cry gene contents. Eight of the 76 isolates (10.52%) contained the cry4Aa, cry4Ba or cry10Aa genes, these isolates were carried out against A. aegypti larvae on bioassay. The presence or absence of specific cry genes was associated with the observed average larval mortalities. From the 76 isolates, seven (9.2%) were potentially able to control A. aegypti larvae. Therefore these are promising isolates for the biological control of A. aegypti larvae.
Descrição
Palavras-chave
dengue, Biological control, Dipteran, 16S rRNA, Dengue, Controle biológico, Dipterous, rRNA 16S
Como citar
Brazilian Journal of Biology. Instituto Internacional de Ecologia, v. 72, n. 2, p. 243-247, 2012.