Research and Reports in Tropical Medicine (Feb 2017)

Isolation and genetic characterization of Lysinibacillus sphaericus strains found in mosquito larvae (Diptera: Culicidae)

  • Cavados CFG,
  • Pires ES,
  • Chaves JQ,
  • Alvarez DN,
  • Benites Gil H,
  • Braz Ribeiro de Oliveira I,
  • de Barros Pinto Viviani Cunha A,
  • Pereira da Cunha de Araújo-Coutinho CJ

Journal volume & issue
Vol. Volume 8
pp. 17 – 20

Abstract

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Clara de Fátima Gomes Cavados,1 Eder Soares Pires,1 Jeane Quintanilha Chaves,1 Danielle Nunes Alvarez,1 Helio Benites Gil,2 Iris Braz Ribeiro de Oliveira,2 Andrea de Barros Pinto Viviani Cunha,2 Carlos José Pereira da Cunha de Araújo-Coutinho2 1Laboratory of Bacterial Physiology, Fundação Oswaldo Cruz, Instituto Oswaldo Cruz, Rio de Janeiro, 2Superintendência de Controle de Endemias – SUCEN, São Paulo, Brazil Introduction: Lysinibacillus sphaericus is a highly effective and specific bioinsecticide used for the control of Culicidae larvae. Objective: This study aimed to identify and characterize L. sphaericus strains isolated from Culex quinquefasciatus larvae in Brazil. Methods: C. quinquefasciatus larvae were collected from streams in the urban area of São Paulo state. L. sphaericus strains were identified through cytomorphology, biochemical, and physiological analyses. Qualitative bioassays were performed to evaluate the toxicity of the strains against C. quinquefasciatus. The crystal compound protein pattern of L. sphaericus strains was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Five reference strains were used as standards in all tests performed. Repetitive extragenic palindromic elements-polymerase chain reaction (REP-PCR) was utilized in an attempt to differentiate pathogenic and nonpathogenic isolates. Results: Twenty-one strains were isolated. Only one presented toxic activity against C. quinquefasciatus. REP-PCR results identified 23 patterns among the 26 strains used in the study, and the fragment analysis showed low similarity (16%) between L. sphaericus isolates and the five reference strains. Conclusion: Comparison of strains isolated in this study using REP-PCR showed a low similarity to other strains, demonstrating the high intraspecific variability for L. sphaericus. Keywords: Lysinibacillus sphaericus, Culicidae, SDS-PAGE, qualitative bioassays, REP-PCR, mosquitoes, entomopathogenic bacteria 

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