Stability, oviposition attraction, and larvicidal activity of binary toxin from Bacillus sphaericus expressed in Escherichia coli.
Bacillus sphaericus produces a two-chain binary toxin composed of BinA (42 kDa) and BinB (51 kDa), which are deposited as parasporal crystals during sporulation. The toxin is highly active against Culex larvae and Aedes and Anopheles mosquitoes, which are the principal vectors for the transmission of malaria, yellow fever, encephalitis, and dengue. The use of B. sphaericus and Bacillus thuringiensis in mosquito control programs is limited by their sedimentation in still water. In this study, the binA and binB genes were cloned and the recombinant BinAB protein was expressed in three strains of Escherichia coli. These recombinant strains were used in a toxicity assay against Culex quinquefasciatus larvae. The highest expression level was achieved when both proteins were expressed in a single operon construct. The BinAB protein expressed in the E. coli Arctic strain showed higher larvicidal activity than either of the recombinant proteins from the E. coli Ril or pLysS strains. Furthermore, it had the highest oviposition attraction (49.1%, P < 0.05). These data suggest that biologically active recombinant BinA and BinB toxins might be useful in mosquito control programs, delivered by inactivated bacterial cells or in traps.
Centro de Desenvolvimento Tecnológico, Núcleo Biotecnologia, UFPel, Campus Universitário, s/n, Caixa Postal 354, Pelotas, RS, 96010-900, Brazil. dmpluc@gmail.com
Luciano
L
da Silva Pinto
Relber Aguiar
RA
Gonçales
Fabricio Rochedo
FR
Conceição
Paula Ferreira
PF
Knabah
Sibele
S
Borsuk
Vinicius Farias
VF
Campos
Francisco Vassiliepe
FV
Arruda
Fabio Pereira Leivas
FP
Leite
D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics; D001427:Bacterial Toxins / Q000235:genetics / Q000302:isolation & purification / Q000633:toxicity*; D002630:Chemotactic Factors / Q000302:isolation & purification / Q000494:pharmacology*; D003465:Culex / Q000187:drug effects*; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D007306:Insecticides / Q000302:isolation & purification / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects; D010058:Oviposition / Q000187:drug effects*; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000633:toxicity; D016019:Survival Analysis
D001427:Bacterial Toxins; D002630:Chemotactic Factors; D007306:Insecticides; D011994:Recombinant Proteins; C046134:binB protein, Bacillus sphaericus