Expression of the Bacillus thuringiensis Mosquitocidal Toxin Cry11Aa in the Aquatic Bacterium Asticcacaulis excentricus

Abstract

A mosquitocidal aquatic bacterium has been developed by introducing an operon containing the cry11Aa, and p20 genes from Bacillus thuringiensis subsp. israelensis (Bti) into the gram-negative aquatic bacterium Asticcacaulis excentricus. After transformation, the cry11Aa gene was successfully expressed in recombinant A. excentricus under the tac promoter, at the level of 0.04 pg/cell. The recombinant bacteria were toxic to Aedes aegypti larvae with an LC(50) of 6.83 x 10(5) cells/mL. We believe that these bacteria may have potential as genetically engineered microorganisms for the control of mosquito larvae.

Genetic Improvement of Bt Strains and Development of Novel Biopesticides

“…Various bacteria have been manipulated in this way including species of cyanobacteria belonging to the genus Synechococcus (Chungjatupornchai 1990;Soltes-Rak et al 1993), Caulobacter crescentus (Thanabalu et al 1992), Anabaena sp. (Khasdan et al 2003) and Asticcacaulis excentricus (Armengol et al 2005) but, to date, none of these recombinant organisms has been commercially developed.…”

Beyond the spore – past and future developments of Bacillus thuringiensis as a biopesticide

“…Various bacteria have manipulated in this way including Ancylobacter aquaticus, Enterobacter amnigenus, Synechococcus sp., Caulobacter crescentus, Asticcacaulis excentricus and Anabena sp. (Khasdan et al 2003;Armengol et al 2005). Although some of the results are promising there are many issues concerning the release of live, genetically modified bacteria into the environment, which need to be addressed before products can be fully developed.…”