Conjugative Transfer of Insecticidal Plasmid pHT73 from Bacillus thuringiensis to B. anthracis and Compatibility of This Plasmid with pXO1 and pXO2

Abstract

Bacillus anthracis, the etiologic agent of anthrax, is genetically close to and commonly shares a giant gene pool with B. cereus and B. thuringiensis. In view of the human pathogenicity and the long persistence in the environment of B. anthracis, there is growing concern about the effects of genetic exchange with B. anthracis on public health. In this work, we demonstrate that an insecticidal plasmid, pHT73, from B. thuringiensis strain KTO could be efficiently transferred into two attenuated B. anthracis strains, Ba63002R (pXO1+ pXO2-) and Ba63605R (pXOl- pXO2 +), by conjugation in liquid medium in the laboratory, with transfer rates of 2.3 X 10-4 and 1.6 x 10-4 CFU/donor, respectively. The B. anthracis transconjugants containing both pHT73 and pXO1 or pXO2 could produce crystal protein CrylAc encoded by plasmid pHT73 and had high toxicity to Helicoverpa armigera larvae. Furthermore, the compatibility and stability of pHT73 with pXO1/pXO2 were demonstrated. The data are informative for further investigation of the safety of B. thuringiensis and closely related strains in food and in the environment. Copyright © 2010, American Society for Microbiology. All Rights Reserved.