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- Title
Kinetics of plasmid transfer among Bacillus cereus group strains within lepidopteran larvae.
- Authors
Yuan, Y. M.; Hu, X. M.; Liu, H. Z.; Hansen, Bjarne Munk; Yan, J. P.; Yuan, Z. M.
- Abstract
The cry toxin encoding plasmid pHT73 was transferred from Bacillus thuringiensis subspecies kurstaki KT0 to six B. cereus group strains in three lepidopteran ( Spodoptera exigua, Plutella xyllostella and Helicoverpa armigera) larvae by conjugation. The conjugation kinetics of the plasmid was precisely studied during the larval infection using a new protocol. The infections were performed with both vegetative and sporulated strains. However, larval death only occurred when infections were made with spore and toxin preparations. Likewise, spore germinations of both donor and recipient strains were only observed in killed larvae, 44–56 h post-infection. Accordingly, kinetics showed that gene transfer between B. thuringiensis strain KT0 and other B. cereus strains only took place in dead larvae among vegetatively growing bacteria. The conjugational transfer ratios varied among different strain combinations and different larvae. The highest transfer ratio reached 5.83 × 10−6 CFU/donor between the KT0 and the AW05R recipient in Helicoverpa armigera, and all transconjugants gained the ability to produce the insecticidal crystal. These results indicated that horizontal gene transfer among B. cereus group strains might play a key role for the acquisition of extra plasmids and evolution of these strains in toxin susceptible insect larvae.
- Subjects
BACILLUS cereus; BACILLUS thuringiensis; INSECT larvae; PLASMID genetics; INFECTION
- Publication
Archives of Microbiology, 2007, Vol 187, Issue 6, p425
- ISSN
0302-8933
- Publication type
Article
- DOI
10.1007/s00203-006-0206-5