Conjugation by mosquito pathogenic strains of Bacillus sphaericus
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1Biology Department, Virginia Tech, Blacksburg 24061, USA.
Abstract:
A mosquito pathogenic strain of Bacillus sphaericus carried out the conjugal transfer of plasmid pAM beta 1 to other strains of its own and two other serotypes. However, it was unable to conjugate with mosquito pathogens from three other serotypes, with B. sphaericus of other DNA homology groups or with three other species of Bacillus. Conjugation frequency was highest with a strain having an altered surface layer (S layer). Conjugal transfer of pAM beta 1 was not detected in mosquito larval cadavers. B. sphaericus 2362 was unable to mobilize pUB110 for transfer to strains that had served as recipients of pAM beta 1. These observations suggest that it is unlikely that genetically engineered B. sphaericus carrying a recombinant plasmid could pass that plasmid to other bacteria.
Insights
Conjugal transfer of the plasmid pAM beta 1 between Bacillus sphaericus strains was limited. This suggests genetically engineered bacteria are unlikely to transfer plasmids to other species.
Area of Science:
- Microbiology
- Bacterial genetics
- Insect pathology
Background:
- Bacillus sphaericus is a mosquito pathogen.
- Plasmid transfer is a key mechanism for bacterial adaptation and spread.
Purpose of the Study:
- To investigate the conjugal transfer of plasmid pAM beta 1 in Bacillus sphaericus.
- To assess the potential for horizontal gene transfer between B. sphaericus strains and other bacteria.
Main Methods:
- Conjugation experiments were performed using Bacillus sphaericus strains.
- Plasmid transfer was tested with various B. sphaericus serotypes and other Bacillus species.
- Conjugation frequency was analyzed in relation to bacterial surface layers and in mosquito larval cadavers.
Main Results:
- Plasmid pAM beta 1 transfer occurred within B. sphaericus of the same and two other serotypes.
- Conjugation was unsuccessful with mosquito pathogens from three other serotypes and other Bacillus species.
- Highest conjugation frequency was observed with a B. sphaericus strain exhibiting an altered surface layer (S layer).
- Conjugal transfer of pAM beta 1 was not detected in mosquito larval cadavers.
- Mobilization of plasmid pUB110 by B. sphaericus 2362 was not observed.
Conclusions:
- Conjugal transfer of plasmids in B. sphaericus is restricted to specific strains and serotypes.
- The potential for horizontal gene transfer from genetically engineered B. sphaericus to other bacteria is likely limited.
- Environmental conditions, such as mosquito larval cadavers, may not support plasmid transfer.