A mosquito pathogenic strain of Bacillus sphaericus carried out the
conjugal transfer of plasmid pAM beta1 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 beta1 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 beta1. These observations
suggest that it is unlikely that genetically engineered B. sphaericus
carrying a recombinant plasmid could pass that plasmid to other bacteria.