The aggregation-mediated conjugation system of Bacillus thuringiensis subsp. israelensis: Host range and kinetics of transfer

Jensen, Gert B.; Andrup, Lars; Wilcks, Andrea; Smidt, Lasse; Poulsen, Otto Melchior

doi:10.1007/s002849900105

Cited by 71 publications

(60 citation statements)

References 48 publications

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“…Frequencies remained around 6.5 ϫ 10 Ϫ1 T/R until 4 h (data not shown). This confirmed previous kinetics studies performed with this plasmid where it was shown that pXO16 conjugation is efficient and fast (23).…”

Section: Resultssupporting

confidence: 91%

“…israelensis. This plasmid displays interesting features, such as fast and efficient transfer frequencies, a specific aggregation phenotype, and the ability to promote the transfer of nonmobilizable plasmids (2,3,4,22,23).…”

Section: Discussionmentioning

confidence: 99%

“…The conjugative system of pXO16 is very efficient, with frequencies reaching 100% in B. thuringiensis subsp. israelensis matings (23). pXO16 was also shown to be able to mobilize small "nonmobilizable" plasmids lacking both a mob gene and an oriT site (3).…”

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confidence: 99%

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Plasmid Capture by the Bacillus thuringiensis Conjugative Plasmid pXO16

et al. 2009

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Conjugation, mobilization, and retromobilization are three related mechanisms of horizontal gene transfer in bacteria. They have been extensively studied in gram-negative species, where retromobilization, the capture of DNA from a recipient by a donor cell, was shown to result from two successive steps: the transfer of the conjugative plasmid from the donor to the recipient followed by the retrotransfer of the mobilizable plasmid to the donor. This successive model was established for gram-negative bacteria but was lacking experimental data from the gram-positive counterparts. In the present work, the mobilization and retromobilization abilities of the conjugative plasmid pXO16 from Bacillus thuringiensis subsp. israelensis were studied using the mobilizable plasmids pUB110 and pE194 and the "nonmobilizable" element pC194 lacking the mob and oriT features (all from Staphylococcus aureus). Experimental data suggested a successive model, since different retromobilization frequencies were observed between the small plasmids. More importantly, retromobilization was shown to be delayed by 50 and 150 min for pUB110 and pE194, respectively, compared to pXO16 conjugation. Natural liquid foods (cow milk, soy milk, and rice milk) were used to evaluate the putative ecological impact of these transfers. In cow and soy milk, conjugation, mobilization, and retromobilization were shown to occur at frequencies of 8.0 ؋ 10 ؊1 , 1.0 ؋ 10 ؊2 , and 1.2 ؋ 10 ؊4 transconjugants per recipient, respectively. These data are comparable to those obtained with LB medium and about 10-fold lower than in the case of rice milk. Taken together, these results emphasize the potential role of plasmid capture played by B. thuringiensis in natural environments.

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Section: Resultssupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

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Plasmid Capture by the Bacillus thuringiensis Conjugative Plasmid pXO16

et al. 2009

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“…israelensis cured of its three small circular plasmids . GBJ002 (Jensen et al, 1996), a B. thuringiensis sv. israelensis 4Q2-72-derived strain cured of all its plasmids, was used as an indicator strain for phage experiments.…”

Section: Methodsmentioning

confidence: 99%

pGIL01, a linear tectiviral plasmid prophage originating from Bacillus thuringiensis serovar israelensis

Verheust

Jensen²,

Mahillon

2003

Microbiology

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Bacillus thuringiensis serovar israelensis harbours, in addition to several circular plasmids, a small linear molecule of about 15 kb. Sequence analysis of this molecule, named pGIL01, showed the presence of at least 30 ORFs, five of which displayed similarity with proteins involved in phage systems: a B-type family DNA polymerase, a LexA-like repressor, two potential muramidases and a DNA-packaging protein (distantly related to the P9 protein of the tectiviral phage PRD1). Experimental evidence confirmed that pGIL01 indeed corresponds to the linear prophage of a temperate phage. This bacteriophage, named GIL01, produces small turbid plaques and is sensitive to organic solvents, which suggests the presence of lipid components in its capsid. Experiments using proteases and exonucleases also revealed that proteins are linked to the genomes of both pGIL01 prophage and GIL01 phage at their 59 extremities. Altogether, these features are reminiscent of those of phages found in the Tectiviridae family, and more specifically of those of PRD1, a broad-host-range phage of Gram-negative bacteria. Dot-blot hybridization, PFGE, PCR and RFLP analyses also showed the presence of pGIL01 variants in the Bacillus cereus group. INTRODUCTIONBacillus thuringiensis, the most widely used entomopathogenic bacterium, belongs to the Bacillus cereus sensu lato group. This cluster also includes B. cereus sensu stricto, an opportunist organism implicated in food poisoning (Granum & Lund, 1997), Bacillus anthracis, a human and animal pathogen, Bacillus mycoides and Bacillus pseudomycoides, characterized by their rhizoid growth (Nakamura, 1998), and the psychrotolerant Bacillus weihenstephanensis (Lechner et al., 1998). Despite their broad virulence, these bacteria are genetically closely related (their 16S RNA gene sequences share more than 99 % identity) and could be regarded as pertaining to a single species (Ash et al., 1991;Helgason et al., 2000).B. thuringiensis strains produce, during their sporulation, crystal toxins (delta-endotoxins) that are highly toxic to a number of insect larvae belonging to the orders Lepidoptera, Diptera and Coleoptera, but harmless to vertebrates. Classically, the numerous entomopathogenic B. thuringiensis strains, which have their own specific insecticidal activity, have been classified in different serotypes on the basis of their flagellar antigens. B. thuringiensis serovar (sv.) israelensis is active against dipteran species and is therefore one of the bioinsecticides of choice to control black flies and mosquitoes, both important vectors of human and animal diseases (for a recent review, see Glare & O'Callaghan, 2000).B. thuringiensis sv. israelensis strain H14 has been reported to contain at least eight DNA molecules, including three small (5?4, 6?7 and 7?6 kb) and four large (128, 145, 240 and 350 kb) circular plasmids, and one linear molecule (G. Jensen & L. Andrup, unpublished results). The pathogenicity of this strain only depends on the presence of the 128 kb plasmid which encodes the Cry and Cyt...

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“…In reality, it is only the insect-toxic effect that differentiates the two species. The genes coding for insect toxins are found primarily on large plasmids in B. thuringiensis (5), and in the laboratory, these plasmids can be lost or transferred horizontally to other bacilli (16,17,28,30,47); hence, a B. thuringiensis strain can be transformed into a B. cereus strain and vice versa. We have previously isolated B. thuringiensis from the feces of exposed persons (29), and in this study, we have shown that commercial preparations of B. thuringiensis subsp.…”

Section: Discussionmentioning

confidence: 99%

Bacillus thuringiensis in Fecal Samples from Greenhouse Workers after Exposure to B. thuringiensis -Based Pesticides

Jensen

Larsen

Jacobsen

et al. 2002

Appl Environ Microbiol

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In a study of occupational exposure to Bacillus thuringiensis, 20 exposed greenhouse workers were examined for Bacillus cereus-like bacteria in fecal samples and on biomonitoring filters. Bacteria with the following characteristics were isolated from eight individuals: intracellular crystalline inclusions characteristic of B. thuringiensis, genes for and production of B. cereus enterotoxins, and positivity for cry11 as determined by PCR. DNA fingerprints of the fecal isolates were identical to those of strains isolated from the commercial products used. Work processes (i.e., spraying) correlated with the presence of B. thuringiensis in the fecal samples (10 2 to 10 3 CFU/g of feces). However, no gastrointestinal symptoms correlated with the presence of B. thuringiensis in the fecal samples.

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The aggregation-mediated conjugation system of Bacillus thuringiensis subsp. israelensis: Host range and kinetics of transfer

Cited by 71 publications

References 48 publications

Plasmid Capture by the Bacillus thuringiensis Conjugative Plasmid pXO16

Plasmid Capture by the Bacillus thuringiensis Conjugative Plasmid pXO16

pGIL01, a linear tectiviral plasmid prophage originating from Bacillus thuringiensis serovar israelensis

Bacillus thuringiensis in Fecal Samples from Greenhouse Workers after Exposure to B. thuringiensis -Based Pesticides

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