pXO16, the large conjugative plasmid from Bacillus thuringiensis serovar israelensis displays an extended host spectrum

Hinnekens, Pauline; Koné, Klèma Marcel; Fayad, Nancy; Leprince, Audrey; Mahillon, Jacques

doi:10.1016/j.plasmid.2019.02.004

Cited by 14 publications

(12 citation statements)

References 23 publications

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“…B. cytotoxicus transformants containing the shuttle pMAD::UD underwent successive non-permissive incubation cycles as follow: two at 43 • C, one at 45 • C and a last one at 50 • C. Up to 10 −7 serial dilutions were made from the last cycle culture (50 • C) and spread on LB agar supplemented with kanamycin and 20 µg/µL of X-Gal (Sigma-Aldrich™, Overijse, Belgium). Since pMAD contains a β-galactosidase cassette, five white colonies (indicating pMAD absence) on X-Gal LB agar were re-streaked on LB agar supplemented with kanamycin and incubated overnight at 30 • C. Using filter mating as described by Hinnekens et al [29], the cytK-1 KO mutation was mobilized from B. cytotoxicus strain E28.3.1 cytK−1-KO-A (Derivative of E28.3 cytK−1-KO-A containing pXO16::Tn5401) into E8.1 via conjugation [24]. The candidate transconjugants strains were PCR-screened to check the effective replacement of cytK-1 gene by Kan R gene.…”

Section: This Work Pdg783mentioning

confidence: 99%

New Insights into the Potential Cytotoxic Role of Bacillus cytotoxicus Cytotoxin K-1

Koné

Hinnekens

Jovanović

et al. 2021

Toxins

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The thermotolerant representative of the Bacillus cereus group, Bacillus cytotoxicus, reliably harbors the coding gene of cytotoxin K-1 (CytK-1). This protein is a highly cytotoxic variant of CytK toxin, initially recovered from a diarrheal foodborne outbreak that caused the death of three people. In recent years, the cytotoxicity of B. cytotoxicus has become controversial, with some strains displaying a high cytotoxicity while others show no cytotoxicity towards cell lines. In order to better circumscribe the potential pathogenic role of CytK-1, knockout (KO) mutants were constructed in two B. cytotoxicus strains, E8.1 and E28.3. The complementation of the cytK-1 KO mutation was implemented in a mutant strain lacking in the cytK-1 gene. Using the tetrazolium salt (MTT) method, cytotoxicity tests of the cytK-1 KO and complemented mutants, as well as those of their wild-type strains, were carried out on Caco-2 cells. The results showed that cytK-1 KO mutants were significantly less cytotoxic than the parental wild-type strains. However, the complemented mutant was as cytotoxic as the wild-type, suggesting that CytK-1 is the major cytotoxicity factor in B. cytotoxicus.

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Section: This Work Pdg783mentioning

confidence: 99%

New Insights into the Potential Cytotoxic Role of Bacillus cytotoxicus Cytotoxin K-1

Koné

Hinnekens

Jovanović

et al. 2021

Toxins

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“…Plasmids are part of the mobile genetic elements (MGEs) repertoire of each strain. Some of these extrachromosomal entities can be conjugative (24), mobilizable or of prophage-like nature (25).…”

Section: Downloaded Frommentioning

confidence: 99%

“…Plasmids are part of the repertoire of mobile genetic elements (MGEs) of each strain. Some of these extrachromosomal entities can be conjugative ( 24 ), mobilizable, or of prophage-like nature ( 25 ). Another group of MGEs are transposable elements (TEs), which can move from one location to another within the same genome.…”

Section: Introductionmentioning

confidence: 99%

A Novel Antidipteran Bacillus thuringiensis Strain: Unusual Cry Toxin Genes in a Highly Dynamic Plasmid Environment

Fayad

Kambris

Chamy

et al. 2021

Appl Environ Microbiol

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Bacillus thuringiensis emerged as a major bioinsecticide on the global market. It offers a valuable alternative to chemical products classically utilized to control pest insects. Despite the efficiency of several strains and products available on the market, the scientific community is always on the lookout for novel toxins that can replace or supplement the existing products. In this study, H3, a novel B. thuringiensis strain showing mosquitocidal activity, was isolated from Lebanese soil and characterized at an in vivo, genomic and proteomic levels. H3 parasporal crystal is toxic on its own but displays an unusual killing profile with a higher LC50 than the reference B. thuringiensis serovar israelensis crystal proteins. In addition, H3 has a different toxicity order: it is more toxic to Aedes albopictus and Anopheles gambiae than to Culex pipiens. Whole genome sequencing and crystal analysis revealed that H3 can produce eleven novel Cry proteins, eight of which are assembled in genes with an orf1-gap-orf2 organization, where orf2 is a potential Cry4-type crystallization domain. Moreover, pH3-180, the toxin-carrying plasmid, holds a wide repertoire of mobile genetic elements that amount to ca. 22% of its size., including novel insertion sequences and class II transposable elements Two other large plasmids present in H3 carry genetic determinants for the production of many interesting molecules - such as chitinase, cellulase and bacitracin - that may add up to H3 bioactive properties. This study therefore reports a novel mosquitocidal Bacillus thuringiensis strain with unusual Cry toxin genes in a rich mobile DNA environment. IMPORTANCE Bacillus thuringiensis, a soil entomopathogenic bacteria, is at the base of many sustainable eco-friendly bio-insecticides. Hence stems the need to continually characterize insecticidal toxins. H3 is an anti-dipteran B. thuringiensis strain, isolated from Lebanese soil, whose parasporal crystal contains eleven novel Cry toxins and no Cyt toxins. In addition to its individual activity, H3 showed potential as a co-formulant with classic commercialized B. thuringiensis products, to delay the emergence of resistance and to shorten the time required for killing. On a genomic level, H3 holds three large plasmids, one of which carries the toxin-coding genes, with four occurrences of the distinct orf1-gap-orf2 organization. Moreover, this plasmid is extremely rich in mobile genetic elements, unlike its two co-residents. This highlights the important underlying evolutionary traits between toxin-carrying plasmids and the adaptation of a B. thuringiensis strain to its environment and insect host spectrum.

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“…Bacillus cytotoxicus strains carrying the putative conjugative plasmids were used as donors (E8.1 for plasmids pE81-84 and pE81-53, and E28.3 for pE283-80), while strain E17.4, which did not carry those plasmids, was used as recipient. Spontaneous streptomycin-resistant mutants of the donor (100 μg ml −1 ) and rifampicin-resistant mutants (50 μg ml −1 ) of recipient strains were used in filter-mating experiments as previously described by Hinnekens et al (2019). After the mating, 100 CFUs of the potential transconjugants were PCR-screened for the presence of the conjugative plasmids.…”

Section: Bacterial Conjugationmentioning

confidence: 99%

“…It is related to the 53-kb plasmid found in clades B and C of B. cytotoxicus strains (Stevens et al, 2019), as well as to plasmids pCE3 from Bacillus paranthracis strain BC307 (NZ_CP047088.1) and pBCM1301 from B. cereus strain M13 (NZ_CP016361.1; Figure 5). In order to assess the potential mobility of pE81-53, filter-mating conjugation experiments (Hinnekens et al, 2019) were carried out between a streptomycin-resistant mutant strain E8.1 (donor) and a rifampicin-resistant mutant of E17.4 (recipient). After mating, the presence of pE81-53 in the recipient strain was detected via PCR.…”

Section: Extrachromosomal Diversitymentioning

confidence: 99%

Bacillus cytotoxicus Genomics: Chromosomal Diversity and Plasmidome Versatility

et al. 2021

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Bacillus cytotoxicus is the thermotolerant representative of the Bacillus cereus group. This group, also known as B. cereus sensu lato, comprises both beneficial and pathogenic members and includes psychrotolerant and thermotolerant species. Bacillus cytotoxicus was originally recovered from a fatal outbreak in France in 1998. This species forms a remote cluster from the B. cereus group members and reliably contains the cytk-1 gene, coding for a cytotoxic variant of cytotoxin K. Although this species was originally thought to be homogenous, intra-species diversity has been recently described with four clades, six random amplified polymorphic DNA (RAPD) patterns, and 11 plasmids profiles. This study aimed to get new insights into the genomic diversity of B. cytotoxicus and to decipher the underlying chromosomal and plasmidial variations among six representative isolates through whole genome sequencing (WGS). Among the six sequenced strains, four fitted the previously described genomic clades A and D, while the remaining two constituted new distinct branches. As for the plasmid content of these strains, three large plasmids were putatively conjugative and three small ones potentially mobilizable, harboring coding genes for putative leaderless bacteriocins. Mobile genetic elements, such as prophages, Insertion Sequences (IS), and Bacillus cereus repeats (bcr) greatly contributed to the B. cytotoxicus diversity. As for IS elements and bcr, IS3 and bcr1 were the most abundant elements and, along with the group II intron B.c.I8, were found in all analyzed B. cytotoxicus strains. When compared to other B. cytotoxicus strains, the type-strain NVH 391-98 displayed a relatively low number of IS. Our results shed new light on the contribution of mobile genetic elements to the genome plasticity of B. cytotoxicus and their potential role in horizontal gene transfer.

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pXO16, the large conjugative plasmid from Bacillus thuringiensis serovar israelensis displays an extended host spectrum

Cited by 14 publications

References 23 publications

New Insights into the Potential Cytotoxic Role of Bacillus cytotoxicus Cytotoxin K-1

New Insights into the Potential Cytotoxic Role of Bacillus cytotoxicus Cytotoxin K-1

A Novel Antidipteran Bacillus thuringiensis Strain: Unusual Cry Toxin Genes in a Highly Dynamic Plasmid Environment

Bacillus cytotoxicus Genomics: Chromosomal Diversity and Plasmidome Versatility

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