Conjugative transfer, stability and expression of a plasmid encoding a<i>cry</i>1Ac gene in<i>Bacillus cereus</i>group strains

Hu, Xiaomin; Hansen, Benni Winding; Eilenberg, Jørgen; Hendriksen, Niels Bohse; Smidt, Lasse; Yuan, Zhiming; Jensen, Gert B.

doi:10.1016/s0378-1097(03)00925-x

Cited by 41 publications

(34 citation statements)

References 34 publications

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“…There was no sign of crystals in sporulated cultures of the B. cereus ST-8 strains that were examined by light and electron microscopy, and Western blots using an anti-Cry1 antiserum revealed a trace of crystal protein in strain S58 but none in the other two strains (data not shown). Presumably, these are strains that have lost most or all of the Cry plasmids, supporting the concept of the fluidity of plasmid-borne crystal protein synthesis in this lineage (22).…”

Section: Discussionmentioning

confidence: 63%

Population Structure and Evolution of the Bacillus cereus Group

Priest¹,

Barker²,

Baillie³

et al. 2004

J Bacteriol

337

395

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Representative strains of the Bacillus cereus group of bacteria, including Bacillus anthracis (11 isolates), B. cereus (38 isolates), Bacillus mycoides (1 isolate), Bacillus thuringiensis (53 isolates from 17 serovars), and Bacillus weihenstephanensis (2 isolates) were assigned to 59 sequence types (STs) derived from the nucleotide sequences of seven alleles, glpF, gmk, ilvD, pta, pur, pycA, and tpi. Comparisons of the maximum likelihood (ML) tree of the concatenated sequences with individual gene trees showed more congruence than expected by chance, indicating a generally clonal structure to the population. The STs followed two major lines of descent. Clade 1 comprised B. anthracis strains, numerous B. cereus strains, and rare B. thuringiensis strains, while clade 2 included the majority of the B. thuringiensis strains together with some B. cereus strains. Other species were allocated to a third, heterogeneous clade. The ML trees and split decomposition analysis were used to assign STs to eight lineages within clades 1 and 2. These lineages were defined by bootstrap analysis and by a preponderance of fixed differences over shared polymorphisms among the STs. Lineages were named with reference to existing designations: Anthracis, Cereus I, Cereus II, Cereus III, Kurstaki, Sotto, Thuringiensis, and Tolworthi. Strains from some B. thuringiensis serovars were wholly or largely assigned to a single ST, for example, serovar aizawai isolates were assigned to ST-15, serovar kenyae isolates were assigned to ST-13, and serovar tolworthi isolates were assigned to ST-23, while other serovars, such as serovar canadensis, were genetically heterogeneous. We suggest a revision of the nomenclature in which the lineage and clone are recognized through name and ST designations in accordance with the clonal structure of the population.

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Section: Discussionmentioning

confidence: 63%

Population Structure and Evolution of the Bacillus cereus Group

Priest¹,

Barker²,

Baillie³

et al. 2004

J Bacteriol

337

395

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“…These genes are responsible for the production of different Cry toxins that form insecticidal crystal protein inclusions. Some of these large plasmids have been found to have conjugative transfer capability (12,20). For instance, plasmid pHT73 from B. thuringiensis subsp.…”

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confidence: 99%

Distribution, Diversity, and Potential Mobility of Extrachromosomal Elements Related to the Bacillus anthracis pXO1 and pXO2 Virulence Plasmids

Auwera

Timmery

et al. 2009

Appl Environ Microbiol

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The presence of a pXO1-and/or pXO2-like plasmid(s) in clinical isolates of Bacillus cereus sensu stricto and in strains of the biopesticide Bacillus thuringiensis has been reported recently, and the pXO2-like plasmid pBT9727 and another pXO2-like plasmid, pAW63, were found to be conjugative. In this study, a total of 1,000 B. cereus group isolates were analyzed for the presence of pXO1-and pXO2-like replicons and for the presence of pXO2-related conjugative modules. pXO1-and pXO2-like replicons were present in ca. 6.6% and 7.7% of random environmental samples, respectively, and ca. 1.54% of the strains were positive for pXO2-like transfer module genes. Only the strains harboring a pXO2-like replicon also contained the corresponding transfer genes. For the strains which contained a pXO1-and/or pXO2-like replicon(s), a large plasmid(s) whose size was similar to that of pXO1-like and/or pXO2-like plasmids was also observed, but none of these isolates were found to carry the Bacillus anthracis toxin or capsule virulence genes. Furthermore, 17 of 22 pXO2-like plasmids containing the transfer modules were able to self-transfer and to mobilize small plasmids. No pXO1-or pXO2-like plasmid lacking the cognate transfer modules has been found to have transfer potential. In the strains possessing the putative pXO2-like conjugative apparatus, variations in the presence of the group II introns B.th.I.1 and B.th.I.2 were observed, suggesting that there is important flexibility in the conjugation modules and their regulation. There was no consistent correlation between a pXO2-like repA dendrogram and the presence of the tra region or between a virB4 dendrogram and transfer ability. Discrepancies between pXO2-like repA and virB4 dendrograms were also observed, indicating that the evolution of pXO2 is an active process.The Bacillus cereus group includes Bacillus anthracis, B. cereus sensu stricto, Bacillus thuringiensis, Bacillus mycoides, Bacillus pseudomycoides, and Bacillus weihenstephanensis. All members of this group are genetically closely related and could be considered members of a single species or taxon (15,16,24,25). Several of their major phenotypic features, including their virulence spectra, are directly associated with large plasmids. In B. anthracis, the anthrax toxin and capsule genes responsible for anthrax disease are located on the 182-kb pXO1 and 95-kb pXO2 plasmids, respectively (26, 27). These plasmids are not self-transmissible but can be mobilized by conjugative plasmids, such as pXO14 from B. thuringiensis (29). The biopesticide properties that are the main characteristics of B. thuringiensis and distinguish it from B. cereus are due to large plasmids carrying cry genes. These genes are responsible for the production of different Cry toxins that form insecticidal crystal protein inclusions. Some of these large plasmids have been found to have conjugative transfer capability (12,20). For instance, plasmid pHT73 from B. thuringiensis subsp. kurstaki carries cry toxin genes and is conjugative (41). Another ...

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“…The set of plasmids harbored in a strain are normally visualized by agarose gel electrophoresis, where they form an electrophoretic pattern of bands, according to their differential migration in the gel. Although B. thuringiensis plasmids have been studied either to locate cry genes (9, 21) or to transfer them between different strains and species (3,5,10,15,30), plasmid patterns have frequently been used to characterize strains (2, 29, 33), especially compared to those of standard strains (16,17,27). A plasmid pattern seems to be related to each strain, serotype, or any other subspecific group.…”

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confidence: 99%

Plasmid Patterns of Bacillus thuringiensis Type Strains

Reyes-Ramírez

Ibarra

2008

Appl Environ Microbiol

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Practically all Bacillus thuringiensis strains contain a set of self-replicating, extrachromosomal DNA molecules or plasmids, which vary in number and size in the different strains. The plasmid patterns obtained from gel electrophoresis have previously been used as a tool to characterize strains, but comparison of the plasmid patterns has been limited in the number and diversity of strains analyzed. In this report, we were able to compare the plasmid patterns of 83 type strains (out of 84) and 47 additional strains from six serotypes. The information obtained from this comparison showed the importance of this tool as a strain characterization procedure and indicates the complexity and uniqueness of this feature. For example, with one exception, all type strains showed a unique plasmid pattern. All were unique in such a way that none showed even a single comigrating plasmid in the agarose gels, and therefore, cluster analysis was impossible, indicating that plasmid patterns are qualitative rather than quantitative features. Furthermore, comparison between strains belonging to the same serotype showed a great difference in variability. Some serotypes (e.g., israelensis) showed the same basic pattern among all its strains, while other serotypes (e.g., morrisoni) showed a great diversity of patterns. These results indicate that plasmid patterns are valuable tools to discriminate strains below the serotype level.Bacillus thuringiensis is a ubiquitous bacterium (25) isolated from a great diversity of habitats, which include soil, insects, stored crop products (31), phylloplane (32), and aquatic habitats (18). Its great biotechnological success resides in the production of highly specific insecticidal proteins (Cry proteins) simultaneously with the sporulation phase. These Cry proteins are coded by genes (cry genes) harbored in megaplasmids (10,14,21,34), although it has also been suggested that they are present in the chromosome (21). Plasmids have also been associated with the production of a different toxin called ␤-exotoxin (23). The relevance of plasmids in B. thuringiensis strains is assumed by the regular presence of a set of plasmids, which can vary in number from 1 to 17 and in size from 2 to 80 MDa (2, 9). The set of plasmids harbored in a strain are normally visualized by agarose gel electrophoresis, where they form an electrophoretic pattern of bands, according to their differential migration in the gel. Although B. thuringiensis plasmids have been studied either to locate cry genes (9, 21) or to transfer them between different strains and species (3,5,10,15,30), plasmid patterns have frequently been used to characterize strains (2, 29, 33), especially compared to those of standard strains (16,17,27). A plasmid pattern seems to be related to each strain, serotype, or any other subspecific group.In a plasmid pattern, two different groups of plasmids can be recognized: those that are Յ30 MDa and those that are Ն30 MDa, called megaplasmids. For practical purposes, each group is divided by the so-called chromos...

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Conjugative transfer, stability and expression of a plasmid encoding acry1Ac gene inBacillus cereusgroup strains

Cited by 41 publications

References 34 publications

Population Structure and Evolution of the Bacillus cereus Group

Population Structure and Evolution of the Bacillus cereus Group

Distribution, Diversity, and Potential Mobility of Extrachromosomal Elements Related to the Bacillus anthracis pXO1 and pXO2 Virulence Plasmids

Plasmid Patterns of Bacillus thuringiensis Type Strains

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