Characterization and Whole Genome Sequencing of AR23, a Highly Toxic Bacillus thuringiensis Strain Isolated from Lebanese Soil

Fayad, Nancy; Patiño-Navarrete, Rafael; Kambris, Zakaria; Antoun, Mandy C.; Osta, Mike A.; Chopineau, Joël; Mahillon, Jacques; Chamy, Laure El; Sanchis, Vincent; Awad, Mireille Kallassy

doi:10.1007/s00284-019-01775-9

Cited by 10 publications

(14 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Despite the presence of rearrangements and sequence inversions also that have been linked to the variability of genetically related species 32 , the strains from this study, HD-789 and AM65-52 showed collinear chromosomes. Although the polymorphism analysis indicated the presence of various SNPs in the Bti isolates, none of the mutations reported was related to the insecticidal activity 33 . The SNP-based phylogeny revealed close relation among the four isolates and other Bti isolates (HD-789 and AM65-52), in agreement with previous study 33 , reinforcing the close genetic relationship among these bacteria.…”

Section: Discussionmentioning

confidence: 91%

“…Although the polymorphism analysis indicated the presence of various SNPs in the Bti isolates, none of the mutations reported was related to the insecticidal activity 33 . The SNP-based phylogeny revealed close relation among the four isolates and other Bti isolates (HD-789 and AM65-52), in agreement with previous study 33 , reinforcing the close genetic relationship among these bacteria.…”

Section: Discussionmentioning

confidence: 91%

“…In addition, pBtoxis also presents sequences with functions predicted to increase crystal formation and subsequent cell viability, acting as chaperones 32,36 . The additional cry4Ba coding gene in plasmid pBtoxis-like has been reported to account for the increased effectiveness in mosquito larvae killing of Bti strain 33 . In the present study, SNPs analysis of the plasmids carrying the genes encoding the mosquitocidal endotoxins did not reveal any mutation in pT0131-4 what could explain the high toxicity of T0131 strain.…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Comparative genomic analysis and mosquito larvicidal activity of four Bacillus thuringiensis serovar israelensis strains

Alves

Melo

Oliveira

et al. 2020

Sci Rep

View full text Add to dashboard Cite

Bacillus thuringiensis serovar israelensis (Bti) is used to control insect vectors of human and animal diseases. in the present study, the toxicity of four strains of Bti, named T0124, T0131, T0137, and T0139, toward Aedes aegypti and Culex quinquefasciatus larvae was analyzed. The T0131 strain showed the highest larvicidal activity against A. aegypti (Lc 50 = 0.015 µg/ml) and C. quinquefasciatus larvae (Lc 50 = 0.035 µg/ml) when compared to the other strains. Furthermore, the genomic sequences of the four strains were obtained and compared. These Bti strains had chromosomes sizes of approximately 5.4 Mb with GC contents of ~35% and 5472-5477 putative coding regions. Three small plasmids (5.4, 6.8, and 7.6 kb) and three large plasmids (127, 235, and 359 kb) were found in the extrachromosomal content of all four strains. the Snp-based phylogeny revealed close relationship among isolates from this study and other Bti isolates, and SNPs analysis of the plasmids 127 kb did not reveal any mutations in δ-endotoxins genes. This newly acquired sequence data for these Bti strains may be useful in the search for novel insecticidal toxins to improve existing ones or develop new strategies for the biological control of important insect vectors of human and animal diseases.

show abstract

Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Comparative genomic analysis and mosquito larvicidal activity of four Bacillus thuringiensis serovar israelensis strains

Alves

Melo

Oliveira

et al. 2020

Sci Rep

View full text Add to dashboard Cite

show abstract

“…Moreover, B. thuringiensis sv. israelensis is known to be more toxic to Culex than to Aedes and Anopheles larvae (49), contrary to H3. Since the dose-and time-dependent killing profiles are indications of activity via specific receptors in the insect midgut.…”

Section: Discussionmentioning

confidence: 93%

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

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…Moreover, a recent publication reported that 4Q7 could be cured of this element, and pBtic235 was itself identified as a separate band on gel electrophoresis [ 13 ]. A natural B. thuringiensis serovar israelensis strain was also recently sequenced and found to lack a pBtic235 element [ 37 ]. Further studies of 4Q7 and strains similar to GSX002, the 4Q7 derivative cured of pBtic235 [ 13 ], should provide an explicit model for the complete genome structure and termination of chromosomal DNA replication in these strains.…”

Section: Discussionmentioning

confidence: 99%

Long inverted repeats around the chromosome replication terminus in the model strain Bacillus thuringiensis serovar israelensis BGSC 4Q7

et al. 2020

View full text Add to dashboard Cite

Bacillus thuringiensis serovar israelensis is the most widely used natural biopesticide against mosquito larvae worldwide. Its lineage has been actively studied and a plasmid-free strain, B . thuringiensis serovar israelensis BGSC 4Q7 (4Q7), has been produced. Previous sequencing of the genome of this strain has revealed the persistent presence of a 235 kb extrachromosomal element, pBtic235, which has been shown to be an inducible prophage, although three putative chromosomal prophages have been lost. Moreover, a 492 kb region, potentially including the standard replication terminus, has also been deleted in the 4Q7 strain, indicating an absence of essential genes in this area. We reanalysed the genome coverage distribution of reads for the previously sequenced variant strain, and sequenced two independently maintained samples of the 4Q7 strain. A 553 kb area, close to the 492 kb deletion, was found to be duplicated. This duplication presumably restored the equal sizes of the replichores, and a balanced functioning of replication termination. An analysis of genome assembly graphs revealed a transient association of the host chromosome with the pBtic235 element. This association may play a functional role in the replication of the bacterial chromosome, and the termination of this process in particular. The genome-restructuring events detected may modify the genetic status of cytotoxic or haemolytic toxins, potentially influencing strain virulence. Twelve of the single-nucleotide variants identified in 4Q7 were probably due to the procedure used for strain construction or were present in the precursor of this strain. No sequence variants were found in pBtic235, but the distribution of the corresponding 4Q7 reads indicates a significant difference from counterparts in natural B. thuringiensis serovar israelensis strains, suggesting a duplication or over-replication in 4Q7. Thus, the 4Q7 strain is not a pure plasmid-less offshoot, but a highly genetically modified derivative of its natural ancestor. In addition to potentially influencing virulence, genome-restructuring events can modify the replication termination machinery. These findings have potential implications for the conclusions of virulence studies on 4Q7 as a model, but they also raise interesting fundamental questions about the functioning of the Bacillus genome.

show abstract

Characterization and Whole Genome Sequencing of AR23, a Highly Toxic Bacillus thuringiensis Strain Isolated from Lebanese Soil

Cited by 10 publications

References 62 publications

Comparative genomic analysis and mosquito larvicidal activity of four Bacillus thuringiensis serovar israelensis strains

Comparative genomic analysis and mosquito larvicidal activity of four Bacillus thuringiensis serovar israelensis strains

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

Long inverted repeats around the chromosome replication terminus in the model strain Bacillus thuringiensis serovar israelensis BGSC 4Q7

Contact Info

Product

Resources

About