Mechanism of action of Bacillus thuringiensis insecticidal toxins and their use in the control of insect pests

2015 ◽  
pp. 858-873 ◽  
Author(s):  
Alejandra Bravo ◽  
Diana L. Martínez de Castro ◽  
Jorge Sánchez ◽  
Pablo Emiliano Cantón ◽  
Gretel Mendoza ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Mechanism Of Action ◽  
Insect Pests ◽  
Insecticidal Toxins

scholarly journals Retargeting of the Bacillus thuringiensis toxin Cyt2Aa against hemipteran insect pests

2013 ◽  
Vol 110 (21) ◽  
pp. 8465-8470 ◽  
Author(s):  
N. P. Chougule ◽  
H. Li ◽  
S. Liu ◽  
L. B. Linz ◽  
K. E. Narva ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Insect Pests ◽  
Bacillus Thuringiensis Toxin ◽  
Hemipteran Insect

scholarly journals Transcriptional Analysis of the Toxin-Coding Plasmid pBtoxis from Bacillus thuringiensis subsp. israelensis

2006 ◽  
Vol 72 (3) ◽  
pp. 1771-1776 ◽  
Author(s):  
Claudia Stein ◽  
Gareth W. Jones ◽  
Tanya Chalmers ◽  
Colin Berry
Keyword(s):  
Gene Regulation ◽  
Bacillus Thuringiensis ◽  
Transcriptional Regulators ◽  
Transcriptional Analysis ◽  
Host Bacterium ◽  
Large Plasmid ◽  
Coding Sequences ◽  
Physiological Processes ◽  
Insecticidal Toxins

ABSTRACT In Bacillus thuringiensis subsp. israelensis all of the insecticidal toxins are encoded on a single, large plasmid, pBtoxis. Sequencing of this plasmid revealed 125 potential coding sequences, many of which have predicted functions in gene regulation and physiological processes, such as germination. As a first step in understanding the possible role of pBtoxis in its host bacterium, a survey of the transcription of genes with predicted functions was carried out. Whereas many coding sequences, including those previously identified as probable pseudogenes, were not transcribed, mRNA was detected for 29 of the 40 sequences surveyed. Several of these sequences, including eight with similarities to the sequences of known transcriptional regulators, may influence wider gene regulation and thus may alter the phenotype of the host bacterium.

Mechanism of Action of the Cytolytic Toxin of Bacillus thuringiensis israelensis

1989 ◽  
pp. 169-188
Author(s):  
Sarjeet S. Gill ◽  
Edward Chow ◽  
Gur Jai Pal Singh ◽  
Patricia Pietrantonio ◽  
Shu-Mai Dai ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Mechanism Of Action ◽  
Bacillus Thuringiensis Israelensis

scholarly journals A Strain of Bacillus thuringiensis Containing a Novel cry7Aa2 Gene that Is Toxic to Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae)

Insects ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 259 ◽  
Author(s):  
Mikel Domínguez-Arrizabalaga ◽  
Maite Villanueva ◽  
Ana Beatriz Fernandez ◽  
Primitivo Caballero
Keyword(s):  
Amino Acid ◽  
Bacillus Thuringiensis ◽  
Molecular Mass ◽  
Leptinotarsa Decemlineata ◽  
Insect Pests ◽  
Amino Acid Residues ◽  
Cry Protein ◽  
Lc50 Value ◽  
Leptinotarsa Decemlineata Say

The genome of the Bacillus thuringiensis BM311.1 strain was sequenced and assembled in 359 contigs containing a total of 6,390,221 bp. The plasmidic ORF of a putative cry gene from this strain was identified as a potential novel Cry protein of 1138 amino acid residues with a 98% identity compared to Cry7Aa1 and a predicted molecular mass of 129.4 kDa. The primary structure of Cry7Aa2, which had eight conserved blocks and the classical structure of three domains, differed in 28 amino acid residues from that of Cry7Aa1. The cry7Aa2 gene was amplified by PCR and then expressed in the acrystalliferous strain BMB171. SDS-PAGE analysis confirmed the predicted molecular mass for the Cry7Aa2 protein and revealed that after in vitro trypsin incubation, the protein was degraded to a toxin of 62 kDa. However, when treated with digestive fluids from Leptinotarsa decemlineata larvae, one major proteinase-resistant fragment of slightly smaller size was produced. The spore and crystal mixture produced by the wild-type BM311.1 strain against L. decemlineata neonate larvae resulted in a LC50 value of 18.8 μg/mL, which was statistically similar to the estimated LC50 of 20.8 μg/mL for the recombinant BMB17-Cry7Aa2 strain. In addition, when this novel toxin was activated in vitro with commercial trypsin, the LC50 value was reduced 3.8-fold to LC50 = 4.9 μg/mL. The potential advantages of Cry7Aa2 protoxin compared to Cry7Aa1 protoxin when used in the control of insect pests are discussed.

scholarly journals Bacillus thuringiensis Bioinsecticides Induce Developmental Defects in Non-Target Drosophila melanogaster Larvae

Insects ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 697
Author(s):  
Marie-Paule Nawrot-Esposito ◽  
Aurélie Babin ◽  
Matthieu Pasco ◽  
Marylène Poirié ◽  
Jean-Luc Gatti ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Bacillus Thuringiensis ◽  
Developmental Time ◽  
Probiotic Bacterium ◽  
Intestinal Cell ◽  
Cellular Mechanisms ◽  
Developmental Defects ◽  
Insecticidal Toxins ◽  
Bacterium Bacillus ◽  
Protein Rich

Bioinsecticides made from the bacterium Bacillus thuringiensis (Bt) are the bestselling bioinsecticide worldwide. Among Bt bioinsecticides, those based on the strain Bt subsp. kurstaki (Btk) are widely used in farming to specifically control pest lepidopteran larvae. Although there is much evidence of the lack of acute lethality of Btk products for non-target animals, only scarce data are available on their potential non-lethal developmental adverse effects. Using a concentration that could be reached in the field upon sprayings, we show that Btk products impair growth and developmental time of the non-target dipteran Drosophila melanogaster. We demonstrate that these effects are mediated by the synergy between Btk bacteria and Btk insecticidal toxins. We further show that Btk bioinsecticides trigger intestinal cell death and alter protein digestion without modifying the food intake and feeding behavior of the larvae. Interestingly, these harmful effects can be mitigated by a protein-rich diet or by adding the probiotic bacterium Lactobacillus plantarum into the food. Finally, we unravel two new cellular mechanisms allowing the larval midgut to maintain its integrity upon Btk aggression: First the flattening of surviving enterocytes and second, the generation of new immature cells arising from the adult midgut precursor cells. Together, these mechanisms participate to quickly fill in the holes left by the dying enterocytes.

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