Occurrence and Linkage Between Secreted Insecticidal Toxins in Natural Isolates of Bacillus thuringiensis

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.

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Microbial Utilization of Free and Clay-Bound Insecticidal Toxins from Bacillus thuringiensis and Their Retention of Insecticidal Activity after Incubation with Microbes.

Applied and Environmental Microbiology ◽

10.1128/aem.63.9.3561-3568.1997 ◽

1997 ◽

Vol 63 (9) ◽

pp. 3561-3568 ◽

Cited By ~ 110

Author(s):

J Koskella ◽

G Stotzky

Keyword(s):

Bacillus Thuringiensis ◽

Insecticidal Activity ◽

Microbial Utilization ◽

Insecticidal Toxins

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Identification and Characterization of Receptors for Insecticidal Toxins from Bacillus thuringiensis

Soil Biology - Biocontrol of Lepidopteran Pests ◽

10.1007/978-3-319-14499-3_4 ◽

2015 ◽

pp. 71-88

Author(s):

Ricardo A. Grande-Cano ◽

Isabel Gómez

Keyword(s):

Bacillus Thuringiensis ◽

Insecticidal Toxins ◽

Identification And Characterization

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

The Comprehensive Sourcebook of Bacterial Protein Toxins ◽

10.1016/b978-0-12-800188-2.00030-6 ◽

2015 ◽

pp. 858-873 ◽

Cited By ~ 4

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

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Insecticidal toxins of Bacillus thuringiensis

FEMS Microbiology Letters ◽

10.1016/0378-1097(80)90002-6 ◽

1980 ◽

Vol 8 (1) ◽

pp. 1-7 ◽

Cited By ~ 27

Author(s):

P Lüthy

Keyword(s):

Bacillus Thuringiensis ◽

Insecticidal Toxins

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

Insects ◽

10.3390/insects11100697 ◽

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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