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Pomari E, Orza P, Bernardi M, Fracchetti F, Campedelli I, De Marta P, Recchia A, Paradies P, Buonfrate D. A Pilot Study for the Characterization of Bacillus spp. and Analysis of Possible B. thuringiensis/ Strongyloides stercoralis Correlation. Microorganisms 2024; 12:1603. [PMID: 39203445 PMCID: PMC11356623 DOI: 10.3390/microorganisms12081603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2024] [Revised: 07/31/2024] [Accepted: 08/02/2024] [Indexed: 09/03/2024] Open
Abstract
Differentiating between Bacillus species is relevant in human medicine. Bacillus thuringiensis toxins might be effective against Strongyloides stercoralis, a nematode causing relevant human morbidity. Our first objective was to evaluate genomic and MALDI-TOF identification methods for B. thuringiensis. Our secondary objective was to evaluate a possible negative selection pressure of B. thuringiensis against S. stercoralis. PCR and Sanger were compared to MALDI-TOF on a collection of 44 B. cereus group strains. B. thuringiensis toxin genes were searched on 17 stool samples from S. stercoralis-infected and uninfected dogs. Metagenomic 16S rRNA was used for microbiome composition. The inter-rate agreement between PCR, Sanger, and MALDI-TOF was 0.631 k (p-value = 6.4 × 10-10). B. thuringiensis toxins were not found in dogs' stool. Bacteroidota and Bacillota were the major phyla in the dogs' microbiome (both represented >20% of the total bacterial community). Prevotella was underrepresented in all Strongyloides-positive dogs. However, the general composition of bacterial communities was not significantly linked with S. stercoralis infection. The genomic methods allowed accurate differentiation between B. thuringiensis and B. cereus. There was no association between B. thuringiensis and S. stercoralis infection, but further studies are needed to confirm this finding. We provide the first descriptive results about bacterial fecal composition in dogs with S. stercoralis infection.
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Affiliation(s)
- Elena Pomari
- Department of Infectious, Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar di Valpolicella, 37024 Verona, Italy; (P.O.); (M.B.); (D.B.)
| | - Pierantonio Orza
- Department of Infectious, Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar di Valpolicella, 37024 Verona, Italy; (P.O.); (M.B.); (D.B.)
| | - Milena Bernardi
- Department of Infectious, Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar di Valpolicella, 37024 Verona, Italy; (P.O.); (M.B.); (D.B.)
| | - Fabio Fracchetti
- Microbion srl, San Giovanni Lupatoto, 37057 Verona, Italy; (F.F.); (I.C.); (P.D.M.)
| | - Ilenia Campedelli
- Microbion srl, San Giovanni Lupatoto, 37057 Verona, Italy; (F.F.); (I.C.); (P.D.M.)
| | - Patrick De Marta
- Microbion srl, San Giovanni Lupatoto, 37057 Verona, Italy; (F.F.); (I.C.); (P.D.M.)
| | - Alessandra Recchia
- Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), Veterinary Section, University of Bari “Aldo Moro”, Valenzano, 70010 Bari, Italy; (A.R.); (P.P.)
| | - Paola Paradies
- Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), Veterinary Section, University of Bari “Aldo Moro”, Valenzano, 70010 Bari, Italy; (A.R.); (P.P.)
| | - Dora Buonfrate
- Department of Infectious, Tropical Diseases and Microbiology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar di Valpolicella, 37024 Verona, Italy; (P.O.); (M.B.); (D.B.)
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Skrzecz I, Sierpińska A, Tumialis D. Entomopathogens in the integrated management of forest insects: from science to practice. PEST MANAGEMENT SCIENCE 2024; 80:2503-2514. [PMID: 37983918 DOI: 10.1002/ps.7871] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 10/30/2023] [Accepted: 11/20/2023] [Indexed: 11/22/2023]
Abstract
The most important aim of the integrated management of forest insect pests remains the prevention of insect outbreaks, which are a consequence of the interaction of many factors in forest ecosystems, including species composition, age and health of the forest, soil type, the presence of natural enemies, and climatic factors. Integrated pest management until now has been achieved using measures aimed at shaping the functioning of stands in a changing environment. The aim of this review is to summarize research on the use of entomopathogens (microorganisms and nematodes) in the management of forest insect pests and to identify the principal knowledge gaps. We briefly describe the main research directions on the use of pathogens and nematodes to control insect pests and discuss limitations affecting their implementation. Research on entomopathogens for the biocontrol of forest insects has provided a wealth of knowledge that can be used effectively to reduce insect populations. Despite this, few entomopathogens are currently used in integrated pest management in forestry. They are applied in inoculation or inundation biocontrol strategies. While the use of entomopathogens in forest pest management shows great promise, practical implementation remains a distant goal. Consequently, sustainable reduction of forest pests, mainly native species, will be largely based on conservation biological control, which aims to modify the environment to favor the activity of natural enemies that regulate pest populations. This type of biocontrol can be supported by a range of silvicultural measures to increase the resilience of stands to insect infestations. © 2023 Society of Chemical Industry.
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Affiliation(s)
- Iwona Skrzecz
- Department of Forest Protection, Forest Research Institute, Raszyn, Poland
| | - Alicja Sierpińska
- Department of Forest Protection, Forest Research Institute, Raszyn, Poland
| | - Dorota Tumialis
- Department of Animal Environment Biology, Institute of Animal Sciences, Warsaw University of Life Sciences, Warsaw, Poland
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Chattopadhyay P, Banerjee G, Mukherjee S. Recent trends of modern bacterial insecticides for pest control practice in integrated crop management system. 3 Biotech 2017; 7:60. [PMID: 28444605 DOI: 10.1007/s13205-017-0717-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 03/31/2017] [Indexed: 10/19/2022] Open
Abstract
Food security and safety are the major concern in ever expanding human population on the planet earth. Each and every year insect pests cause a serious damage in agricultural field that cost billions of dollars annually to farmers. The loss in term of productivity and high cost of chemical pesticides enhance the production cost. Irrespective use of chemical pesticides (such as Benzene hexachloride, Endosulfan, Aldicarb, and Fenobucarb) in agricultural field raised several types of environmental issues. Furthermore, continuous use of chemical pesticides creates a selective pressure which helps in emerging of resistance pest. These excess chemical pesticide residues also contaminate the environment including the soil and water. Therefore, the biological control of insect pest in the agricultural field gains more importance due to food safety and environment friendly nature. In this regard, bacterial insecticides offer better alternative to chemical pesticides. It not only helps to establish food security through fighting against insect pests but also ensure the food safety. In this review, we have categorized insect pests and the corresponding bacterial insecticides, and critically analyzed the importance and mode of action of bacterial pesticides. We also have summarized the use of biopesticides in integrated pest management system. We have tried to focus the future research area in this field for the upcoming scientists.
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de Souza Machado AA, Zarfl C, Rehse S, Kloas W. Low-Dose Effects: Nonmonotonic Responses for the Toxicity of a Bacillus thuringiensis Biocide to Daphnia magna. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:1679-1686. [PMID: 28001053 DOI: 10.1021/acs.est.6b03056] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Currently, there is a trend toward an increasing use of biopesticides assumed to be environmentally friendly, such as Bacillus thuringiensis (Bt). Studies of the Bt toxicity to nontarget organisms have reported low effects at high exposure levels, which is interpreted as indicating negligible risk to nontarget organisms. We investigated the response of the nontarget organism Daphnia magna to waterborne DiPel ES, a globally used Bt formulation. Neonates and adults were exposed for 48 h to a wide range of concentrations, and immobilization and mortality were monitored. Whole body biomarkers (body weight, protein, chitobiase, catalase, xenobiotic metabolism, and acetylcholinesterase) were measured in the adults. The immobilization and mortality of the neonates were affected in a nonmonotonic and inverted U-shaped pattern with EC50s that were ∼105-fold lower than those reported by the manufacturer. The immobilization of adults demonstrated a similar pattern, but significant mortality was not observed. The biomarker results revealed multiphasic dose-response curves, which suggested toxicity mechanisms that affected various physiological pathways. The main particle size in exposure media was in the size range of bacterial spores and crystal toxins. However, the chemical heterogeneity was nonmonotonic, with a change in the phase at the maximum of toxicity (∼5 μL L-1), which might explain the observed nonmonotonic effects. These results demonstrate the vulnerability of a nontarget organism to a biopesticide that is considered to be safe, while challenging the universal applicability of the central ecotoxicological assumption of monotonicity.
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Affiliation(s)
- Anderson Abel de Souza Machado
- Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin , 14195 Berlin, Germany
- School of Geography, Queen Mary, University of London , London E1 4NS, United Kingdom
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries , 12587 Berlin, Germany
| | - Christiane Zarfl
- Center for Applied Geosciences, Eberhard Karls Universität Tübingen , 72074 Tübingen, Germany
| | - Saskia Rehse
- Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin , 14195 Berlin, Germany
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries , 12587 Berlin, Germany
| | - Werner Kloas
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries , 12587 Berlin, Germany
- Faculty of Life Sciences, Humboldt-Universität zu Berlin , 10099 Berlin, Germany
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Abdelmalek N, Sellami S, Ben Kridis A, Tounsi S, Rouis S. Molecular characterisation of Bacillus thuringiensis strain MEB4 highly toxic to the Mediterranean flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). PEST MANAGEMENT SCIENCE 2016; 72:913-921. [PMID: 26103535 DOI: 10.1002/ps.4066] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 05/01/2015] [Accepted: 06/18/2015] [Indexed: 06/04/2023]
Abstract
BACKGROUND Cry2 proteins play an essential role in current Bacillus thuringiensis (Bt) applications and in the prevention of insect resistance to Cry1A toxins. This paper reports on the screening and characterisation of novel Bt strains harbouring effective cry2A-type genes and higher insecticidal activity to Ephestia kuehniella. RESULTS A total of 29 native Bt strains were screened to search for the potent strain against E. kuehniella. The plasmid pattern of the selected strains showed interesting variability. PCR-RFLP analysis of two amplified regions showed high sequence identity within the selected cry2A-type genes. SDS-PAGE and western blot analysis revealed the presence of Cry2Aa toxin only in the MEB4 and BLB240 strains. The activation of Cry2Aa protoxins by larval midgut juice, trypsin or chymotrypsin enzymes revealed significant differences in terms of proteolysis profiles. Interestingly, a 49 kDa band was detected in the proteolysis pattern of BLB240, suggesting the presence of a chymotrypsin cleavage site that might have affected its insecticidal activity. Further, bioassays demonstrated that MEB4 (103.08 ± 36 µg g(-1)) was more active than BLB240 (153.77 ± 45.65 µg g(-1)) against E. kuehniella. CONCLUSION Based on its potent insecticidal activity, the MEB4 strain could be considered to be an effective alternative agent for the control of E. kuehniella.
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Affiliation(s)
- Nouha Abdelmalek
- Laboratory of Plant Protection and Improvement (Biopesticides Team), Centre of Biotechnology, University of Sfax, Sfax, Tunisia
| | - Sameh Sellami
- Laboratory of Plant Protection and Improvement (Biopesticides Team), Centre of Biotechnology, University of Sfax, Sfax, Tunisia
| | - Asma Ben Kridis
- Laboratory of Plant Protection and Improvement (Biopesticides Team), Centre of Biotechnology, University of Sfax, Sfax, Tunisia
| | - Slim Tounsi
- Laboratory of Plant Protection and Improvement (Biopesticides Team), Centre of Biotechnology, University of Sfax, Sfax, Tunisia
| | - Souad Rouis
- Laboratory of Plant Protection and Improvement (Biopesticides Team), Centre of Biotechnology, University of Sfax, Sfax, Tunisia
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van Frankenhuyzen K. Cross-order and cross-phylum activity of Bacillus thuringiensis pesticidal proteins. J Invertebr Pathol 2013; 114:76-85. [PMID: 23747826 DOI: 10.1016/j.jip.2013.05.010] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 05/20/2013] [Accepted: 05/21/2013] [Indexed: 10/26/2022]
Abstract
The increasing number of Bacillus thuringiensis proteins with pesticidal activities across orders and phyla raises the question how widespread cross-activities are and if they are of sufficient biological significance to have implications for ecological safety of those proteins in pest control applications. Cross-activity is reported for 27 proteins and 69 taxa and is substantiated by reasonable evidence (mortality estimates) in 19 cases involving 45 taxa. Cross-activities occur in 13 primary rank families across three classes of pesticidal proteins (Cry, Cyt and Vip), and comprise 13 proteins affecting species across two orders, five proteins affecting three orders and one protein affecting four orders, all within the class Insecta. Cross-activity was quantified (LC50 estimates) for 16 proteins and 25 taxa. Compared to toxicity ranges established for Diptera-, Coleoptera-, Lepidoptera- and Nematoda-active proteins, 13 cross-activities are in the low-toxicity range (10-1000μg/ml), 12 in the medium - (0.10-10μg/ml) and two in the high-toxicity range (0.01-0.10μg/ml). Although cross-activities need to be viewed with caution until they are confirmed through independent testing, current evidence suggests that cross-activity of B. thuringiensis pesticidal proteins needs to be taken into consideration when designing and approving their use in pest control applications.
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Affiliation(s)
- Kees van Frankenhuyzen
- Great Lakes Forestry Centre, Canadian Forest Service, Natural Resources Canada, 1219 Queen Street East, Sault Ste. Marie, Ontario P6A 2E5, Canada.
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Activity of Bacillus thuringiensis cyt1Ba crystal protein against hymenopteran forest pests. J Invertebr Pathol 2013; 113:160-2. [DOI: 10.1016/j.jip.2013.03.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 03/11/2013] [Accepted: 03/18/2013] [Indexed: 11/20/2022]
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Chang X, Wu Q, Wang S, Wang R, Yang Z, Chen D, Jiao X, Mao Z, Zhang Y. Determining the involvement of two aminopeptidase Ns in the resistance of Plutella xylostella to the Bt toxin Cry1Ac: cloning and study of in vitro function. J Biochem Mol Toxicol 2012; 26:60-70. [PMID: 22371317 DOI: 10.1002/jbt.20401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The cloning, expression in vitro, and characterization of two aminopeptidase Ns (APN5s and APN2s) isolated from the midgut of Cry1Ac-resistant (R) and susceptible (S) strains of Plutella xylostella larvae are presented in this paper. The deduced amino acid sequences of APN5s included C-terminal GPI-modification sites, the gluzincin aminopeptidase motif GATEN, and three N-glycosylated sites; those of APN2s had no GPI-modification sites, had gluzincin aminopeptidase motif GAMEN, and had four N-glycosylated sites. O-glycosylated sites were not predicted for either APN. Because APN2R and APN2S cDNAs contained the same nucleotides, only full-length cDNAs encoding APN5R and APN5S were expressed in Trichoplusia ni cells. Far-Western blotting showed that the expressed receptor APN5 bound to the Cry1Ac toxin. An enzyme-specific activity experiment also showed that APN5 genes were expressed in T. ni cells. ELISA revealed no differences in the binding of expression proteins from the resistant and susceptible strain with Cry1Ac.
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Affiliation(s)
- Xiaoli Chang
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China
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Short-term evaluation in growing rats of diet containing Bacillus thuringiensis Cry1Ia12 entomotoxin: nutritional responses and some safety aspects. J Biomed Biotechnol 2010; 2010. [PMID: 20862341 PMCID: PMC2939432 DOI: 10.1155/2010/630267] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2010] [Revised: 08/03/2010] [Accepted: 08/11/2010] [Indexed: 11/18/2022] Open
Abstract
The Cry1Ia12 entomotoxin from a Brazilian Bacillus thuringiensis strain is currently being expressed in cotton cultivars to confer resistance to insect-pests. The present study aimed to assess the effects of a diet containing Cry1Ia12 protein on growing rats. A test diet containing egg white and Cry1Ia12 (0.1% of total protein) as a protein source was offered to rats for ten days. In addition, an acute toxicity bioassay was performed in rats with a single oral dose of the entomotoxin (12 mg/animal). No adverse effects were observed in the animals receiving the test diet when compared to those receiving a control diet (egg white). The analysed parameters included relative dry weight of internal organs, duodenum histology, blood biochemistry, and nutritional parameters. The results of the acute toxicity test showed no mortality or behaviour alteration. Thus, Cry1Ia12 toxin at the tested concentration does not cause deleterious effects on growing rats when incorporated in the diet for 10 days.
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Frankenhuyzen KV. Insecticidal activity of Bacillus thuringiensis crystal proteins. J Invertebr Pathol 2009; 101:1-16. [DOI: 10.1016/j.jip.2009.02.009] [Citation(s) in RCA: 251] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Accepted: 02/22/2009] [Indexed: 10/21/2022]
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Investigating the properties of Bacillus thuringiensis Cry proteins with novel loop replacements created using combinatorial molecular biology. Appl Environ Microbiol 2008; 74:3497-511. [PMID: 18408065 DOI: 10.1128/aem.02844-07] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Cry proteins are a large family of crystalline toxins produced by Bacillus thuringiensis. Individually, the family members are highly specific, but collectively, they target a diverse range of insects and nematodes. Domain II of the toxins is important for target specificity, and three loops at its apex have been studied extensively. There is considerable interest in determining whether modifications in this region may lead to toxins with novel specificity or potency. In this work, we studied the effect of loop substitution on toxin stability and specificity. For this purpose, sequences derived from antibody complementarity-determining regions (CDR) were used to replace native domain II apical loops to create "Crybodies." Each apical loop was substituted either individually or in combination with a library of third heavy-chain CDR (CDR-H3) sequences to create seven distinct Crybody types. An analysis of variants from each library indicated that the Cry1Aa framework can tolerate considerable sequence diversity at all loop positions but that some sequence combinations negatively affect structural stability and protease sensitivity. CDR-H3 substitution showed that loop position was an important determinant of insect toxicity: loop 2 was essential for activity, whereas the effects of substitutions at loop 1 and loop 3 were sequence dependent. Unexpectedly, differences in toxicity did not correlate with binding to cadherins--a major class of toxin receptors--since all Crybodies retained binding specificity. Collectively, these results serve to better define the role of the domain II apical loops as determinants of specificity and establish guidelines for their modification.
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Xue J, Liang G, Crickmore N, Li H, He K, Song F, Feng X, Huang D, Zhang J. Cloning and characterization of a novel Cry1A toxin fromBacillus thuringiensiswith high toxicity to the Asian corn borer and other lepidopteran insects. FEMS Microbiol Lett 2008; 280:95-101. [DOI: 10.1111/j.1574-6968.2007.01053.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Specific activity of a Bacillus thuringiensis strain against Locusta migratoria manilensis. J Invertebr Pathol 2008; 98:169-76. [PMID: 18359040 DOI: 10.1016/j.jip.2008.02.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Revised: 01/12/2008] [Accepted: 02/13/2008] [Indexed: 11/21/2022]
Abstract
Bacillus thuringiensis (Bt) has played an important role in biocontrol of pests. However, insecticidal activity of B. thuringiensis against locusts has been rarely reported. Bt strain BTH-13 exhibiting specific activity to locusts was isolated from a soil sample in China and characterized. Its bipyramidal parasporal crystal is mainly composed of a protein of 129kDa, and produces a mature toxin of 64kDa after activation. The pattern of total DNA from BTH-13 showed a large and three small plasmid bands. Known delta-endotoxin genes, cry1Aa, cry1Ab, cry1Ac, cry1C, cry3, cry4 and cry7Aa were not found from strain BTH-13 by PCR amplification. The sequence analysis of a DNA fragment produced by PCR amplification with degenerate cry-selective primers revealed that the fragment encoded a delta-endotoxin segment, which exhibited some similarity to several Cry proteins (41% of the highest similarity to Cry7Ba1). Toxicity tests were performed against Locusta migratoria manilensis, and the results demonstrated that trypsin-treated sporulated cultures and crystal proteins had high toxicity to larval and adult locusts. Cry toxin of BTH-13 was detected on the midguts of treated locusts using immunofluorescent technology, which confirmed the site of action of the crystal proteins in their toxicity for locusts.
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Pigott CR, Ellar DJ. Role of receptors in Bacillus thuringiensis crystal toxin activity. Microbiol Mol Biol Rev 2007; 71:255-81. [PMID: 17554045 PMCID: PMC1899880 DOI: 10.1128/mmbr.00034-06] [Citation(s) in RCA: 402] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Bacillus thuringiensis produces crystalline protein inclusions with insecticidal or nematocidal properties. These crystal (Cry) proteins determine a particular strain's toxicity profile. Transgenic crops expressing one or more recombinant Cry toxins have become agriculturally important. Individual Cry toxins are usually toxic to only a few species within an order, and receptors on midgut epithelial cells have been shown to be critical determinants of Cry specificity. The best characterized of these receptors have been identified for lepidopterans, and two major receptor classes have emerged: the aminopeptidase N (APN) receptors and the cadherin-like receptors. Currently, 38 different APNs have been reported for 12 different lepidopterans. Each APN belongs to one of five groups that have unique structural features and Cry-binding properties. While 17 different APNs have been reported to bind to Cry toxins, only 2 have been shown to mediate toxin susceptibly in vivo. In contrast, several cadherin-like proteins bind to Cry toxins and confer toxin susceptibility in vitro, and disruption of the cadherin gene has been associated with toxin resistance. Nonetheless, only a small subset of the lepidopteran-specific Cry toxins has been shown to interact with cadherin-like proteins. This review analyzes the interactions between Cry toxins and their receptors, focusing on the identification and validation of receptors, the molecular basis for receptor recognition, the role of the receptor in resistant insects, and proposed models to explain the sequence of events at the cell surface by which receptor binding leads to cell death.
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Affiliation(s)
- Craig R Pigott
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom
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Konecka E, Kaznowski A, Ziemnicka J, Ziemnicki K, Paetz H. Analysis of cry Gene Profiles in Bacillus Thuringiensis Strains Isolated During Epizootics in Cydia pomonella L. Curr Microbiol 2007; 55:217-22. [PMID: 17657530 DOI: 10.1007/s00284-007-0085-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Accepted: 04/05/2007] [Indexed: 11/27/2022]
Abstract
The crystal morphology and the profiles of genes encoding protein toxins (Cry and Cyt) were analyzed in 12 Bacillus thuringiensis strains isolated during epizootics in laboratory culture lines of Cydia pomonella, 2 isolates cultured from Leucoma salicis larvae, and 9 reference strains. Epizootic isolates produced crystals of the same bipyramidal shape; however, they revealed a variety of number and type of cry genes. Genes cry1I, cry2Ab, and cry9B were the most frequently observed in epizootic strains. Gene cry1I was noted in of 50% epizootic isolates. Eighty-three percent of them harbored gene cry2Ab. Gene cry9B was found for 42% of strains isolated during epizootics. Three isolates showed the largest number of cry genes and their variety; hence, they were chosen for the toxicity assay of their crystals and spores on C. pomonella larvae. One of them had approximately sixfold higher insecticidal activity than the reference strain B. thuringiensis subsp. kurstaki BTK STANDARD.
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Affiliation(s)
- Edyta Konecka
- Department of Microbiology, Institute of Experimental Biology, Adam Mickiewicz University, Fredry 10, 61-701, Poznań, Poland
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Konecka E, Kaznowski A, Ziemnicka J, Ziemnicki K. Molecular and phenotypic characterisation of Bacillus thuringiensis isolated during epizootics in Cydia pomonella L. J Invertebr Pathol 2007; 94:56-63. [PMID: 17027023 DOI: 10.1016/j.jip.2006.08.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 08/01/2006] [Accepted: 08/16/2006] [Indexed: 11/18/2022]
Abstract
Twelve Bacillus thuringiensis strains were isolated from intestinal tracts of Cydia pomonella larvae during epizootics in different laboratory insect culture lines. Phenotypic and genetic similarity of these isolates, together with two cultured from Leucoma salicis larvae and 14 reference B. thuringiensis strains were determined. The epizootic bacteria did not form a single group based on numerical analysis of biochemical properties. Simple RAPD method with only one primer does not allow estimating the genetic similarity of B. thuringiensis strains. We propose a novel strategy based on combining several DNA patterns obtained by RAPD technique with different primers for B. thuringiensis typing. Majority of infections in the C. pomonella culture lines were caused by bacteria with different genotypes. However, two isolates cultured from infected insects at different time (one strain was isolated in 1990 and the other in 1992) had identical DNA fingerprint that suggested a possibility of these bacteria to survive in the laboratory and to cause infections in different years. The results of SDS-PAGE of whole-cell proteins revealed a possibility to apply protein profile analysis in epidemiological investigations of infections caused by B. thuringiensis. Strains with identical DNA patterns had very similar whole-cell protein profiles.
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Affiliation(s)
- Edyta Konecka
- Department of Microbiology, Institute of Experimental Biology, Adam Mickiewicz University, Fredry 10, 61-701 Poznań, Poland
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Molecular approaches for identification and construction of novel insecticidal genes for crop protection. World J Microbiol Biotechnol 2005. [DOI: 10.1007/s11274-005-9027-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Wei JZ, Hale K, Carta L, Platzer E, Wong C, Fang SC, Aroian RV. Bacillus thuringiensis crystal proteins that target nematodes. Proc Natl Acad Sci U S A 2003; 100:2760-5. [PMID: 12598644 PMCID: PMC151414 DOI: 10.1073/pnas.0538072100] [Citation(s) in RCA: 242] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bacillus thuringiensis (Bt) crystal proteins are pore-forming toxins used as insecticides around the world. Previously, the extent to which these proteins might also target the invertebrate phylum Nematoda has been mostly ignored. We have expressed seven different crystal toxin proteins from two largely unstudied Bt crystal protein subfamilies. By assaying their toxicity on diverse free-living nematode species, we demonstrate that four of these crystal proteins are active against multiple nematode species and that each nematode species tested is susceptible to at least one toxin. We also demonstrate that a rat intestinal nematode is susceptible to some of the nematicidal crystal proteins, indicating these may hold promise in controlling vertebrate-parasitic nematodes. Toxicity in nematodes correlates with damage to the intestine, consistent with the mechanism of crystal toxin action in insects. Structure-function analyses indicate that one novel nematicidal crystal protein can be engineered to a small 43-kDa active core. These data demonstrate that at least two Bt crystal protein subfamilies contain nematicidal toxins.
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Affiliation(s)
- Jun-Zhi Wei
- Section of Cell and Developmental Biology, University of California, San Diego, CA 92093-0349, USA
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