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Sample records for bacillus thuringiensis cry1ab

  1. Cry1Ab protein from Bacillus thuringiensis and MON810 cry1Ab-transgenic maize exerts no adjuvant effect after airway exposure.

    Science.gov (United States)

    Andreassen, M; Bøhn, T; Wikmark, O-G; Van den Berg, J; Løvik, M; Traavik, T; Nygaard, U C

    2015-03-01

    The genetically modified (GM) maize event MON810 has been inserted with a processed version of the transgene, cry1Ab, derived from the soil bacterium Bacillus thuringiensis (Bt) to express proteins with insecticidal properties. Such proteins may introduce new allergens and also act as adjuvants that promote allergic responses. While focus has been on safe consumption and hence the oral exposure to GM food and feed, little is known regarding inhalation of pollen and desiccated airborne plant material from GM crops. The aim of this study was to investigate whether plant material from the Cry1Ab-expressing maize variety MON810, or trypsin-activated Cry1Ab (trypCry1Ab) protein produced in recombinant bacteria, may act as adjuvants against the allergen ovalbumin (OVA) in a mouse model of airway allergy. A clear proallergic adjuvant effect of the mucosal adjuvant cholera toxin (CT) was demonstrated, determined as increased specific IgE, eosinophils and Th2 cytokines in MLN cell supernates, while no elevation in OVA-specific antibodies or cytokine release from MLN cells after stimulation with OVA were observed in mice receiving Cry1Ab-containing plant materials or the trypCry1Ab protein. Our data suggest that Cry1Ab proteins had no detectable systemic adjuvant effect in mice after airway exposure. Further experiments with purified plant proteins, as well as long-term exposures needs be conducted to further evaluate exposures experienced in real-life situations. PMID:25564738

  2. Effect of gamma irradiation on nutritional components and Cry1Ab protein in the transgenic rice with a synthetic cry1Ab gene from Bacillus thuringiensis

    International Nuclear Information System (INIS)

    The effects of gamma irradiation on the transgenic rice containing a synthetic cry1Ab gene from Bacillus thuringiensis were investigated. There was almost no difference in the content of the major nutritional components, i.e. crude protein, crude lipid, eight essential amino acids and total ash between the irradiated grains and the non-irradiated transgenic rice. However, the amounts of Cry1Ab protein and apparent amylose in the irradiated transgenic rice were reduced significantly by the doses higher than 200 Gy. In vivo observation showed that Cry1Ab protein contents also decreased in the fresh leaf tissues of survival seedlings after irradiation with 200 Gy or higher doses and showed inhibition of seedling growth. The results indicate that gamma irradiation might improve the quality of transgenic rice due to removal of the toxic Cry1Ab protein

  3. Effect of gamma irradiation on nutritional components and Cry1Ab protein in the transgenic rice with a synthetic cry1Ab gene from Bacillus thuringiensis

    Science.gov (United States)

    Wu, Dianxing; Ye, Qingfu; Wang, Zhonghua; Xia, Yingwu

    2004-01-01

    The effects of gamma irradiation on the transgenic rice containing a synthetic cry1Ab gene from Bacillus thuringiensis were investigated. There was almost no difference in the content of the major nutritional components, i.e. crude protein, crude lipid, eight essential amino acids and total ash between the irradiated grains and the non-irradiated transgenic rice. However, the amounts of Cry1Ab protein and apparent amylose in the irradiated transgenic rice were reduced significantly by the doses higher than 200 Gy. In vivo observation showed that Cry1Ab protein contents also decreased in the fresh leaf tissues of survival seedlings after irradiation with 200 Gy or higher doses and showed inhibition of seedling growth. The results indicate that gamma irradiation might improve the quality of transgenic rice due to removal of the toxic Cry1Ab protein.

  4. Effect of gamma irradiation on nutritional components and Cry1Ab protein in the transgenic rice with a synthetic cry1Ab gene from Bacillus thuringiensis[Transgenic rice; Gamma irradiation; Nutritional components; Cry1Ab protein

    Energy Technology Data Exchange (ETDEWEB)

    Wu Dianxing E-mail: dxwu@zju.edu.cn; Ye Qingfu; Wang Zhonghua; Xia Yingwu

    2004-01-01

    The effects of gamma irradiation on the transgenic rice containing a synthetic cry1Ab gene from Bacillus thuringiensis were investigated. There was almost no difference in the content of the major nutritional components, i.e. crude protein, crude lipid, eight essential amino acids and total ash between the irradiated grains and the non-irradiated transgenic rice. However, the amounts of Cry1Ab protein and apparent amylose in the irradiated transgenic rice were reduced significantly by the doses higher than 200 Gy. In vivo observation showed that Cry1Ab protein contents also decreased in the fresh leaf tissues of survival seedlings after irradiation with 200 Gy or higher doses and showed inhibition of seedling growth. The results indicate that gamma irradiation might improve the quality of transgenic rice due to removal of the toxic Cry1Ab protein.

  5. Expression of cry1Ab gene from a novel Bacillus thuringiensis strain SY49-1 active on pest insects.

    Science.gov (United States)

    Azizoglu, Ugur; Ayvaz, Abdurrahman; Yılmaz, Semih; Karabörklü, Salih; Temizgul, Rıdvan

    2016-01-01

    In this study, the cry1Ab gene of previously characterized and Lepidoptera-, Diptera-, and Coleoptera-active Bacillus thuringiensis SY49-1 strain was cloned, expressed and individually tested on Ephestia kuehniella (Lepidoptera: Pyralidae) and Plodia interpunctella (Lepidoptera: Pyralidae) larvae. pET-cry1Ab plasmids were constructed by ligating the cry1Ab into pET28a (+) expression vector. Constructed plasmids were transferred to an Escherichia coli BL21 (DE3) strain rendered competent with CaCl2. Isopropyl β-d-1-thiogalactopyranoside was used to induce the expression of cry1Ab in E. coli BL21(DE3), and consequently, ∼130kDa of Cry1Ab was obtained. Bioassay results indicated that recombinant Cry1Ab at a dose of 1000μgg(-1) caused 40% and 64% mortality on P. interpunctella and E. kuehniella larvae, respectively. However, the mortality rates of Bt SY49-1 strains' spore-crystal mixture at the same dose were observed to be 70% on P. interpunctella and 90% on E. kuehniella larvae. The results indicated that cry1Ab may be considered as a good candidate in transgenic crop production and as an alternative biocontrol agent in controlling stored product moths.

  6. Expression of cry1Ab gene from a novel Bacillus thuringiensis strain SY49-1 active on pest insects.

    Science.gov (United States)

    Azizoglu, Ugur; Ayvaz, Abdurrahman; Yılmaz, Semih; Karabörklü, Salih; Temizgul, Rıdvan

    2016-01-01

    In this study, the cry1Ab gene of previously characterized and Lepidoptera-, Diptera-, and Coleoptera-active Bacillus thuringiensis SY49-1 strain was cloned, expressed and individually tested on Ephestia kuehniella (Lepidoptera: Pyralidae) and Plodia interpunctella (Lepidoptera: Pyralidae) larvae. pET-cry1Ab plasmids were constructed by ligating the cry1Ab into pET28a (+) expression vector. Constructed plasmids were transferred to an Escherichia coli BL21 (DE3) strain rendered competent with CaCl2. Isopropyl β-d-1-thiogalactopyranoside was used to induce the expression of cry1Ab in E. coli BL21(DE3), and consequently, ∼130kDa of Cry1Ab was obtained. Bioassay results indicated that recombinant Cry1Ab at a dose of 1000μgg(-1) caused 40% and 64% mortality on P. interpunctella and E. kuehniella larvae, respectively. However, the mortality rates of Bt SY49-1 strains' spore-crystal mixture at the same dose were observed to be 70% on P. interpunctella and 90% on E. kuehniella larvae. The results indicated that cry1Ab may be considered as a good candidate in transgenic crop production and as an alternative biocontrol agent in controlling stored product moths. PMID:27143037

  7. 40 CFR 174.529 - Bacillus thuringiensis modified Cry1Ab protein as identified under OECD Unique Identifier SYN...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bacillus thuringiensis modified Cry1Ab protein as identified under OECD Unique Identifier SYN-IR67B-1 in cotton; exemption from the requirement of a tolerance. 174.529 Section 174.529 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS PROCEDURES...

  8. A cadherin-like protein influences Bacillus thuringiensis Cry1Ab toxicity in the oriental armyworm, Mythimna separata.

    Science.gov (United States)

    Wang, Ling; Jiang, Xingfu; Luo, Lizhi; Stanley, David; Sappington, Thomas W; Zhang, Lei

    2013-06-01

    Cadherins comprise a family of calcium-dependent cell adhesion proteins that act in cell-cell interactions. Cadherin-like proteins (CADs) in midguts of some insects act as receptors that bind some of the toxins produced by the Bacillus thuringiensis (Bt). We cloned a CAD gene associated with larval midguts prepared from Mythimna separata. The full-length cDNA (MsCAD1, GenBank Accession No. JF951432) is 5642 bp, with an open reading frame encoding a 1757 amino acid and characteristics typical of insect CADs. Expression of MsCAD1 is predominantly in midgut tissue, with highest expression in the 3rd- to 6th-instars and lowest in newly hatched larvae. Knocking-down MsCAD1 decreased Cry1Ab susceptibility, indicated by reduced developmental time, increased larval weight and reduced larval mortality. We expressed MsCAD1 in E. coli and recovered the recombinant protein, rMsCAD1, which binds Cry1Ab toxin. Truncation analysis and binding experiments revealed that a contiguous 209-aa, located in CR11 and CR12, is the minimal Cry1Ab binding region. These results demonstrate that MsCAD1 is associated with Cry1Ab toxicity and is one of the Cry1Ab receptors in this insect. The significance of this work lies in identifying MsCAD1 as a Cry1Ab receptor, which helps understand the mechanism of Cry1Ab toxicity and of potential resistance to Bt in M. separata. PMID:23754724

  9. Composition of the Putative Prepore Complex of Bacillus thuringiensis Cry1Ab Toxin

    OpenAIRE

    Nair, Manoj S; Dean, Donald H.

    2015-01-01

    Prepore formation is hypothesized to be an obligate step in the insertion of Cry1Ab toxin into insect brush border membrane vesicles. We examined the architecture of the putative prepore when isolated using the published protocols [1] [2]. Our results demonstrate that the putative prepore form of Cry1Ab is a combination of receptor proteins attached to the toxin, when purified. The results also suggest that this prepore form as prepared by the methods published is different from other membran...

  10. Nanobody-based electrochemical immunoassay for Bacillus thuringiensis Cry1Ab toxin by detecting the enzymatic formation of polyaniline

    International Nuclear Information System (INIS)

    We describe an electrochemical immunoassay for the Cry1Ab toxin that is produced by Bacillus thuringiensis. It is making use of a nanobody (a heavy-chain only antibody) that was selected from an immune phage displayed library. A biotinylated primary nanobody and a HRP-conjugated secondary nanobody were applied in a sandwich immunoassay where horseradish peroxidase (HRP) is used to produce polyaniline (PANI) from aniline. PANI can be easily detected by differential pulse voltammetry at a working voltage as low as 40 mV (vs. Ag/AgCl) which makes the assay fairly selective. This immunoassay for Cry1Ab has an analytical range from 0.1 to 1000 ng∙mL-1 and a 0.07 ng∙mL-1 lower limit of detection. The average recoveries of the toxin from spiked samples are in the range from 102 to 114 %, with a relative standard deviation of <7.5 %. The results demonstrated that the assay represented an attractive alternative to existing immunoassays in enabling affordable, sensitive, robust and specific determination of this toxin. (author)

  11. Induction of Manduca sexta Larvae Caspases Expression in Midgut Cells by Bacillus thuringiensis Cry1Ab Toxin

    Directory of Open Access Journals (Sweden)

    Helena Porta

    2011-01-01

    Full Text Available Bacillus thuringiensis produces crystal toxins known as Cry that are highly selective against important agricultural and human health-related insect pests. Cry proteins are pore-forming toxins that interact with specific receptors in the midgut cell membrane of susceptible larvae making pores that cause osmotic shock, leading finally to insect death. In the case of pore-forming toxins that are specific to mammalian cells, death responses at low doses may induce apoptosis or pyroptosis, depending on the cell type. The death mechanism induced by Cry toxins in insect midgut cells is poorly understood. Here, we analyze the caspases expression by RT-PCR analysis, showing that the initial response of Manduca sexta midgut cells after low dose of Cry1Ab toxin administration involves a fast and transient accumulation of caspase-1 mRNA, suggesting that pyroptosis was activated by Cry1Ab toxin as an initial response but was repressed later. In contrast, caspase-3 mRNA requires a longer period of time of toxin exposure to be activated but presents a sustained activation, suggesting that apoptosis may be a cell death mechanism induced also at low dose of toxin.

  12. In Silico Modeling and Functional Interpretations of Cry1Ab15 Toxin from Bacillus thuringiensis BtB-Hm-16

    Directory of Open Access Journals (Sweden)

    Sudhanshu Kashyap

    2013-01-01

    Full Text Available The theoretical homology based structural model of Cry1Ab15 δ-endotoxin produced by Bacillus thuringiensis BtB-Hm-16 was predicted using the Cry1Aa template (resolution 2.25 Å. The Cry1Ab15 resembles the template structure by sharing a common three-domain extending conformation structure responsible for pore-forming and specificity determination. The novel structural differences found are the presence of β0 and α3, and the absence of α7b, β1a, α10a, α10b, β12, and α11a while α9 is located spatially downstream. Validation by SUPERPOSE and with the use of PROCHECK program showed folding of 98% of modeled residues in a favourable and stable orientation with a total energy Z-score of −6.56; the constructed model has an RMSD of only 1.15 Å. These increments of 3D structure information will be helpful in the design of domain swapping experiments aimed at improving toxicity and will help in elucidating the common mechanism of toxin action.

  13. Geographical susceptibility of Louisiana and Texas populations of sugarcane borer, Diatraea saccharalis (F.) (Lepidopetera: Crambidae) to Bacillus thuringiensis Cry1Ab protein

    Science.gov (United States)

    The susceptibility of 18 field populations of the sugarcane borer, Diatraea saccharalis (F.) to two sources of Bacillus thuringiensis Cry1Ab protein was determined by laboratory bioassays. Fifteen of the 18 field populations were collected from seven locations across Louisiana and the other 3 popula...

  14. Dominant negative phenotype of Bacillus thuringiensis Cry1Ab, Cry11Aa and Cry4Ba mutants suggest hetero-oligomer formation among different Cry toxins.

    NARCIS (Netherlands)

    Carmona, D.; Rodriguez-Almazan, C.; Munoz-Garay, C.; Portugal, L.; Perez, C.; Maagd, de R.A.; Bakker, P.; Soberon, M.; Bravo, A.

    2011-01-01

    Background - Bacillus thuringiensis Cry toxins are used worldwide in the control of different insect pests important in agriculture or in human health. The Cry proteins are pore-forming toxins that affect the midgut cell of target insects. It was shown that non-toxic Cry1Ab helix a-4 mutants had a d

  15. 40 CFR 174.511 - Bacillus thuringiensis Cry1Ab protein in all plants; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bacillus thuringiensis Cry1Ab protein in all plants; exemption from the requirement of a tolerance. 174.511 Section 174.511 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS PROCEDURES AND REQUIREMENTS FOR PLANT-INCORPORATED PROTECTANTS...

  16. Different Effects of Bacillus thuringiensis Toxin Cry1Ab on Midgut Cell Transmembrane Potential of Mythimna separata and Agrotis ipsilon Larvae

    Directory of Open Access Journals (Sweden)

    Yingying Wang

    2015-12-01

    Full Text Available Bacillus thuringiensis (Bt Cry toxins from the Cry1A family demonstrate significantly different toxicities against members of the family Noctuidae for unknown reasons. In this study, membrane potential was measured and analyzed in freshly isolated midgut samples from Mythimna separata and Agrotis ipsilon larvae under oral administration and in vitro incubation with Bt toxin Cry1Ab to elucidate the mechanism of action for further control of these pests. Bioassay results showed that the larvae of M. separata achieved a LD50 of 258.84 ng/larva at 24 h after ingestion; M. separata larvae were at least eightfold more sensitive than A. ipsilon larvae to Cry1Ab. Force-feeding showed that the observed midgut apical-membrane potential (Vam of M. separata larvae was significantly depolarized from −82.9 ± 6.6 mV to −19.9 ± 7.2 mV at 8 h after ingestion of 1 μg activated Cry1Ab, whereas no obvious changes were detected in A. ipsilon larvae with dosage of 5 μg Cry1Ab. The activated Cry1Ab caused a distinct concentration-dependent depolarization of the apical membrane; Vam was reduced by 50% after 14.7 ± 0.2, 9.8 ± 0.4, and 7.6 ± 0.6 min of treatment with 1, 5, and 10 μg/mL Cry1Ab, respectively. Cry1Ab showed a minimal effect on A. ipsilon larvae even at 20 μg/mL, and Vam decreased by 26.3% ± 2.3% after 15 min. The concentrations of Cry1Ab displayed no significant effect on the basolateral side of the epithelium. The Vam of A. ipsilon (−33.19 ± 6.29 mV, n = 51 was only half that of M. separata (−80.94 ± 6.95 mV, n = 75. The different degrees of sensitivity to Cry1Ab were speculatively associated with various habits, as well as the diverse physiological or biochemical characteristics of the midgut cell membranes.

  17. Different Effects of Bacillus thuringiensis Toxin Cry1Ab on Midgut Cell Transmembrane Potential of Mythimna separata and Agrotis ipsilon Larvae.

    Science.gov (United States)

    Wang, Yingying; Hu, Zhaonong; Wu, Wenjun

    2015-12-01

    Bacillus thuringiensis (Bt) Cry toxins from the Cry1A family demonstrate significantly different toxicities against members of the family Noctuidae for unknown reasons. In this study, membrane potential was measured and analyzed in freshly isolated midgut samples from Mythimna separata and Agrotis ipsilon larvae under oral administration and in vitro incubation with Bt toxin Cry1Ab to elucidate the mechanism of action for further control of these pests. Bioassay results showed that the larvae of M. separata achieved a LD50 of 258.84 ng/larva at 24 h after ingestion; M. separata larvae were at least eightfold more sensitive than A. ipsilon larvae to Cry1Ab. Force-feeding showed that the observed midgut apical-membrane potential (V(am)) of M. separata larvae was significantly depolarized from -82.9 ± 6.6 mV to -19.9 ± 7.2 mV at 8 h after ingestion of 1 μg activated Cry1Ab, whereas no obvious changes were detected in A. ipsilon larvae with dosage of 5 μg Cry1Ab. The activated Cry1Ab caused a distinct concentration-dependent depolarization of the apical membrane; V(am) was reduced by 50% after 14.7 ± 0.2, 9.8 ± 0.4, and 7.6 ± 0.6 min of treatment with 1, 5, and 10 μg/mL Cry1Ab, respectively. Cry1Ab showed a minimal effect on A. ipsilon larvae even at 20 μg/mL, and V(am) decreased by 26.3% ± 2.3% after 15 min. The concentrations of Cry1Ab displayed no significant effect on the basolateral side of the epithelium. The V(am) of A. ipsilon (-33.19 ± 6.29 mV, n = 51) was only half that of M. separata (-80.94 ± 6.95 mV, n = 75). The different degrees of sensitivity to Cry1Ab were speculatively associated with various habits, as well as the diverse physiological or biochemical characteristics of the midgut cell membranes. PMID:26694463

  18. Peptide isolated from Cry1Ab16 toxin present in Bacillus thuringiensis: Synthesis and morphology data for layer-by-layer films studied by atomic force microscopy.

    Science.gov (United States)

    Plácido, Alexandra; de Oliveira Farias, Emanuel Airton; Marani, Mariela M; Gomes Vasconcelos, Andreanne; Leite, José R S A; Delerue-Matos, Cristina

    2016-09-01

    The peptide PcL342-354C was obtained from the Cry1Ab16 toxin present in Bacillus thuringiensis ("Computational Modeling Deduced Three Dimensional Structure of Cry1Ab16 Toxin from B. thuringiensis AC11" (Kashyap, 2012) [1]). In this data article, we report the synthesis and characterization of the PcL342-354C peptide by MALDI-TOF/TOF mass spectrometry. In addition, the preparation of layer-by-layer films is shown based on interspersion of this peptide with both polyethylenimine (PEI) and poly(sodium 4-styrenesulfonate) (PSS), self-assembled on ITO (indium tin oxide) electrodes. The morphology of the ITO/PEI/PSS/PcL342-354C film was analyzed using atomic force microscopy (AFM). We also evaluated the effect of the number of bilayers in ITO/PEI/(PSS/PcL342-354C) n on the morphology of the film using AFM amplitude images. Further details about this study were published elsewhere, "Layer-by-layer films containing peptides of the Cry1Ab16 toxin from B. thuringiensis for potential biotechnological applications," (Plácido et al., 2016) [2]. PMID:27294178

  19. Peptide isolated from Cry1Ab16 toxin present in Bacillus thuringiensis: Synthesis and morphology data for layer-by-layer films studied by atomic force microscopy.

    Science.gov (United States)

    Plácido, Alexandra; de Oliveira Farias, Emanuel Airton; Marani, Mariela M; Gomes Vasconcelos, Andreanne; Leite, José R S A; Delerue-Matos, Cristina

    2016-09-01

    The peptide PcL342-354C was obtained from the Cry1Ab16 toxin present in Bacillus thuringiensis ("Computational Modeling Deduced Three Dimensional Structure of Cry1Ab16 Toxin from B. thuringiensis AC11" (Kashyap, 2012) [1]). In this data article, we report the synthesis and characterization of the PcL342-354C peptide by MALDI-TOF/TOF mass spectrometry. In addition, the preparation of layer-by-layer films is shown based on interspersion of this peptide with both polyethylenimine (PEI) and poly(sodium 4-styrenesulfonate) (PSS), self-assembled on ITO (indium tin oxide) electrodes. The morphology of the ITO/PEI/PSS/PcL342-354C film was analyzed using atomic force microscopy (AFM). We also evaluated the effect of the number of bilayers in ITO/PEI/(PSS/PcL342-354C) n on the morphology of the film using AFM amplitude images. Further details about this study were published elsewhere, "Layer-by-layer films containing peptides of the Cry1Ab16 toxin from B. thuringiensis for potential biotechnological applications," (Plácido et al., 2016) [2].

  20. Dominant negative phenotype of Bacillus thuringiensis Cry1Ab, Cry11Aa and Cry4Ba mutants suggest hetero-oligomer formation among different Cry toxins.

    Directory of Open Access Journals (Sweden)

    Daniela Carmona

    Full Text Available BACKGROUND: Bacillus thuringiensis Cry toxins are used worldwide in the control of different insect pests important in agriculture or in human health. The Cry proteins are pore-forming toxins that affect the midgut cell of target insects. It was shown that non-toxic Cry1Ab helix α-4 mutants had a dominant negative (DN phenotype inhibiting the toxicity of wildtype Cry1Ab when used in equimolar or sub-stoichiometric ratios (1∶1, 0.5∶1, mutant∶wt indicating that oligomer formation is a key step in toxicity of Cry toxins. METHODOLOGY/PRINCIPAL FINDINGS: The DN Cry1Ab-D136N/T143D mutant that is able to block toxicity of Cry1Ab toxin, was used to analyze its capacity to block the activity against Manduca sexta larvae of other Cry1 toxins, such as Cry1Aa, Cry1Ac, Cry1Ca, Cry1Da, Cry1Ea and Cry1Fa. Cry1Ab-DN mutant inhibited toxicity of Cry1Aa, Cry1Ac and Cry1Fa. In addition, we isolated mutants in helix α-4 of Cry4Ba and Cry11Aa, and demonstrate that Cry4Ba-E159K and Cry11Aa-V142D are inactive and completely block the toxicity against Aedes aegypti of both wildtype toxins, when used at sub-stoichiometric ratios, confirming a DN phenotype. As controls we analyzed Cry1Ab-R99A or Cry11Aa-E97A mutants that are located in helix α-3 and are affected in toxin oligomerization. These mutants do not show a DN phenotype but were able to block toxicity when used in 10∶1 or 100∶1 ratios (mutant∶wt probably by competition of binding with toxin receptors. CONCLUSIONS/SIGNIFICANCE: We show that DN phenotype can be observed among different Cry toxins suggesting that may interact in vivo forming hetero-oligomers. The DN phenotype cannot be observed in mutants affected in oligomerization, suggesting that this step is important to inhibit toxicity of other toxins.

  1. A 90-day safety study of genetically modified rice expressing Cry1Ab protein (Bacillus thuringiensis toxin) in Wistar rats

    DEFF Research Database (Denmark)

    Schrøder, Malene; Poulsen, Morten; Wilcks, Andrea;

    2007-01-01

    An animal model for safety assessment of genetically modified foods was tested as part of the SAFOTEST project. In a 90-day feeding study on Wistar rats, the transgenic KMD1 rice expressing Cry1Ab protein was compared to its non-transgenic parental wild type, Xiushui 11. The KMD1 rice contained 15...

  2. Susceptibility of Cry1Ab-resistant and -susceptible Sugarcane Borer (Lepidoptera: crambidae) to Four Bacillus thuringiensis Toxins

    Science.gov (United States)

    Sugarcane borer, Diatraea saccharalis (F.), is a primary corn stalk borer pest targeted by transgenic corn expressing Bacillus thuringiensis (Bt) proteins in many areas of the mid-southern region of the United States. Recently, genes encoding for Cry1A.105 and Cry2Ab2 Bt proteins were transferred in...

  3. Layer-by-layer films containing peptides of the Cry1Ab16 toxin from Bacillus thuringiensis for potential biotechnological applications.

    Science.gov (United States)

    Plácido, Alexandra; de Oliveira Farias, Emanuel Airton; Marani, Mariela M; Vasconcelos, Andreanne G; Mafud, Ana C; Mascarenhas, Yvonne P; Eiras, Carla; Leite, José R S A; Delerue-Matos, Cristina

    2016-04-01

    Cry1Ab16 is a toxin of crystalline insecticidal proteins that has been widely used in genetically modified organisms (GMOs) to gain resistance to pests. For the first time, in this study, peptides derived from the immunogenic Cry1Ab16 toxin (from Bacillus thuringiensis) were immobilized as layer-by-layer (LbL) films. Given the concern about food and environmental safety, a peptide with immunogenic potential, PcL342-354C, was selected for characterization of the electrochemical, optical, and morphological properties. The results obtained by cyclic voltammetry (CV) showed that the peptide have an irreversible oxidation process in electrolyte of 0.1 mol · L(-1) potassium phosphate buffer (PBS) at pH7.2. It was also observed that the electrochemical response of the peptide is governed mainly by charge transfer. In an attempt to maximize the electrochemical signal of peptide, it was intercalated with natural (agar, alginate and chitosan) or synthetic polymers (polyethylenimine (PEI) and poly(sodium 4-styrenesulfonate (PSS)). The presence of synthetic polymers on the film increased the electrochemical signal of PcL342-354C up to 100 times. Images by Atomic Force Microscopy (AFM) showed that the immobilized PcL342-354C formed self-assembled nanofibers with diameters ranging from 100 to 200 nm on the polymeric film. By UV-Visible spectroscopy (UV-Vis) it was observed that the ITO/PEI/PSS/PcL342-354C film grows linearly up to the fifth layer, thereafter tending to saturation. X-ray diffraction confirmed the presence on the films of crystalline ITO and amorphous polypeptide phases. In general, the ITO/PEI/PSS/PcL342-354C film characterization proved that this system is an excellent candidate for applications in electrochemical sensors and other biotechnological applications for GMOs and environmental indicators.

  4. Construction of occluded recombinant baculoviruses containing the full-length cry1Ab and cry1Ac genes from Bacillus thuringiensis

    Directory of Open Access Journals (Sweden)

    B.M. Ribeiro

    1998-06-01

    Full Text Available The administration of baculoviruses to insects for bioassay purposes is carried out, in most cases, by contamination of food surfaces with a known amount of occlusion bodies (OBs. Since per os infection is the natural route of infection, occluded recombinant viruses containing crystal protein genes (cry1Ab and cry1Ac from Bacillus thuringiensis were constructed for comparison with the baculovirus prototype Autographa californica nucleopolyhedrovirus (AcNPV. The transfer vector pAcUW2B was used for construction of occluded recombinant viruses. The transfer vector containing the crystal protein genes was cotransfected with linearized DNA from a non-occluded recombinant virus. The isolation of recombinant viruses was greatly facilitated by the reduction of background "wild type" virus and the increased proportion of recombinant viruses. Since the recombinant viruses containing full-length and truncated forms of the crystal protein genes did not seem to improve the pathogenicity of the recombinant viruses when compared with the wild type AcNPV, and in order to compare expression levels of the full-length crystal proteins produced by non-occluded and occluded recombinant viruses the full-length cry1Ab and cry1Ac genes were chosen for construction of occluded recombinant viruses. The recombinant viruses containing full-length and truncated forms of the crystal protein genes did not seem to improve its pathogenicity but the size of the larvae infected with the recombinant viruses was significantly smaller than that of larvae infected with the wild type virus.

  5. Layer-by-layer films containing peptides of the Cry1Ab16 toxin from Bacillus thuringiensis for potential biotechnological applications.

    Science.gov (United States)

    Plácido, Alexandra; de Oliveira Farias, Emanuel Airton; Marani, Mariela M; Vasconcelos, Andreanne G; Mafud, Ana C; Mascarenhas, Yvonne P; Eiras, Carla; Leite, José R S A; Delerue-Matos, Cristina

    2016-04-01

    Cry1Ab16 is a toxin of crystalline insecticidal proteins that has been widely used in genetically modified organisms (GMOs) to gain resistance to pests. For the first time, in this study, peptides derived from the immunogenic Cry1Ab16 toxin (from Bacillus thuringiensis) were immobilized as layer-by-layer (LbL) films. Given the concern about food and environmental safety, a peptide with immunogenic potential, PcL342-354C, was selected for characterization of the electrochemical, optical, and morphological properties. The results obtained by cyclic voltammetry (CV) showed that the peptide have an irreversible oxidation process in electrolyte of 0.1 mol · L(-1) potassium phosphate buffer (PBS) at pH7.2. It was also observed that the electrochemical response of the peptide is governed mainly by charge transfer. In an attempt to maximize the electrochemical signal of peptide, it was intercalated with natural (agar, alginate and chitosan) or synthetic polymers (polyethylenimine (PEI) and poly(sodium 4-styrenesulfonate (PSS)). The presence of synthetic polymers on the film increased the electrochemical signal of PcL342-354C up to 100 times. Images by Atomic Force Microscopy (AFM) showed that the immobilized PcL342-354C formed self-assembled nanofibers with diameters ranging from 100 to 200 nm on the polymeric film. By UV-Visible spectroscopy (UV-Vis) it was observed that the ITO/PEI/PSS/PcL342-354C film grows linearly up to the fifth layer, thereafter tending to saturation. X-ray diffraction confirmed the presence on the films of crystalline ITO and amorphous polypeptide phases. In general, the ITO/PEI/PSS/PcL342-354C film characterization proved that this system is an excellent candidate for applications in electrochemical sensors and other biotechnological applications for GMOs and environmental indicators. PMID:26838914

  6. Dominant negative mutants of Bacillus thuringiensis Cry1Ab toxin function as anti-toxins: demonstration of the role of oligomerization in toxicity.

    Directory of Open Access Journals (Sweden)

    Claudia Rodríguez-Almazán

    Full Text Available BACKGROUND: Bacillus thuringiensis Cry toxins, that are used worldwide in insect control, kill insects by a mechanism that depends on their ability to form oligomeric pores that insert into the insect-midgut cells. These toxins are being used worldwide in transgenic plants or spray to control insect pests in agriculture. However, a major concern has been the possible effects of these insecticidal proteins on non-target organisms mainly in ecosystems adjacent to agricultural fields. METHODOLOGY/PRINCIPAL FINDINGS: We isolated and characterized 11 non-toxic mutants of Cry1Ab toxin affected in different steps of the mechanism of action namely binding to receptors, oligomerization and pore-formation. These mutant toxins were analyzed for their capacity to block wild type toxin activity, presenting a dominant negative phenotype. The dominant negative phenotype was analyzed at two levels, in vivo by toxicity bioassays against susceptible Manduca sexta larvae and in vitro by pore formation activity in black lipid bilayers. We demonstrate that some mutations located in helix alpha-4 completely block the wild type toxin activity at sub-stoichiometric level confirming a dominant negative phenotype, thereby functioning as potent antitoxins. CONCLUSIONS/SIGNIFICANCE: This is the first reported case of a Cry toxin dominant inhibitor. These data demonstrate that oligomerization is a fundamental step in Cry toxin action and represent a potential mechanism to protect special ecosystems from the possible effect of Cry toxins on non-target organisms.

  7. Dominant Negative Mutants of Bacillus thuringiensis Cry1Ab Toxin Function as Anti-Toxins: Demonstration of the Role of Oligomerization in Toxicity

    Science.gov (United States)

    Rodríguez-Almazán, Claudia; Zavala, Luis Enrique; Muñoz-Garay, Carlos; Jiménez-Juárez, Nuria; Pacheco, Sabino; Masson, Luke; Soberón, Mario; Bravo, Alejandra

    2009-01-01

    Background Bacillus thuringiensis Cry toxins, that are used worldwide in insect control, kill insects by a mechanism that depends on their ability to form oligomeric pores that insert into the insect-midgut cells. These toxins are being used worldwide in transgenic plants or spray to control insect pests in agriculture. However, a major concern has been the possible effects of these insecticidal proteins on non-target organisms mainly in ecosystems adjacent to agricultural fields. Methodology/Principal Findings We isolated and characterized 11 non-toxic mutants of Cry1Ab toxin affected in different steps of the mechanism of action namely binding to receptors, oligomerization and pore-formation. These mutant toxins were analyzed for their capacity to block wild type toxin activity, presenting a dominant negative phenotype. The dominant negative phenotype was analyzed at two levels, in vivo by toxicity bioassays against susceptible Manduca sexta larvae and in vitro by pore formation activity in black lipid bilayers. We demonstrate that some mutations located in helix α-4 completely block the wild type toxin activity at sub-stoichiometric level confirming a dominant negative phenotype, thereby functioning as potent antitoxins. Conclusions/Significance This is the first reported case of a Cry toxin dominant inhibitor. These data demonstrate that oligomerization is a fundamental step in Cry toxin action and represent a potential mechanism to protect special ecosystems from the possible effect of Cry toxins on non-target organisms. PMID:19440244

  8. Ser170 of Bacillus thuringiensis Cry1Ab δ-endotoxin becomes anchored in a hydrophobic moiety upon insertion of this protein into Manduca sexta brush border membranes

    Directory of Open Access Journals (Sweden)

    Alzate Oscar

    2009-10-01

    Full Text Available Abstract Background Three spin-labeled mutant proteins, mutated at the beginning, middle, and end of α-helix 5 of the Bacillus thuringiensis Cry1Ab δ-endotoxin, were used to study the involvement of these specific amino acid residues in ion transport and to determine conformational changes in the vicinity of these residues when the protein was translocated into a biological membrane. Results Amino acid residue leucine 157, located in the N-terminal portion of α-helix 5, showed no involvement in ion transport, and the environment that surrounds the residue did not show any change when transferred into the biological membrane. Serine 170, located in the middle of the α-helix, showed no involvement in ion transport, but our findings indicate that in the membrane-bound state this residue faces an environment that makes the spin less mobile, as opposed to the mobility observed in an aqueous environment. Serine 176, located in the C-terminal end of the α-helix 5 is shown to be involved in ion transport activity. Conclusion Ion transport data for L157, S170, and S176, along with the mobility of the spin-labels, structural characterization of the resulting proteins, and toxicity assays against a target insect, suggest that the toxin undergoes conformational changes upon protein translocation into the midgut membrane. These conformational changes result in the midregion of the α-helix 5 being exposed to a hydrophobic-like environment. The location of these three residues in the toxin suggests that the entire α-helix becomes inserted in the insect midgut membrane.

  9. Unlinked genetic loci control the reduced transcription of aminopeptidase N 1 and 3 in the European corn borer and determine tolerance to Bacillus thuringiensis Cry1Ab toxin

    Science.gov (United States)

    Crystalline (Cry) toxins from Bacillus thuringiensis (Bt) control insect feeding damage on crop plants via foliar applications or by expression within transgenic plants, but continued Bt use is threatened by the buildup of insect resistance traits. Aminopeptidase N (apn) gene family members encode m...

  10. A Comparison of Soil microbial community structure, protozoa and nematodes in field plots of conventional and genetically modified maize expressing the Bacillus thuringiensis Cry1Ab toxin

    DEFF Research Database (Denmark)

    Griffiths, B. S.; Caul, S.; Thompson, J.;

    2005-01-01

    Field trials were established at three European sites (Denmark, Eastern France, South-West France) of genetically modified maize (Zea mays L.) expressing the CryIAb Bacillus thuringiensis toxin (Bt), the near-isogenic non-Bt cultivar, another conventional maize cultivar and grass. Soil from Denmark...

  11. Identification of differentially expressed microRNAs between Bacillus thuringiensis Cry1Ab-resistant and -susceptible strains of Ostrinia furnacalis.

    Science.gov (United States)

    Xu, Li-Na; Ling, Ying-Hui; Wang, Yue-Qin; Wang, Zhen-Ying; Hu, Ben-Jin; Zhou, Zi-Yan; Hu, Fei; He, Kang-Lai

    2015-01-01

    The Asian corn borer (ACB), Ostrinia furnacalis (Guenée), can develop strong resistance to Cry1Ab, the most widely commercialized Cry toxin for Bt maize worldwide. It is essential to understand the mechanism of resistance for management of this species, but information on the post-transcriptional regulation of Bt resistance in this target insect is limited. In the present study, RNA was extracted from the ACB in various larval stages (1-5 instar) from Cry1Ab-sensitive (ACB-BtS) and -resistant (ACB-AbR) strains, each of which included two biological replicates. Using Illumina sequencing, a total of 23,809,890 high-quality reads were collected from the four ACB libraries. The numbers of known microRNAs (miRNAs) were 302 and 395 for ACB-BtS and 268 and 287 for ACB-AbR. Using Mireap software, we identified 32 and 16 potential novel miRNAs for ACB-BtS and 18 and 22 for ACB-AbR. Among them, 21 known and 1 novel miRNAs had significantly different expression between ACB-BtS and ACB-AbR. Several miRNAs were observed to target potential Bt receptor genes, such as aminopeptidase N and cadherin-like protein. The glycosylphosphatidylinositol-anchor biosynthetic process and ABC transporters pathway were identified through Gene Ontology and KEGG pathway analysis of target genes of the differentially expressed miRNAs. PMID:26486179

  12. Single amino acid insertions in extracellular loop 2 of Bombyx mori ABCC2 disrupt its receptor function for Bacillus thuringiensis Cry1Ab and Cry1Ac but not Cry1Aa toxins.

    Science.gov (United States)

    Tanaka, Shiho; Miyamoto, Kazuhisa; Noda, Hiroaki; Endo, Haruka; Kikuta, Shingo; Sato, Ryoichi

    2016-04-01

    In a previous report, seven Cry1Ab-resistant strains were identified in the silkworm, Bombyx mori; these strains were shown to have a tyrosine insertion at position 234 in extracellular loop 2 of the ABC transporter C2 (BmABCC2). This insertion was confirmed to destroy the receptor function of BmABCC2 and confer the strains resistance against Cry1Ab and Cry1Ac. However, these strains were susceptible to Cry1Aa. In this report, we examined the mechanisms of the loss of receptor function of the transporter by expressing mutations in Sf9 cells. After replacement of one or two of the five amino acid residues in loop 2 of the susceptible BmABCC2 gene [BmABCC2_S] with alanine, cells still showed susceptibility, retaining the receptor function. Five mutants with single amino acid insertions at position 234 in BmABCC2 were also generated, resulting in loop 2 having six amino acids, which corresponds to replacing the tyrosine insertion in the resistant BmABCC2 gene [BmABCC2_R(+(234)Y)] with another amino acid. All five mutants exhibited loss of function against Cry1Ab and Cry1Ac. These results suggest that the amino acid sequence in loop 2 is less important than the loop size (five vs. six amino acids) or loop structure for Cry1Ab and Cry1Ac activity. Several domain-swapped mutant toxins were then generated among Cry1Aa, Cry1Ab, and Cry1Ac, which are composed of three domains. Swapped mutants containing domain II of Cry1Ab or Cry1Ac did not kill Sf9 cells expressing BmABCC2_R(+(234)Y), suggesting that domain II of the Cry toxin is related to the interaction with the receptor function of BmABCC2. This also suggests that different reactions against Bt-toxins in some B. mori strains, that is, Cry1Ab resistance or Cry1Aa susceptibility, are attributable to structural differences in domain II of Cry1A toxins.

  13. Single amino acid insertions in extracellular loop 2 of Bombyx mori ABCC2 disrupt its receptor function for Bacillus thuringiensis Cry1Ab and Cry1Ac but not Cry1Aa toxins.

    Science.gov (United States)

    Tanaka, Shiho; Miyamoto, Kazuhisa; Noda, Hiroaki; Endo, Haruka; Kikuta, Shingo; Sato, Ryoichi

    2016-04-01

    In a previous report, seven Cry1Ab-resistant strains were identified in the silkworm, Bombyx mori; these strains were shown to have a tyrosine insertion at position 234 in extracellular loop 2 of the ABC transporter C2 (BmABCC2). This insertion was confirmed to destroy the receptor function of BmABCC2 and confer the strains resistance against Cry1Ab and Cry1Ac. However, these strains were susceptible to Cry1Aa. In this report, we examined the mechanisms of the loss of receptor function of the transporter by expressing mutations in Sf9 cells. After replacement of one or two of the five amino acid residues in loop 2 of the susceptible BmABCC2 gene [BmABCC2_S] with alanine, cells still showed susceptibility, retaining the receptor function. Five mutants with single amino acid insertions at position 234 in BmABCC2 were also generated, resulting in loop 2 having six amino acids, which corresponds to replacing the tyrosine insertion in the resistant BmABCC2 gene [BmABCC2_R(+(234)Y)] with another amino acid. All five mutants exhibited loss of function against Cry1Ab and Cry1Ac. These results suggest that the amino acid sequence in loop 2 is less important than the loop size (five vs. six amino acids) or loop structure for Cry1Ab and Cry1Ac activity. Several domain-swapped mutant toxins were then generated among Cry1Aa, Cry1Ab, and Cry1Ac, which are composed of three domains. Swapped mutants containing domain II of Cry1Ab or Cry1Ac did not kill Sf9 cells expressing BmABCC2_R(+(234)Y), suggesting that domain II of the Cry toxin is related to the interaction with the receptor function of BmABCC2. This also suggests that different reactions against Bt-toxins in some B. mori strains, that is, Cry1Ab resistance or Cry1Aa susceptibility, are attributable to structural differences in domain II of Cry1A toxins. PMID:26928903

  14. Shared midgut binding sites for Cry1A.105, Cry1Aa, Cry1Ab, Cry1Ac and Cry1Fa proteins from Bacillus thuringiensis in two important corn pests, Ostrinia nubilalis and Spodoptera frugiperda.

    Directory of Open Access Journals (Sweden)

    Carmen Sara Hernández-Rodríguez

    Full Text Available First generation of insect-protected transgenic corn (Bt-corn was based on the expression of Cry1Ab or Cry1Fa proteins. Currently, the trend is the combination of two or more genes expressing proteins that bind to different targets. In addition to broadening the spectrum of action, this strategy helps to delay the evolution of resistance in exposed insect populations. One of such examples is the combination of Cry1A.105 with Cry1Fa and Cry2Ab to control O. nubilalis and S. frugiperda. Cry1A.105 is a chimeric protein with domains I and II and the C-terminal half of the protein from Cry1Ac, and domain III almost identical to Cry1Fa. The aim of the present study was to determine whether the chimeric Cry1A.105 has shared binding sites either with Cry1A proteins, with Cry1Fa, or with both, in O. nubilalis and in S. frugiperda. Brush-border membrane vesicles (BBMV from last instar larval midguts were used in competition binding assays with (125I-labeled Cry1A.105, Cry1Ab, and Cry1Fa, and unlabeled Cry1A.105, Cry1Aa, Cry1Ab, Cry1Ac, Cry1Fa, Cry2Ab and Cry2Ae. The results showed that Cry1A.105, Cry1Ab, Cry1Ac and Cry1Fa competed with high affinity for the same binding sites in both insect species. However, Cry2Ab and Cry2Ae did not compete for the binding sites of Cry1 proteins. Therefore, according to our results, the development of cross-resistance among Cry1Ab/Ac, Cry1A.105, and Cry1Fa proteins is possible in these two insect species if the alteration of shared binding sites occurs. Conversely, cross-resistance between these proteins and Cry2A proteins is very unlikely in such case.

  15. Hematotoxicity and genotoxicity evaluations in Swiss mice intraperitoneally exposed to Bacillus thuringiensis (var kurstaki) spore crystals genetically modified to express individually Cry1Aa, Cry1Ab, Cry1Ac, or Cry2Aa.

    Science.gov (United States)

    Mezzomo, Bélin Poletto; Miranda-Vilela, Ana Luisa; Barbosa, Lilian Carla Pereira; Albernaz, Vanessa Lima; Grisolia, Cesar Koppe

    2016-08-01

    Bacillus thuringiensis (Bt) has been widely used in foliar sprays as part of integrated pest management strategies against insect pests of agricultural crops. Since the advent of genetically modified plants expressing Bt δ-endotoxins, the bioavailability of Cry proteins has increased, and therefore for biosafety reasons their adverse effects should be studied, mainly for nontarget organisms. We evaluated, in Swiss mice, the hematotoxicity and genotoxicity of the genetically modified strains of Bt spore crystals Cry1Aa, 1Ab, 1Ac, or 2Aa at 27 mg/kg, and Cry1Aa, 1Ab and 2Aa also at 136 and 270 mg/kg, administered with a single intraperitoneal injection 24 h before euthanasia. Controls received filtered water or cyclophosphamide. Blood samples collected by cardiac puncture were used to perform hemogram, and bone marrow was extracted for the micronucleus test. Bt spore crystals presented toxicity for lymphocytes when in higher doses, which varied according to the type of spore crystal studied, besides promoting cytotoxic and genotoxic effects for the erythroid lineage of bone marrow, mainly at highest doses. Although the profile of such adverse side effects can be related to their high level of exposure, which is not commonly found in the environment, results indicated that these Bt spore crystals were not harmless to mice. This suggests that a more specific approach should be taken to increase knowledge about their toxicological properties and to establish the toxicological risks to nontarget organisms. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 970-978, 2016.

  16. Hematotoxicity and genotoxicity evaluations in Swiss mice intraperitoneally exposed to Bacillus thuringiensis (var kurstaki) spore crystals genetically modified to express individually Cry1Aa, Cry1Ab, Cry1Ac, or Cry2Aa.

    Science.gov (United States)

    Mezzomo, Bélin Poletto; Miranda-Vilela, Ana Luisa; Barbosa, Lilian Carla Pereira; Albernaz, Vanessa Lima; Grisolia, Cesar Koppe

    2016-08-01

    Bacillus thuringiensis (Bt) has been widely used in foliar sprays as part of integrated pest management strategies against insect pests of agricultural crops. Since the advent of genetically modified plants expressing Bt δ-endotoxins, the bioavailability of Cry proteins has increased, and therefore for biosafety reasons their adverse effects should be studied, mainly for nontarget organisms. We evaluated, in Swiss mice, the hematotoxicity and genotoxicity of the genetically modified strains of Bt spore crystals Cry1Aa, 1Ab, 1Ac, or 2Aa at 27 mg/kg, and Cry1Aa, 1Ab and 2Aa also at 136 and 270 mg/kg, administered with a single intraperitoneal injection 24 h before euthanasia. Controls received filtered water or cyclophosphamide. Blood samples collected by cardiac puncture were used to perform hemogram, and bone marrow was extracted for the micronucleus test. Bt spore crystals presented toxicity for lymphocytes when in higher doses, which varied according to the type of spore crystal studied, besides promoting cytotoxic and genotoxic effects for the erythroid lineage of bone marrow, mainly at highest doses. Although the profile of such adverse side effects can be related to their high level of exposure, which is not commonly found in the environment, results indicated that these Bt spore crystals were not harmless to mice. This suggests that a more specific approach should be taken to increase knowledge about their toxicological properties and to establish the toxicological risks to nontarget organisms. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 970-978, 2016. PMID:25899034

  17. Molecular characterization and RNA interference of three midgut aminopeptidase N isozymes from bacillus thuringiensis-susceptible and -resistant strains of sugarcane borer diatraea saccharalis

    Science.gov (United States)

    Aminopeptidase N (APN) proteins located at the midgut epithelium of some lepidopterous species have been implicated as receptors for insecticidal proteins from Bacillus thuringiensis. cDNAs of three APN isoforms, DsAPN1, DsAPN2, and DsAPN3, from Cry1Ab-susceptible (Cry1Ab-SS) and -resistant (Cry1Ab-...

  18. Down regulation of a gene for cadherin, but not alkaline phosphatase, associated with Cry1Ab resistance in the sugarcane borer Diatraea saccharalis.

    Directory of Open Access Journals (Sweden)

    Yunlong Yang

    Full Text Available The sugarcane borer, Diatraea saccharalis, is a major target pest of transgenic corn expressing Bacillus thuringiensis (Bt proteins (i.e., Cry1Ab in South America and the mid-southern region of the United States. Evolution of insecticide resistance in such target pests is a major threat to the durability of transgenic Bt crops. Understanding the pests' resistance mechanisms will facilitate development of effective strategies for delaying or countering resistance. Alterations in expression of cadherin- and alkaline phosphatase (ALP have been associated with Bt resistance in several species of pest insects. In this study, neither the activity nor gene regulation of ALP was associated with Cry1Ab resistance in D. saccharalis. Total ALP enzymatic activity was similar between Cry1Ab-susceptible (Cry1Ab-SS and -resistant (Cry1Ab-RR strains of D. saccharalis. In addition, expression levels of three ALP genes were also similar between Cry1Ab-SS and -RR, and cDNA sequences did not differ between susceptible and resistant larvae. In contrast, altered expression of a midgut cadherin (DsCAD1 was associated with the Cry1Ab resistance. Whereas cDNA sequences of DsCAD1 were identical between the two strains, the transcript abundance of DsCAD1 was significantly lower in Cry1Ab-RR. To verify the involvement of DsCAD1 in susceptibility to Cry1Ab, RNA interference (RNAi was employed to knock-down DsCAD1 expression in the susceptible larvae. Down-regulation of DsCAD1 expression by RNAi was functionally correlated with a decrease in Cry1Ab susceptibility. These results suggest that down-regulation of DsCAD1 is associated with resistance to Cry1Ab in D. saccharalis.

  19. Variability in the cadherin gene in an Ostrinia nubilalis strain selected for Cry1Ab resistance.

    Science.gov (United States)

    Bel, Yolanda; Siqueira, Herbert A A; Siegfried, Blair D; Ferré, Juan; Escriche, Baltasar

    2009-03-01

    Transgenic corn expressing Cry1Ab (a Bacillus thuringiensis toxin) is highly effective in the control of Ostrinia nubilalis. For its toxic action, Cry1Ab has to bind to specific insect midgut proteins. To date, in three Lepidoptera species resistance to a Cry1A toxin has been conferred by mutations in cadherin, a protein of the Lepidoptera midgut membrane. The implication of cadherin in the resistance of an Ostrinia nubilalis colony (Europe-R) selected with Bacillus thuringiensis Cry1Ab protoxin was investigated. Several major mutations in the cadherin (cdh) gene were found, which introduced premature termination codons and/or large deletions (ranging from 1383 to 1701bp). The contribution of these major mutations to the resistance was analyzed in resistant individuals that survived exposure to a high concentration of Cry1Ab protoxin. The results indicated that the presence of major mutations was drastically reduced in individuals that survived exposure. Previous inheritance experiments with the Europe-R strain indicated the involvement of more than one genetic locus and reduced amounts of the cadherin receptor. The results of the present work support a polygenic inheritance of resistance in the Europe-R strain, in which mutations in the cdh gene would contribute to resistance by means of an additive effect. PMID:19114103

  20. Characterization of the mechanism of action of the genetically modified Cry1AbMod toxin that is active against Cry1Ab-resistant insects.

    Science.gov (United States)

    Muñóz-Garay, Carlos; Portugal, Leivi; Pardo-López, Liliana; Jiménez-Juárez, Nuria; Arenas, Ivan; Gómez, Isabel; Sánchez-López, Rosana; Arroyo, Raquel; Holzenburg, Andreas; Savva, Christos G; Soberón, Mario; Bravo, Alejandra

    2009-10-01

    Bacillus thuringiensis Cry toxins are used in the control of insect pests. They are pore-forming toxins with a complex mechanism that involves the sequential interaction with receptors. They are produced as protoxins, which are activated by midgut proteases. Activated toxin binds to cadherin receptor, inducing an extra cleavage including helix alpha-1, facilitating the formation of a pre-pore oligomer. The toxin oligomer binds to secondary receptors such as aminopeptidase and inserts into lipid rafts forming pores and causing larval death. The primary threat to efficacy of Bt-toxins is the evolution of insect resistance. Engineered Cry1AMod toxins, devoid of helix alpha-1, could be used for the control of resistance in lepidopterans by bypassing the altered cadherin receptor, killing resistant insects affected in this receptor. Here we analyzed the mechanism of action of Cry1AbMod. We found that alkaline pH and the presence of membrane lipids facilitates the oligomerization of Cry1AbMod. In addition, tryptophan fluorescence emission spectra, ELISA binding to pure aminopeptidase receptor, calcein release assay and analysis of ionic-conductance in planar lipid bilayers, indicated that the secondary steps in mode of action that take place after interaction with cadherin receptor such as oligomerization, receptor binding and pore formation are similar in the Cry1AbMod and in the wild type Cry1Ab. Finally, the membrane-associated structure of Cry1AbMod oligomer was analyzed by electron crystallography showing that it forms a complex with a trimeric organization. PMID:19559004

  1. Transgenic Cry1Ab rice does not impact ecological fitness and predation of a generalist spider.

    Directory of Open Access Journals (Sweden)

    Jun-Ce Tian

    Full Text Available BACKGROUND: The commercial release of rice genetically engineered to express a Cry1Ab protein from Bacillus thuringiensis (Bt for control of Lepidoptera in China is a subject of debate. One major point of the debate has focused on the ecological safety of Bt rice on nontarget organisms, especially predators and parasitoids that help control populations of insect pests. METHODOLOGY/PRINCIPAL FINDINGS: A tritrophic bioassay was conducted to evaluate the potential impact of Cry1Ab-expressing rice on fitness parameters of a predaceous ground spider (Pardosa pseudoannulata (Bösenberg et Strand that had fed on Bt rice-fed brown planthopper (Nilaparvata lugens (Stål nymphs. Survival, development time and fecundity of this spider were not different when they were fed with Bt rice-fed or non-Bt rice-fed prey. Furthermore, ELISA and PCR gut assays, as well as a functional response trial, indicated that predation by P. pseudoannulata was not significantly different in Bt rice or non-Bt rice fields. CONCLUSIONS/SIGNIFICANCE: The transgenic Cry1Ab rice lines tested in this study had no adverse effects on the survival, developmental time and fecundity of P. pseudoannulata in the laboratory or on predation under field conditions. This suggests that this important predator would not be harmed if transgenic Cry1Ab rice were commercialized.

  2. Effects of Cry1Ab Transgenic Maize on Lifecycle and Biomarker Responses of the Earthworm, Eisenia Andrei

    OpenAIRE

    Mark Maboeta; Johnnie van den Berg; Frances van der Merwe; Carlos Bezuidenhout

    2012-01-01

    A 28-day study was conducted to determine the effects of the Bacillus thuringiensis Cry1Ab toxin on the earthworm Eisenia andrei. Previously, investigations have been limited to life-cycle level effects of this protein on earthworms, and mostly on E. fetida. In this study several endpoints were compared which included biomass changes, cocoon production, hatching success, a cellular metal-stress biomarker (Neutral Red Retention Time; NRRT) and potential genotoxic effects in terms of Randomly A...

  3. Aquatic degradation of Cry1Ab protein and decomposition dynamics of transgenic corn leaves under controlled conditions.

    Science.gov (United States)

    Böttger, Rita; Schaller, Jörg; Lintow, Sven; Gert Dudel, E

    2015-03-01

    The increasing cultivation of genetically modified corn plants (Zea mays) during the last decades is suggested as a potential risk to the environment. One of these genetically modified variety expressed the insecticidal Cry1Ab protein originating from Bacillus thuringiensis (Bt), resulting in resistance against Ostrinia nubilalis, the European corn borer. Transgenic litter material is extensively studied regarding the decomposition in soils. However, only a few field studies analyzed the fate of the Cry1Ab protein and the impact of green and senescent leaf litter from corn on the decomposition rate and related ecosystem functions in aquatic environments. Consequently, a microbial litter decomposition experiment was conducted under controlled semi-natural conditions in batch culture using two maize varieties: one variety with Cry1Ab and another one with the appertaining Iso-line as control treatment. The results showed no significant differences between the treatment with Cry1Ab and the Iso-line regarding loss of total mass in dry weight of 43% for Iso-line and 45% for Bt-corn litter, lignin content increased to 137.5% (Iso-line) and 115.7% (Bt-corn), and phenol loss decreased by 53.6% (Iso-line), 62.2% (Bt-corn) during three weeks of the experiment. At the end of the experiment Cry1Ab protein was still detected with 6% of the initial concentration. A slightly but significant lower cellulose content was found for the Cry1Ab treatment compared to the Iso-line litter at the end of the experiment. The significant higher total protein (25%) and nitrogen (25%) content in Bt corn, most likely due to the additionally expression of the transgenic protein, may increase the microbial cellulose degradation and decrease microbial lignin degradation. In conclusion a relevant year by year input of protein and therefore nitrogen rich Bt corn litter into aquatic environments may affect the balanced nutrient turnover in aquatic ecosystems. PMID:25553417

  4. Aquatic degradation of Cry1Ab protein and decomposition dynamics of transgenic corn leaves under controlled conditions.

    Science.gov (United States)

    Böttger, Rita; Schaller, Jörg; Lintow, Sven; Gert Dudel, E

    2015-03-01

    The increasing cultivation of genetically modified corn plants (Zea mays) during the last decades is suggested as a potential risk to the environment. One of these genetically modified variety expressed the insecticidal Cry1Ab protein originating from Bacillus thuringiensis (Bt), resulting in resistance against Ostrinia nubilalis, the European corn borer. Transgenic litter material is extensively studied regarding the decomposition in soils. However, only a few field studies analyzed the fate of the Cry1Ab protein and the impact of green and senescent leaf litter from corn on the decomposition rate and related ecosystem functions in aquatic environments. Consequently, a microbial litter decomposition experiment was conducted under controlled semi-natural conditions in batch culture using two maize varieties: one variety with Cry1Ab and another one with the appertaining Iso-line as control treatment. The results showed no significant differences between the treatment with Cry1Ab and the Iso-line regarding loss of total mass in dry weight of 43% for Iso-line and 45% for Bt-corn litter, lignin content increased to 137.5% (Iso-line) and 115.7% (Bt-corn), and phenol loss decreased by 53.6% (Iso-line), 62.2% (Bt-corn) during three weeks of the experiment. At the end of the experiment Cry1Ab protein was still detected with 6% of the initial concentration. A slightly but significant lower cellulose content was found for the Cry1Ab treatment compared to the Iso-line litter at the end of the experiment. The significant higher total protein (25%) and nitrogen (25%) content in Bt corn, most likely due to the additionally expression of the transgenic protein, may increase the microbial cellulose degradation and decrease microbial lignin degradation. In conclusion a relevant year by year input of protein and therefore nitrogen rich Bt corn litter into aquatic environments may affect the balanced nutrient turnover in aquatic ecosystems.

  5. Monarch larvae sensitivity to Bacillus thuringiensis- purified proteins and pollen.

    Science.gov (United States)

    Hellmich, R L; Siegfried, B D; Sears, M K; Stanley-Horn, D E; Daniels, M J; Mattila, H R; Spencer, T; Bidne, K G; Lewis, L C

    2001-10-01

    Laboratory tests were conducted to establish the relative toxicity of Bacillus thuringiensis (Bt) toxins and pollen from Bt corn to monarch larvae. Toxins tested included Cry1Ab, Cry1Ac, Cry9C, and Cry1F. Three methods were used: (i) purified toxins incorporated into artificial diet, (ii) pollen collected from Bt corn hybrids applied directly to milkweed leaf discs, and (iii) Bt pollen contaminated with corn tassel material applied directly to milkweed leaf discs. Bioassays of purified Bt toxins indicate that Cry9C and Cry1F proteins are relatively nontoxic to monarch first instars, whereas first instars are sensitive to Cry1Ab and Cry1Ac proteins. Older instars were 12 to 23 times less susceptible to Cry1Ab toxin compared with first instars. Pollen bioassays suggest that pollen contaminants, an artifact of pollen processing, can dramatically influence larval survival and weight gains and produce spurious results. The only transgenic corn pollen that consistently affected monarch larvae was from Cry1Ab event 176 hybrids, currently corn planted and for which re-registration has not been applied. Results from the other types of Bt corn suggest that pollen from the Cry1Ab (events Bt11 and Mon810) and Cry1F, and experimental Cry9C hybrids, will have no acute effects on monarch butterfly larvae in field settings. PMID:11559841

  6. VERTICAL MOVEMENT IN SOIL OF INSECTICIDAL CRY1AB PROTEIN FROM BACILLUS THURINGIENSIS. (R826107)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  7. Cry1Ab-expressing rice did not influence expression of fecundity-related genes in the wolf spider Pardosa pseudoannulata.

    Science.gov (United States)

    Wang, Juan; Peng, Yuan-De; He, Chao; Wei, Bao-Yang; Liang, Yun-Shan; Yang, Hui-Lin; Wang, Zhi; Stanley, David; Song, Qi-Sheng

    2016-10-30

    The impact of Bacillus thuringiensis (Bt) toxin proteins on non-target predatory arthropods is not well understood at the cellular and molecular levels. Here, we investigated the potential effects of Cry1Ab expressing rice on fecundity of the wolf spider, Pardosa pseudoannulata, and some of the underlying molecular mechanisms. The results indicated that brown planthoppers (BPHs) reared on Cry1Ab-expressing rice accumulated the Cry toxin and that reproductive parameters (pre-oviposition period, post-oviposition stage, number of eggs, and egg hatching rate) of the spiders that consumed BPHs reared on Bt rice were not different from those that consumed BPHs reared on the non-Bt control rice. The accumulated Cry1Ab did not influence several vitellin (Vt) parameters, including stored energy and amino acid composition, during one generation. We considered the possibility that the Cry toxins exert their influence on beneficial predators via more subtle effects detectable at the molecular level in terms of gene expression. This led us to transcriptome analysis to detect differentially expressed genes in the ovaries of spiders exposed to dietary Cry1Ab and their counterpart control spiders. Eight genes, associated with vitellogenesis, vitellogenin receptor activity, and vitellin membrane formation were not differentially expressed between ovaries from the treated and control spiders, confirmed by qPCR analysis. We infer that dietary Cry1Ab expressing rice does not influence fecundity, nor expression levels of Vt-associated genes in P. pseudoannulata. PMID:27452121

  8. Bacillus thuringiensis Cry1A toxins are versatile proteins with multiple modes of action: two distinct pre-pores are involved in toxicity

    OpenAIRE

    Gómez, Isabel; Sánchez, Jorge; Muñoz-Garay, Carlos; Matus, Violeta; Gill, Sarjeet S.; Soberón, Mario; Bravo, Alejandra

    2014-01-01

    Cry proteins from Bacillus thuringiensis are insecticidal PFTs (pore-forming toxins). In the present study, we show that two distinct functional pre-pores of Cry1Ab are formed after binding of the protoxin or the protease-activated toxin to the cadherin receptor, but before membrane insertion. Both pre-pores actively induce pore formation, although with different characteristics, and contribute to the insecticidal activity. We also analysed the oligomerization of the mutant Cry1AbMod protein....

  9. Resistance to Bacillus thuringiensis endotoxins in the European corn borer (Ostrinia nubilalis)

    Science.gov (United States)

    The European corn borer, Ostrinia nubilalis (Hübner), is the primary target of the widely adopted transgenic corn events MON810 and Bt11, expressing the Bacillus thuringiensis (Bt) insecticidal toxin, Cry1Ab. Resistant strains of O. nubilalis have been selected in the laboratory by exposure to Bt ...

  10. Monarch larvae sensitivity to Bacillus thuringiensis- purified proteins and pollen

    OpenAIRE

    Hellmich, Richard L; Blair D Siegfried; Sears, Mark K.; Stanley-Horn, Diane E.; Daniels, Michael J.; Mattila, Heather R.; Spencer, Terrence; Bidne, Keith G.; Lewis, Leslie C.

    2001-01-01

    Laboratory tests were conducted to establish the relative toxicity of Bacillus thuringiensis (Bt) toxins and pollen from Bt corn to monarch larvae. Toxins tested included Cry1Ab, Cry1Ac, Cry9C, and Cry1F. Three methods were used: (i) purified toxins incorporated into artificial diet, (ii) pollen collected from Bt corn hybrids applied directly to milkweed leaf discs, and (iii) Bt pollen contaminated with corn tassel material applied directly to milkweed leaf discs. Bioassays of purified Bt tox...

  11. Bacillus thuringiensis delta-endotoxin binding to brush border membrane vesicles of rice stem borers.

    Science.gov (United States)

    Alcantara, Edwin P; Aguda, Remedios M; Curtiss, April; Dean, Donald H; Cohen, Michael B

    2004-04-01

    The receptor binding step in the molecular mode of action of five delta-endotoxins (Cry1Ab, Cry1Ac, Cry1C, Cry2A, and Cry9C) from Bacillus thuringiensis was examined to find toxins with different receptor sites in the midgut of the striped stem borer (SSB) Chilo suppressalis (Walker) and yellow stem borer (YSB) Scirpophaga incertulas (Walker) (Lepidoptera: Pyralidae). Homologous competition assays were used to estimate binding affinities (K(com)) of (125)I-labelled toxins to brush border membrane vesicles (BBMV). The SSB BBMV affinities in decreasing order was: Cry1Ab = Cry1Ac > Cry9C > Cry2A > Cry1C. In YSB, the order of decreasing affinities was: Cry1Ac > Cry1Ab > Cry9C = Cry2A > Cry1C. The number of binding sites (B(max)) estimated by homologous competition binding among the Cry toxins did not affect toxin binding affinity (K(com)) to both insect midgut BBMVs. Results of the heterologous competition binding assays suggest that Cry1Ab and Cry1Ac compete for the same binding sites in SSB and YSB. Other toxins bind with weak (Cry1C, Cry2A) or no affinity (Cry9C) to Cry1Ab and Cry1Ac binding sites in both species. Cry2A had the lowest toxicity to 10-day-old SSB and Cry1Ab and Cry1Ac were the most toxic. Taken together, the results of this study show that Cry1Ab or Cry1Ac could be combined with either Cry1C, Cry2A, or Cry9C for more durable resistance in transgenic rice. Cry1Ab should not be used together with Cry1Ac because a mutation in one receptor site could diminish binding of both toxins. PMID:15027071

  12. Tobacco plants expressing the Cry1AbMod toxin suppress tolerance to Cry1Ab toxin of Manduca sexta cadherin-silenced larvae.

    Science.gov (United States)

    Porta, Helena; Jiménez, Gladys; Cordoba, Elizabeth; León, Patricia; Soberón, Mario; Bravo, Alejandra

    2011-07-01

    Cry toxins produced by Bacillus thuringiensis bacteria are insecticidal proteins used worldwide in the control of different insect pests. Alterations in toxin-receptor interaction represent the most common mechanism to induce resistance to Cry toxins in lepidopteran insects. Cry toxins bind with high affinity to the cadherin protein present in the midgut cells and this interaction facilitates the proteolytic removal of helix α-1 and pre-pore oligomer formation. Resistance to Cry toxins has been linked with mutations in the cadherin gene. One strategy effective to overcome larval resistance to Cry1A toxins is the production of Cry1AMod toxins that lack helix α-1. Cry1AMod are able to form oligomeric structures without binding to cadherin receptor and were shown to be toxic to cadherin-silenced Manduca sexta larvae and Pectinophora gossypiella strain with resistance linked to mutations in a cadherin gene. We developed Cry1AbMod tobacco transgenic plants to analyze if Cry1AMod toxins can be expressed in transgenic crops, do not affect plant development and are able to control insect pests. Our results show that production of the Cry1AbMod toxin in transgenic plants does not affect plant development, since these plants exhibited healthy growth, produced abundant seeds, and were virtually undistinguishable from control plants. Most importantly, Cry1AbMod protein produced in tobacco plants retains its functional toxic activity against susceptible and tolerant M. sexta larvae due to the silencing of cadherin receptor by RNAi. These results suggest that CryMod toxins could potentially be expressed in other transgenic crops to protect them against both toxin-susceptible and resistant lepidopteran larvae affected in cadherin gene. PMID:21621616

  13. Ingestion of Bt corn pollen containing Cry1Ab/2Aj or Cry1Ac does not harm Propylea japonica larvae

    OpenAIRE

    Yanmin Liu; Qingsong Liu; Yanan Wang; Xiuping Chen; Xinyuan Song; Jörg Romeis; Yunhe Li; Yufa Peng

    2016-01-01

    Propylea japonica (Thunberg) (Coleoptera: Coccinellidae) is a prevalent pollen consumer in corn fields and is therefore exposed to insecticidal proteins contained in the pollen of insect-resistant transgenic corn cultivars expressing Cry proteins derived from Bacillus thuringiensis (Bt). In the present study, the potential effect of Cry1Ab/2Aj- or Cry1Ac-containing transgenic Bt corn pollen on the fitness of P. japonica larvae was evaluated. The results show that the larval developmental time...

  14. Fate of the insecticidal Cry1Ab protein of GM crops in two agricultural soils as revealed by ¹⁴C-tracer studies.

    Science.gov (United States)

    Valldor, Petra; Miethling-Graff, Rona; Martens, Rainer; Tebbe, Christoph C

    2015-09-01

    Insecticidal delta-endotoxins of Bacillus thuringiensis are among the most abundant recombinant proteins released by genetically modified (GM) crops into agricultural soils worldwide. However, there is still controversy about their degradation and accumulation in soils. In this study, (14)C-labelled Cry1Ab protein was applied to soil microcosms at two concentrations (14 and 50 μg g(-1) soil) to quantify the mineralization of Cry1Ab, its incorporation into the soil microbial biomass, and its persistence in two soils which strongly differed in their texture but not in silt or pH. Furthermore, ELISA was used to quantify Cry1Ab and its potential immunoreactive breakdown products in aqueous soil extracts. In both soils, (14)CO2-production was initially very high and then declined during a total monitoring period of up to 135 days. A total of 16 to 23 % of the (14)C activity was incorporated after 29 to 37 days into the soil microbial biomass, indicating that Cry1Ab protein was utilized by microorganisms as a growth substrate. Adsorption in the clay-rich soil was the most important factor limiting microbial degradation; as indicated by higher degradation rates in the more sandy soil, extremely low concentrations of immunoreactive Cry1Ab molecules in the soils' aqueous extracts and a higher amount of (14)C activity bound to the soil with more clay. Ecological risk assessments of Bt-crops should therefore consider that the very low concentrations of extractable Cry1Ab do not reflect the actual elimination of the protein from soils but that, on the other hand, desorbed proteins mineralize quickly due to efficient microbial degradation.

  15. INSECTICIDAL TOXIN FROM BACILLUS THURINGIENSIS IS RELEASED FROM ROOTS OF TRANSGENIC BT CORN IN VITRO AND IN SITU. (R826107)

    Science.gov (United States)

    AbstractThe insecticidal toxin encoded by the cry1Ab gene from Bacillus thuringiensis was released in root exudates from transgenic Bt corn during 40 days of growth in soil amended to 0, 3, 6, 9, or 12% (v/v) with montmorillonite or kaolinite in a...

  16. Effects of Bacillus thuringiensis (Bt) corn on soil Folsomia fimetaria, Folsomia candida (Collembola), Hypoaspis aculeifer (Acarina) and Enchytraeus crypticus (Oligochaeta)

    DEFF Research Database (Denmark)

    Ke, X.; Krogh, P. H.

    The effects of the Cry1Ab toxin from Bacillus thuringiensis (corn variety Cascade Bt MON810 and DeKalb variety 618 Bt) were studied on survival and reproduction of the soil collembolan Folsomia fimetaria, Folsomia candida, the collembolan predator mite Hypoaspis aculeifer and enchytraeids...

  17. Assessing the impact of Cry1Ab-expressing corn pollen on monarch butterfly larvae in field studies

    OpenAIRE

    Stanley-Horn, Diane E.; Dively, Galen P.; Hellmich, Richard L; Mattila, Heather R.; Sears, Mark K.; Rose, Robyn; Jesse, Laura C. H.; Losey, John E.; Obrycki, John J.; Lewis, Les

    2001-01-01

    Survival and growth of monarch larvae, Danaus plexippus (L.), after exposure to either Cry1Ab-expressing pollen from three Bacillus thuringiensis (Bt) corn (Zea mays L.) events differing in toxin expression or to the insecticide, λ-cyhalothrin, were examined in field studies. First instars exposed to low doses (≈22 grains per cm2) of event-176 pollen gained 18% less weight than those exposed to Bt11 or Mon810 pollen after a 5-day exposure period. Larvae exposed to 67 pollen grains per cm2 on ...

  18. Effects of transgenic Bacillus thuringiensis maize grain on B. thuringiensis-susceptible Plodia interpunctella (Lepidoptera: Pyralidae).

    Science.gov (United States)

    Giles, K L; Hellmich, R L; Iverson, C T; Lewis, L C

    2000-06-01

    Percentage survivorship, developmental time, adult body length, and sex ratio of Plodia interpunctella (Hübner) reared on field-produced grain from sixteen cultivars of maize, Zea mays L., including several transgenic Bacillus thuringiensis (Bt) Berliner hybrids and selected non-Bt isolines, were evaluated under laboratory conditions. Compared with isolines, development was delayed and survivorship reduced for P. interpunctella reared on grain from transgenic hybrids with the CaMV/35s promoter that express Cry1Ab protein. Similarly, compared with non-Bt hybrids, a transgenic hybrid with the CaMV/35s promoter that expresses Cry9C protein delayed development, decreased survivorship, and caused reductions in adult body length of P. interpunctella. In contrast, no significant differences in P. interpunctella developmental times or survivorship were observed between transgenic hybrids with the PEPC promoter expressing Cry1Ab and their isolines. Additionally, developmental time, survivorship, and adult body length were similar between P. interpunctella reared on a transgenic hybrid with the CaMV/35s promoter expressing Cry1Ac and non-Bt hybrids. Our data demonstrate that transgenic Bt maize grain, especially grain from hybrids with the CaMV/35s promoter expressing Cry1Ab or Cry9C, can significantly affect B. thuringiensis-susceptible P. interpunctella populations up to 4 or 5 mo after harvest.

  19. Inhibition of Helicoverpa zea (Lepidoptera: Noctuidae) Growth by Transgenic Corn Expressing Bt Toxins and Development of Resistance to Cry1Ab.

    Science.gov (United States)

    Reisig, Dominic D; Reay-Jones, Francis P F

    2015-08-01

    Transgenic corn, Zea mays L., that expresses the Bacillus thuringiensis (Bt) toxin Cry1Ab is only moderately toxic to Helicoverpa zea (Boddie) and has been planted commercially since 1996. Growth and development of H. zea was monitored to determine potential changes in susceptibility to this toxin over time. Small plots of corn hybrids expressing Cry1F, Cry1F × Cry1Ab, Cry1Ab × Cry3Bb1, Cry1A.105 × Cry2Ab2 × Cry3Bb1, Cry1A.105 × Cry2Ab2, and Vip3Aa20 × Cry1Ab × mCry3A were planted in both 2012 and 2013 inNorth and South Carolina with paired non-Bt hybrids from the same genetic background. H. zea larvae were sampled on three time periods from ears and the following factors were measured: kernel area injured (cm(2)) by H. zea larvae, larval number per ear, larval weight, larval length, and larval head width. Pupae were sampled on a single time period and the following factors recorded: number per ear, weight, time to eclosion, and the number that eclosed. There was no reduction in larval weight, number of insect entering the pupal stadium, pupal weight, time to eclosion, and number of pupae able to successfully eclose to adulthood in the hybrid expressing Cry1Ab compared with a non-Bt paired hybrid. As Cry1Ab affected these in 1996, H. zea may be developing resistance to Cry1Ab in corn, although these results are not comprehensive, given the limited sampling period, size, and geography. We also found that the negative impacts on larval growth and development were greater in corn hybrids with pyramided traits compared with single traits.

  20. Inhibition of Helicoverpa zea (Lepidoptera: Noctuidae) Growth by Transgenic Corn Expressing Bt Toxins and Development of Resistance to Cry1Ab.

    Science.gov (United States)

    Reisig, Dominic D; Reay-Jones, Francis P F

    2015-08-01

    Transgenic corn, Zea mays L., that expresses the Bacillus thuringiensis (Bt) toxin Cry1Ab is only moderately toxic to Helicoverpa zea (Boddie) and has been planted commercially since 1996. Growth and development of H. zea was monitored to determine potential changes in susceptibility to this toxin over time. Small plots of corn hybrids expressing Cry1F, Cry1F × Cry1Ab, Cry1Ab × Cry3Bb1, Cry1A.105 × Cry2Ab2 × Cry3Bb1, Cry1A.105 × Cry2Ab2, and Vip3Aa20 × Cry1Ab × mCry3A were planted in both 2012 and 2013 inNorth and South Carolina with paired non-Bt hybrids from the same genetic background. H. zea larvae were sampled on three time periods from ears and the following factors were measured: kernel area injured (cm(2)) by H. zea larvae, larval number per ear, larval weight, larval length, and larval head width. Pupae were sampled on a single time period and the following factors recorded: number per ear, weight, time to eclosion, and the number that eclosed. There was no reduction in larval weight, number of insect entering the pupal stadium, pupal weight, time to eclosion, and number of pupae able to successfully eclose to adulthood in the hybrid expressing Cry1Ab compared with a non-Bt paired hybrid. As Cry1Ab affected these in 1996, H. zea may be developing resistance to Cry1Ab in corn, although these results are not comprehensive, given the limited sampling period, size, and geography. We also found that the negative impacts on larval growth and development were greater in corn hybrids with pyramided traits compared with single traits. PMID:26314074

  1. Production of the {sup 14}C-labeled insecticidal protein Cry1Ab for soil metabolic studies using a recombinant Escherichia coli in small-scale batch fermentations

    Energy Technology Data Exchange (ETDEWEB)

    Valldor, Petra; Miethling-Graff, Rona; Dockhorn, Susanne; Martens, Rainer; Tebbe, Christoph C. [Federal Research Institute for Rural Areas, Forestry and Fisheries, Braunschweig (Germany). Thuenen Institute (vTI) for Biodiversity

    2012-10-15

    Insecticidal Cry proteins naturally produced by Bacillus thuringiensis are a major recombinant trait expressed by genetically modified crops. They are released into the soil during and after cropping. The objective of this study was to produce {sup 14}C-labeled Cry1Ab proteins for soil metabolic studies in scope of their environmental risk assessment. Cry1Ab was synthesized as a protoxin by Escherichia coli HB101 pMP in 200-mL liquid batch culture fermentations and purified from inclusion bodies after trypsin digestion. For cultivation, U-{sup 14}C-glycerol was the main carbon source. Inclusion bodies were smaller and Cry1Ab yield was lower when the initial amount of total organic carbon in the cultivation broth was below 6.4 mg C L{sup -1}. Concentrations of 12.6 g {sup 14}C-labeled glycerol L{sup -1} (1 % v/v) resulted in the production of 17.1 mg {sup 14}C-Cry1Ab L{sup -1} cultivation medium. {sup 14}C mass balances showed that approx. 50 % of the label was lost by respiration and 20 % remained in the growth media, while the residual activity was associated with biomass. Depending on the production batch, 0.01 to 0.05 % of the total {sup 14}C originated from Cry1Ab. In the presence of 2.04 MBq {sup 14}C-labeled carbon sources, a specific activity of up to 268 Bq mg{sup -1} {sup 14}C-Cry1Ab was obtained. A more than threefold higher specific activity was achieved with 4.63 MBq and an extended cultivation period of 144 h. This study demonstrates that {sup 14}C-labeled Cry1Ab can be obtained from batch fermentations with E. coli in the presence of a simple {sup 14}C-labeled carbon source. It also provides a general strategy to produce {sup 14}C-labeled proteins useful for soil metabolic studies. (orig.)

  2. Susceptibility of legume pod borer (LPB), Maruca vitrata to delta-endotoxins of Bacillus thuringiensis (Bt) in Taiwan.

    Science.gov (United States)

    Srinivasan, R

    2008-01-01

    Baseline susceptibility of legume pod borer (LPB) to the insecticidal crystal proteins (ICPs) from Bacillus thuringiensis, viz, Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ca and Cry2Aa was assessed in Taiwan. Insect bioassays were performed by incorporating the Bt delta-endotoxins into the LPB artificial diet. The efficacy of different Bt delta-endotoxins against second instar larvae of LPB showed that the toxin Cry1Ab was the most potent toxin (LC(50) 0.207ppm), followed by Cry1Ca, Cry1Aa, Cry2Aa and Cry1Ac in descending order, with LC(50)s 0.477ppm, 0.812ppm, 1.058ppm and 1.666ppm, respectively. Hence, Cry1Ab and/or Cry1Ca toxins would provide effective control of early larval stages of LPB.

  3. Activity of Bacillus thuringiensis D(delta)-endotoxins against codling moth (Cydia pomonella L.) larvae

    NARCIS (Netherlands)

    Boncheva, R.; Dukiandjiev, S.; Minkov, I.; Maagd, de R.A.; Naimov, S.

    2006-01-01

    Solubilized protoxins of nine Cry1 and one hybrid Cry1 ¿-endotoxin from Bacillus thuringiensis were tested for their activity against larvae of the codling moth (Cydia pomonella L). Cry1Da was the most toxic, followed by Cry1Ab, Cry1Ba, and Cry1Ac, while Cry1Aa, Cry1Fa, Cry1Ia, and SN19 were still l

  4. A cadherin-like protein influences Bacillus thuringiensis Cry1Ab toxicity in the oriental armyworm, Mythimna separata

    Science.gov (United States)

    A cadherin-like gene associated with larval midgut tissues was cloned from oriental armyworm, Mythimna separata (Walker). The full-length complementary DNA (cDNA) (named Ms-CAD, GenBank accession no. JF951432) was 5642 base pairs (bp) long, with an open reading frame encoding a 1757 amino acid polyp...

  5. Ingestion of Bt corn pollen containing Cry1Ab/2Aj or Cry1Ac does not harm Propylea japonica larvae.

    Science.gov (United States)

    Liu, Yanmin; Liu, Qingsong; Wang, Yanan; Chen, Xiuping; Song, Xinyuan; Romeis, Jörg; Li, Yunhe; Peng, Yufa

    2016-01-01

    Propylea japonica (Thunberg) (Coleoptera: Coccinellidae) is a prevalent pollen consumer in corn fields and is therefore exposed to insecticidal proteins contained in the pollen of insect-resistant transgenic corn cultivars expressing Cry proteins derived from Bacillus thuringiensis (Bt). In the present study, the potential effect of Cry1Ab/2Aj- or Cry1Ac-containing transgenic Bt corn pollen on the fitness of P. japonica larvae was evaluated. The results show that the larval developmental time was significantly shorter when P. japonica larvae were fed pollen from Bt corn cultivars rather than control pollen but that pupation rate, eclosion rate, and adult fresh weight were not significantly affected. In the feeding experiments, the stability of the Cry proteins in the food sources was confirmed. When Bt corn pollen passed through the gut of P. japonica, 23% of Cry1Ab/2Aj was digested. The results demonstrate that consumption of Bt corn pollen containing Cry1Ab/2Aj or Cry1Ac has no detrimental effect on P. japonica larvae; the shortened developmental time of larvae that consumed these proteins was likely attributable to unknown differences in the nutritional composition between the Bt-transgenic and control corn pollen. PMID:27005950

  6. Expression of Cry1Ab and Cry2Ab by a polycistronic transgene with a self-cleavage peptide in rice.

    Directory of Open Access Journals (Sweden)

    Qichao Zhao

    Full Text Available Insect resistance to Bacillus thuringiensis (Bt crystal protein is a major threat to the long-term use of transgenic Bt crops. Gene stacking is a readily deployable strategy to delay the development of insect resistance while it may also broaden insecticidal spectrum. Here, we report the creation of transgenic rice expressing discrete Cry1Ab and Cry2Ab simultaneously from a single expression cassette using 2A self-cleaving peptides, which are autonomous elements from virus guiding the polycistronic viral gene expression in eukaryotes. The synthetic coding sequences of Cry1Ab and Cry2Ab, linked by the coding sequence of a 2A peptide from either foot and mouth disease virus or porcine teschovirus-1, regardless of order, were all expressed as discrete Cry1Ab and Cry2Ab at high levels in the transgenic rice. Insect bioassays demonstrated that the transgenic plants were highly resistant to lepidopteran pests. This study suggested that 2A peptide can be utilized to express multiple Bt genes at high levels in transgenic crops.

  7. Effects of Cry1Ab transgenic maize on lifecycle and biomarker responses of the earthworm, Eisenia andrei.

    Science.gov (United States)

    van der Merwe, Frances; Bezuidenhout, Carlos; van den Berg, Johnnie; Maboeta, Mark

    2012-01-01

    A 28-day study was conducted to determine the effects of the Bacillus thuringiensis Cry1Ab toxin on the earthworm Eisenia andrei. Previously, investigations have been limited to life-cycle level effects of this protein on earthworms, and mostly on E. fetida. In this study several endpoints were compared which included biomass changes, cocoon production, hatching success, a cellular metal-stress biomarker (Neutral Red Retention Time; NRRT) and potential genotoxic effects in terms of Randomly Amplified Polymorphic DNA sequences (RAPDs). NRRT results indicated no differences between treatments (p > 0.36), and NRRT remained the same for both treatments at different times during the experiment (p = 0.18). Likewise, no significant differences were found for cocoon production (p = 0.32) or hatching success (p = 0.29). Conversely, biomass data indicated a significant difference between the control treatment and the Bt treatment from the second week onwards (p andrei to Cry1Ab proteins produced by Bt maize. PMID:23235452

  8. Effects of Cry1Ab Transgenic Maize on Lifecycle and Biomarker Responses of the Earthworm, Eisenia Andrei

    Directory of Open Access Journals (Sweden)

    Mark Maboeta

    2012-12-01

    Full Text Available A 28-day study was conducted to determine the effects of the Bacillus thuringiensis Cry1Ab toxin on the earthworm Eisenia andrei. Previously, investigations have been limited to life-cycle level effects of this protein on earthworms, and mostly on E. fetida. In this study several endpoints were compared which included biomass changes, cocoon production, hatching success, a cellular metal-stress biomarker (Neutral Red Retention Time; NRRT and potential genotoxic effects in terms of Randomly Amplified Polymorphic DNA sequences (RAPDs. NRRT results indicated no differences between treatments (p > 0.36, and NRRT remained the same for both treatments at different times during the experiment (p = 0.18. Likewise, no significant differences were found for cocoon production (p = 0.32 or hatching success (p = 0.29. Conversely, biomass data indicated a significant difference between the control treatment and the Bt treatment from the second week onwards (p < 0.001, with the Bt treatment losing significantly more weight than the isoline treatment. Possible confounding factors were identified that might have affected the differences in weight loss between groups. From the RAPD profiles no conclusive data were obtained that could link observed genetic variation to exposure of E. andrei to Cry1Ab proteins produced by Bt maize.

  9. Consequences for Protaphorura armata (Collembola: Onychiuridae) following exposure to genetically modified Bacillus thuringiensis (Bt) maize and non-Bt maize

    DEFF Research Database (Denmark)

    Heckmann, L.-H.; Griffiths, B. S.; Caul, S.;

    2006-01-01

    Studies on the effect of genetically modified Bacillus thuringiensis (Bt) crops on true soil dwelling non-target arthropods are scarce. The objective of this study was to assess the influence of a 4-week exposure to two Bt maize varieties (Cry1Ab) Cascade and MEB307 on the collembolan Protaphorura...

  10. Toxicity and mode of action of insecticidal Cry1A proteins from Bacillus thuringiensis in an insect cell line, CF-1.

    Science.gov (United States)

    Portugal, Leivi; Gringorten, J Lawrence; Caputo, Guido F; Soberón, Mario; Muñoz-Garay, Carlos; Bravo, Alejandra

    2014-03-01

    Bacillus thuringiensis Cry toxins are insecticidal proteins used to control insect pests. The interaction of Cry toxins with the midgut of susceptible insects is a dynamic process involving activation of the toxin, binding to midgut receptors in the apical epithelium and conformational changes in the toxin molecule, leading to pore formation and cell lysis. An understanding of the molecular events underlying toxin mode of action is essential for the continued use of Cry toxins. In this work, we examined the mechanism of action of Cry1A toxins in the lepidopteran cell line CF-1, using native Cry1Ab and mutant forms of this protein that interfer with different steps in the mechanism of action, specifically, receptor binding, oligomerization or pore formation. These mutants lost activity against both Manduca sexta larvae and CF-1 cells. We also analyzed a mutation created in domain I of Cry1Ab, in which helix α-1 and part of helix α-2 were deleted (Cry1AbMod). Cry1AbMod is able to oligomerize in the absence of toxin receptors, and although it shows reduced activity against some susceptible insects, it kills insect pests that have developed resistance to native Cry1Ab. Cry1AbMod showed enhanced toxicity to CF-1, suggesting that oligomerization of native Cry1Ab may be a limiting step in its activity against CF-1 cells. The toxicity of Cry1Ac and Cry1AcMod were also analyzed. Our results suggest that some of the steps in the mode of action of Cry1A toxins are conserved in vivo in insect midgut cells and in vitro in an established cell line, CF-1. PMID:24189038

  11. Effects of two varieties of Bacillus thuringiensis maize on the biology of Plodia interpunctella.

    Science.gov (United States)

    Gryspeirt, Aiko; Grégoire, Jean-Claude

    2012-05-01

    On the market since 1996, genetically modified plants expressing an insecticidal toxin (Cry toxin stemmed from Bacillus thuringiensis) target several lepidopteran and coleopteran pests. In this study, we assessed the impact of two varieties of Bt maize producing different toxins (Cry1Ab or Cry1Fa, respectively) on the biology of a storage pest: Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae). The Indianmeal moths were susceptible to both toxins but showed an escape behavior only from Cry1Fa. The weight of females issued from larvae reared on Cry1Ab increased with increasing toxin concentration, but adults of both sexes reared on Cry1Fa had decreased weight. Both toxins increased development time from egg to adult regardless of sex and had no impact on the male adult lifespan. Finally, we recorded a time lag between metamorphosis from the non-Bt and the Bt diets, which increased proportionally to Cry concentration in the Bt diet.

  12. Efeito fungistático de Bacillus thuringiensis e de outras bactérias sobre alguns fungos fitopatogênicos Fungistatic effect of Bacillus thuringiensis and of other bacteria on some plant pathogenic fungi

    OpenAIRE

    Carlos Brasil Batista Junior; Ulisses Brigatto Albino; Alexandre Martin Martines; Dennis Panayotes Saridakis; Leopoldo Sussumu Matsumoto; Marco Antonio Avanzi; Galdino Andrade

    2002-01-01

    Quatro isolados bacterianos da rizosfera de Drosera villosa var. villosa (B1, B2, B3, B4) e dois isolados de Bacillus thuringiensis (B5 e B6), sendo B6 produtor da toxina bioinseticida Cry1Ab, foram avaliados quanto à capacidade de inibir os fungos fitopatogênicos Fusarium solani f. sp. phaseoli, Fusarium solani f. sp. glycines, Fusarium oxysporum e Colletotrichum sp. A cepa mais efetiva foi B1 que inibiu o crescimento dos quatro fungos até o 26º dia. B. thuringiensis inibiu o crescimento de ...

  13. Efeito fungistático de Bacillus thuringiensis e de outras bactérias sobre alguns fungos fitopatogênicos Fungistatic effect of Bacillus thuringiensis and of other bacteria on some plant pathogenic fungi

    Directory of Open Access Journals (Sweden)

    Carlos Brasil Batista Junior

    2002-08-01

    Full Text Available Quatro isolados bacterianos da rizosfera de Drosera villosa var. villosa (B1, B2, B3, B4 e dois isolados de Bacillus thuringiensis (B5 e B6, sendo B6 produtor da toxina bioinseticida Cry1Ab, foram avaliados quanto à capacidade de inibir os fungos fitopatogênicos Fusarium solani f. sp. phaseoli, Fusarium solani f. sp. glycines, Fusarium oxysporum e Colletotrichum sp. A cepa mais efetiva foi B1 que inibiu o crescimento dos quatro fungos até o 26º dia. B. thuringiensis inibiu o crescimento de três destes, o que indica que possui atividade antifúngica e abre um novo campo de estudo para a utilização do B. thuringiensis.Four bacteria isolates from the rhizosphere of Drosera villosa var. villosa (B1, B2, B3, B4 and two Bacillus thuringiensis isolates (B5 e B6, being B6 a bioinsecticidal Cry1Ab protein producer, were tested for their capacity to inhibit phytopathogenic fungi such as Fusarium solani f. sp. phaseoli, Fusarium solani f. sp. glycines, Fusarium oxysporum and Colletotrichum sp. The B1 isolate was highly effective and inhibited all fungi up to the 26th day. B. thuringiensis inhibited the growth of three fungi, and this result opens a new area to study and test B. thuringiensis.

  14. Cross-resistance and inheritance of resistance to Bacillus thuringiensis toxin Cry1Ac in diamondback moth (Plutella xylostella L) from lowland Malaysia.

    Science.gov (United States)

    Sayyed, A H; Wright, D J

    2001-05-01

    A field population of Plutella xylostella from Malaysia (SERD4) was divided into five sub-populations and four were selected (G2-G5) with the Bacillus thuringiensis insecticidal crystal (Cry) toxins Cry1Ac, Cry1Ab, Cry1Ca and Cry1Da. Bioassay at G6 gave resistance ratios of 88, 5, 2 and 3 for Cry1Ac, Cry1Ab, Cry1Ca and Cry1Da respectively compared with the unselected sub-population (UNSEL-SERD4). The Cry1Ac-selected population showed little cross-resistance to Cry1Ab, Cry1Ca and Cry1Da, (3-, 2- and 3-fold compared with UNSEL-SERD4), whereas the Cry1Ab-SEL sub-population showed marked cross-resistance to Cry1Ac (40-fold), much greater than Cry1Ab itself. In contrast, the Cry1Ca- and Cry1Da-SEL sub-population showed little if any cross-resistance to Cry1Ac and Cry1Ab. The mode of inheritance of resistance to Cry1Ac was examined in Cry1Ac-selected SERD4 by standard reciprocal crosses and back-crosses using a laboratory insecticide-susceptible population (ROTH). Logit regression analysis of F1 reciprocal crosses indicated that resistance to Cry1Ac was inherited as an incompletely dominant trait. At the highest dose of Cry1Ac tested, resistance was recessive, while at the lowest dose it was almost completely dominant. The F2 progeny from a back-cross of F1 progeny with ROTH were tested with a concentration of Cry1Ac that would kill 100% of ROTH. The mortality ranged between 50 and 95% in seven families of back-cross progeny, which indicated that more than one allele on separate loci were responsible for resistance to Cry1Ac. PMID:11374157

  15. Characterization of cDNAs encoding serine proteases and their transcriptional responses to Cry1Ab protoxin in the gut of Ostrinia nubilalis larvae.

    Directory of Open Access Journals (Sweden)

    Jianxiu Yao

    Full Text Available Serine proteases, such as trypsin and chymotrypsin, are the primary digestive enzymes in lepidopteran larvae, and are also involved in Bacillus thuringiensis (Bt protoxin activation and protoxin/toxin degradation. We isolated and sequenced 34 cDNAs putatively encoding trypsins, chymotrypsins and their homologs from the European corn borer (Ostrinia nubilalis larval gut. Our analyses of the cDNA-deduced amino acid sequences indicated that 12 were putative trypsins, 12 were putative chymotrypsins, and the remaining 10 were trypsin and chymotrypsin homologs that lack one or more conserved residues of typical trypsins and chymotrypsins. Reverse transcription PCR analysis indicated that all genes were highly expressed in gut tissues, but one group of phylogenetically-related trypsin genes, OnTry-G2, was highly expressed in larval foregut and midgut, whereas another group, OnTry-G3, was highly expressed in the midgut and hindgut. Real-time quantitative PCR analysis indicated that several trypsin genes (OnTry5 and OnTry6 were significantly up-regulated in the gut of third-instar larvae after feeding on Cry1Ab protoxin from 2 to 24 h, whereas one trypsin (OnTry2 was down-regulated at all time points. Four chymotrypsin and chymotrypsin homolog genes (OnCTP2, OnCTP5, OnCTP12 and OnCTP13 were up-regulated at least 2-fold in the gut of the larvae after feeding on Cry1Ab protoxin for 24 h. Our data represent the first in-depth study of gut transcripts encoding expanded families of protease genes in O. nubilalis larvae and demonstrate differential expression of protease genes that may be related to Cry1Ab intoxication and/or resistance.

  16. Consumption of Bt maize pollen expressing Cry1Ab or Cry3Bb1 does not harm adult green Lacewings, Chrysoperla carnea (Neuroptera: Chrysopidae.

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    Yunhe Li

    Full Text Available Adults of the common green lacewing, Chrysoperla carnea (Stephens (Neuroptera: Chrysopidae, are prevalent pollen-consumers in maize fields. They are therefore exposed to insecticidal proteins expressed in the pollen of insect-resistant, genetically engineered maize varieties expressing Cry proteins derived from Bacillus thuringiensis (Bt. Laboratory experiments were conducted to evaluate the impact of Cry3Bb1 or Cry1Ab-expressing transgenic maize (MON 88017, Event Bt176 pollen on fitness parameters of adult C. carnea. Adults were fed pollen from Bt maize varieties or their corresponding near isolines together with sucrose solution for 28 days. Survival, pre-oviposition period, fecundity, fertility and dry weight were not different between Bt or non-Bt maize pollen treatments. In order to ensure that adults of C. carnea are not sensitive to the tested toxins independent from the plant background and to add certainty to the hazard assessment, adult C. carnea were fed with artificial diet containing purified Cry3Bb1 or Cry1Ab at about a 10 times higher concentration than in maize pollen. Artificial diet containing Galanthus nivalis agglutinin (GNA was included as a positive control. No differences were found in any life-table parameter between Cry protein containing diet treatments and control diet. However, the pre-oviposition period, daily and total fecundity and dry weight of C. carnea were significantly negatively affected by GNA-feeding. In both feeding assays, the stability and bioactivity of Cry proteins in the food sources as well as the uptake by C. carnea was confirmed. These results show that adults of C. carnea are not affected by Bt maize pollen and are not sensitive to Cry1Ab and Cry3Bb1 at concentrations exceeding the levels in pollen. Consequently, Bt maize pollen consumption will pose a negligible risk to adult C. carnea.

  17. Comparison of susceptibility of Chilo suppressalis and Bombyx mori to five Bacillus thuringiensis proteins.

    Science.gov (United States)

    Jiao, Yaoyu; Yang, Yan; Meissle, Michael; Peng, Yufa; Li, Yunhe

    2016-05-01

    Transformation of rice with genes encoding insecticidal Cry proteins from Bacillus thuringiensis (Bt) should confer high resistance to target lepidopteran pests, such as Chilo suppressalis, and low toxicity to non-target organisms, such as silkworm Bombyx mori. Five purified Cry proteins that have been used for plant transformation were tested using dietary exposure assays. The susceptibility of C. suppressalis larvae to the five insecticidal proteins in the decreasing order was: Cry1Ca>Cry1Ab>Cry1Ac>Cry2Aa>Cry1Fa. However, the toxicities of the Cry proteins to B. mori were in the order: Cry1Fa>Cry1Ca>Cry2Aa>Cry1Ab>Cry1Ac. The Cry1Ca, Cry1Ab and Cry1Ac proteins exhibited relatively high toxicity to C. suppressalis larvae, with EC50 values of 16.4, 45.8 and 89.6ng/g, respectively. The toxicities of the three Cry proteins to B. mori larvae were 8, 14, and 22times lower, with EC50 values of 138.3, 628.4 and 1939.2ng/g, respectively. The Cry1Fa and Cry2Aa proteins showed high toxicity to B. mori larvae, with EC50 values of 135.7 and 373.9ng/g, respectively, but low toxicity to C. suppressalis larvae, with EC50 values of 6092.1 and 1208.5ng/g, respectively. We thus conclude that Cry1Ab, Cry1Ac and Cry1Ca are appropriate for transforming rice to control lepidopteran rice pests. In contrast, Cry1Fa and Cry2Aa are not appropriate due to their high toxicity to silkworm larvae and low activity against the target pest.

  18. The Cry1Ab Protein Has Minor Effects on the Arbuscular Mycorrhizal Fungal Communities after Five Seasons of Continuous Bt Maize Cultivation

    Science.gov (United States)

    Shu, Yinghua; Zhang, Yanyan; Feng, Yuanjiao; Wang, Jianwu

    2015-01-01

    The cultivation of genetically modified plants (GMP) has raised concerns regarding the plants’ ecological safety. A greenhouse experiment was conducted to assess the impact of five seasons of continuous Bt (Bacillus thuringiensis) maize cultivation on the colonisation and community structure of the non-target organisms arbuscular mycorrhizal fungi (AMF) in the maize roots, bulk soils and rhizospheric soils using the terminal restriction fragment length polymorphism (T-RFLP) analysis of the 28S ribosomal DNA and sequencing methods. AMF colonisation was significantly higher in the two Bt maize lines that express Cry1Ab, 5422Bt1 (event Bt11) and 5422CBCL (MON810) than in the non-Bt isoline 5422. No significant differences were observed in the diversity of the AMF community between the roots, bulk soils and rhizospheric soils of the Bt and non-Bt maize cultivars. The AMF genus Glomus was dominant in most of the samples, as detected by DNA sequencing. A clustering analysis based on the DNA sequence data suggested that the sample types (i.e., the samples from the roots, bulk soils or rhizospheric soils) might have greater influence on the AMF community phylotypes than the maize cultivars. This study indicated that the Cry1Ab protein has minor effects on the AMF communities after five seasons of continuous Bt maize cultivation. PMID:26717324

  19. The Cry1Ab Protein Has Minor Effects on the Arbuscular Mycorrhizal Fungal Communities after Five Seasons of Continuous Bt Maize Cultivation.

    Science.gov (United States)

    Zeng, Huilan; Tan, Fengxiao; Shu, Yinghua; Zhang, Yanyan; Feng, Yuanjiao; Wang, Jianwu

    2015-01-01

    The cultivation of genetically modified plants (GMP) has raised concerns regarding the plants' ecological safety. A greenhouse experiment was conducted to assess the impact of five seasons of continuous Bt (Bacillus thuringiensis) maize cultivation on the colonisation and community structure of the non-target organisms arbuscular mycorrhizal fungi (AMF) in the maize roots, bulk soils and rhizospheric soils using the terminal restriction fragment length polymorphism (T-RFLP) analysis of the 28S ribosomal DNA and sequencing methods. AMF colonisation was significantly higher in the two Bt maize lines that express Cry1Ab, 5422Bt1 (event Bt11) and 5422CBCL (MON810) than in the non-Bt isoline 5422. No significant differences were observed in the diversity of the AMF community between the roots, bulk soils and rhizospheric soils of the Bt and non-Bt maize cultivars. The AMF genus Glomus was dominant in most of the samples, as detected by DNA sequencing. A clustering analysis based on the DNA sequence data suggested that the sample types (i.e., the samples from the roots, bulk soils or rhizospheric soils) might have greater influence on the AMF community phylotypes than the maize cultivars. This study indicated that the Cry1Ab protein has minor effects on the AMF communities after five seasons of continuous Bt maize cultivation. PMID:26717324

  20. Loop replacements with gut-binding peptides in Cry1Ab domain II enhanced toxicity against the brown planthopper, Nilaparvata lugens (Stål)

    Science.gov (United States)

    Shao, Ensi; Lin, Li; Chen, Chen; Chen, Hanze; Zhuang, Haohan; Wu, Songqing; Sha, Li; Guan, Xiong; Huang, Zhipeng

    2016-01-01

    Bacillus thuringiensis (Bt) Cry toxins have been used widely in pest managements. However, Cry toxins are not effective against sap-sucking insects (Hemiptera), which limits the application of Bt for pest management. In order to extend the insecticidal spectrum of Bt toxins to the rice brown planthopper (BPH), Nilaparvata lugens, we modified Cry1Ab putative receptor binding domains with selected BPH gut-binding peptides (GBPs). Three surface exposed loops in the domain II of Cry1Ab were replaced with two GBPs (P2S and P1Z) respectively. Bioassay results showed that toxicity of modified toxin L2-P2S increased significantly (~9 folds) against BPH nymphs. In addition, damage of midgut cells was observed from the nymphs fed with L2-P2S. Our results indicate that modifying Cry toxins based on the toxin-gut interactions can broaden the insecticidal spectrum of Bt toxin. This method provides another approach for the development of transgenic crops with novel insecticidal activity against hemipteran insects and insect populations resistant to current Bt transgenic crops. PMID:26830331

  1. Loop replacements with gut-binding peptides in Cry1Ab domain II enhanced toxicity against the brown planthopper, Nilaparvata lugens (Stål).

    Science.gov (United States)

    Shao, Ensi; Lin, Li; Chen, Chen; Chen, Hanze; Zhuang, Haohan; Wu, Songqing; Sha, Li; Guan, Xiong; Huang, Zhipeng

    2016-01-01

    Bacillus thuringiensis (Bt) Cry toxins have been used widely in pest managements. However, Cry toxins are not effective against sap-sucking insects (Hemiptera), which limits the application of Bt for pest management. In order to extend the insecticidal spectrum of Bt toxins to the rice brown planthopper (BPH), Nilaparvata lugens, we modified Cry1Ab putative receptor binding domains with selected BPH gut-binding peptides (GBPs). Three surface exposed loops in the domain II of Cry1Ab were replaced with two GBPs (P2S and P1Z) respectively. Bioassay results showed that toxicity of modified toxin L2-P2S increased significantly (~9 folds) against BPH nymphs. In addition, damage of midgut cells was observed from the nymphs fed with L2-P2S. Our results indicate that modifying Cry toxins based on the toxin-gut interactions can broaden the insecticidal spectrum of Bt toxin. This method provides another approach for the development of transgenic crops with novel insecticidal activity against hemipteran insects and insect populations resistant to current Bt transgenic crops. PMID:26830331

  2. Degradation and detection of transgenic Bacillus thuringiensis DNA and proteins in flour of three genetically modified rice events submitted to a set of thermal processes.

    Science.gov (United States)

    Wang, Xiaofu; Chen, Xiaoyun; Xu, Junfeng; Dai, Chen; Shen, Wenbiao

    2015-10-01

    This study aimed to investigate the degradation of three transgenic Bacillus thuringiensis (Bt) genes (Cry1Ab, Cry1Ac, and Cry1Ab/Ac) and the corresponding encoded Bt proteins in KMD1, KF6, and TT51-1 rice powder, respectively, following autoclaving, cooking, baking, or microwaving. Exogenous Bt genes were more stable than the endogenous sucrose phosphate synthase (SPS) gene, and short DNA fragments were detected more frequently than long DNA fragments in both the Bt and SPS genes. Autoclaving, cooking (boiling in water, 30 min), and baking (200 °C, 30 min) induced the most severe Bt protein degradation effects, and Cry1Ab protein was more stable than Cry1Ac and Cry1Ab/Ac protein, which was further confirmed by baking samples at 180 °C for different periods of time. Microwaving induced mild degradation of the Bt and SPS genes, and Bt proteins, whereas baking (180 °C, 15 min), cooking and autoclaving led to further degradation, and baking (200 °C, 30 min) induced the most severe degradation. The findings of the study indicated that degradation of the Bt genes and proteins somewhat correlated with the treatment intensity. Polymerase chain reaction, enzyme-linked immunosorbent assay, and lateral flow tests were used to detect the corresponding transgenic components. Strategies for detecting transgenic ingredients in highly processed foods are discussed.

  3. Degradation and detection of transgenic Bacillus thuringiensis DNA and proteins in flour of three genetically modified rice events submitted to a set of thermal processes.

    Science.gov (United States)

    Wang, Xiaofu; Chen, Xiaoyun; Xu, Junfeng; Dai, Chen; Shen, Wenbiao

    2015-10-01

    This study aimed to investigate the degradation of three transgenic Bacillus thuringiensis (Bt) genes (Cry1Ab, Cry1Ac, and Cry1Ab/Ac) and the corresponding encoded Bt proteins in KMD1, KF6, and TT51-1 rice powder, respectively, following autoclaving, cooking, baking, or microwaving. Exogenous Bt genes were more stable than the endogenous sucrose phosphate synthase (SPS) gene, and short DNA fragments were detected more frequently than long DNA fragments in both the Bt and SPS genes. Autoclaving, cooking (boiling in water, 30 min), and baking (200 °C, 30 min) induced the most severe Bt protein degradation effects, and Cry1Ab protein was more stable than Cry1Ac and Cry1Ab/Ac protein, which was further confirmed by baking samples at 180 °C for different periods of time. Microwaving induced mild degradation of the Bt and SPS genes, and Bt proteins, whereas baking (180 °C, 15 min), cooking and autoclaving led to further degradation, and baking (200 °C, 30 min) induced the most severe degradation. The findings of the study indicated that degradation of the Bt genes and proteins somewhat correlated with the treatment intensity. Polymerase chain reaction, enzyme-linked immunosorbent assay, and lateral flow tests were used to detect the corresponding transgenic components. Strategies for detecting transgenic ingredients in highly processed foods are discussed. PMID:26277627

  4. Estirpes de Bacillus thuringiensis efetivas contra insetos das ordens Lepidoptera, Coleoptera e Diptera Bacillus thuringiensis strains effective against insects of Lepidoptera, Coleoptera and Diptera orders

    Directory of Open Access Journals (Sweden)

    Lílian Botelho Praça

    2004-01-01

    Full Text Available O objetivo deste trabalho foi selecionar entre 300 estirpes de Bacillus thuringiensis as efetivas simultaneamente contra larvas de Spodoptera frugiperda J.E. Smith e Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae, Anthonomus grandis Boheman (Coleoptera: Curculionidae, Aedes aegypti Linnaeus e Culex quinquefasciatus Say (Diptera: Culicidae. Foram selecionadas duas estirpes de B. thuringiensis, denominadas S234 e S997, que apresentaram atividade contra as três ordens de insetos. As estirpes foram caracterizadas por métodos morfológicos, bioquímicos e moleculares. As mesmas apresentaram duas proteínas principais de 130 e 65 kDa, produtos de reação em cadeia da polimerase de tamanho esperado para a detecção dos genes cry1Aa, cry1Ab, cry1Ac, cry1B e cry2 e cristais bipiramidais, cubóides e esféricos.The aim of this work was to select among 300 strains of Bacillus thuringiensis those which are simultaneously effective against larvae of Spodoptera frugiperda J.E. Smith and Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae, Anthonomus grandis Boheman (Coleoptera: Curculionidae, Aedes aegypti Linnaeus and Culex quinquefasciatus Say (Diptera: Culicidae. Two strains of B. thuringiensis were selected, S234 and S997, which presented activity against those three insect orders. Both strains were characterized by morphological, biochemical and molecular methods. They have presented two main proteins with 130 and 65 kDa, polimerase chain reaction products with expected sizes for detection of the genes cry1Aa, cry1Ab, cry1Ac, cry1B and cry2 and bipiramidal, cubical and spherical crystals.

  5. Efeito fungistático de Bacillus thuringiensis e de outras bactérias sobre alguns fungos fitopatogênicos

    OpenAIRE

    Batista Junior Carlos Brasil; Albino Ulisses Brigatto; Martines Alexandre Martin; Saridakis Dennis Panayotes; Matsumoto Leopoldo Sussumu; Avanzi Marco Antonio; Andrade Galdino

    2002-01-01

    Quatro isolados bacterianos da rizosfera de Drosera villosa var. villosa (B1, B2, B3, B4) e dois isolados de Bacillus thuringiensis (B5 e B6), sendo B6 produtor da toxina bioinseticida Cry1Ab, foram avaliados quanto à capacidade de inibir os fungos fitopatogênicos Fusarium solani f. sp. phaseoli, Fusarium solani f. sp. glycines, Fusarium oxysporum e Colletotrichum sp. A cepa mais efetiva foi B1 que inibiu o crescimento dos quatro fungos até o 26º dia. B. thuringiensis inibiu o crescimento de ...

  6. A 90-day subchronic feeding study of genetically modified rice expressing Cry1Ab protein in Sprague-Dawley rats.

    Science.gov (United States)

    Song, Huan; He, Xiaoyun; Zou, Shiying; Zhang, Teng; Luo, Yunbo; Huang, Kunlun; Zhu, Zhen; Xu, Wentao

    2015-04-01

    Bacillus thuringiensis (Bt) transgenic rice line (mfb-MH86) expressing a synthetic cry1Ab gene can be protected against feeding damage from Lepidopteran insects, including Sesamia inferens, Chilo suppressalis, Tryporyza incertulas and Cnaphalocrocis medinalis. Rice flour from mfb-MH86 and its near-isogenic control MH86 was separately formulated into rodent diets at concentrations of 17.5, 35 and 70 % (w/w) for a 90-day feeding test with rats, and all of the diets were nutritionally balanced. In this study, the responses of rats fed diets containing mfb-MH86 were compared to those of rats fed flour from MH86. Overall health, body weight and food consumption were comparable between groups fed diets containing mfb-MH86 and MH86. Blood samples were collected prior to sacrifice and a few significant differences (p genetically modified (GM) and non-GM diets. However, the values of these parameters were within the normal ranges of values for rats of this age and sex, thus not considered treatment related. In addition, upon sacrifice a large number of organs were weighed, macroscopic and histopathological examinations were performed with only minor changes to report. In conclusion, these results demonstrated that no toxic effect was observed in the conditions of the experiment, based on the different parameters assessed. GM rice mfb-MH86 is as safe and nutritious as non-GM rice.

  7. Bacillus thuringiensis (Bt)

    Science.gov (United States)

    2004-01-01

    Bacillus thuringiensis (Bt), a natural bacteria found all over the Earth, has a fairly novel way of getting rid of unwanted insects. Bt forms a protein substance (shown on the right) that is not harmful to humans, birds, fish or other vertebrates. When eaten by insect larvae the protein causes a fatal loss of appetite. For over 25 years agricultural chemical companies have relied heavily upon safe Bt pesticides. New space based research promises to give the insecticide a new dimension in effectiveness and applicability. Researchers from the Consortium for Materials Development in Space along with industrial affiliates such as Abott Labs and Pern State University flew Bt on a Space Shuttle mission in the fall of 1996. Researchers expect that the Shuttle's microgravity environment will reveal new information about the protein that will make it more effective against a wider variety of pests.

  8. Toxicity of Bacillus thuringiensis crystal proteins against eri silkworm, Samia cynthia ricini (Lepidoptera: Saturniidae).

    Science.gov (United States)

    Sandeep Kumar, Donthula; Tarakeswari, Muddanuru; Lakshminarayana, Maddukuri; Sujatha, Mulpuri

    2016-07-01

    Ten purified crystal proteins of Bacillus thuringiensis (Bt) were tested at concentrations ranging from 2.93 to 3000ng/cm(2) for their toxicity to eri silkworm through protein paint bioassays using castor leaves. Based on LC50 values, Cry1Aa (2.6ng/cm(2)) was highly toxic followed by Cry1Ac (29.3ng/cm(2)) and Cry1Ab (68.7ng/cm(2)). The Cry1Ca and Cry1Ea proteins were moderately toxic to eri silkworm larvae and resulted in 23% and 28% mortality, respectively at the highest concentration tested (3000ng/cm(2)). Only reduction in larval weight was observed with Cry2Aa, Cry1Da and Cry9Aa proteins while Cry3Aa and Cry1Ba proteins were found to be nontoxic. PMID:27377590

  9. Toxicity of Bacillus thuringiensis crystal proteins against eri silkworm, Samia cynthia ricini (Lepidoptera: Saturniidae).

    Science.gov (United States)

    Sandeep Kumar, Donthula; Tarakeswari, Muddanuru; Lakshminarayana, Maddukuri; Sujatha, Mulpuri

    2016-07-01

    Ten purified crystal proteins of Bacillus thuringiensis (Bt) were tested at concentrations ranging from 2.93 to 3000ng/cm(2) for their toxicity to eri silkworm through protein paint bioassays using castor leaves. Based on LC50 values, Cry1Aa (2.6ng/cm(2)) was highly toxic followed by Cry1Ac (29.3ng/cm(2)) and Cry1Ab (68.7ng/cm(2)). The Cry1Ca and Cry1Ea proteins were moderately toxic to eri silkworm larvae and resulted in 23% and 28% mortality, respectively at the highest concentration tested (3000ng/cm(2)). Only reduction in larval weight was observed with Cry2Aa, Cry1Da and Cry9Aa proteins while Cry3Aa and Cry1Ba proteins were found to be nontoxic.

  10. Comparison of Bacillus thuringiensis and Bacillus cereus

    International Nuclear Information System (INIS)

    Bacillus cereus and Bacillus thuringiensis are closely related, spore forming soil bacteria. B. thuringiensis produces insecticidal crystal proteins during sporulation and these toxins are the most important biopesticides in the world today. Genomes of the B. thuringiensis and B. cereus strains were analysed by pulsed field gel electrophoresis after treatment of the DNA with the restriction enzyme NotI. The NotI fingerprint patterns varied both within the B. thuringiensis and the B. cereus strains. The size of the fragments varied between 15 and 1350 kb. When physical maps of the B. thuringiensis and B. cereus strains were compared, B. thuringiensis appeared to be as closely related to B. cereus as the B. cereus strains were to each other. Nine out of 12 B. thuringiensis strains and 18 out of 25 B. cereus strains produced enterotoxins. The close relationship between B. thuringiensis and B. cereus should be taken into consideration when B. thuringiensis is used as a biopesticide. (author). 10 refs, 4 figs, 1 tab

  11. Adsorption of insecticidal Cry1Ab protein to humic substances. 1. Experimental approach and mechanistic aspects.

    Science.gov (United States)

    Sander, Michael; Tomaszewski, Jeanne E; Madliger, Michael; Schwarzenbach, René P

    2012-09-18

    Adsorption is a key process affecting the fate of insecticidal Cry proteins (Bt toxins), produced by genetically modified Bt crops, in soils. However, the mechanisms of adsorption to soil organic matter (SOM) remain poorly understood. This work assesses the forces driving the adsorption of Cry1Ab to Leonardite humic acid (LHA), used as a model for SOM. We studied the effects of solution pH and ionic strength (I) on adsorption using a quartz crystal microbalance with dissipation monitoring and optical waveguide lightmode spectroscopy. Initial Cry1Ab adsorption rates were close to diffusion-limited and resulted in extensive adsorption, even at pH >6, at which LHA and Cry1Ab carry negative net charges. Adsorption increased with decreasing I at pH >6, indicating Cry1Ab-LHA patch-controlled electrostatic attraction via positively charged domains of Cry1Ab. Upon rinsing, only a fraction of Cry1Ab desorbed, suggesting a range of interaction energies of Cry1Ab with LHA. Different interaction energies likely resulted from nonuniformity in the LHA surface polarity, with higher Cry1Ab affinities to more apolar LHA regions due to the hydrophobic effect. Contributions from the hydrophobic effect were substantiated by comparison of the adsorption of Cry1Ab and the reference proteins albumin and lysozyme to LHA and to apolar and polar model surfaces. PMID:22862304

  12. Multi-method approach for characterizing the interaction between Fusarium verticillioides and Bacillus thuringiensis subsp. Kurstaki.

    Directory of Open Access Journals (Sweden)

    Liliana O Rocha

    Full Text Available Bacterial antagonists used as biocontrol agents represent part of an integrated management program to reduce pesticides in the environment. Bacillus thuringiensis is considered a good alternative as a biocontrol agent for suppressing plant pathogens such as Fusarium. In this study, we used microscopy, flow cytometry, indirect immunofluorescence, and high performance liquid chromatography to determine the interaction between B. thuringiensis subsp. kurstaki LFB-FIOCRUZ (CCGB 257 and F. verticillioides MRC 826, an important plant pathogen frequently associated with maize. B. thuringiensis showed a strong in vitro suppressive effect on F. verticillioides growth and inhibited fumonisin production. Flow cytometry analysis was found to be adequate for characterizing the fungal cell oscillations and death during these interactions. Further studies of the antagonistic effect of this isolate against other fungi and in vivo testing are necessary to determine the efficacy of B. thuringiensis subsp. kurstaki in controlling plant pathogens. This is the first report on the use of flow cytometry for quantifying living and apoptotic F. verticillioides cells and the B. thuringiensis Cry 1Ab toxin.

  13. Assessing the impact of Cry1Ab-expressing corn pollen on monarch butterfly larvae in field studies.

    Science.gov (United States)

    Stanley-Horn, D E; Dively, G P; Hellmich, R L; Mattila, H R; Sears, M K; Rose, R; Jesse, L C; Losey, J E; Obrycki, J J; Lewis, L

    2001-10-01

    Survival and growth of monarch larvae, Danaus plexippus (L.), after exposure to either Cry1Ab-expressing pollen from three Bacillus thuringiensis (Bt) corn (Zea mays L.) events differing in toxin expression or to the insecticide, lambda-cyhalothrin, were examined in field studies. First instars exposed to low doses ( approximately 22 grains per cm(2)) of event-176 pollen gained 18% less weight than those exposed to Bt11 or Mon810 pollen after a 5-day exposure period. Larvae exposed to 67 pollen grains per cm(2) on milkweed leaves from within an event-176 field exhibited 60% lower survivorship and 42% less weight gain compared with those exposed to leaves from outside the field. In contrast, Bt11 pollen had no effect on growth to adulthood or survival of first or third instars exposed for 5 days to approximately 55 and 97 pollen grains per cm(2), respectively. Similarly, no differences in larval survivorship were observed after a 4-day exposure period to leaves with 504-586 (within fields) or 18-22 (outside the field) pollen grains per cm(2) collected from Bt11 and non-Bt sweet-corn fields. However, survivorship and weight gain were drastically reduced in non-Bt fields treated with lambda-cyhalothrin. The effects of Bt11 and Mon810 pollen on the survivorship of larvae feeding 14 to 22 days on milkweeds in fields were negligible. Further studies should examine the lifetime and reproductive impact of Bt11 and Mon810 pollen on monarchs after long-term exposure to naturally deposited pollen. PMID:11559839

  14. A mathematical model of exposure of non-target Lepidoptera to Bt-maize pollen expressing Cry1Ab within Europe.

    Science.gov (United States)

    Perry, J N; Devos, Y; Arpaia, S; Bartsch, D; Gathmann, A; Hails, R S; Kiss, J; Lheureux, K; Manachini, B; Mestdagh, S; Neemann, G; Ortego, F; Schiemann, J; Sweet, J B

    2010-05-01

    Genetically modified (GM) maize MON810 expresses a Cry1Ab insecticidal protein, derived from Bacillus thuringiensis (Bt), toxic to lepidopteran target pests such as Ostrinia nubilalis. An environmental risk to non-target Lepidoptera from this GM crop is exposure to harmful amounts of Bt-containing pollen deposited on host plants in or near MON810 fields. An 11-parameter mathematical model analysed exposure of larvae of three non-target species: the butterflies Inachis io (L.), Vanessa atalanta (L.) and moth Plutella xylostella (L.), in 11 representative maize cultivation regions in four European countries. A mortality-dose relationship was integrated with a dose-distance relationship to estimate mortality both within the maize MON810 crop and within the field margin at varying distances from the crop edge. Mortality estimates were adjusted to allow for physical effects; the lack of temporal coincidence between the susceptible larval stage concerned and the period over which maize MON810 pollen is shed; and seven further parameters concerned with maize agronomy and host-plant ecology. Sublethal effects were estimated and allowance made for aggregated pollen deposition. Estimated environmental impact was low: in all regions, the calculated mortality rate for worst-case scenarios was less than one individual in every 1572 for the butterflies and one in 392 for the moth.

  15. Consequences for Protaphorura armata (Collembola: Onychiuridae) following exposure to genetically modified Bacillus thuringiensis (Bt) maize and non-Bt maize

    International Nuclear Information System (INIS)

    Studies on the effect of genetically modified Bacillus thuringiensis (Bt) crops on true soil dwelling non-target arthropods are scarce. The objective of this study was to assess the influence of a 4-week exposure to two Bt maize varieties (Cry1Ab) Cascade and MEB307 on the collembolan Protaphorura armata. For comparison three non-Bt maize varieties, Rivaldo (isogenic to Cascade), Monumental (isogenic to MEB307) and DK242, and two control diets based on baker's yeast (uncontaminated and contaminated with Bt toxin Cry1Ab) were also tested. Due to a lower C:N ratio, individuals reared on yeast performed significantly better in all of the measured endpoints than those reared on maize. P. armata performed equally well when reared on two Bt and three non-Bt maize varieties. Although there were no negative effects of Bt maize in this experiment, we recommend future studies on Bt crops to focus on species interactions in long-term, multi-species experiments. - Protaphorura armata performed equally well when reared on two Bt and three non-Bt maize varieties

  16. Impact of six transgenic Bacillus thuringiensis rice lines on four nontarget thrips species attacking rice panicles in the paddy field.

    Science.gov (United States)

    Akhtar, Z R; Tian, J C; Chen, Y; Fang, Q; Hu, C; Peng, Y F; Ye, G Y

    2013-02-01

    As a key component of ecological risk assessments, nontarget effects of Bacillus thuringiensis (Bt) rice have been tested under laboratory and field conditions for various organisms. A 2-yr field experiment was conducted to observe the nontarget effects of six transgenic rice lines (expressing the Cry1Ab or fused protein of Cry1Ab and Cry1Ac) on four nontarget thrips species including Frankliniella intonsa (Trybom), F. tenuicornis (Uzel), Haplothrips aculeatus (F.), and H. tritici (Kurd), as compared with their rice parental control lines. Two sampling methods including the beat plate and plastic bag method were used to monitor the population densities of the four thrips species for 2 yr. The results showed that the seasonal average densities of four tested thrips species in Bt rice plots were significantly lower than or very similar to those in the non-Bt rice plots depending on rice genotypes, sampling methods, and years. Among all six tested Bt rice lines, transgenic B1 and KMD2 lines suppressed the population of these tested thrips species the most. Our results indicate that the tested Bt rice lines are unlikely to result in high population pressure of thrips species in comparison with non-Bt rice. In some cases, Bt rice lines could significantly suppress thrips populations in the rice ecosystem. In addition, compatibility of Bt rice, with rice host plant resistance to nontarget sucking pests is also discussed within an overall integrated pest management program for rice. PMID:23339799

  17. Consequences for Protaphorura armata (Collembola: Onychiuridae) following exposure to genetically modified Bacillus thuringiensis (Bt) maize and non-Bt maize

    Energy Technology Data Exchange (ETDEWEB)

    Heckmann, Lars-Henrik [National Environmental Research Institute, Department of Terrestrial Ecology, Vejlsovej 25, PO Box 314, DK-8600 Silkeborg (Denmark); Griffiths, Bryan S. [Scottish Crop Research Institute, Department of Soil Plant Dynamics, Invergowrie, Dundee DD2 5DA (United Kingdom); Caul, Sandra [Scottish Crop Research Institute, Department of Soil Plant Dynamics, Invergowrie, Dundee DD2 5DA (United Kingdom); Thompson, Jacqueline [Scottish Crop Research Institute, Department of Soil Plant Dynamics, Invergowrie, Dundee DD2 5DA (United Kingdom); Pusztai-Carey, Marianne [Case Western Reserve University, Cleveland, OH 44106 (United States); Moar, William J. [Auburn University, Department of Entomology and Plant Pathology, Auburn, AL 36849 (United States); Andersen, Mathias N. [Danish Institute of Agricultural Sciences, Research Centre Foulum, PO Box 50, DK-8830 Tjele (Denmark); Krogh, Paul Henning [National Environmental Research Institute, Department of Terrestrial Ecology, Vejlsovej 25, PO Box 314, DK-8600 Silkeborg (Denmark)]. E-mail: phk@dmu.dk

    2006-07-15

    Studies on the effect of genetically modified Bacillus thuringiensis (Bt) crops on true soil dwelling non-target arthropods are scarce. The objective of this study was to assess the influence of a 4-week exposure to two Bt maize varieties (Cry1Ab) Cascade and MEB307 on the collembolan Protaphorura armata. For comparison three non-Bt maize varieties, Rivaldo (isogenic to Cascade), Monumental (isogenic to MEB307) and DK242, and two control diets based on baker's yeast (uncontaminated and contaminated with Bt toxin Cry1Ab) were also tested. Due to a lower C:N ratio, individuals reared on yeast performed significantly better in all of the measured endpoints than those reared on maize. P. armata performed equally well when reared on two Bt and three non-Bt maize varieties. Although there were no negative effects of Bt maize in this experiment, we recommend future studies on Bt crops to focus on species interactions in long-term, multi-species experiments. - Protaphorura armata performed equally well when reared on two Bt and three non-Bt maize varieties.

  18. The end of a myth—Bt (Cry1Ab) maize does not harm green lacewings

    Science.gov (United States)

    Romeis, Jörg; Meissle, Michael; Naranjo, Steven E.; Li, Yunhe; Bigler, Franz

    2014-01-01

    A concern with Bt-transgenic insect-resistant plants is their potential to harm non-target organisms. Early studies reported that Cry1Ab-producing Bt maize and purified Cry1Ab harmed larvae of the green lacewing, Chrysoperla carnea. Although these effects could not be confirmed in subsequent studies, some authors still refer to them as evidence that Bt maize harms beneficial species. We provide a comprehensive review of the studies evaluating the effects of Bt (Cry1Ab) maize on C. carnea. The evidence indicates that this important predator is not affected by Bt maize or by the produced Cry1Ab protein. We discuss how conceptual models can assist environmental risk assessments, and we emphasize the importance of robust and reproducible studies. PMID:25161661

  19. The end of a myth-Bt (Cry1Ab) maize does not harm green lacewings.

    Science.gov (United States)

    Romeis, Jörg; Meissle, Michael; Naranjo, Steven E; Li, Yunhe; Bigler, Franz

    2014-01-01

    A concern with Bt-transgenic insect-resistant plants is their potential to harm non-target organisms. Early studies reported that Cry1Ab-producing Bt maize and purified Cry1Ab harmed larvae of the green lacewing, Chrysoperla carnea. Although these effects could not be confirmed in subsequent studies, some authors still refer to them as evidence that Bt maize harms beneficial species. We provide a comprehensive review of the studies evaluating the effects of Bt (Cry1Ab) maize on C. carnea. The evidence indicates that this important predator is not affected by Bt maize or by the produced Cry1Ab protein. We discuss how conceptual models can assist environmental risk assessments, and we emphasize the importance of robust and reproducible studies.

  20. Chitinolitic activity in proteic extracts of Bacillus thuringiensis toxic to boll weevil (Anthonomus grandis)

    Energy Technology Data Exchange (ETDEWEB)

    Silva, T.S; Rocha, T.L. [EMBRAPA Recursos Geneticos e Biotecnologia, DF (Brazil); Vasconcelos, E.A.R [Universidade de Brasilia (UnB), DF (Brazil); Grossi-de-Sa, M.F. [Universidade Catolica de Brasilia, DF (Brazil)

    2008-07-01

    Full text: Bacillus thuringiensis (Bt) is a spore forming bacteria, which produces Cry proteins toxic towards several insect orders. Bt S 811 strain produces at least three Cry toxins: Cry1Ab, Cry1Ia12, and Cry8, and shown toxicity to insects from Coleoptera order. In order to characterize the production of theses toxins, and check its activity against Boll weevil larvae, proteic extracts from Bt cells and supernatant proteins from the bacterial culture, were obtained at different stages of cell cycle; 8, 16, 24, and 32 hours after inoculation (HAI). Proteins from 32 HAI of the supernatant, and 8 HAI of the cellular fractions, shown highest activity towards the Boll weevil larvae. Western blotting assays using anti-Cry8 and anti-Cry1I were carried out to analyse these toxins in the Bt proteic extracts. The existence of a Cry8 was detected at 8 HAI in the cellular fraction, what allow associate this molecule with the toxicity of this fraction. However, toxicity observed at 32 HAI in the supernatant fraction, was not possible to be associated with Cry8 or Cry1Ia toxins, indicating that there are another protein(s) responsible for the toxicity. A protein homo log to Cry1Ab was identified by 'Peptide Mass Fingerprint' at 32 HAI of the supernatant fraction and a chitin binding protein was identified by 2DE/MS/MS in this same stage and chitinolitic activity was also observed by enzymatic assay. All our data suggest a possible synergism between Cry toxins and a chitinase in the activity of this strain towards Boll weevil.

  1. Chitinolitic activity in proteic extracts of Bacillus thuringiensis toxic to boll weevil (Anthonomus grandis)

    International Nuclear Information System (INIS)

    Full text: Bacillus thuringiensis (Bt) is a spore forming bacteria, which produces Cry proteins toxic towards several insect orders. Bt S 811 strain produces at least three Cry toxins: Cry1Ab, Cry1Ia12, and Cry8, and shown toxicity to insects from Coleoptera order. In order to characterize the production of theses toxins, and check its activity against Boll weevil larvae, proteic extracts from Bt cells and supernatant proteins from the bacterial culture, were obtained at different stages of cell cycle; 8, 16, 24, and 32 hours after inoculation (HAI). Proteins from 32 HAI of the supernatant, and 8 HAI of the cellular fractions, shown highest activity towards the Boll weevil larvae. Western blotting assays using anti-Cry8 and anti-Cry1I were carried out to analyse these toxins in the Bt proteic extracts. The existence of a Cry8 was detected at 8 HAI in the cellular fraction, what allow associate this molecule with the toxicity of this fraction. However, toxicity observed at 32 HAI in the supernatant fraction, was not possible to be associated with Cry8 or Cry1Ia toxins, indicating that there are another protein(s) responsible for the toxicity. A protein homo log to Cry1Ab was identified by 'Peptide Mass Fingerprint' at 32 HAI of the supernatant fraction and a chitin binding protein was identified by 2DE/MS/MS in this same stage and chitinolitic activity was also observed by enzymatic assay. All our data suggest a possible synergism between Cry toxins and a chitinase in the activity of this strain towards Boll weevil

  2. Transcriptional silencing and developmental reactivation of cry1Ab gene in transgenic rice

    Institute of Scientific and Technical Information of China (English)

    WU; Gang(吴刚); CUI; Hairui(崔海瑞); SHU; Qingyao(舒庆尧); YE; Gongyin(叶恭银); XIA; Yingwu(夏英武); GAO; Mingwei(高明蔚); Illimar; Altosaar; LI; Yi(李毅)

    2002-01-01

    One transgenic rice line lacking Cry1Ab expression product was screened in the progenies of Agrobacterium-transformed transgenic rice variety Zhong 8215 with a cry1Ab gene under field releasing conditions by using GUS histochemical assay and Western blot. Molecular hybridization results revealed that the cry1Ab gene was silenced in the transgenic rice variety Zhong 8215 and two copies of ubiquitin promoter were integrated into the rice genome. The silencing of cry1Ab gene in transgenic rice was found to be due to the methylation of the ubiquitin promoter as revealed by methylation analysis. Meanwhile, different concentrations of demethylation reagent 5-azacytidine combining with different treatment time were employed to treat the silenced transgenic rice seeds. The results indicated that 5-azacytidine could reactivate 8%-30% of the silenced transgenic rice plants and the expression level of the reactivated cry1Ab transgene could reach as high as 0.147% of the total soluble protein. Treatment with low concentration of 5-azacytidine(45 mg/L for 1 d and 2 d) could lead to the highest reactivation ratio and the highest expression level of the cry1Ab gene.

  3. Cry1Ab protein from Bt transgenic rice does not residue in rhizosphere soil

    International Nuclear Information System (INIS)

    Expression of Cry1Ab protein in Bt transgenic rice (KMD) and its residue in the rhizosphere soil during the whole growth in field, as well as degradation of the protein from KMD straw in five soils under laboratory incubation were studied. The residue of Cry1Ab protein in KMD rhizosphere soil was undetectable (below the limit of 0.5 ng/g air-dried soil). The Cry1Ab protein contents in the shoot and root of KMD were 3.23-8.22 and 0.68-0.89 μg/g (fresh weight), respectively. The half-lives of the Cry1Ab protein in the soils amended with KMD straw (4%, w/w) ranged from 11.5 to 34.3 d. The residence time of the protein varied significantly in a Fluvio-marine yellow loamy soil amended with KMD straw at the rate of 3, 4 and 7%, with half-lives of 9.9, 13.8 and 18 d, respectively. In addition, an extraction method for Cry1Ab protein in soil was developed, with extraction efficiencies of 46.4-82.3%. - Cry1Ab protein was not detected in the rhizosphere soil of field-grown Bt transgenic rice

  4. Altered binding of the Cry1Ac toxin to larval membranes but not to the toxin-binding protein in Plodia interpunctella selected for resistance to different Bacillus thuringiensis isolates.

    Science.gov (United States)

    Mohammed, S I; Johnson, D E; Aronson, A I

    1996-11-01

    Immunoblotting and cytochemical procedures were used to determine whether toxin binding was altered in strains of the Indianmeal moth, Plodia interpunctella, selected for resistance to various strains of Bacillus thuringiensis. Each of these B. thuringiensis subspecies produces a mixture of protoxins, primarily Cry1 types, and the greatest insect resistance is to the Cry1A protoxins. In several cases, however, there was also resistance to toxins not present in the B. thuringiensis strains used for selection. The Cry1Ab and Cry1Ac toxins bound equally well over a range of toxin concentrations and times of incubation to a single protein of ca. 80-kDa in immunoblots of larval membrane extracts from all of the colonies. This binding protein is essential for toxicity since a mutant Cry1Ac toxin known to be defective in binding and thus less toxic bound poorly to the 80-kDa protein. This binding protein differed in size from the major aminopeptidase N antigens implicated in toxin binding in other insects. Binding of fluorescently labeled Cry1Ac or Cry1Ab toxin to larval sections was found at the tips of the brush border membrane prepared from the susceptible but not from any of the resistant P. interpunctella. Accessibility of a major Cry1A-binding protein appears to be altered in resistant larvae and could account for their broad resistance to several B. thuringiensis toxins.

  5. Complete Genome of Bacillus thuringiensis Myophage Spock

    OpenAIRE

    Maroun, Justin W.; Whitcher, Kelvin J.; Chamakura, Karthik R.; Kuty Everett, Gabriel F.

    2013-01-01

    Bacillus thuringiensis is a Gram-positive, sporulating soil microbe with valuable pesticide-producing properties. The study of bacteriophages of B. thuringiensis could provide new biotechnological tools for the use of this bacterium. Here, we present the complete annotated genome of Spock, a myophage of B. thuringiensis, and describe its features.

  6. Cry Proteins from Bacillus thuringiensis Active against Diamondback Moth and Fall Armyworm.

    Science.gov (United States)

    Silva, M C; Siqueira, H A A; Silva, L M; Marques, E J; Barros, R

    2015-08-01

    Biopesticides based on Bacillus thuringiensis and genetically modified plants with genes from this bacterium have been used to control Plutella xylostella (L.) and Spodoptera frugiperda (J.E. Smith). However, the selection pressure imposed by these technologies may undermine the efficiency of this important alternative to synthetic insecticides. Toxins with different modes of action allow a satisfactory control of these insects. The purpose of this study was to characterize the protein and gene contents of 20 B. thuringiensis isolates from soil and insect samples collected in several areas of Northeast Brazil which are active against P. xylostella and S. frugiperda. Protein profiles were obtained by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Polymerase chain reaction assays were used to determine toxin genes present within bacterial isolates. The protein profile of the majority of the isolates produced bands of approximately 130 kDa, suggesting the presence of Cry1, Cry8 and Cry9 proteins. The gene content of the isolates of B. thuringiensis investigated showed different gene profiles. Isolates LIIT-4306 and LIIT-4311 were the most actives against both species, with LC50 of 0.03 and 0.02 × 10(8) spores mL(-1), respectively, for P. xylostella, and LC50 of 0.001 × 10(8) spores mL(-1) for S. frugiperda. These isolates carried the cry1, cry1Aa, cry1Ab, cry1Ac, cry1B, cry1C, cry1D, cry1F, cry2, cry2A, cry8, and cry9C genes. The obtained gene profiles showed great potential for the control of P. xylostella and S. frugiperda, primarily because of the presence of several cry1A genes, which are found in isolates of B. thuringiensis active against these insects. PMID:26070631

  7. Efficient transformation of Bacillus thuringiensis requires nonmethylated plasmid DNA.

    OpenAIRE

    Macaluso, A; Mettus, A M

    1991-01-01

    The transformation efficiency of Bacillus thuringiensis depends upon the source of plasmid DNA. DNA isolated from B. thuringiensis, Bacillus megaterium, or a Dam- Dcm- Escherichia coli strain efficiently transformed several B. thuringiensis strains, B. thuringiensis strains were grouped according to which B. thuringiensis backgrounds were suitable sources of DNA for transformation of other B. thuringiensis strains, suggesting that B. thuringiensis strains differ in DNA modification and restri...

  8. Effects of Two Varieties of Bacillus thuringiensis Maize on the Biology of Plodia interpunctella

    Directory of Open Access Journals (Sweden)

    Jean-Claude Grégoire

    2012-05-01

    Full Text Available On the market since 1996, genetically modified plants expressing an insecticidal toxin (Cry toxin stemmed from Bacillus thuringiensis target several lepidopteran and coleopteran pests. In this study, we assessed the impact of two varieties of Bt maize producing different toxins (Cry1Ab or Cry1Fa, respectively on the biology of a storage pest: Plodia interpunctella (Hübner (Lepidoptera: Pyralidae. The Indianmeal moths were susceptible to both toxins but showed an escape behavior only from Cry1Fa. The weight of females issued from larvae reared on Cry1Ab increased with increasing toxin concentration, but adults of both sexes reared on Cry1Fa had decreased weight. Both toxins increased development time from egg to adult regardless of sex and had no impact on the male adult lifespan. Finally, we recorded a time lag between metamorphosis from the non-Bt and the Bt diets, which increased proportionally to Cry concentration in the Bt diet.

  9. Preparative Purification and Bioassay of Bt Toxin from Cry1Ab Transgenic Rice

    Institute of Scientific and Technical Information of China (English)

    WU Jian-min; YE Qin-fu

    2004-01-01

    A method of extracting and purifying Cry1Ab protein(Bt toxin) from Cry1Ab transgenic rice was established. Most of the Bt toxin present in the tissue of Cry1Ab transgenic rice was extracted effectively with a solution of 50 mmol/LNa2CO3 and NaHCO3. The crude protein containing Bt toxin was obtained after the pretreatment of Cry1Ab transgenic rice with ultra-filtration, ammonium sulfate precipitation and centrifugation. The dialysed crude protein was futher separated on DEAE Sephadex A-50 columns and Sephadex G-150 columns. The protein bound on DEAE Sephadex A-50 gel was eluted with buffer solution B(10 mmol/L trisHCl buffer+1. 0 mmol/L EDTA, pH=8.0) mixed with 0. 1, 0. 3, 0. 5 and 0. 8 mol/L NaCl in a discontinuous gradient elution mode. The peak of the Bt toxin eluted from the columns was identified by ELISA and bioassayed with larvae of tobacco hornworms and silkworms. The purity and the bioactivity of the Bt toxin were determined by means of SDS-PAGE and larvicidal assay, respectively. The purity of the Bt toxin obtained by this method is high, and its insecticidal activity is retained after the toxin is purified.

  10. Discrimination of Transgenic Rice containing the Cry1Ab Protein using Terahertz Spectroscopy and Chemometrics

    Science.gov (United States)

    Xu, Wendao; Xie, Lijuan; Ye, Zunzhong; Gao, Weilu; Yao, Yang; Chen, Min; Qin, Jianyuan; Ying, Yibin

    2015-07-01

    Spectroscopic techniques combined with chemometrics methods have proven to be effective tools for the discrimination of objects with similar properties. In this work, terahertz time-domain spectroscopy (THz-TDS) combined with discriminate analysis (DA) and principal component analysis (PCA) with derivative pretreatments was performed to differentiate transgenic rice (Hua Hui 1, containing the Cry1Ab protein) from its parent (Ming Hui 63). Both rice samples and the Cry1Ab protein were ground and pressed into pellets for terahertz (THz) measurements. The resulting time-domain spectra were transformed into frequency-domain spectra, and then, the transmittances of the rice and Cry1Ab protein were calculated. By applying the first derivative of the THz spectra in conjunction with the DA model, the discrimination of transgenic from non-transgenic rice was possible with accuracies up to 89.4% and 85.0% for the calibration set and validation set, respectively. The results indicated that THz spectroscopic techniques and chemometrics methods could be new feasible ways to differentiate transgenic rice.

  11. BOOK REVIEW – BACILLUS THURINGIENSIS: A CORNERSTONE OF MODERN AGRICULTURE BACILLUS THURINGIENSIS

    Science.gov (United States)

    Are you interested in the technical issues surrounding the use of Bacillus thuringiensis pesticidal traits as sprays and as plant incorporated protectants (transgenic crops)? Should the dimensions of human health, ecology, entomology, risk assessment, resistance management, and d...

  12. Fluorescent Amplified Fragment Length Polymorphism Analysis of Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis Isolates

    OpenAIRE

    Hill, Karen K.; Ticknor, Lawrence O.; Okinaka, Richard T.; Asay, Michelle; Blair, Heather; Bliss, Katherine A.; Laker, Mariam; Pardington, Paige E.; Richardson, Amber P.; Tonks, Melinda; Beecher, Douglas J.; Kemp, John D.; Kolstø, Anne-Brit; Wong, Amy C. Lee; Keim, Paul

    2004-01-01

    DNA from over 300 Bacillus thuringiensis, Bacillus cereus, and Bacillus anthracis isolates was analyzed by fluorescent amplified fragment length polymorphism (AFLP). B. thuringiensis and B. cereus isolates were from diverse sources and locations, including soil, clinical isolates and food products causing diarrheal and emetic outbreaks, and type strains from the American Type Culture Collection, and over 200 B. thuringiensis isolates representing 36 serovars or subspecies were from the U.S. D...

  13. DNA degradation in genetically modified rice with Cry1Ab by food processing methods: implications for the quantification of genetically modified organisms.

    Science.gov (United States)

    Xing, Fuguo; Zhang, Wei; Selvaraj, Jonathan Nimal; Liu, Yang

    2015-05-01

    Food processing methods contribute to DNA degradation, thereby affecting genetically modified organism detection and quantification. This study evaluated the effect of food processing methods on the relative transgenic content of genetically modified rice with Cry1Ab. In steamed rice and rice noodles, the levels of Cry1Ab were ⩾ 100% and processing methods of sweet rice wine had the most severe degradation effects on Pubi and Cry1Ab. In steamed rice and rice noodles, Cry1Ab was the most stable, followed by SPS and Pubi. However, in rice crackers and sweet rice wine, SPS was the most stable, followed by Cry1Ab and Pubi. Therefore, Cry1Ab is a better representative of transgenic components than is Pubi because the levels of Cry1Ab were less affected compared to Pubi.

  14. Narrow terahertz attenuation signatures in Bacillus thuringiensis.

    Science.gov (United States)

    Zhang, Weidong; Brown, Elliott R; Viveros, Leamon; Burris, Kellie P; Stewart, C Neal

    2014-10-01

    Terahertz absorption signatures from culture-cultivated Bacillus thuringiensis were measured with a THz photomixing spectrometer operating from 400 to 1200 GHz. We observe two distinct signatures centered at ∼955 and 1015 GHz, and attribute them to the optically coupled particle vibrational resonance (surface phonon-polariton) of Bacillus spores. This demonstrates the potential of the THz attenuation signatures as "fingerprints" for label-free biomolecular detection. PMID:23821459

  15. Narrow terahertz attenuation signatures in Bacillus thuringiensis.

    Science.gov (United States)

    Zhang, Weidong; Brown, Elliott R; Viveros, Leamon; Burris, Kellie P; Stewart, C Neal

    2014-10-01

    Terahertz absorption signatures from culture-cultivated Bacillus thuringiensis were measured with a THz photomixing spectrometer operating from 400 to 1200 GHz. We observe two distinct signatures centered at ∼955 and 1015 GHz, and attribute them to the optically coupled particle vibrational resonance (surface phonon-polariton) of Bacillus spores. This demonstrates the potential of the THz attenuation signatures as "fingerprints" for label-free biomolecular detection.

  16. Genome Sequence of Bacillus thuringiensis subsp. kurstaki Strain HD-1

    OpenAIRE

    Day, Michael; Ibrahim, Mohamed; Dyer, David; Bulla, Lee

    2014-01-01

    We report here the complete genome sequence of Bacillus thuringiensis subsp. kurstaki strain HD-1, which serves as the primary U.S. reference standard for all commercial insecticidal formulations of B. thuringiensis manufactured around the world.

  17. The Complete Genome Sequence of Bacillus thuringiensis AlHakam

    Energy Technology Data Exchange (ETDEWEB)

    Challacombe, Jean F.; Altherr, Michael R.; Xie, Gary; Bhotika,Smriti S.; Brown, Nancy; Bruce, David; Campbell, Connie S.; Campbell,Mary L.; Chen, Jin; Chertkov, Olga; Cleland, Cathy; Dimitrijevic, Mira; Doggett, Norman A.; Fawcett, John J.; Glavina, Tijana; Goodwin, Lynne A.; Green, Lance D.; Han, Cliff S.; Hill, Karen K.; Hitchcock, Penny; Jackson, Paul J.; Keim, Paul; Kewalramani, Avinash Ramesh; Longmire, Jon; Lucas, Susan; Malfatti, Stephanie; Martinez, Diego; McMurry, Kim; Meincke, Linda J.; Misra, Monica; Moseman, Bernice L.; Mundt, Mark; Munk,A. Christine; Okinaka, Richard T.; Parson-Quintana, B.; Reilly, LeePhilip; Richardson, Paul; Robinson, Donna L.; Rubin, Eddy; Saunders,Elizabeth; Tapia, Roxanne; Tesmer, Judith G.; Thayer, Nina; Thompson,Linda S.; Tice, Hope; Ticknor, Lawrence O.; Wills, Patti L.; Gilna, Paul; Brettin, Thomas S.

    2007-04-01

    Bacillus thuringiensis is an insect pathogen that is widelyused as a biopesticide (3). Here we report the finished, annotated genomesequence of B. thuringiensis Al Hakam, which was collected in Iraq by theUnited Nations Special Commission (2).

  18. A pangenomic study of Bacillus thuringiensis

    Institute of Scientific and Technical Information of China (English)

    Yongjun Fang; Songnian Hu; Jie Zhang; Ibrahim A1-Mssallem; Jun Yu; Zhaolong Li; Jiucheng Liu; Changlong Shu; Xumin Wang; Xiaowei Zhang; Xiaoguang Yu; Duojun Zhao; Guiming Liu

    2011-01-01

    Bacillus thuringiensis (B.thuringiensis) is a soil-dwelling Gram-positive bacterium and its plasmid-encoded toxins (Cry) are commonly used as biological alternatives to pesticides.In a pangenomic study,we sequenced seven B.thuringiensis isolates in both high coverage and base quality using the next-generation sequencing platform.The B.thuringiensis pangenome was extrapolated to have 4196 core genes and an asymptotic value of 558 unique genes when a new genome is added.Compared to the pangenomes of its closely related species of the same genus,B.thuringiensis pangenome shows an open characteristic,similar to B.cereus but not to B.anthracis; the latter has a closed pangenome.We also found extensive divergence among the seven B.thuringiensis genome assemblies,which harbor ample repeats and single nucleotide polymorphisms (SNPs).The identities among orthologous genes are greater than 84.5% and the hotspots for the genome variations were discovered in genomic regions of 2.3-2.8 Mb and 5.0-5.6 Mb.We concluded that high-coverage sequence assemblies from multiple strains,before all the gaps are closed,are very useful for pangenomic studies.

  19. Aminopeptidase N isoforms from the midgut of Bombyx mori and Plutella xylostella -- their classification and the factors that determine their binding specificity to Bacillus thuringiensis Cry1A toxin.

    Science.gov (United States)

    Nakanishi, Kazuko; Yaoi, Katsuro; Nagino, Yasushi; Hara, Hirotaka; Kitami, Madoka; Atsumi, Shogo; Miura, Nami; Sato, Ryoichi

    2002-05-22

    Novel aminopeptidase N (APN) isoform cDNAs, BmAPN3 and PxAPN3, from the midguts of Bombyx mori and Plutella xylostella, respectively, were cloned, and a total of eight APN isoforms cloned from B. mori and P. xylostella were classified into four classes. Bacillus thuringiensis Cry1Aa and Cry1Ab toxins were found to bind to specific APN isoforms from the midguts of B. mori and P. xylostella, and binding occurred with fragments that corresponded to the BmAPN1 Cry1Aa toxin-binding region of each APN isoform. The results suggest that APN isoforms have a common toxin-binding region, and that the apparent specificity of Cry1Aa toxin binding to each intact APN isoform seen in SDS-PAGE is determined by factors such as expression level in conjunction with differences in binding affinity. PMID:12023048

  20. Genetic Basis of Cry1F-Resistance in a Laboratory Selected Asian Corn Borer Strain and Its Cross-Resistance to Other Bacillus thuringiensis Toxins.

    Science.gov (United States)

    Wang, Yueqin; Wang, Yidong; Wang, Zhenying; Bravo, Alejandra; Soberón, Mario; He, Kanglai

    2016-01-01

    The Asian corn borer (ACB), Ostrinia furnacalis (Guenée) (Lepidoptera: Crambidae), is the most destructive insect pest of corn in China. Susceptibility to the Cry1F toxin derived from Bacillus thuringiensis has been demonstrated for ACB, suggesting the potential for Cry1F inclusion as part of an insect pest management program. Insects can develop resistance to Cry toxins, which threatens the development and use of Bt formulations and Bt crops in the field. To determine possible resistance mechanisms to Cry1F, a Cry1F-resistant colony of ACB (ACB-FR) that exhibited more than 1700-fold resistance was established through selection experiments after 49 generations of selection under laboratory conditions. The ACB-FR strain showed moderate cross-resistance to Cry1Ab and Cry1Ac of 22.8- and 26.9-fold, respectively, marginally cross-resistance to Cry1Ah (3.7-fold), and no cross-resistance to Cry1Ie (0.6-fold). The bioassay responses of progeny from reciprocal F1 crosses to different Cry1 toxin concentrations indicated that the resistance trait to Cry1Ab, Cry1Ac and Cry1F has autosomal inheritance with no maternal effect or sex linked. The effective dominance (h) of F1 offspring was calculated at different concentrations of Cry1F, showing that h decreased as concentration of Cry1F increased. Finally, the analysis of actual and expected mortality of the progeny from a backcross (F1 × resistant strain) indicated that the inheritance of the resistance to Cry1F in ACB-FR was due to more than one locus. The present study provides an understanding of the genetic basis of Cry1F resistance in ACB-FR and also shows that pyramiding Cry1F with Cry1Ah or Cry1Ie could be used as a strategy to delay the development of ACB resistance to Bt proteins.

  1. Ostrinia nubilalis parasitism and the field abundance of non-target insects in transgenic Bacillus thuringiensis corn (Zea mays).

    Science.gov (United States)

    Bourguet, Denis; Chaufaux, Josette; Micoud, Annie; Delos, Marc; Naibo, Bernard; Bombarde, Fany; Marque, Gilles; Eychenne, Nathalie; Pagliari, Carine

    2002-10-01

    In this study, we evaluated in field trials the effects on non-target species, of transgenic corn producing the Cry1Ab toxin of Bacillus thuringiensis (Bt). In 1998, we collected Ostrinia nubilalis (Hübner) larvae from transgenic Bt corn (Novartis Hybrid 176) and non-Bt corn at four geographical sites. We found a significant variation in parasitism by the tachinids Lydella thompsoni (Herting) and Pseudoperichaeta nigrolineata (Walker) among sites, and more parasitism in non-Bt than in Bt fields. The Bt effect did not vary significantly among fields. In 1999, we performed a field experiment at two sites, comparing the temporal abundance of non-target arthropods in Bt corn (Monsanto Hybrid MON810) and non-Bt corn. The non-target insects studied included the aphids Metopolophium dirhodum (Walker), Rhopalosiphum padi (L.) and Sitobion avenae (F.), the bug Orius insidiosus (Say), the syrphid Syrphus corollae (Meigen), the ladybird Coccinella septempunctata (L.), the lacewing Chrysoperla carnea (Stephens), thrips and hymenopteran parasitoids. For all species but one, the number of individuals varied greatly over the season but did not differ between the types of corn. The only exception was thrips which, at one site, was significantly more abundant in Bt corn than in non-Bt corn. However this difference did not remain significant when we took the multiple tests into account. Implications for pest resistance management, population dynamics and risk assessment are discussed.

  2. Histopathological effects and determination of the putative receptor of Bacillus thuringiensis Cry1Da toxin in Spodoptera littoralis midgut.

    Science.gov (United States)

    BenFarhat-Touzri, Dalel; Saadaoui, Marwa; Abdelkefi-Mesrati, Lobna; Saadaoui, Imen; Azzouz, Hichem; Tounsi, Slim

    2013-02-01

    Bacillus thuringiensis subsp. aizawai strain HD133, known by its effectiveness against Spodoptera species, produces many insecticidal proteins including Cry1Ab, Cry1Ca and Cry1Da. In the present study, the insecticidal activity of Cry1Da against Spodoptera littoralis was investigated. It showed toxicity with an LC(50) of 224.4 ng/cm(2) with 95% confidence limits of (178.61-270.19) and an LC(90) of 467.77 ng/cm(2) with 95% confidence limits of (392.89-542.65). The midgut histopathology of Cry1Da fed larvae showed vesicle formation in the apical region, vacuolization and destruction of epithelial cells. Biotinylated-activated Cry1Da toxin bound protein of about 65 kDa on blots of S. littoralis brush border membrane preparations. This putative receptor differs in molecular size from those recognized by Cry1C and Vip3A which are active against this polyphagous insect. This difference in midgut receptors strongly supports the use of Cry1Da as insecticidal agent, particularly in case of Cry and/or Vip-resistance management. PMID:23220238

  3. Three toxins, two receptors, one mechanism: Mode of action of Cry1A toxins from Bacillus thuringiensis in Heliothis virescens.

    Science.gov (United States)

    Bretschneider, Anne; Heckel, David G; Pauchet, Yannick

    2016-09-01

    Insecticidal crystal (Cry) proteins from Bacillus thuringiensis (Bt) are highly active against Lepidoptera. However, field-evolved resistance to Bt toxins is on the rise. The 12-cadherin domain protein HevCaLP and the ABC transporter HevABCC2 are both genetically linked to Cry toxin resistance in Heliothis virescens. We investigated their interaction using stably expressing non-lytic clonal Sf9 cell lines expressing either protein or both together. Untransfected Sf9 cells are innately sensitive to Cry1Ca toxin, but not to Cry1A toxins; and quantitative PCR revealed negligible expression of genes involved in Cry1A toxicity such as cadherin, ABCC2, alkaline phosphatase (ALP) and aminopeptidase N (APN). Cry1Aa, Cry1Ab or Cry1Ac caused swelling of Sf9 cells expressing HevABCC2, and caused faster swelling, lysis and up to 86% mortality in cells expressing both proteins. No such effect was observed in control Sf9 cells or in cells expressing only HevCaLP. The results of a mixing experiment demonstrated that both proteins need to be expressed within the same cell for high cytotoxicity, and suggest a novel role for HevCaLP. Binding assays showed that the toxin-receptor interaction is specific. Our findings confirm that HevABCC2 is the central target in Cry1A toxin mode of action, and that HevCaLP plays a supporting role in increasing Cry1A toxicity.

  4. Three toxins, two receptors, one mechanism: Mode of action of Cry1A toxins from Bacillus thuringiensis in Heliothis virescens.

    Science.gov (United States)

    Bretschneider, Anne; Heckel, David G; Pauchet, Yannick

    2016-09-01

    Insecticidal crystal (Cry) proteins from Bacillus thuringiensis (Bt) are highly active against Lepidoptera. However, field-evolved resistance to Bt toxins is on the rise. The 12-cadherin domain protein HevCaLP and the ABC transporter HevABCC2 are both genetically linked to Cry toxin resistance in Heliothis virescens. We investigated their interaction using stably expressing non-lytic clonal Sf9 cell lines expressing either protein or both together. Untransfected Sf9 cells are innately sensitive to Cry1Ca toxin, but not to Cry1A toxins; and quantitative PCR revealed negligible expression of genes involved in Cry1A toxicity such as cadherin, ABCC2, alkaline phosphatase (ALP) and aminopeptidase N (APN). Cry1Aa, Cry1Ab or Cry1Ac caused swelling of Sf9 cells expressing HevABCC2, and caused faster swelling, lysis and up to 86% mortality in cells expressing both proteins. No such effect was observed in control Sf9 cells or in cells expressing only HevCaLP. The results of a mixing experiment demonstrated that both proteins need to be expressed within the same cell for high cytotoxicity, and suggest a novel role for HevCaLP. Binding assays showed that the toxin-receptor interaction is specific. Our findings confirm that HevABCC2 is the central target in Cry1A toxin mode of action, and that HevCaLP plays a supporting role in increasing Cry1A toxicity. PMID:27456115

  5. Binding specificity of Bacillus thuringiensis Cry1Aa for purified, native Bombyx mori aminopeptidase N and cadherin-like receptors

    Directory of Open Access Journals (Sweden)

    Jenkins Jeremy L

    2001-10-01

    Full Text Available Abstract Background To better understand the molecular interactions of Bt toxins with non-target insects, we have examined the real-time binding specificity and affinity of Cry1 toxins to native silkworm (Bombyx mori midgut receptors. Previous studies on B. mori receptors utilized brush border membrane vesicles or purifed receptors in blot-type assays. Results The Bombyx mori (silkworm aminopeptidase N (APN and cadherin-like receptors for Bacillus thuringiensis insecticidal Cry1Aa toxin were purified and their real-time binding affinities for Cry toxins were examined by surface plasmon resonance. Cry1Ab and Cry1Ac toxins did not bind to the immobilized native receptors, correlating with their low toxicities. Cry1Aa displayed moderate affinity for B. mori APN (75 nM, and unusually tight binding to the cadherin-like receptor (2.6 nM, which results from slow dissociation rates. The binding of a hybrid toxin (Aa/Aa/Ac was identical to Cry1Aa. Conclusions These results indicate domain II of Cry1Aa is essential for binding to native B. mori receptors and for toxicity. Moreover, the high-affinity binding of Cry1Aa to native cadherin-like receptor emphasizes the importance of this receptor class for Bt toxin research.

  6. Transgenic Bacillus thuringiensis (Bt) rice is safer to aquatic ecosystems than its non-transgenic counterpart.

    Science.gov (United States)

    Li, Guangsheng; Wang, Yongmo; Liu, Biao; Zhang, Guoan

    2014-01-01

    Rice lines genetically modified with the crystal toxin genes from Bacillus thuringiensis (Bt) have experienced rapid development, with biosafety certificates for two Bt rice lines issued in 2009. There has still been no commercial release of these lines yet due to public concerns about human health and environmental risks. Some studies confirmed that Bt rice was as safe as conventional rice to non-target organisms when pesticides were not applied, however, pesticides are still required in Bt rice to control non-lepidopteran pests. In this study, we assessed the environmental effects of two Bt rice lines expressing either the cry1Ab/1Ac or cry2A genes, respectively, by using zooplanktons as indicator species under normal field management practices using pesticides when required. In the whole rice growing season, non-Bt rice was sprayed 5 times while Bt rice was sprayed 2 times, which ensured both rice achieved a normal yield. Field investigations showed that rice type (Bt and non-Bt) significantly influenced zooplankton abundance and diversity, which were up to 95% and 80% lower in non-Bt rice fields than Bt rice fields. Laboratory rearing showed that water from non-Bt rice fields was significantly less suitable for the survival and reproduction of Daphnia magna and Paramecium caudatum in comparison with water from Bt rice fields. Higher pesticide residues were detected in the water from non-Bt than Bt rice fields, accounting for the bad performance of zooplankton in non-Bt field water. Our results demonstrate that Bt rice is safer to aquatic ecosystems than non-Bt rice, and its commercialization will be beneficial for biodiversity restoration in rice-based ecosystems.

  7. Transgenic Bacillus thuringiensis (Bt rice is safer to aquatic ecosystems than its non-transgenic counterpart.

    Directory of Open Access Journals (Sweden)

    Guangsheng Li

    Full Text Available Rice lines genetically modified with the crystal toxin genes from Bacillus thuringiensis (Bt have experienced rapid development, with biosafety certificates for two Bt rice lines issued in 2009. There has still been no commercial release of these lines yet due to public concerns about human health and environmental risks. Some studies confirmed that Bt rice was as safe as conventional rice to non-target organisms when pesticides were not applied, however, pesticides are still required in Bt rice to control non-lepidopteran pests. In this study, we assessed the environmental effects of two Bt rice lines expressing either the cry1Ab/1Ac or cry2A genes, respectively, by using zooplanktons as indicator species under normal field management practices using pesticides when required. In the whole rice growing season, non-Bt rice was sprayed 5 times while Bt rice was sprayed 2 times, which ensured both rice achieved a normal yield. Field investigations showed that rice type (Bt and non-Bt significantly influenced zooplankton abundance and diversity, which were up to 95% and 80% lower in non-Bt rice fields than Bt rice fields. Laboratory rearing showed that water from non-Bt rice fields was significantly less suitable for the survival and reproduction of Daphnia magna and Paramecium caudatum in comparison with water from Bt rice fields. Higher pesticide residues were detected in the water from non-Bt than Bt rice fields, accounting for the bad performance of zooplankton in non-Bt field water. Our results demonstrate that Bt rice is safer to aquatic ecosystems than non-Bt rice, and its commercialization will be beneficial for biodiversity restoration in rice-based ecosystems.

  8. Extent of Variation of the Bacillus thuringiensis Toxin Reservoir: the Case of the Geranium Bronze, Cacyreus marshalli Butler (Lepidoptera: Lycaenidae)

    Science.gov (United States)

    Herrero, Salvador; Borja, Marisé; Ferré, Juan

    2002-01-01

    Despite the fact that around 200 cry genes from Bacillus thuringiensis have already been cloned, only a few Cry proteins are toxic towards a given pest. A crucial step in the mode of action of Cry proteins is binding to specific sites in the midgut of susceptible insects. Binding studies in insects that have developed cross-resistance discourage the combined use of Cry proteins sharing the same binding site. If resistance management strategies are to be implemented, the arsenal of Cry proteins suitable to control a given pest may be not so vast as it might seem at first. The present study evaluates the potential of B. thuringiensis for the control of a new pest, the geranium bronze (Cacyreus marshalli Butler), a butterfly that is threatening the popularity of geraniums in Spain. Eleven of the most common Cry proteins from the three lepidopteran-active Cry families (Cry1, Cry2, and Cry9) were tested against the geranium bronze for their toxicity and binding site relationships. Using 125I-labeled Cry1A proteins we found that, of the seven most active Cry proteins, six competed for binding to the same site. For the long-term control of the geranium bronze with B. thuringiensis-based insecticides it would be advisable to combine any of the Cry proteins sharing the binding site (preferably Cry1Ab, since it is the most toxic) with those not competing for the same site. Cry1Ba would be the best choice of these proteins, since it is significantly more toxic than the others not binding to the common site. PMID:12147511

  9. Isolation of bacillus thuringiensis from different samples from Mansehra District

    International Nuclear Information System (INIS)

    The insecticidal activity of Bacillus thuringiensis has made it very interesting for the control of a variety of agricultural pests and human disease vectors. The present study is an attempt to explore the potential and diversity. of Bacillus thuringiensis. from the local environment for the control of cotton spotted bollworm (Earias sp.), a major pest of cotton. Two hundred and ninety eight samples of soil, grain dust, wild animal dung, birds dropping, decaying leaves and dead insects were collected from different ecological environments of Mansehra District yielding 438 Bacillus thuringiensis isolates that produce parasporal crystalline inclusions. In this study the soil samples were found to be the richest source for Bacillus thuringiensis. (author)

  10. Investigations of immunogenic, allergenic and adjuvant properties of Cry1Ab protein after intragastric exposure in a food allergy model in mice

    OpenAIRE

    Andreassen, Monica; Bøhn, Thomas; Wikmark, Odd-Gunnar; Bodin, Johanna; Traavik, Terje; Løvik, Martinus; Nygaard, Unni Cecilie

    2016-01-01

    Background In genetically modified (GM) crops there is a risk that the inserted genes may introduce new allergens and/or adjuvants into the food and feed chain. The MON810 maize, expressing the insecticidal Cry1Ab toxin, is grown in many countries worldwide. In animal models, intranasal and intraperitoneal immunisations with the purified Cry1Ab proteins have induced immune responses, and feeding trials with Cry1Ab-containing feed have revealed some altered immune responses. Previous investiga...

  11. Complete Genome Sequence of Bacillus thuringiensis Bacteriophage BMBtp2

    OpenAIRE

    Dong, Zhaoxia; Peng, Donghai; Wang, Yueying; Zhu, Lei; Ruan, Lifang; Sun, Ming

    2013-01-01

    Bacillus thuringiensis is an insect pathogen which has been widely used for biocontrol. During B. thuringiensis fermentation, lysogenic bacteriophages cause severe losses of yield. Here, we announce the complete genome sequence of a bacteriophage, BMBtp2, which is induced from B. thuringiensis strain YBT-1765, which may be helpful to clarify the mechanism involved in bacteriophage contamination.

  12. Characterization of the parasporal inclusion of Bacillus thuringiensis subsp. kyushuensis.

    OpenAIRE

    Held, G. A.; Kawanishi, C. Y.; Huang, Y. S.

    1990-01-01

    Electron microscopy of Bacillus thuringiensis subsp. kyushuensis revealed that the parasporal inclusions are composed of a homogeneous center surrounded by a thick, electron-dense coating. Antibodies directed against the 135- and 65-kilodalton B. thuringiensis subsp. israelensis peptides cross-reacted with the 70- and 26-kilodalton peptides, respectively, of B. thuringiensis subsp. kyushuensis.

  13. Structural relatedness between mosquitocidal endotoxins of Bacillus thuringiensis subsp. israelensis.

    OpenAIRE

    Garduno, F; Thorne, L.; Walfield, A M; Pollock, T J

    1988-01-01

    A mosquitocidal toxin gene, cloned from Bacillus thuringiensis subsp. israelensis, was introduced into mutant crystal-negative B. thuringiensis subsp. israelensis cells. Partial toxicity to mosquitos was restored. The 58-kilodalton cloned gene product is a minor protein component of B. thuringiensis subsp. israelensis crystals and is structurally related to a major, 135-kilodalton crystal toxin.

  14. Transgenic cry1Ab/vip3H+epsps Rice with Insect and Herbicide Resistance Acted No Adverse Impacts on the Population Growth of a Non-Target Herbivore, the White-Backed Planthopper, Under Laboratory and Field Conditions

    Institute of Scientific and Technical Information of China (English)

    LU Zeng-bin; HAN Nai-shun; TIAN Jun-ce; PENG Yu-fa; HU Cui; GUO Yu-yuan; SHEN Zhi-cheng; YE Gong-yin

    2014-01-01

    Numerous Bt rice lines expressing Cry protein derived from Bacillus thuringiensis Berliner (Bt) have been developed since 1989. However, the potential risks posed by Bt rice on non-target organisms still remain debate. The white-backed planthopper (WBPH), Sogatella furcifera (Horváth), is one of the most economically important insect pests of rice in Asian countries and also one of the main non-target herbivores of transgenic rice. In the current study, impacts of transgenic cry1Ab/vip3H+epsps rice (G6H1) with both insect and herbicide resistance on WBPH were evaluated to ascertain whether this transgenic rice line had potential risks for this sap-sucking pest under laboratory and ifeld conditions. The laboratory results showed that no signiifcant difference in egg developmental duration, nymphal survival rate and female fecundity was found for WBPH between G6H1 and its non-transgenic isoline (XS110). However, the development duration of nymphs was signiifcantly shorter and female longevity signiifcantly longer when WBPH fed on G6H1 by comparison with those on its control. To verify the results found in laboratory, a 3-yr ifeld trial was conducted to monitor WBPH population using both the vacuum-suction machine and beat plate methods. Although the seasonal density of WBPH nymphs and total density of nymphs and adults were not signiifcantly affected by transgenic rice regardless of the sampling methods, the seasonal density of WBPH adults in transgenic rice plots was slightly lower than that in the control when using the vacuum-suction machine. Based on these results both from laboratory and ifeld, it is clear that our tested transgenic rice line will not lead higher population of WBPH. However, long-term ifeld experiments to monitor the population dynamics of WPBH at large scale need to be conducted to conifrm the present conclusions in future.

  15. Worldwide Abundance and Distribution of Bacillus thuringiensis Isolates

    OpenAIRE

    Martin, Phyllis A. W.; Travers, Russell S.

    1989-01-01

    We found the insect control agent Bacillus thuringiensis to be a ubiquitous soil microorganism. Using acetate selection to screen soil samples, we isolated B. thuringiensis in 785 of 1,115 soil samples. These samples were obtained in the United States and 29 other countries. A total of 48% of the B. thuringiensis isolates (8,916 isolates) fit the biochemical description of known varieties, while 52% represented undescribed B. thuringiensis types. Over 60% (1,052 isolates) of the isolates test...

  16. Association of bioassays and molecular characterization to select new Bacillus thuringiensis isolates effective against Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

    International Nuclear Information System (INIS)

    The fall armyworm, Spodoptera frugiperda (J. E. Smith), is one of the main corn pests and Bacillus thuringiensis is important in its control because of its entomopathogenic property. The objective of this study was the molecular characterization of B. thuringiensis isolates for cry1 locus presence and the assessment of the efficiency of these isolates in controlling S. frugiperda caterpillars. Gral-cry1 was used in the PCR analyses to confirm the presence of the cry1 locus in 15 isolates. A 3 x 108 spore/ml suspension bathed the diet used to feed 30 caterpillars per isolate, with three replications. The cry1 locus type genes of the different isolates were identified for five gene subclasses; linear regression analyses were carried out to ascertain possible associations between the presence of an individual cry1 locus gene and high levels of toxicity. All the DNAs amplified with Gral-cry1 presented an amplification product with the expected size. Regarding the levels of insecticide efficiency against the cob worm, 41 isolates presented 100% mortality and 16 presented an index between 70% and 90%. The cry1Ab gene was present in 80 isolates, cryb in 69 isolates, cry1Ac in all the isolates and cryv and cry1E in 93 and 27 isolates, respectively. The values regarding the individual effect of each gene on caterpillar mortality were significant at 1% probability for the cry1Ac and cry1E genes. (author)

  17. Inactivation of Spores of Bacillus anthracis Sterne, Bacillus cereus, and Bacillus thuringiensis subsp. israelensis by Chlorination

    OpenAIRE

    Rice, E W; Adcock, N. J.; Sivaganesan, M; Rose, L. J.

    2005-01-01

    Three species of Bacillus were evaluated as potential surrogates for Bacillus anthracis for determining the sporicidal activity of chlorination as commonly used in drinking water treatment. Spores of Bacillus thuringiensis subsp. israelensis were found to be an appropriate surrogate for spores of B. anthracis for use in chlorine inactivation studies.

  18. A 52-week safety study in cynomolgus macaques for genetically modified rice expressing Cry1Ab/1Ac protein.

    Science.gov (United States)

    Mao, Jie; Sun, Xing; Cheng, Jian-Hua; Shi, Yong-Jie; Wang, Xin-Zheng; Qin, Jun-Jie; Sang, Zhi-Hong; He, Kun; Xia, Qing

    2016-09-01

    A 52-week feeding study in cynomolgus macaques was carried out to evaluate the safety of Bt rice Huahui 1 (HH1), a transgenic rice line expressing Cry1Ab/1Ac protein. Monkeys were fed a diet with 20% or 60% HH1 rice, 20% or 60% parental rice (Minghui 63, MH63), normal diet, normal diet spiked with purified recombinant Cry1Ab/1Ac fusion protein or bovine serum albumin (BSA) respectively. During the feeding trail, clinical observations were conducted daily, and multiple parameters, including body weight, body temperature, electrocardiogram, hematology, blood biochemistry, serum metabolome and gut microbiome were examined at regular intervals. Upon sacrifice, the organs were weighted, and the macroscopic, microscopic and electron microscopic examinations were performed. The results show no adverse or toxic effects of Bt rice HH1 or Cry1Ab/1Ac fusion protein on monkeys. Therefore, the present 52-week primate feeding study suggests that the transgenic rice containing Cry 1Ab/1Ac is equivalent to its parental rice line MH63.

  19. A 52-week safety study in cynomolgus macaques for genetically modified rice expressing Cry1Ab/1Ac protein.

    Science.gov (United States)

    Mao, Jie; Sun, Xing; Cheng, Jian-Hua; Shi, Yong-Jie; Wang, Xin-Zheng; Qin, Jun-Jie; Sang, Zhi-Hong; He, Kun; Xia, Qing

    2016-09-01

    A 52-week feeding study in cynomolgus macaques was carried out to evaluate the safety of Bt rice Huahui 1 (HH1), a transgenic rice line expressing Cry1Ab/1Ac protein. Monkeys were fed a diet with 20% or 60% HH1 rice, 20% or 60% parental rice (Minghui 63, MH63), normal diet, normal diet spiked with purified recombinant Cry1Ab/1Ac fusion protein or bovine serum albumin (BSA) respectively. During the feeding trail, clinical observations were conducted daily, and multiple parameters, including body weight, body temperature, electrocardiogram, hematology, blood biochemistry, serum metabolome and gut microbiome were examined at regular intervals. Upon sacrifice, the organs were weighted, and the macroscopic, microscopic and electron microscopic examinations were performed. The results show no adverse or toxic effects of Bt rice HH1 or Cry1Ab/1Ac fusion protein on monkeys. Therefore, the present 52-week primate feeding study suggests that the transgenic rice containing Cry 1Ab/1Ac is equivalent to its parental rice line MH63. PMID:27338709

  20. BACILLUS THURINGIENSIS ELASTASES WITH INSECTICIDE ACTIVITY

    Directory of Open Access Journals (Sweden)

    E. V. Matseliukh

    2015-10-01

    Full Text Available The purpose of the research was a screening of proteases with elastase activity among Bacillus thuringiensis strains, their isolation, partially purification, study of physicochemical properties and insecticide activity in relation to the larvae of the Colorado beetle. The objects of the investigation were 18 strains of B. thuringiensis, isolated from different sources: sea water, dry biological product "Bitoksibatsillin" and also from natural populations of Colorado beetles of the Crimea, Kherson, Odesa, Mykolaiv and Zaporizhiia regions of Ukraine. Purification of enzymes with elastase activity isolated from above mentioned strains was performed by gel-chromatography and insecticide activity was studied on the 3–4 larvae instar of Colorado beetle. The ability of a number of B. thuringiensis strains to synthesize the proteases with elastase activity has been established. The most active were enzymes obtained from strains IMV B-7465, IMV B-7324 isolated from sea water, and strains 9, 902, Bt-H and 0-239 isolated from Colorado beetles. The study of the physicochemical properties of the partially purified proteases of these strains showed that they belonged to enzymes of the serine type. Peptidases of a number of B. thuringiensis strains (IMV B-7324, IMV B-7465, 902, 0-239, 9 are metal-dependent enzymes. Optimal conditions of action of all tested enzymes are the neutral and alkaline рН values and the temperatures of 30–40 °С. The studies of influence of the complex enzyme preparations and partially purified ones of B. thuringiensis strains on the larvae instar of Colorado beetles indicated that enzymes with elastase activity could be responsible for insecticide action of the tested strains.

  1. Genome Differences That Distinguish Bacillus anthracis from Bacillus cereus and Bacillus thuringiensis

    OpenAIRE

    Radnedge, Lyndsay; Agron, Peter G.; Hill, Karen K.; Jackson, Paul J.; Ticknor, Lawrence O; Keim, Paul; Andersen, Gary L.

    2003-01-01

    The three species of the group 1 bacilli, Bacillus anthracis, B. cereus, and B. thuringiensis, are genetically very closely related. All inhabit soil habitats but exhibit different phenotypes. B. anthracis is the causative agent of anthrax and is phylogenetically monomorphic, while B. cereus and B. thuringiensis are genetically more diverse. An amplified fragment length polymorphism analysis described here demonstrates genetic diversity among a collection of non-anthrax-causing Bacillus speci...

  2. Degradation of Cry1Ab Protein Within Transgenic Bt Maize Tissue by Composite Microbial System of MC1

    Institute of Scientific and Technical Information of China (English)

    Meng Yao; Gu Wan-rong; Ye Le-fu; Chen Dong-sheng; Li Jing; Wei Shi

    2014-01-01

    Environmental safety issues involved in transgenic plants have become the concern of researchers, practitioners and policy makers in recent years. Potential differences between Bt maize (ND1324 and ND2353 expressing the insecticidal Cry1Ab protein) and near-isogenic non-Bt varieties (ND1392 and ND223) in their influence on the composite microbial system of MC1 during the fermentation process were studied during 2011-2012. Cry1Ab protein in Bt maize residues didn't affect characteristics of lignocellulose degradation by MC1, pH of fermentation broth decreasing at initial stage and increasing at later stage of degradation. The quality of various volatile products in fermentation broth showed that no significant difference of residues fermentation existed between Bt maize and non-Bt maize. During the fermentation MC1 efficiently degraded maize residues by 83%-88%, and cellulose, hemicelluloses and lignin content decreased by 70%-72%, 72%-75% and 30%-37%, respectively. Besides that, no consistent difference was found between Bt and non-Bt maize residues lignocellulose degradation by MC1 during the fermentation process. MC1 degraded 88%-89% Cry1Ab protein in Bt maize residues, and in the fermentation broth of MC1 and bacteria of MC1 Cry1Ab protein was not detected. DGGE profile analyses revealed that the microbial community drastically changed during 1-3 days and became stable until the 9th day. Though the dominant strains at different fermentation stages had significantly changed, no difference on the dominant strains was observed between Bt and non-Bt maize at different stages. Our study indicated that Cry1Ab protein did not influence the growth characteristic of MC1.

  3. Expressed sequence tags from larval gut of the European corn borer (Ostrinia nubilalis: Exploring candidate genes potentially involved in Bacillus thuringiensis toxicity and resistance

    Directory of Open Access Journals (Sweden)

    Crespo Andre LB

    2009-06-01

    Full Text Available Abstract Background Lepidoptera represents more than 160,000 insect species which include some of the most devastating pests of crops, forests, and stored products. However, the genomic information on lepidopteran insects is very limited. Only a few studies have focused on developing expressed sequence tag (EST libraries from the guts of lepidopteran larvae. Knowledge of the genes that are expressed in the insect gut are crucial for understanding basic physiology of food digestion, their interactions with Bacillus thuringiensis (Bt toxins, and for discovering new targets for novel toxins for use in pest management. This study analyzed the ESTs generated from the larval gut of the European corn borer (ECB, Ostrinia nubilalis, one of the most destructive pests of corn in North America and the western world. Our goals were to establish an ECB larval gut-specific EST database as a genomic resource for future research and to explore candidate genes potentially involved in insect-Bt interactions and Bt resistance in ECB. Results We constructed two cDNA libraries from the guts of the fifth-instar larvae of ECB and sequenced a total of 15,000 ESTs from these libraries. A total of 12,519 ESTs (83.4% appeared to be high quality with an average length of 656 bp. These ESTs represented 2,895 unique sequences, including 1,738 singletons and 1,157 contigs. Among the unique sequences, 62.7% encoded putative proteins that shared significant sequence similarities (E-value ≤ 10-3with the sequences available in GenBank. Our EST analysis revealed 52 candidate genes that potentially have roles in Bt toxicity and resistance. These genes encode 18 trypsin-like proteases, 18 chymotrypsin-like proteases, 13 aminopeptidases, 2 alkaline phosphatases and 1 cadherin-like protein. Comparisons of expression profiles of 41 selected candidate genes between Cry1Ab-susceptible and resistant strains of ECB by RT-PCR showed apparently decreased expressions in 2 trypsin-like and 2

  4. Association of bioassays and molecular characterization to select new Bacillus thuringiensis isolates effective against Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae); Associacao de bioensaios e caracterizacao molecular para selecao de novos isolados de Bacillus thuringiensis efetivos contra Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

    Energy Technology Data Exchange (ETDEWEB)

    Fatoretto, Julio C.; Sena, Janete A.D.; Lemos, Manoel V.F. [UNESP, Jaboticabal, SP (Brazil). Faculdade de Ciencias Agrarias e Veterinarias. Dept. de Biologia Aplicada a Agropecuaria; Barreto, Marliton R. [Universidade Federal do Mato Grosso (UFMT), Cuiaba, MT (Brazil). Inst. Universitario do Norte Matogrossense (IUNMAT)]. E-mail: mrbarreto@pop.com.br; Junior Boica, Arlindo L. (UNESP), Jaboticabal, SP (Brazil). Faculdade de Ciencias Agrarias e Veterinarias. Dept. de Fitossanidade)

    2007-09-15

    The fall armyworm, Spodoptera frugiperda (J. E. Smith), is one of the main corn pests and Bacillus thuringiensis is important in its control because of its entomopathogenic property. The objective of this study was the molecular characterization of B. thuringiensis isolates for cry1 locus presence and the assessment of the efficiency of these isolates in controlling S. frugiperda caterpillars. Gral-cry1 was used in the PCR analyses to confirm the presence of the cry1 locus in 15 isolates. A 3 x 108 spore/ml suspension bathed the diet used to feed 30 caterpillars per isolate, with three replications. The cry1 locus type genes of the different isolates were identified for five gene subclasses; linear regression analyses were carried out to ascertain possible associations between the presence of an individual cry1 locus gene and high levels of toxicity. All the DNAs amplified with Gral-cry1 presented an amplification product with the expected size. Regarding the levels of insecticide efficiency against the cob worm, 41 isolates presented 100% mortality and 16 presented an index between 70% and 90%. The cry1Ab gene was present in 80 isolates, cryb in 69 isolates, cry1Ac in all the isolates and cryv and cry1E in 93 and 27 isolates, respectively. The values regarding the individual effect of each gene on caterpillar mortality were significant at 1% probability for the cry1Ac and cry1E genes. (author)

  5. The Phylloplane as a Source of Bacillus thuringiensis Variants

    OpenAIRE

    Smith, Robert A.; Couche, Graham A.

    1991-01-01

    Novel variants of Bacillus thuringiensis were isolated from the phylloplane of deciduous and conifer trees as well as of other plants. These isolates displayed a range of toxicity towards Trichoplusia ni. Immunoblot and toxin protein analysis indicate that these strains included representatives of the three principal B. thuringiensis pathotypes active against larvae of the orders Lepidoptera, Diptera, and Coleoptera. We propose that B. thuringiensis be considered part of the common leaf micro...

  6. Determinación de la presencia de genes cry en cepas nativas de Bacillus thuringiensis

    Directory of Open Access Journals (Sweden)

    Chaparro Giraldo Luis Alejandro

    2004-12-01

    Full Text Available A partir de dos tipos de muestras, suelo asociado a cultivos de papa (Solanum tuberosum y polvo asociado a sitios de almacenamiento de granos (cereales colectado en las centrales de Corabastos y Paloquemao en Bogotá, se aislaron 88 cepas nativas de Bacillus thuringiensis bacilo
    grampositivo patógeno de insectos plaga de cultivos agrícolas. De las 88 cepas obtenidas 57 de ellas se escogieron para separarlas posteriormente mediante subcultivos en virtud a sus características fenotípicas al interior de la colonia llevando esto a obtener un número de 145 cepas nuevas para un total de 176 cepas de B. thuringiensis caracterizadas  morfológicamente y por su patrón de formas de las ICPs mediante microscopía de contraste de fases, y de las proteínas Cry arrojado por los perfiles de SDS-PAGE; en el total de cepas hubo presencia predominante de ICPs con forma romboide acompañadas por al menos otras dos formas distintas, y mostraron perfiles electroforéticos de proteínas de peso molecular entre el rango de 130, 116 y 60 kDa. Del total de cepas B. thuringiensis nativas aisladas en este estudio, 59 (30 de suelos y 29 de polvo fueron analizadas mediante la técnica PCR, encontrando que 100% de ellas son portadoras de alguno de los seis tipos de genes cry1 estudiados cry1Aa5 (71,2%, cry1Ab9 (66,1%, cry1Ac5 (45,8%, cry1Ba1 (39%, cry1Ca3 (49,1%, y cry1Da1 (71,2%; adicionalmente se observó la presencia de productos génicos inespecíficos, posiblemente nuevos, amplificados por la PCR y relacionados con los genes cry1C (55,9%, cry1B (30,5% y otros genes cry1 no estudiados por este método en al menos el 50% de las cepas estudiadas. De acuerdo con estos resultados se estableció un total de 19 genotipos diferentes según los genes cry1 estudiados, presentados por las cepas nativas en estudio determinando que estos son diferentes en composición genética según la fuente de procedencia del aislamiento, permitiendo establecer estrecha correlaci

  7. BOOK REVIEW: BACILLUS THURINGIENSIS: A CORNERSTONE OF MODERN AGRICULTURE

    Science.gov (United States)

    Are you interested in the technical issues surrounding the use of Bacillus thuringiensis pesticidal traits as sprays and as plant incorporated protectants (transgenic crops)? Should the dimensions of human health, ecology, entomology, risk assessment, resistance management, and d...

  8. Ecological aspects of Bacillus thuringiensis in an Oxisol Ecologia do Bacillus thuringiensis num Latossolo

    Directory of Open Access Journals (Sweden)

    Lessandra Heck Paes Leme Ferreira

    2003-02-01

    Full Text Available Bacillus thuringiensis is a Gram positive, sporangial bacterium, known for its insecticidal habilities. Survival and conjugation ability of B. thuringiensis strains were investigated; vegetative cells were evaluated in non-sterile soil. Vegetative cells decreased rapidly in number, and after 48 hours the population was predominantly spores. No plasmid transfer was observed in non-sterile soil, probably because the cells died and the remaining cells sporulated quickly. Soil is not a favorable environment for B. thuringiensis multiplication and conjugation. The fate of purified B. thuringiensis toxin was analyzed by extractable toxin quantification using ELISA. The extractable toxin probably declined due to binding on surface-active particles in the soil.O comportamento de células vegetativas do Bacillus thuringiensis foi estudado em solo não esterilizado. Após o inóculo grande parte das células morrem e o restante esporula em 24 horas. Não foi observada conjugação provavelmente porque poucas células sobrevivem no solo e rapidamente esporulam, mostrando que este não é o ambiente propício para a multiplicação e conjugação desta bactéria. A toxina purificada, portanto livre de células, diminui rapidamente sua quantidade em solo não esterilizado. Provavelmente a ligação da toxina na fração argilosa do solo é a principal responsável por este fenômeno.

  9. Bacillus thuringiensis in Fecal Samples from Greenhouse Workers after Exposure to B. thuringiensis-Based Pesticides

    OpenAIRE

    Jensen, Gert B.; Larsen, Preben; Jacobsen, Bodil L.; Madsen, Bodil; Smidt, Lasse; Andrup, Lars

    2002-01-01

    In a study of occupational exposure to Bacillus thuringiensis, 20 exposed greenhouse workers were examined for Bacillus cereus-like bacteria in fecal samples and on biomonitoring filters. Bacteria with the following characteristics were isolated from eight individuals: intracellular crystalline inclusions characteristic of B. thuringiensis, genes for and production of B. cereus enterotoxins, and positivity for cry11 as determined by PCR. DNA fingerprints of the fecal isolates were identical t...

  10. Bacillus thuringiensis Conjugation in Simulated Microgravity

    Science.gov (United States)

    Beuls, Elise; van Houdt, Rob; Leys, Natalie; Dijkstra, Camelia; Larkin, Oliver; Mahillon, Jacques

    2009-10-01

    Spaceflight experiments have suggested a possible effect of microgravity on the plasmid transfer among strains of the Gram-positive Bacillus thuringiensis, as opposed to no effect recorded for Gram-negative conjugation. To investigate these potential effects in a more affordable experimental setup, three ground-based microgravity simulators were tested: the Rotating Wall Vessel (RWV), the Random Positioning Machine (RPM), and a superconducting magnet. The bacterial conjugative system consisted in biparental matings between two B. thuringiensis strains, where the transfer frequencies of the conjugative plasmid pAW63 and its ability to mobilize the nonconjugative plasmid pUB110 were assessed. Specifically, potential plasmid transfers in a 0-g position (simulated microgravity) were compared to those obtained under 1-g (normal gravity) condition in each device. Statistical analyses revealed no significant difference in the conjugative and mobilizable transfer frequencies between the three different simulated microgravitational conditions and our standard laboratory condition. These important ground-based observations emphasize the fact that, though no stimulation of plasmid transfer was observed, no inhibition was observed either. In the case of Gram-positive bacteria, this ability to exchange plasmids in weightlessness, as occurs under Earth's conditions, should be seen as particularly relevant in the scope of spread of antibiotic resistances and bacterial virulence.

  11. A high-throughput, in-vitro assay for Bacillus thuringiensis insecticidal proteins.

    Science.gov (United States)

    Izumi Willcoxon, Michi; Dennis, Jaclyn R; Lau, Sabina I; Xie, Weiping; You, You; Leng, Song; Fong, Ryan C; Yamamoto, Takashi

    2016-01-10

    A high-throughput, in-vitro assay for Bacillus thuringiensis (Bt) insecticidal proteins designated as Cry was developed and evaluated for screening a large number of Cry protein variants produced by DNA shuffling. This automation-amenable assay exploits an insect cell line expressing a single receptor of Bt Cry proteins. The Cry toxin used to develop this assay is a variant of the Cry1Ab protein called IP1-88, which was produced previously by DNA shuffling. Cell mortality caused by the activated Bt Cry toxin was determined by chemical cell viability assay in 96/384-well microtiter plates utilizing CellTiter 96(®) obtained from Promega. A widely-accepted mode-of-action theory of certain Bt Cry proteins suggests that the activated toxin binds to one or more receptors and forms a pore through the insect gut epithelial cell apical membrane. A number of insect proteins such as cadherin-like protein (Cad), aminopeptidase-N (APN), alkaline phosphatase (ALP) and ABC transporter (ABCC) have been identified as the receptors of Bt Cry toxins. In this study, Bt Cry toxin receptors Ostrinia nubilalis (European corn borer) cadherin-like protein (On-Cad) and aminopeptidase-N 1 and 3 (On-APN1, On-APN3) and Spodoptera frugiperda (fall armyworm) cadherin-like protein (Sf-Cad) were cloned in an insect cell line, Sf21, and a mammalian cell line, Expi293F. It was observed by ligand blotting and immunofluorescence microscopy that trypsin-activated IP1-88 bound to On-Cad and On-APN1, but not Sf-Cad or On-APN3. In contrast, IP1-88 bound only to APN1 in BBMV (Brush Border Membrane Vesicles) prepared from the third and fourth-instar O. nubilalis larval midgut. The sensitivity of the recombinant cells to the toxin was then tested. IP1-88 showed no toxicity to non-recombinant Sf21 and Expi293F. Toxicity was observed only when the On-Cad gene was cloned and expressed. Sf-Cad and On-APN1 were not able to make those cells sensitive to the toxin. Since the expression of On-Cad alone was

  12. Bacillus thuringiensis: legado para el siglo XXI Bacillus thuringiensis: the legacy to the XXI century

    Directory of Open Access Journals (Sweden)

    Orduz S.

    1998-06-01

    Full Text Available

    Los insecticidas basados en la bacteria Bacillus thuringiensis son el principal renglón productivo del mercado mundial de biopesticidas. La investigación dedicada a esta área, promovida por la urgente necesidad de resolver problemas agrícolas y de salud pública, ha dado lugar a un conocimiento exhaustivo de su biología. La diversidad de cepas diferentes de B. thuringiensis ha permitido desarrollar productos principalmente, pero no exclusivamente, para el control de insectos. Con los nuevos desarrollos de la biología molecular, se ha logrado comprender su mecanismo de acción a nivel molecular y también se ha logrado extender sus capacidades entomopatógenas. Como producto de su amplio uso en muchos países, se han presentado casos de resistencia en poblaciones de insectos susceptibles. Con esta revisión se pretende elaborar un contexto teórico del estado actual de la investigación sobre B. thuringiensis, describiendo brevemente el conocimiento sobre esta bacteria, haciendo hincapié en los fenómenos biológicos que subyacen su actividad tóxica y la problemática que se avecina en el próximo siglo con los fenómenos de resistencia cada vez más comunes, todo esto analizado desde una perspectiva biotecnológica.

    Bacillus thuringiensis-based insecticides are the main production line of the biopesticides world market. The research devoted to this area, promoted by the necessity to solve problems in agriculture and public health has resulted in an exhaustive knowledge of its biology. The diversity of the B. thuringiensis strains has permitted to develop several products mainly, but not exclusively, for insect control. With the new developments in the field of molecular biology, it has been possible to understand the molecular basis of the mode of action and to increase the range of activity as well. As a result

  13. Complete Genome Sequence of Bacillus thuringiensis Bacteriophage Smudge.

    Science.gov (United States)

    Cornell, Jessica L; Breslin, Eileen; Schuhmacher, Zachary; Himelright, Madison; Berluti, Cassandra; Boyd, Charles; Carson, Rachel; Del Gallo, Elle; Giessler, Caris; Gilliam, Benjamin; Heatherly, Catherine; Nevin, Julius; Nguyen, Bryan; Nguyen, Justin; Parada, Jocelyn; Sutterfield, Blake; Tukruni, Muruj; Temple, Louise

    2016-01-01

    Smudge, a bacteriophage enriched from soil using Bacillus thuringiensis DSM-350 as the host, had its complete genome sequenced. Smudge is a myovirus with a genome consisting of 292 genes and was identified as belonging to the C1 cluster of Bacillus phages. PMID:27540049

  14. Complete Genome of Bacillus thuringiensis Myophage BigBertha

    OpenAIRE

    Ting, Jose H.; Smyth, Trinity B.; Chamakura, Karthik R.; Kuty Everett, Gabriel F.

    2013-01-01

    BigBertha is a myophage of Bacillus thuringiensis, a widely used biocontrol agent that is active against many insect pests of plants. Here, we present the complete annotated genome of BigBertha. The genome shares 85.9% sequence identity with Bacillus cereus phage B4.

  15. Complete Genome Sequence of Bacillus thuringiensis Bacteriophage Smudge

    Science.gov (United States)

    Cornell, Jessica L.; Breslin, Eileen; Schuhmacher, Zachary; Himelright, Madison; Berluti, Cassandra; Boyd, Charles; Carson, Rachel; Del Gallo, Elle; Giessler, Caris; Gilliam, Benjamin; Heatherly, Catherine; Nevin, Julius; Nguyen, Bryan; Nguyen, Justin; Parada, Jocelyn; Sutterfield, Blake; Tukruni, Muruj

    2016-01-01

    Smudge, a bacteriophage enriched from soil using Bacillus thuringiensis DSM-350 as the host, had its complete genome sequenced. Smudge is a myovirus with a genome consisting of 292 genes and was identified as belonging to the C1 cluster of Bacillus phages. PMID:27540049

  16. Complete Genome Sequence of Bacillus thuringiensis Bacteriophage Smudge.

    Science.gov (United States)

    Cornell, Jessica L; Breslin, Eileen; Schuhmacher, Zachary; Himelright, Madison; Berluti, Cassandra; Boyd, Charles; Carson, Rachel; Del Gallo, Elle; Giessler, Caris; Gilliam, Benjamin; Heatherly, Catherine; Nevin, Julius; Nguyen, Bryan; Nguyen, Justin; Parada, Jocelyn; Sutterfield, Blake; Tukruni, Muruj; Temple, Louise

    2016-08-18

    Smudge, a bacteriophage enriched from soil using Bacillus thuringiensis DSM-350 as the host, had its complete genome sequenced. Smudge is a myovirus with a genome consisting of 292 genes and was identified as belonging to the C1 cluster of Bacillus phages.

  17. UJI TOKSISITAS ISOLAT Bacillus thuringiensis dari Kabupaten Lahat, Palembang, Sumatera Selatan TERHADAP LARVA NYAMUK Culex sp.

    OpenAIRE

    Chandra, Welianto

    2016-01-01

    This study aims to determine the optimal concentration of isolates of Bacillus thuringiensis to control larvae of the mosquito Culex sp. The method used is the isolation of the bacterium Bacillus thuringiensis, then the inoculation of bacteria. Bacillus thuringiensis mud samples, as much as 25 grams, obtained in the area of Lahat, South Sumatra containing Bacillus thuringiensis which includes five districts, namely Sub Gumay Talang, Jaray, Kikim West, South Kikim, and Central Kikim. Gumay ...

  18. Genetic Basis of Cry1F-Resistance in a Laboratory Selected Asian Corn Borer Strain and Its Cross-Resistance to Other Bacillus thuringiensis Toxins

    Science.gov (United States)

    Wang, Yueqin; Wang, Yidong; Wang, Zhenying; Bravo, Alejandra; Soberón, Mario; He, Kanglai

    2016-01-01

    The Asian corn borer (ACB), Ostrinia furnacalis (Guenée) (Lepidoptera: Crambidae), is the most destructive insect pest of corn in China. Susceptibility to the Cry1F toxin derived from Bacillus thuringiensis has been demonstrated for ACB, suggesting the potential for Cry1F inclusion as part of an insect pest management program. Insects can develop resistance to Cry toxins, which threatens the development and use of Bt formulations and Bt crops in the field. To determine possible resistance mechanisms to Cry1F, a Cry1F-resistant colony of ACB (ACB-FR) that exhibited more than 1700-fold resistance was established through selection experiments after 49 generations of selection under laboratory conditions. The ACB-FR strain showed moderate cross-resistance to Cry1Ab and Cry1Ac of 22.8- and 26.9-fold, respectively, marginally cross-resistance to Cry1Ah (3.7-fold), and no cross-resistance to Cry1Ie (0.6-fold). The bioassay responses of progeny from reciprocal F1 crosses to different Cry1 toxin concentrations indicated that the resistance trait to Cry1Ab, Cry1Ac and Cry1F has autosomal inheritance with no maternal effect or sex linked. The effective dominance (h) of F1 offspring was calculated at different concentrations of Cry1F, showing that h decreased as concentration of Cry1F increased. Finally, the analysis of actual and expected mortality of the progeny from a backcross (F1 × resistant strain) indicated that the inheritance of the resistance to Cry1F in ACB-FR was due to more than one locus. The present study provides an understanding of the genetic basis of Cry1F resistance in ACB-FR and also shows that pyramiding Cry1F with Cry1Ah or Cry1Ie could be used as a strategy to delay the development of ACB resistance to Bt proteins. PMID:27518813

  19. Genetic Basis of Cry1F-Resistance in a Laboratory Selected Asian Corn Borer Strain and Its Cross-Resistance to Other Bacillus thuringiensis Toxins.

    Science.gov (United States)

    Wang, Yueqin; Wang, Yidong; Wang, Zhenying; Bravo, Alejandra; Soberón, Mario; He, Kanglai

    2016-01-01

    The Asian corn borer (ACB), Ostrinia furnacalis (Guenée) (Lepidoptera: Crambidae), is the most destructive insect pest of corn in China. Susceptibility to the Cry1F toxin derived from Bacillus thuringiensis has been demonstrated for ACB, suggesting the potential for Cry1F inclusion as part of an insect pest management program. Insects can develop resistance to Cry toxins, which threatens the development and use of Bt formulations and Bt crops in the field. To determine possible resistance mechanisms to Cry1F, a Cry1F-resistant colony of ACB (ACB-FR) that exhibited more than 1700-fold resistance was established through selection experiments after 49 generations of selection under laboratory conditions. The ACB-FR strain showed moderate cross-resistance to Cry1Ab and Cry1Ac of 22.8- and 26.9-fold, respectively, marginally cross-resistance to Cry1Ah (3.7-fold), and no cross-resistance to Cry1Ie (0.6-fold). The bioassay responses of progeny from reciprocal F1 crosses to different Cry1 toxin concentrations indicated that the resistance trait to Cry1Ab, Cry1Ac and Cry1F has autosomal inheritance with no maternal effect or sex linked. The effective dominance (h) of F1 offspring was calculated at different concentrations of Cry1F, showing that h decreased as concentration of Cry1F increased. Finally, the analysis of actual and expected mortality of the progeny from a backcross (F1 × resistant strain) indicated that the inheritance of the resistance to Cry1F in ACB-FR was due to more than one locus. The present study provides an understanding of the genetic basis of Cry1F resistance in ACB-FR and also shows that pyramiding Cry1F with Cry1Ah or Cry1Ie could be used as a strategy to delay the development of ACB resistance to Bt proteins. PMID:27518813

  20. Mechanism of Insect Resistance to the Microbial Insecticide Bacillus thuringiensis

    Science.gov (United States)

    van Rie, J.; McGaughey, W. H.; Johnson, D. E.; Barnett, B. D.; van Mellaert, H.

    1990-01-01

    Receptor binding studies show that resistance of a laboratory-selected Plodia interpunctella strain to a Bacillus thuringiensis insecticidal crystal protein (ICP) is correlated with a 50-fold reduction in affinity of the membrane receptor for this protein. The strain is sensitive to a second type of ICP that apparently recognizes a different receptor. Understanding the mechanism of resistance will provide strategies to prevent or delay resistance and hence prolong the usefulness of B. thuringiensis ICPs as environmentally safe insecticides.

  1. Ultra-violet-resistant mutants of Bacillus thuringiensis

    International Nuclear Information System (INIS)

    One of the main disadvantages of using Bacillus thuringiensis as an insecticide is that the spore and crystal preparations applied to foliage are readily washed away by rain and are inactivated by sunlight. Spores from some strains of B. thuringiensis have been shown to be highly sensitive to u.v. light. This study has demonstrated how mutants with increased resistance to u.v., isolated by successive rounds of u.v. irradiation, and additionally with increased specific pathogenicity can be isolated. These techniques should be applied to strains that are frequently used in the industrial production of B.thuringiensis toxin. (author)

  2. Ultra-violet-resistant mutants of Bacillus thuringiensis

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D.R.; Karunakaran, V. (Polytechnic of Central London (UK). Faculty of Engineering and Science, School of Biological and Health Sciences); Burges, H.D. (Institute of Horticultural Research, Littlehampton (UK)); Hacking, A.J. (Reading Univ. (UK). Dextra Labs.Ltd.)

    1991-06-01

    One of the main disadvantages of using Bacillus thuringiensis as an insecticide is that the spore and crystal preparations applied to foliage are readily washed away by rain and are inactivated by sunlight. Spores from some strains of B. thuringiensis have been shown to be highly sensitive to u.v. light. This study has demonstrated how mutants with increased resistance to u.v., isolated by successive rounds of u.v. irradiation, and additionally with increased specific pathogenicity can be isolated. These techniques should be applied to strains that are frequently used in the industrial production of B.thuringiensis toxin. (author).

  3. Specificities of monoclonal antibodies against the activated delta-endotoxin of Bacillus thuringiensis var. thuringiensis.

    OpenAIRE

    Huber-Lukac, M; Lüthy, P; Braun, D G

    1983-01-01

    Eight hybrid cell lines secreting monoclonal antibodies directed against the activated delta-endotoxin of Bacillus thuringiensis var. thuringiensis were grown in BALB/c mice. Ascites fluids were collected, and the antibodies were purified by antigen-affinity chromatography. The specificity of each monoclonal antibody for the toxin and protoxin was established by the indirect enzyme-linked immunosorbent assay. All the antibodies consisted of gamma 1 heavy and kappa light chains. They were reac...

  4. Plasmid-associated sensitivity of Bacillus thuringiensis to UV light

    International Nuclear Information System (INIS)

    Spores and vegetative cells of Bacillus thuringiensis were more sensitive to UV light than were spores or cells of plasmid-cured B. thuringiensis strains or of the closely related Bacillus cereus. Introduction of B. thuringiensis plasmids into B. cereus by cell mating increased the UV sensitivity of the cells and spores. Protoxins encoded by one or more B. thuringiensis plasmids were not involved in spore sensitivity, since a B. thuringiensis strain conditional for protoxin accumulation was equally sensitive at the permissive and nonpermissive temperatures. In addition, introduction of either a cloned protoxin gene, the cloning vector, or another plasmid not containing a protoxin gene into a plasmid-cured strain of B. thuringiensis all increased the UV sensitivity of the spores. Although the variety of small, acid-soluble proteins was the same in the spores of all strains examined, the quantity of dipicolinic acid was about twice as high in the plasmid-containing strains, and this may account for the differences in UV sensitivity of the spores. The cells of some strains harboring only B. thuringiensis plasmids were much more sensitive than cells of any of the other strains, and the differences were much greater than observed with spores

  5. Plasmid-associated sensitivity of Bacillus thuringiensis to UV light

    Energy Technology Data Exchange (ETDEWEB)

    Benoit, T.G.; Wilson, G.R.; Bull, D.L.; Aronson, A.I. (Department of Agriculture, College Station, TX (USA))

    1990-08-01

    Spores and vegetative cells of Bacillus thuringiensis were more sensitive to UV light than were spores or cells of plasmid-cured B. thuringiensis strains or of the closely related Bacillus cereus. Introduction of B. thuringiensis plasmids into B. cereus by cell mating increased the UV sensitivity of the cells and spores. Protoxins encoded by one or more B. thuringiensis plasmids were not involved in spore sensitivity, since a B. thuringiensis strain conditional for protoxin accumulation was equally sensitive at the permissive and nonpermissive temperatures. In addition, introduction of either a cloned protoxin gene, the cloning vector, or another plasmid not containing a protoxin gene into a plasmid-cured strain of B. thuringiensis all increased the UV sensitivity of the spores. Although the variety of small, acid-soluble proteins was the same in the spores of all strains examined, the quantity of dipicolinic acid was about twice as high in the plasmid-containing strains, and this may account for the differences in UV sensitivity of the spores. The cells of some strains harboring only B. thuringiensis plasmids were much more sensitive than cells of any of the other strains, and the differences were much greater than observed with spores.

  6. Microarray detection and qPCR screening of potential biomarkers of Folsomia candida (Collembola: Isotomidae) exposed to Bt proteins (Cry1Ab and Cry1Ac)

    International Nuclear Information System (INIS)

    The impact of Bt proteins on non-target arthropods is less understood than their effects on target organisms where the mechanism of toxic action is known. Here, we report the effects of two Bt proteins, Cry1Ab and Cry1Ac, on gene expression in the non-target collembolan, Folsomia candida. A customized microarray was used to study gene expression in F. candida specimens that were exposed to Cry1Ab and Cry1Ac. All selected transcripts were subsequently confirmed by qPCR. Eleven transcripts were finally verified, and three of them were annotated. The responses of all eleven transcripts were tested in specimens for both Cry1Ab and Cry1Ac at a series of concentrations. These transcripts were separated into two and three groups for Cry1Ab and Cry1Ac, respectively, depend on their expression levels. However, those eleven transcripts did not respond to the Bt proteins in Bt-rice residues. -- Highlights: • We examined the effects of Bt proteins on gene expression of Folsomia candida. • Eleven transcripts were up-regulated by Bt proteins (Cry1Ab and Cry1Ac). • Only three of the eleven transcripts were annotated. • The responses of 11 transcripts were tested on both Cry1Ab and Cry1Ac. • These transcripts did not respond to the Bt proteins in Bt-rice residues. -- Eleven potential molecular biomarkers of Folsomia candida to Cry1Ab and Cry1Ac were screened by microarray and qPCR analysis

  7. Inheritance Patterns, Dominance and Cross-Resistance of Cry1Ab- and Cry1Ac-Selected Ostrinia furnacalis (Guenée

    Directory of Open Access Journals (Sweden)

    Tiantao Zhang

    2014-09-01

    Full Text Available Two colonies of Asian corn borer, Ostrinia furnacalis (Guenée, artificially selected from a Bt-susceptible colony (ACB-BtS for resistance to Cry1Ab (ACB-AbR and Cry1Ac (ACB-AcR toxins, were used to analyze inheritance patterns of resistance to Cry1 toxins. ACB-AbR and ACB-AcR evolved significant levels of resistance, with resistance ratios (RR of 39-fold and 78.8-fold to Cry1Ab and Cry1Ac, respectively. The susceptibility of ACB-AbR larvae to Cry1Ac and Cry1F toxins, which had not previously been exposed, were significantly reduced, being >113-fold and 48-fold, respectively. Similarly, susceptibility of ACB-AcR larvae to Cry1Ab and Cry1F were also significantly reduced (RR > nine-fold, RR > 18-fold, respectively, indicating cross-resistance among Cry1Ab, Cry1Ac, and Cry1F toxins. However, ACB-AbR and ACB-AcR larvae were equally susceptible to Cry1Ie as were ACB-BtS larvae, indicating no cross-resistance between Cry1Ie and Cry1Ab or Cry1Ac toxins; this may provide considerable benefits in preventing or delaying the evolution of resistance in ACB to Cry1Ab and Cry1Ac toxins. Backcrossing studies indicated that resistance to Cry1Ab toxin was polygenic in ACB-AbR, but monogenic in ACB-AcR, whilst resistance to Cry1Ac toxin was primarily monogenic in both ACB-AbR and ACB-AcR, but polygenic as resistance increased.

  8. Aerobic granulation of pure bacterial strain Bacillus thuringiensis

    Institute of Scientific and Technical Information of China (English)

    Sunil S ADAV; Duu-Jong LEE

    2008-01-01

    The objective of this study is to cultivate aer-obic granules by pure bacterial strain, Bacillus thuringien-sis, in a sequencing batch reactor. Stable granules sized 2.0-2.2 mm were formed in the reactor after a five-week cultivation. These granules exhibited excellent settling attributes, and degraded phenol at rates of 1.49 and concentration, respectively. Confocal laser scanning microscopic test results show that Bacillus thuringiensis was distributed over the initial small aggregates, and the outer edge of the granule was away from the core regime in the following stage.

  9. Cry1Ab treatment has no effects on viability of cultured porcine intestinal cells, but triggers Hsp70 expression.

    Directory of Open Access Journals (Sweden)

    Angelika Bondzio

    Full Text Available In vitro testing can contribute to reduce the risk that the use of genetically modified (GM crops and their proteins show unintended toxic effects. Here we introduce a porcine intestinal cell culture (IPEC-J2 as appropriate in vitro model and tested the possible toxic potential of Cry1Ab protein, commonly expressed in GM-maize. For comprehensive risk assessment we used WST-1 conversion and ATP content as metabolic markers for proliferation, lactate dehydrogenase release as indicator for cells with compromised membrane and transepithelial electrical resistance as parameter indicating membrane barrier function. The results were compared to the effects of valinomycin, a potassium ionophore, known to induce cytotoxic effects in most mammalian cell types. Whereas no toxicity was observed after Cry1Ab treatment, valinomycin induced a decrease in IPEC-J2 viability. This was confirmed by dynamic monitoring of cellular responses. Additionally, two dimensional differential in-gel electrophoresis was performed. Only three proteins were differentially expressed. The functions of these proteins were associated with responses to stress. The up-regulation of heat shock protein Hsp70 was verified by Western blotting as well as by enzyme-linked immunosorbent assay and may be related to a protective function. These findings suggest that the combination of in vitro testing and proteomic analysis may serve as a promising tool for mechanism based safety assessment.

  10. A system for the directed evolution of the insecticidal protein from Bacillus thuringiensis.

    Science.gov (United States)

    Ishikawa, Hiroshi; Hoshino, Yasushi; Motoki, Yutaka; Kawahara, Takuma; Kitajima, Mika; Kitami, Madoka; Watanabe, Ayako; Bravo, Alejandra; Soberon, Mario; Honda, Atsuko; Yaoi, Katsuro; Sato, Ryoichi

    2007-06-01

    Theoretically, the activity of AB-type toxin molecules such as the insecticidal toxin (Cry toxin) from B. thuringiensis, which have one active site and two binding site, is improved in parallel with the binding affinity to its receptor. In this experiment, we tried to devise a method for the directed evolution of Cry toxins to increase the binding affinity to the insect receptor. Using a commercial T7 phage-display system, we expressed Cry1Aa toxin on the phage surface as fusions with the capsid protein 10B. These recombinant phages bound to a cadherin-like protein that is one of the Cry1Aa toxin receptors in the model target insect Bombyx mori. The apparent affinity of Cry1Aa-expressing phage for the receptor was higher than that of Cry1Ab-expressing phage. Phages expressing Cry1Aa were isolated from a mixed suspension of phages expressing Cry1Ab and concentrated by up to 130,000-fold. Finally, random mutations were made in amino acid residues 369-375 in domain 2 of Cry1Aa toxin, the mutant toxins were expressed on phages, and the resulting phage library was screened with cadherin-like protein-coated beads. As a result, phages expressing abnormal or low-affinity mutant toxins were excluded, and phages with high-affinity mutant toxins were selected. These results indicate that a method combining T7 phage display with selection using cadherin-like protein-coated magnetic beads can be used to increase the activity of easily obtained, low-activity Cry toxins from bacteria. PMID:17914188

  11. Impacts of Environmental Factors on Degradation of Cry1Ab Insecticidal Protein in Leaf-Blade Powders of Transgenic Bt Rice

    Institute of Scientific and Technical Information of China (English)

    BAI Yao-yu; JIANG Ming-xing; CHENG Jia-an

    2007-01-01

    The determination of the environmental fate of Bt insecticidal protein released by Bt rice plants in paddy soils is a key issue in its ecological risk assessment. In this study, the impacts of soil water content, pH, and temperature on the degradation of Cry1Ab protein expressed in the leaves of Bt rice KMD2 were studied in the laboratory. Three types of paddy soils were used, i.e., blue clayey paddy soil, pale paddy soil on quaternary red soil, and marine-fluvigenic yellow loamy paddy soil. Ground powders of KMD2 leaf blades were mixed with each type of soil, and degradation dynamics of Cry1Ab were measured using enzyme-linked immunosorbent assay (ELISA). The degradation rate of Cry1Ab was high at the early experimental stage, but slowed down steadily at middle and later stages, which could be described by exponential equations, with the half-life period of degradation determined as 1.8-4.0 d. The soil water content, pH, and temperature could affect the degradation of Cry1Ab, but the effects of soil pH and temperature were relatively greater. In general,Cry 1 Ab degradations were slower under lower soil pH and temperature conditions, especially for marine-fluvigenic yellow loamy paddy soil.

  12. Bacteriocins synthesized by Bacillus thuringiensis: generalities and potential applications

    Science.gov (United States)

    Salazar-Marroquín, Elma Laura; Galán-Wong, Luis J.; Moreno-Medina, Víctor Ricardo; Reyes-López, Miguel Ángel; Pereyra-Alférez, Benito

    2016-01-01

    The members of the Bacillus thuringiensis group, commonly known as Bt, produce a huge number of metabolites, which show biocidal and antagonistic activity. B. thuringiensis is widely known for synthesizing Cry, Vip and Cyt proteins, active against insects and other parasporins with biocidal activity against certain types of cancerous cells. Nevertheless, B. thuringiensis also synthesizes compounds with antimicrobial activity, especially bacteriocins. Some B. thuringiensis bacteriocins resemble lantibiotics and other small linear peptides (class IIa) from the lactic acid bacteria bacteriocins classification system. Although many bacteriocins produced by Bt have been reported, there is no proper classification for them. In this work, we have grouped these based on molecular weight and functionality. Bacteriocins are small peptides synthesized by bacteria, presenting inhibitory activity against Gram-positive and Gram-negative bacteria and to a lesser extent against fungi. These molecules represent a good study model in the search for microbial control alternatives. Lactic acid bacteria produces a huge number of these types of molecules with great potential. Nonetheless, members of the Bacillus, cereus group, especially B. thuringiensis, emerge as an attractive alternative for obtaining bacteriocins showing novel activities. This review describes the potential applications of B. thuringiensis bacteriocins in the control of foodborne pathogens, environment and medical area. PMID:27340340

  13. Regulation of cry Gene Expression in Bacillus thuringiensis

    OpenAIRE

    Chao Deng; Qi Peng; Fuping Song; Didier Lereclus

    2014-01-01

    Bacillus thuringiensis differs from the closely related Bacillus cereus group species by its ability to produce crystalline inclusions. The production of these crystals mainly results from the expression of the cry genes, from the stability of their transcripts and from the synthesis, accumulation and crystallization of large amounts of insecticidal Cry proteins. This process normally coincides with sporulation and is regulated by various factors operating at the transcriptional, post-transcr...

  14. Transfer of the toxin protein genes of Bacillus sphaericus into Bacillus thuringiensis subsp. israelensis and their expression.

    OpenAIRE

    Bourgouin, C.; Delécluse, A; La Torre, F.; Szulmajster, J

    1990-01-01

    The genes encoding the toxic determinants of Bacillus sphaericus have been expressed in a nontoxic and a toxic strain of Bacillus thuringiensis subsp. israelensis. In both cases, the B. sphaericus toxin proteins were produced at a high level during sporulation of B. thuringiensis and accumulated as crystalline structures. B. thuringiensis transformants expressing B. sphaericus and B. thuringiensis subsp. israelensis toxins did not show a significant enhancement of toxicity against Aedes aegyp...

  15. Draft Genome Sequence of Bacillus thuringiensis NBIN-866 with High Nematocidal Activity

    OpenAIRE

    Liu, Xiaoyan; Zhou, Ronghua; Fu, Guiping; Zhang, Wei; Min, Yong; Tian, Yuxi; Huang, Daye; Wang, Kaimei; Wan, Zhongyi; Yao, Jingwu; Yang, Ziwen

    2014-01-01

    Bacillus thuringiensis NBIN-866, a Gram-positive bacterium, was isolated from soil in China. We announce here the draft genome sequence of strain B. thuringiensis NBIN-866, which possesses highly nematocidal factors, such as proteins and small molecular peptides.

  16. Occurrence and diversity of mosquitocidal strains of Bacillus thuringiensis

    Directory of Open Access Journals (Sweden)

    K. Balaraman

    2005-09-01

    Full Text Available Ever since the discovery of the first Bacillus thuringiensis strain capable of killing mosquito larvae,namely, B. thuringiensis var israelensis, there are several reports from different parts of the worldabout the occurrence of mosquitocidal strains belonging to different subspecies/serotypes numberingthirty-six. The main sources of these wild type strains are soils/sediments, plants, animal feces,sick/moribund insects and waters. The toxicity of the strains within a subspecies/serotype variedwidely. Some of the strains exhibited toxicity to mosquitoes as well as lepidopterans and dipterans(including mosquitoes as well as plant parasitic nematodes.

  17. Phages Preying on Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis: Past, Present and Future

    Directory of Open Access Journals (Sweden)

    Annika Gillis

    2014-07-01

    Full Text Available Many bacteriophages (phages have been widely studied due to their major role in virulence evolution of bacterial pathogens. However, less attention has been paid to phages preying on bacteria from the Bacillus cereus group and their contribution to the bacterial genetic pool has been disregarded. Therefore, this review brings together the main information for the B. cereus group phages, from their discovery to their modern biotechnological applications. A special focus is given to phages infecting Bacillus anthracis, B. cereus and Bacillus thuringiensis. These phages belong to the Myoviridae, Siphoviridae, Podoviridae and Tectiviridae families. For the sake of clarity, several phage categories have been made according to significant characteristics such as lifestyles and lysogenic states. The main categories comprise the transducing phages, phages with a chromosomal or plasmidial prophage state, γ-like phages and jumbo-phages. The current genomic characterization of some of these phages is also addressed throughout this work and some promising applications are discussed here.

  18. Phages preying on Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis: past, present and future.

    Science.gov (United States)

    Gillis, Annika; Mahillon, Jacques

    2014-07-01

    Many bacteriophages (phages) have been widely studied due to their major role in virulence evolution of bacterial pathogens. However, less attention has been paid to phages preying on bacteria from the Bacillus cereus group and their contribution to the bacterial genetic pool has been disregarded. Therefore, this review brings together the main information for the B. cereus group phages, from their discovery to their modern biotechnological applications. A special focus is given to phages infecting Bacillus anthracis, B. cereus and Bacillus thuringiensis. These phages belong to the Myoviridae, Siphoviridae, Podoviridae and Tectiviridae families. For the sake of clarity, several phage categories have been made according to significant characteristics such as lifestyles and lysogenic states. The main categories comprise the transducing phages, phages with a chromosomal or plasmidial prophage state, γ-like phages and jumbo-phages. The current genomic characterization of some of these phages is also addressed throughout this work and some promising applications are discussed here. PMID:25010767

  19. Microarray detection and qPCR screening of potential biomarkers of Folsomia candida (Collembola: Isotomidae) exposed to Bt proteins (Cry1Ab and Cry1Ac)

    DEFF Research Database (Denmark)

    Yuan, Yiyang; Krogh, Paul Henning; Bai, Xue;

    2014-01-01

    The impact of Bt proteins on non-target arthropods is less understood than their effects on target organisms where the mechanism of toxic action is known. Here, we report the effects of two Bt proteins, Cry1Ab and Cry1Ac, on gene expression in the non-target collembolan, Folsomia candida...

  20. Microarray detection and qPCR screening of potential biomarkers of Folsomia candida (Collembola: Isotomidae) exposed to Bt proteins (Cry1Ab and Cry1Ac).

    Science.gov (United States)

    Yuan, Yiyang; Krogh, Paul Henning; Bai, Xue; Roelofs, Dick; Chen, Fajun; Zhu-Salzman, Keyan; Liang, Yuyong; Sun, Yucheng; Ge, Feng

    2014-01-01

    The impact of Bt proteins on non-target arthropods is less understood than their effects on target organisms where the mechanism of toxic action is known. Here, we report the effects of two Bt proteins, Cry1Ab and Cry1Ac, on gene expression in the non-target collembolan, Folsomia candida. A customized microarray was used to study gene expression in F. candida specimens that were exposed to Cry1Ab and Cry1Ac. All selected transcripts were subsequently confirmed by qPCR. Eleven transcripts were finally verified, and three of them were annotated. The responses of all eleven transcripts were tested in specimens for both Cry1Ab and Cry1Ac at a series of concentrations. These transcripts were separated into two and three groups for Cry1Ab and Cry1Ac, respectively, depend on their expression levels. However, those eleven transcripts did not respond to the Bt proteins in Bt-rice residues.

  1. Genetic Differentiation between Sympatric Populations of Bacillus cereus and Bacillus thuringiensis

    Science.gov (United States)

    Vilas-Boas, Gislayne; Sanchis, Vincent; Lereclus, Didier; Lemos, Manoel Victor F.; Bourguet, Denis

    2002-01-01

    Little is known about genetic exchanges in natural populations of bacteria of the spore-forming Bacillus cereus group, because no population genetics studies have been performed with local sympatric populations. We isolated strains of Bacillus thuringiensis and B. cereus from small samples of soil collected at the same time from two separate geographical sites, one within the forest and the other at the edge of the forest. A total of 100 B. cereus and 98 B. thuringiensis strains were isolated and characterized by electrophoresis to determine allelic composition at nine enzymatic loci. We observed genetic differentiation between populations of B. cereus and B. thuringiensis. Populations of a given Bacillus species—B. thuringiensis or B. cereus—were genetically more similar to each other than to populations of the other Bacillus species. Hemolytic activity provided further evidence of this genetic divergence, which remained evident even if putative clones were removed from the data set. Our results suggest that the rate of gene flow was higher between strains of the same species, but that exchanges between B. cereus and B. thuringiensis were nonetheless possible. Linkage disequilibrium analysis revealed sufficient recombination for B. cereus populations to be considered panmictic units. In B. thuringiensis, the balance between clonal proliferation and recombination seemed to depend on location. Overall, our data indicate that it is not important for risk assessment purposes to determine whether B. cereus and B. thuringiensis belong to a single or two species. Assessment of the biosafety of pest control based on B. thuringiensis requires evaluation of the extent of genetic exchange between strains in realistic natural conditions. PMID:11872495

  2. Production of Protocatechuic Acid in Bacillus Thuringiensis ATCC33679

    Directory of Open Access Journals (Sweden)

    Bianca L. Garner

    2012-03-01

    Full Text Available Protocatechuic acid, or 3,4-dihydroxybenzoic acid, is produced by both soil and marine bacteria in the free form and as the iron binding component of the siderophore petrobactin. The soil bacterium, Bacillus thuringiensis kurstaki ATCC 33679, contains the asb operon, but does not produce petrobactin. Iron restriction resulted in diminished B. thuringiensis kurstaki ATCC 33679 growth and the production of catechol(s. The gene product responsible for protocatechuic acid (asbF and its receptor (fatB were expressed during stationary phase growth. Gene expression varied with growth temperature, with optimum levels occurring well below the Bacillus anthracis virulence temperature of 37 °C. Regulation of protocatechuic acid suggests a possible role for this compound during soil growth cycles.

  3. A Comprehensive Assessment of the Effects of Transgenic Cry1Ac/Cry1Ab Rice Huahui 1 on Adult Micraspis discolor (Fabricius (Coleoptera: Coccinellidae.

    Directory of Open Access Journals (Sweden)

    Xia Zhou

    Full Text Available Micraspis discolor (Fabricius (Coleoptera: Coccinellidae is a widely distributed coleoptera predator in southern Asia in rice ecosystem, and adult M. discolor feed on both rice pollen and soft-bodied arthropods. Bitrophic bioassay and tritrophic bioassay were conducted to evaluate the potential impact of Cry1Ac/Cry1Ab-expressing rice Huahui 1 and its non-transgenic counterpart Minghui 63 on fitness parameters of adult M. discolor. The results showed that the survival, and fecundity of this beetle' adults were not different when they fed on Bt rice or non-Bt rice pollen or Nilaparvata lugens (Stål reared on Bt rice or non-Bt rice. Toxicity assessment to ensure M. discolor adults were not sensitive to Cry1Ab or Cry1Ac protein independent from the pollen background, M. discolor adults were fed with an artificial diet containing Cry1Ac, Cry1Ab or both protein approximately 10 times higher concentration than in Huahui 1 rice pollen. No difference was detected for any of the life-table parameters tested between Cry protein-containing and pure diet. Artificial diet containing E-64 (N-(trans-Epoxysuccinyl-L-leucine 4-guanidinobutylamide was included as a positive control. In contrast, the pre-oviposition and fecundity of M. discolor were significantly adversely affected by feeding on E-64-containing diet. In both bioassays, the uptakes of Cry protein by adult M. discolor were tested by ELISA measurements. These results indicated that adults of M. discolor are not affected by Cry1Ab- or Cry1Ac-expressing rice pollen and are not sensitive to Cry protein at concentrations exceeding the levels in rice pollen in Huahui1. This suggests that M. discolor adults would not be harmed by Cry1Ac/Cry1Ab rice if Bt rice Huahui 1 were commercialized.

  4. Photoprotection of Bacillus thuringiensis kurstaki from ultraviolet irradiation

    International Nuclear Information System (INIS)

    Irradiation of Bacillus thuringiensis var. kurstaki HD1 at 300-350 nm for up to 12 hr using a photochemical reactor results in a rapid loss of its toxicity to larvae of Heliothis armigera. Photoprotection of the toxic component was obtained by adsorption of cationic chromophores such as acriflavin (AF), methyl green, and rhodamine B to B. thuringiensis. AF gave the best photoprotection and a level of 0.42 mmol/g dye absorbed per gram of B. thuringiensis was highly toxic even after 12 hr of ultraviolet (uv) irradiation as compared to the control (77.5 and 5% of insect mortality, respectively). Ultraviolet and Fourier-transform infrared spectroscopic studies indicate molecular interactions between B. thuringiensis and AF. The nature of these interactions and energy or charge transfer as possible mechanisms of photoprotection are discussed. It is speculated that tryptophan residues are essential for the toxic effect of B. thuringiensis. It is suggested that photoprotection is attained as energy is transferred from the excited tryptophan moieties to the chromophore molecules

  5. Photoprotection of Bacillus thuringiensis kurstaki from ultraviolet irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, E.; Rozen, H.; Joseph, T.; Braun, S.; Margulies, L. (Department of Entomology, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot (Israel))

    1991-05-01

    Irradiation of Bacillus thuringiensis var. kurstaki HD1 at 300-350 nm for up to 12 hr using a photochemical reactor results in a rapid loss of its toxicity to larvae of Heliothis armigera. Photoprotection of the toxic component was obtained by adsorption of cationic chromophores such as acriflavin (AF), methyl green, and rhodamine B to B. thuringiensis. AF gave the best photoprotection and a level of 0.42 mmol/g dye absorbed per gram of B. thuringiensis was highly toxic even after 12 hr of ultraviolet (uv) irradiation as compared to the control (77.5 and 5% of insect mortality, respectively). Ultraviolet and Fourier-transform infrared spectroscopic studies indicate molecular interactions between B. thuringiensis and AF. The nature of these interactions and energy or charge transfer as possible mechanisms of photoprotection are discussed. It is speculated that tryptophan residues are essential for the toxic effect of B. thuringiensis. It is suggested that photoprotection is attained as energy is transferred from the excited tryptophan moieties to the chromophore molecules.

  6. SinR controls enterotoxin expression in Bacillus thuringiensis biofilms.

    Directory of Open Access Journals (Sweden)

    Annette Fagerlund

    Full Text Available The entomopathogen Bacillus thuringiensis produces dense biofilms under various conditions. Here, we report that the transition phase regulators Spo0A, AbrB and SinR control biofilm formation and swimming motility in B. thuringiensis, just as they control biofilm formation and swarming motility in the closely related saprophyte species B. subtilis. However, microarray analysis indicated that in B. thuringiensis, in contrast to B. subtilis, SinR does not control an eps operon involved in exopolysaccharides production, but regulates genes involved in the biosynthesis of the lipopeptide kurstakin. This lipopeptide is required for biofilm formation and was previously shown to be important for survival in the host cadaver (necrotrophism. Microarray analysis also revealed that the SinR regulon contains genes coding for the Hbl enterotoxin. Transcriptional fusion assays, Western blots and hemolysis assays confirmed that SinR controls Hbl expression, together with PlcR, the main virulence regulator in B. thuringiensis. We show that Hbl is expressed in a sustained way in a small subpopulation of the biofilm, whereas almost all the planktonic population transiently expresses Hbl. The gene coding for SinI, an antagonist of SinR, is expressed in the same biofilm subpopulation as hbl, suggesting that hbl transcription heterogeneity is SinI-dependent. B. thuringiensis and B. cereus are enteric bacteria which possibly form biofilms lining the host intestinal epithelium. Toxins produced in biofilms could therefore be delivered directly to the target tissue.

  7. Cytolytic Toxin and Related Genes in Bacillus thuringiensis

    Institute of Scientific and Technical Information of China (English)

    QI Dong-lai; LI Yi-dan; GAO Ji-guo

    2005-01-01

    Bacillus thuringiensis is a ubiquitous gram-positive, spore-forming bacterium that forms parasporal crystal during the stationary phase of its growth cycle. These crystal proteins, including Cry and Cyt protein, are toxic to certain insects. Lately, some problems about Cyt classification, structural characteristic, action mechanism and resistance to Cyt toxin are becoming new hotspots. We review the progress of above problems in several foreign labs.

  8. Studies on the fermentation of bacillus thuringiensis var israelensis

    OpenAIRE

    Pearson, Dermot

    1985-01-01

    During this work the fermentation of Bacillus thuringiensis var israelensis under industrial conditions was studied with respect to the development of a process for the production of a mosquitocidal insecticide elaborated by this organism. This was done by the development of a two-stage inoculum protocol which produced a high biomass-containing inoculum of vegetative cells which were found to be preferable to free spores for use as an inoculum source. In order to optimize the production st...

  9. Genome Sequence of the Endophytic Bacterium Bacillus thuringiensis Strain KB1, a Potential Biocontrol Agent against Phytopathogens

    OpenAIRE

    Jeong, Haeyoung; Jo, Sung Hee; Hong, Chi Eun; Park, Jeong Mee

    2016-01-01

    Bacillus thuringiensis is the most widely known microbial pesticide used in agricultural applications. Herein, we report a draft genome sequence of the endophytic bacterium Bacillus thuringiensis strain KB1, which exhibits antagonism against phytopathogens.

  10. Bacillus thuringiensis: general characteristics and fermentation
    Bacillus thuringiensis: características gerais e fermentação

    OpenAIRE

    Raúl Jorge Hernan Castro-Gómez; Gislayne Trindade Vilas-Bôas; Elisangela Andrade Angelo

    2010-01-01

    The insect control is carried out mostly by chemical products, whose cumulative effects cause serious losses to environmental and human health, highlighting rapid selection of resistant insects. Biological control by entomopathogenic bacteria is an efficient alternative, mainly due to high specificity, absence of resistance in the target insects and low environment residual effect. Bacillus thuringiensis is a Gram-positive spore-forming bacterium that produces a parasporal crystal protein tox...

  11. Bioaccumulation of Cry1Ab protein from an herbivore reduces anti-oxidant enzyme activities in two spider species.

    Directory of Open Access Journals (Sweden)

    Ji Zhou

    Full Text Available Cry proteins are expressed in rice lines for lepidopteran pest control. These proteins can be transferred from transgenic rice plants to non-target arthropods, including planthoppers and then to a predatory spider. Movement of Cry proteins through food webs may reduce fitness of non-target arthropods, although recent publications indicated no serious changes in non-target populations. Nonetheless, Cry protein intoxication influences gene expression in Cry-sensitive insects. We posed the hypothesis that Cry protein intoxication influences enzyme activities in spiders acting in tri-trophic food webs. Here we report on the outcomes of experiments designed to test our hypothesis with two spider species. We demonstrated that the movement of CryAb protein from Drosophila culture medium into fruit flies maintained on the CryAb containing medium and from the flies to the spiders Ummeliata insecticeps and Pardosa pseudoannulata. We also show that the activities of three key metabolic enzymes, acetylcholine esterase (AchE, glutathione peroxidase (GSH-Px, and superoxide dismutase (SOD were significantly influenced in the spiders after feeding on Cry1Ab-containing fruit flies. We infer from these data that Cry proteins originating in transgenic crops impacts non-target arthropods at the physiological and biochemical levels, which may be one mechanism of Cry protein-related reductions in fitness of non-target beneficial predators.

  12. Transformation of Bacillus thuringiensis subsp. galleria protoplasts by plasmid pBC16.

    OpenAIRE

    Alikhanian, S. I.; Ryabchenko, N F; Bukanov, N O; Sakanyan, V A

    1981-01-01

    Protoplasts of the entomopathogenic bacterium Bacillus thuringiensis subsp. galleria were transformed by plasmid pBC16. The frequency of transformation was much lower than that of Bacillus subtilis. All isolated B. thuringiensis transformants were characterized by increased sensitivity to lysozyme as compared with the original strain.

  13. SR450 and Superhawk XP applications of Bacillus thuringiensis israelensis de Barjac against Culex quinquefasciatus Say

    Science.gov (United States)

    Sprayer comparisons and larval morality assays were conducted following SR450 backpack mist blower and Superhawk XP thermal fogger applications of Vectobac® WDG Bacillus thuringiensis israelensis (Bti) de Barjac against Culex quinquefasciatus Say. Bacillus thuringiensis israelensis was applied at m...

  14. [Characterization of crystal-forming bacteria Bacillus thuringiensis subsp. tohokuensis toxic to mosquitos].

    Science.gov (United States)

    Khodyrev, V P; Kalmykova, G V; Burtseva, L I; Glupov, V V

    2006-01-01

    Distribution study of Bacillus thuringiensis strains in Western Siberian soils allowed us to isolate crystal-forming bacteria assigned to a new pathovar of Bacillus thuringiensis ssp. tohokuensis with a toxic effect on mosquito larvae. A description of this bacterial pathovar is presented.

  15. Isolation and Characterization of Coproporphyrin Produced by Four Subspecies of Bacillus thuringiensis

    OpenAIRE

    Harms, R. L.; Martinez, D. R.; Griego, V M

    1986-01-01

    It was found by using spectrophotometric, spectrofluorometric, and high-pressure liquid chromatography that four subspecies of Bacillus thuringiensis produce coproporphyrin. The porphyrin isomer was identified as coproporphyrin I for B. thuringiensis subsp. kurstaki (HD1). The porphyrin was isolated both from spores and from a variety of spent growth media. The quantity of porphyrin released by each Bacillus subspecies differed. The rank order of porphyrin production follows: B. thuringiensis...

  16. Bacillus thuringiensis membrane-damaging toxins acting on mammalian cells.

    Science.gov (United States)

    Celandroni, Francesco; Salvetti, Sara; Senesi, Sonia; Ghelardi, Emilia

    2014-12-01

    Bacillus thuringiensis is widely used as a biopesticide in forestry and agriculture, being able to produce potent species-specific insecticidal toxins and considered nonpathogenic to other animals. More recently, however, repeated observations are documenting the association of this microorganism with various infectious diseases in humans, such as food-poisoning-associated diarrheas, periodontitis, bacteremia, as well as ocular, burn, and wound infections. Similar to B. cereus, B. thuringiensis produces an array of virulence factors acting against mammalian cells, such as phosphatidylcholine- and phosphatidylinositol-specific phospholipase C (PC-PLC and PI-PLC), hemolysins, in particular hemolysin BL (HBL), and various enterotoxins. The contribution of some of these toxins to B. thuringiensis pathogenicity has been studied in animal models of infection, following intravitreous, intranasal, or intratracheal inoculation. These studies lead to the speculation that the activities of PC-PLC, PI-PLC, and HBL are responsible for most of the pathogenic properties of B. thuringiensis in nongastrointestinal infections in mammals. This review summarizes data regarding the biological activity, the genetic basis, and the structural features of these membrane-damaging toxins.

  17. Midgut microbiota and host immunocompetence underlie Bacillus thuringiensis killing mechanism.

    Science.gov (United States)

    Caccia, Silvia; Di Lelio, Ilaria; La Storia, Antonietta; Marinelli, Adriana; Varricchio, Paola; Franzetti, Eleonora; Banyuls, Núria; Tettamanti, Gianluca; Casartelli, Morena; Giordana, Barbara; Ferré, Juan; Gigliotti, Silvia; Ercolini, Danilo; Pennacchio, Francesco

    2016-08-23

    Bacillus thuringiensis is a widely used bacterial entomopathogen producing insecticidal toxins, some of which are expressed in insect-resistant transgenic crops. Surprisingly, the killing mechanism of B. thuringiensis remains controversial. In particular, the importance of the septicemia induced by the host midgut microbiota is still debated as a result of the lack of experimental evidence obtained without drastic manipulation of the midgut and its content. Here this key issue is addressed by RNAi-mediated silencing of an immune gene in a lepidopteran host Spodoptera littoralis, leaving the midgut microbiota unaltered. The resulting cellular immunosuppression was characterized by a reduced nodulation response, which was associated with a significant enhancement of host larvae mortality triggered by B. thuringiensis and a Cry toxin. This was determined by an uncontrolled proliferation of midgut bacteria, after entering the body cavity through toxin-induced epithelial lesions. Consequently, the hemolymphatic microbiota dramatically changed upon treatment with Cry1Ca toxin, showing a remarkable predominance of Serratia and Clostridium species, which switched from asymptomatic gut symbionts to hemocoelic pathogens. These experimental results demonstrate the important contribution of host enteric flora in B. thuringiensis-killing activity and provide a sound foundation for developing new insect control strategies aimed at enhancing the impact of biocontrol agents by reducing the immunocompetence of the host.

  18. Midgut microbiota and host immunocompetence underlie Bacillus thuringiensis killing mechanism.

    Science.gov (United States)

    Caccia, Silvia; Di Lelio, Ilaria; La Storia, Antonietta; Marinelli, Adriana; Varricchio, Paola; Franzetti, Eleonora; Banyuls, Núria; Tettamanti, Gianluca; Casartelli, Morena; Giordana, Barbara; Ferré, Juan; Gigliotti, Silvia; Ercolini, Danilo; Pennacchio, Francesco

    2016-08-23

    Bacillus thuringiensis is a widely used bacterial entomopathogen producing insecticidal toxins, some of which are expressed in insect-resistant transgenic crops. Surprisingly, the killing mechanism of B. thuringiensis remains controversial. In particular, the importance of the septicemia induced by the host midgut microbiota is still debated as a result of the lack of experimental evidence obtained without drastic manipulation of the midgut and its content. Here this key issue is addressed by RNAi-mediated silencing of an immune gene in a lepidopteran host Spodoptera littoralis, leaving the midgut microbiota unaltered. The resulting cellular immunosuppression was characterized by a reduced nodulation response, which was associated with a significant enhancement of host larvae mortality triggered by B. thuringiensis and a Cry toxin. This was determined by an uncontrolled proliferation of midgut bacteria, after entering the body cavity through toxin-induced epithelial lesions. Consequently, the hemolymphatic microbiota dramatically changed upon treatment with Cry1Ca toxin, showing a remarkable predominance of Serratia and Clostridium species, which switched from asymptomatic gut symbionts to hemocoelic pathogens. These experimental results demonstrate the important contribution of host enteric flora in B. thuringiensis-killing activity and provide a sound foundation for developing new insect control strategies aimed at enhancing the impact of biocontrol agents by reducing the immunocompetence of the host. PMID:27506800

  19. Methodology for fast evaluation of Bacillus thuringiensis crystal protein content

    Directory of Open Access Journals (Sweden)

    Alves Lúcia M. Carareto

    2000-01-01

    Full Text Available The development of the production and use of Bacillus thuringiensis in Brazil at a commercial scale faces certain difficulties, among them the establishment of efficient methodologies for the quantitation of toxic products to be commercialized. Presently, the amount of toxin is given in percentage by analyzing the samples total protein content. Such methodology however, does not measure the actual amount of active protein present in the product, since most strains express different endotoxin genes and might even produce b-toxin. Since the various types of toxins exhibit different antigenic characteristics, this work has as objective the utilization of fast immunological techniques to quantify the level of crystal protein. Crystal protein produced by a subspecies of Bacillus thuringiensis var. israelensis was purified by ultracentrifugation and utilized to immunize rabbits and to produce hiperimmune sera. Such sera were latter used to evaluate the level of proteins on commercial bioinsecticide and on laboratory cultures of B. thuringiensis through the immunodot technique. The results were obtained by comparison of data obtained from reactions with known concentrations of crystal protein permitting to evaluate the level of such protein on various materials.

  20. Down regulation of a gene for cadherin but not alkaline phosphatase associated with Cry1Ab resistance in the sugarcane borer Diatraea saccharalis

    Science.gov (United States)

    The sugarcane borer, Diatraea saccharalis, is a major target pest of transgenic corn expressing Bacillus thuringiensis (Bt) proteins in South America and the mid-southern region of the United States. Evolution of insecticide resistance in such target pests is a major threat to the durability of tran...

  1. Effect of Bacillus thuringiensis on microbial functional groups in sorghum rhizosphere Efeito do Bacillus thuringiensis sobre grupos funcionais de microrganismos na rizosfera de sorgo

    OpenAIRE

    Carlos Brasil; Leopoldo Sussumu Matsumoto; Marco Antonio Nogueira; Flavia Regina Spago; Luís Gustavo Rampazo; Marcio Ferreira Cruz; Galdino Andrade

    2006-01-01

    The objective of this work was to assess the effect of two strains of Bacillus thuringiensis var. kurstaki on sorghum rhizosphere microorganisms. The strains were HD1, that produces the bioinsecticidal protein, and 407, that is a mutant non-producer. The strains do not influence microbial population, but reduce plant growth and improve mycorrhizal colonization and free living fixing N2 community.O objetivo deste trabalho foi avaliar o efeito de duas cepas de Bacillus thuringiensis var. kursta...

  2. Cry1Ab rice does not impact biological characters and functional response ofCyrtorhinus lividipennispreying onNilaparvata lugens eggs

    Institute of Scientific and Technical Information of China (English)

    CHEN Yang; LAI Feng-xiang; SUN Yan-qun; HONG Li-ying; TIAN Jun-ce; ZHANG Zhi-tao; FU Qiang

    2015-01-01

    One concern about the use of transgenic plants is their potential risk to natural enemies. In this study, using the eggs of the rice brown planthopper,Nilaparvata lugens, as a food source, we investigated the effects of Cry1Ab rice on the biological characteristics and functional response of an important predatorCyrtorhinus lividipennis. The results showed that the survival ability (adult emergence rate and egg hatching rate), development (egg duration, nymphal developmental duration), adult fresh weight, adult longevity and fecundity ofC. lividipennis on Bt rice plants were not signiifcantly different compared to those on non-Bt rice plants. Furthermore, two important parameters of functional response (instantaneous search rate and handling time) were not signiifcantly affected by Bt rice. In conclusion, the tested Cry1Ab rice does not adversely impact the biological character and functional response ofC. lividipennis.

  3. First application of a microsphere-based immunoassay to the detection of genetically modified organisms (GMOs): quantification of Cry1Ab protein in genetically modified maize.

    Science.gov (United States)

    Fantozzi, Anna; Ermolli, Monica; Marini, Massimiliano; Scotti, Domenico; Balla, Branko; Querci, Maddalena; Langrell, Stephen R H; Van den Eede, Guy

    2007-02-21

    An innovative covalent microsphere immunoassay, based on the usage of fluorescent beads coupled to a specific antibody, was developed for the quantification of the endotoxin Cry1Ab present in MON810 and Bt11 genetically modified (GM) maize lines. In particular, a specific protocol was developed to assess the presence of Cry1Ab in a very broad range of GM maize concentrations, from 0.1 to 100% [weight of genetically modified organism (GMO)/weight]. Test linearity was achieved in the range of values from 0.1 to 3%, whereas fluorescence signal increased following a nonlinear model, reaching a plateau at 25%. The limits of detection and quantification were equal to 0.018 and 0.054%, respectively. The present study describes the first application of quantitative high-throughput immunoassays in GMO analysis.

  4. Bacillus thuringiensis resistance in Plutella - too many trees?

    Science.gov (United States)

    Crickmore, Neil

    2016-06-01

    Plutella xylostella was the first insect for which resistance to Bacillus thuringiensis was reported in the field, yet despite many studies on the nature of this resistance phenotype its genetic and molecular basis remains elusive. Many different factors have been proposed as contributing to resistance, although in many cases it has not been possible to establish a causal link. Indeed, there are so many studies published that it has become very difficult to 'see the wood for the trees'. This article will attempt to clarify our current understanding of Bt resistance in P. xylostella and consider the criteria that are used when validating a particular model. PMID:27436736

  5. TRANSGENIC PLANTS EXPRESSING BACILLUS THURINGIENSIS DELTA-ENDOTOXINS

    Institute of Scientific and Technical Information of China (English)

    Hua-rong,Li; BrendaOppert; KunYanZhu; RandallA.Higgins; Fang-nengHuang; LawrentL.Buschman

    2003-01-01

    Commercial varieties of transgenic Bacillus thuringiensis (Bt) plants have been developed in many countries to control target pests. Initially, the expression of native Bt genes in plants was low due to mRNA instability, improper splicing, and post-translation modifications. Subsequently, modifications of the native Bt genes greatly enhanced expression levels. This is a review of the developments that made modem high-expression transgenic Bt plants possible, with an emphasis on the reasons for the low-level expression of native Bt genes in plant systems, and the techniques that have been used to improve plant expression of Bt toxin genes.

  6. Bacillus thuringiensis resistance in Plutella - too many trees?

    Science.gov (United States)

    Crickmore, Neil

    2016-06-01

    Plutella xylostella was the first insect for which resistance to Bacillus thuringiensis was reported in the field, yet despite many studies on the nature of this resistance phenotype its genetic and molecular basis remains elusive. Many different factors have been proposed as contributing to resistance, although in many cases it has not been possible to establish a causal link. Indeed, there are so many studies published that it has become very difficult to 'see the wood for the trees'. This article will attempt to clarify our current understanding of Bt resistance in P. xylostella and consider the criteria that are used when validating a particular model.

  7. Genetic relationships between sympatric populations of Bacillus cereus and Bacillus thuringiensis, as revealed by rep-PCR genomic fingerprinting

    Directory of Open Access Journals (Sweden)

    Ana Paula S Peruca

    2008-08-01

    Full Text Available The bacterial strain Bacillus cereus is closely related to Bacillus thuringiensis, although any genetic relationship between the two strains is still in debate. Using rep-PCR genomic fingerprinting, we established the genetic relationships between Brazilian sympatric populations of B. cereus and B. thuringiensis simultaneously collected from two geographically separate sites. We observed the formation of both B. thuringiensis and B. cereus clusters, as well as strains of B. cereus that are more closely related to B. thuringiensis than to other B. cereus strains. In addition, lower genetic variability was observed among B. thuringiensis clusters compared to B. cereus clusters, indicating that either the two species should be categorized as separate or that B. thuringiensis may represent a clone from a B. cereus background.

  8. Architecture and High-Resolution Structure of Bacillus thuringiensis and Bacillus cereus Spore Coat Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Plomp, M; Leighton, T; Wheeler, K; Malkin, A

    2005-02-18

    We have utilized atomic force microscopy (AFM) to visualize the native surface topology and ultrastructure of Bacillus thuringiensis and Bacillus cereus spores in water and in air. AFM was able to resolve the nanostructure of the exosporium and three distinctive classes of appendages. Removal of the exosporium exposed either a hexagonal honeycomb layer (B. thuringiensis) or a rodlet outer spore coat layer (B. cereus). Removal of the rodlet structure from B. cereus spores revealed an underlying honeycomb layer similar to that observed with B. thuringiensis spores. The periodicity of the rodlet structure on the outer spore coat of B. cereus was {approx}8 nm, and the length of the rodlets was limited to the cross-patched domain structure of this layer to {approx}200 nm. The lattice constant of the honeycomb structures was {approx}9 nm for both B. cereus and B. thuringiensis spores. Both honeycomb structures were composed of multiple, disoriented domains with distinct boundaries. Our results demonstrate that variations in storage and preparation procedures result in architectural changes in individual spore surfaces, which establish AFM as a useful tool for evaluation of preparation and processing ''fingerprints'' of bacterial spores. These results establish that high-resolution AFM has the capacity to reveal species-specific assembly and nanometer scale structure of spore surfaces. These species-specific spore surface structural variations are correlated with sequence divergences in a spore core structural protein SspE.

  9. Occurrence and significance of Bacillus cereus and Bacillus thuringiensis in ready-to-eat food

    DEFF Research Database (Denmark)

    Rosenquist, Hanne; Ørum-Smidt, Lasse; Andersen, Sigrid R;

    2005-01-01

    had at least one gene or component involved in human diarrhoeal disease, while emetic toxin was related to only one B. cereus strain. A new observation was that 31 out of the 40 randomly selected B. cereus-like strains could be classified as Bacillus thuringiensis due to crystal production and......Among 48,901 samples of ready-to-eat food products at the Danish retail market, 0.5% had counts of Bacillus cereus-like bacteria above 10(4) cfu g(-1). The high counts were most frequently found in starchy, cooked products, but also in fresh cucumbers and tomatoes. Forty randomly selected strains....../or content of cry genes. Thus, a large proportion of the B. cereus-like organisms present in food may belong to B. thuringiensis....

  10. Susceptibility, mechanisms of response and resistance to Bacillus thuringiensis toxins in Spodoptera spp.

    Science.gov (United States)

    Herrero, Salvador; Bel, Yolanda; Hernández-Martínez, Patricia; Ferré, Juan

    2016-06-01

    Bioinsecticides based on Bacillus thuringiensis have long been used as an alternative to synthetic insecticides to control insect pests. In this review, we focus on insects of the genus Spodoptera, including relevant polyphagous species that are primary and secondary pests of many crops, and how B. thuringiensis toxins can be used for Spodoptera spp. pest management. We summarize the main findings related to susceptibility, midgut binding specificity, mechanisms of response and resistance of this insect genus to B. thuringiensis toxins. PMID:27436737

  11. Cross-Resistance to Bacillus thuringiensis Toxin CryIF in the Diamondback Moth (Plutella xylostella)

    OpenAIRE

    Tabashnik, Bruce E; Finson, Naomi; Johnson, Marshall W.; Heckel, David G.

    1994-01-01

    Selection with Bacillus thuringiensis subsp. kurstaki, which contains CryIA and CryII toxins, caused a >200-fold cross-resistance to CryIF toxin from B. thuringiensis subsp. aizawai in the diamondback moth, Plutella xylostella. CryIE was not toxic, but CryIB was highly toxic to both selected and unselected larvae. The results show that extremely high levels of cross-resistance can be conferred across classes of CryI toxins of B. thuringiensis.

  12. An Ultra-Violet Tolerant Wild-Type Strain of Melanin-Producing Bacillus thuringiensis

    OpenAIRE

    Sansinenea, Estibaliz; Salazar, Francisco de, (S.I.); Ramirez, Melanie; Ortiz, Aurelio

    2015-01-01

    Background: Bacillus thuringiensis is the most successful biological control agent used in agriculture, forestry and mosquito control. However, the insecticidal activity of the B. thuringiensis formulation is not very stable and rapidly loses its biological activity under field conditions, due to the ultraviolet radiation in sunlight. Melanin is known to absorb radiation therefore photo protection of B. thuringiensis based on melanin has been extensively studied. Objectives: The aim of this s...

  13. Susceptibility, mechanisms of response and resistance to Bacillus thuringiensis toxins in Spodoptera spp.

    Science.gov (United States)

    Herrero, Salvador; Bel, Yolanda; Hernández-Martínez, Patricia; Ferré, Juan

    2016-06-01

    Bioinsecticides based on Bacillus thuringiensis have long been used as an alternative to synthetic insecticides to control insect pests. In this review, we focus on insects of the genus Spodoptera, including relevant polyphagous species that are primary and secondary pests of many crops, and how B. thuringiensis toxins can be used for Spodoptera spp. pest management. We summarize the main findings related to susceptibility, midgut binding specificity, mechanisms of response and resistance of this insect genus to B. thuringiensis toxins.

  14. Draft Genome Sequence of Bacillus thuringiensis Strain DAR 81934, Which Exhibits Molluscicidal Activity

    OpenAIRE

    Wang, Aisuo; Pattemore, Julie; Ash, Gavin; Williams, Angela; Hane, James

    2013-01-01

    Bacillus thuringiensis has been widely used as a biopesticide for a long time. Its molluscicidal activity, however, is rarely realized. Here, we report the genome sequence of B. thuringiensis strain DAR 81934, a strain with molluscicidal activity against the pest snail Cernuella virgata.

  15. Separation of Protein Crystals from Spores of Bacillus thuringiensis by Ludox Gradient Centrifugation

    OpenAIRE

    Zhu, Yu Sheng; Brookes, Allan; Carlson, Ken; Filner, Philip

    1989-01-01

    A method is described for the purification of Bacillus thuringiensis protein crystals by Ludox gradient centrifugation. This method is simple, inexpensive, fast, and efficient compared with other techniques. It has been successfully used to purify and characterize the protein crystals from several B. thuringiensis strains.

  16. Genome-wide Screening Reveals the Genetic Determinants of an Antibiotic Insecticide in Bacillus thuringiensis*

    OpenAIRE

    Liu, Xiao-Yan; Ruan, Li-Fang; Hu, Zhen-Fei; Peng, Dong-hai; Cao, Shi-Yun; Yu, Zi-Niu; Liu, Yao; Zheng, Jin-Shui; Sun, Ming

    2010-01-01

    Thuringiensin is a thermostable secondary metabolite in Bacillus thuringiensis and has insecticidal activity against a wide range of insects. Until now, the regulatory mechanisms and genetic determinants involved in thuringiensin production have remained unclear. Here, we successfully used heterologous expression-guided screening in an Escherichia coli–Bacillus thuringiensis shuttle bacterial artificial chromosome library, to clone the intact thuringiensin synthesis (thu) cluster. Then the th...

  17. Mode of action of mosquitocidal Bacillus thuringiensis toxins.

    Science.gov (United States)

    Soberón, Mario; Fernández, Luisa E; Pérez, Claudia; Gill, Sarjeet S; Bravo, Alejandra

    2007-04-01

    Cry toxins from Bacillus thuringiensis (Bt) are used for insect control. Their primary action is to lyse midgut epithelial cells. In lepidopteran insects, Cry1A monomeric toxins interact with a first receptor and this interaction triggers toxin oligomerization. The oligomeric structure interacts then with a second GPI-anchored receptor that induces insertion into membrane microdomains and larvae death. In the case of mosquitocidal Bt strains, two different toxins participate, Cry and Cyt. These toxins have a synergistic effect and Cyt1Aa overcomes Cry toxin-resistance. We will summarize recent findings on the identification of Cry receptors in mosquitoes and the mechanism of synergism: Cyt1Aa synergizes or suppresses resistance to Cry toxins by functioning as a Cry membrane-bound receptor. PMID:17145072

  18. Flexibility Analysis of Bacillus thuringiensis Cry1Aa

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xin Min; XIA Li Qiu; YANG Xiao Ping; PENG Xiao Yun

    2015-01-01

    Objective To investigate the flexibility and mobility of the Bacillus thuringiensis toxin Cry1Aa. Methods The graph theory-based program Constraint Network Analysis and normal mode-based program NMsim were used to analyze the global and local flexibility indices as well as the fluctuation of individual residues in detail. Results The decrease in Cry1Aa network rigidity with the increase of temperature was evident. Two phase transition points in which the Cry1Aa structure lost rigidity during the thermal simulation were identified. Two rigid clusters were found in domains I and II. Weak spots were found in C-terminal domain III. Several flexible regions were found in all three domains;the largest residue fluctuation was present in the apical loop2 of domain II. Conclusion Although several flexible regions could be found in all the three domains, the most flexible regions were in the apical loops of domain II.

  19. Nanoscale imaging of Bacillus thuringiensis flagella using atomic force microscopy

    Science.gov (United States)

    Gillis, Annika; Dupres, Vincent; Delestrait, Guillaume; Mahillon, Jacques; Dufrêne, Yves F.

    2012-02-01

    Because bacterial flagella play essential roles in various processes (motility, adhesion, host interactions, secretion), studying their expression in relation to function is an important challenge. Here, we use atomic force microscopy (AFM) to gain insight into the nanoscale surface properties of two wild-type and four mutant strains of Bacillus thuringiensis exhibiting various levels of flagellation. We show that, unlike AFM in liquid, AFM in air is a simple and reliable approach to observe the morphological details of the bacteria, and to quantify the density and dimensions of their flagella. We found that the amount of flagella expressed by the six strains, as observed at the nanoscale, correlates with their microscopic swarming motility. These observations provide novel information on flagella expression in Gram-positive bacteria and demonstrate the power of AFM in genetic studies for the fast assessment of the phenotypic characteristics of bacterial strains altered in cell surface appendages.Because bacterial flagella play essential roles in various processes (motility, adhesion, host interactions, secretion), studying their expression in relation to function is an important challenge. Here, we use atomic force microscopy (AFM) to gain insight into the nanoscale surface properties of two wild-type and four mutant strains of Bacillus thuringiensis exhibiting various levels of flagellation. We show that, unlike AFM in liquid, AFM in air is a simple and reliable approach to observe the morphological details of the bacteria, and to quantify the density and dimensions of their flagella. We found that the amount of flagella expressed by the six strains, as observed at the nanoscale, correlates with their microscopic swarming motility. These observations provide novel information on flagella expression in Gram-positive bacteria and demonstrate the power of AFM in genetic studies for the fast assessment of the phenotypic characteristics of bacterial strains altered in

  20. Occurrence of Toxigenic Bacillus cereus and Bacillus thuringiensis in Doenjang, a Korean Fermented Soybean Paste.

    Science.gov (United States)

    Park, Kyung Min; Kim, Hyun Jung; Jeong, Moon Cheol; Koo, Minseon

    2016-04-01

    This study determined the prevalence and toxin profile of Bacillus cereus and Bacillus thuringiensis in doenjang, a fermented soybean food, made using both traditional and commercial methods. The 51 doenjang samples tested were broadly contaminated with B. cereus; in contrast, only one sample was positive for B. thuringiensis. All B. cereus isolates from doenjang were positive for diarrheal toxin genes. The frequencies of nheABC and hblACD in traditional samples were 22.7 and 0%, respectively, whereas 5.1 and 5.1% of B. cereus isolates from commercial samples possessed nheABC and hblACD, respectively. The detection rate of ces gene was 10.8%. The predominant toxin profile among isolates from enterotoxigenic B. cereus in doenjang was profile 4 (entFM-bceT-cytK). The major enterotoxin genes in emetic B. cereus were cytK, entFM, and nheA genes. The B. thuringiensis isolate was of the diarrheagenic type. These results provide a better understanding of the epidemiology of the enterotoxigenic and emetic B. cereus groups in Korean fermented soybean products.

  1. Binding site alteration is responsible for field-isolated resistance to Bacillus thuringiensis Cry2A insecticidal proteins in two Helicoverpa species.

    Directory of Open Access Journals (Sweden)

    Silvia Caccia

    Full Text Available BACKGROUND: Evolution of resistance by target pests is the main threat to the long-term efficacy of crops expressing Bacillus thuringiensis (Bt insecticidal proteins. Cry2 proteins play a pivotal role in current Bt spray formulations and transgenic crops and they complement Cry1A proteins because of their different mode of action. Their presence is critical in the control of those lepidopteran species, such as Helicoverpa spp., which are not highly susceptible to Cry1A proteins. In Australia, a transgenic variety of cotton expressing Cry1Ac and Cry2Ab (Bollgard II comprises at least 80% of the total cotton area. Prior to the widespread adoption of Bollgard II, the frequency of alleles conferring resistance to Cry2Ab in field populations of Helicoverpa armigera and Helicoverpa punctigera was significantly higher than anticipated. Colonies established from survivors of F(2 screens against Cry2Ab are highly resistant to this toxin, but susceptible to Cry1Ac. METHODOLOGY/PRINCIPAL FINDINGS: Bioassays performed with surface-treated artificial diet on neonates of H. armigera and H. punctigera showed that Cry2Ab resistant insects were cross-resistant to Cry2Ae while susceptible to Cry1Ab. Binding analyses with (125I-labeled Cry2Ab were performed with brush border membrane vesicles from midguts of Cry2Ab susceptible and resistant insects. The results of the binding analyses correlated with bioassay data and demonstrated that resistant insects exhibited greatly reduced binding of Cry2Ab toxin to midgut receptors, whereas no change in (125I-labeled-Cry1Ac binding was detected. As previously demonstrated for H. armigera, Cry2Ab binding sites in H. punctigera were shown to be shared by Cry2Ae, which explains why an alteration of the shared binding site would lead to cross-resistance between the two Cry2A toxins. CONCLUSION/SIGNIFICANCE: This is the first time that a mechanism of resistance to the Cry2 class of insecticidal proteins has been reported

  2. The Regulation of Exosporium-Related Genes in Bacillus thuringiensis

    Science.gov (United States)

    Peng, Qi; Kao, Guiwei; Qu, Ning; Zhang, Jie; Li, Jie; Song, Fuping

    2016-01-01

    Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis (Bt) are spore-forming members of the Bacillus cereus group. Spores of B. cereus group species are encircled by exosporium, which is composed of an external hair-like nap and a paracrystalline basal layer. Despite the extensive studies on the structure of the exosporium-related proteins, little is known about the transcription and regulation of exosporium gene expression in the B. cereus group. Herein, we studied the regulation of several exosporium-related genes in Bt. A SigK consensus sequence is present upstream of genes encoding hair-like nap proteins (bclA and bclB), basal layer proteins (bxpA, bxpB, cotB, and exsY ), and inosine hydrolase (iunH). Mutation of sigK decreased the transcriptional activities of all these genes, indicating that the transcription of these genes is controlled by SigK. Furthermore, mutation of gerE decreased the transcriptional activities of bclB, bxpB, cotB, and iunH but increased the expression of bxpA, and GerE binds to the promoters of bclB, bxpB, cotB, bxpA, and iunH. These results suggest that GerE directly regulates the transcription of these genes, increasing the expression of bclB, bxpB, cotB, and iunH and decreasing that of bxpA. These findings provide insight into the exosporium assembly process at the transcriptional level. PMID:26805020

  3. A 90 day safety assessment of genetically modified rice expressing Cry1Ab/1Ac protein using an aquatic animal model.

    Science.gov (United States)

    Zhu, Hao-Jun; Chen, Yi; Li, Yun-He; Wang, Jia-Mei; Ding, Jia-Tong; Chen, Xiu-Ping; Peng, Yu-Fa

    2015-04-15

    In fields of transgenic Bt rice, frogs are exposed to Bt proteins through consumption of both target and nontarget insects. In the present study, we assessed the risk posed by transgenic rice expressing a Cry1Ab/1Ac fusion protein (Huahui 1, HH1) on the development of Xenopus laevis. For 90 days, froglets were fed a diet with 30% HH1 rice, 30% parental rice (Minghui 63, MH63), or no rice as a control. Body weight and length were measured every 15 days. After sacrificing the froglets, we performed a range of biological, clinical, and pathological assessments. No significant differences were found in body weight (on day 90: 27.7 ± 2.17, 27.4 ± 2.40, and 27.9 ± 1.67 g for HH1, MH63, and control, respectively), body length (on day 90: 60.2 ± 1.55, 59.3 ± 2.33, and 59.7 ± 1.64 mm for HH1, MH63, and control, respectively), animal behavior, organ weight, liver and kidney function, or the microstructure of some tissues between the froglets fed on the HH1-containing diet and those fed on the MH63-containing or control diets. This indicates that frog development was not adversely affected by dietary intake of Cry1Ab/1Ac protein.

  4. Transport of Bacillus thuringiensis var. kurstaki via fomites.

    Science.gov (United States)

    Van Cuyk, Sheila; Veal, Lee Ann B; Simpson, Beverley; Omberg, Kristin M

    2011-09-01

    The intentional and controlled release of an aerosolized bacterium provides an opportunity to investigate the implications of a biological attack. Since 2006, Los Alamos National Laboratory has worked with several urban areas, including Fairfax County, VA, to design experiments to evaluate biodefense concepts of operations using routine spraying of Bacillus thuringiensis var. kurstaki (Btk). Btk is dispersed in large quantities as a slurry to control the gypsy moth, Lymantria dispar. Understanding whether personnel and equipment pick up residual contamination during sampling activities and transport it to other areas is critical for the formulation of appropriate response and recovery plans. While there is a growing body of literature surrounding the transmission of viral diseases via fomites, there is limited information on the transport of Bacillus species via this route. In 2008, LANL investigated whether field sampling activities conducted near sprayed areas, post-spray, resulted in measurable cross-contamination of sampling personnel, equipment, vehicles, and hotel rooms. Viable Btk was detected in all sample types, indicating transport of the agent occurred via fomites.

  5. Screening of Bacillus thuringiensis strains effective against mosquitoes Prospecção de estirpes de Bacillus thuringiensis efetivas contra mosquitos

    Directory of Open Access Journals (Sweden)

    Rose Gomes Monnerat

    2005-02-01

    Full Text Available The objective of this work was to evaluate 210 Bacillus thuringiensis strains against Aedes aegypti and Culex quinquefasciatus larvae to select the most effective. These strains were isolated from different regions of Brazil and are stored in a Bacillus spp. collection at Embrapa Recursos Genéticos e Biotecnologia, Brasília, Brazil. The selected strains were characterized by morphological (microscopy, biochemical (SDS-PAGE 10% and molecular (PCR methods. Six B. thuringiensis strains were identified as mosquito-toxic after the selective bioassays. None of the strains produced the expected PCR products for detection of cry4, cry11 and cyt1A genes. These results indicate that the activity of mosquitocidal Brazilian strains are not related with Cry4, Cry11 or Cyt proteins, so they could be used as an alternative bioinsecticide against mosquitoes.Neste trabalho foram realizados testes de patogenicidade com 210 estirpes de Bacillus thuringiensis contra larvas de Aedes aegypti e Culex quinquefasciatus, a fim de se determinar as mais eficazes. Estas estirpes foram isoladas de diversas regiões do Brasil e estão armazenadas na coleção de Bacillus spp. da Embrapa Recursos Genéticos e Biotecnologia. As estirpes selecionadas foram caracterizadas por métodos morfológicos (microscopia, bioquímicos (SDS-PAGE 10% e moleculares (Reação em Cadeia da Polimerase. Foram selecionadas seis estirpes entomopatogênicas de Bacillus thuringiensis. Nenhuma das estirpes de Bacillus thuringiensis apresentou produtos de PCR esperados para a detecção dos genes cry4, cry11 e cyt1A. A patogenicidade das estirpes não está associada à presença das toxinas Cry4, Cry11 ou Cyt, assim, essas estirpes poderão ser utilizadas para a formatação de um bioinseticida alternativo contra mosquitos.

  6. How Quorum Sensing Connects Sporulation to Necrotrophism in Bacillus thuringiensis.

    Science.gov (United States)

    Perchat, Stéphane; Talagas, Antoine; Poncet, Sandrine; Lazar, Noureddine; Li de la Sierra-Gallay, Inès; Gohar, Michel; Lereclus, Didier; Nessler, Sylvie

    2016-08-01

    Bacteria use quorum sensing to coordinate adaptation properties, cell fate or commitment to sporulation. The infectious cycle of Bacillus thuringiensis in the insect host is a powerful model to investigate the role of quorum sensing in natural conditions. It is tuned by communication systems regulators belonging to the RNPP family and directly regulated by re-internalized signaling peptides. One such RNPP regulator, NprR, acts in the presence of its cognate signaling peptide NprX as a transcription factor, regulating a set of genes involved in the survival of these bacteria in the insect cadaver. Here, we demonstrate that, in the absence of NprX and independently of its transcriptional activator function, NprR negatively controls sporulation. NprR inhibits expression of Spo0A-regulated genes by preventing the KinA-dependent phosphorylation of the phosphotransferase Spo0F, thus delaying initiation of the sporulation process. This NprR function displays striking similarities with the Rap proteins, which also belong to the RNPP family, but are devoid of DNA-binding domain and indirectly control gene expression via protein-protein interactions in Bacilli. Conservation of the Rap residues directly interacting with Spo0F further suggests a common inhibition of the sporulation phosphorelay. The crystal structure of apo NprR confirms that NprR displays a highly flexible Rap-like structure. We propose a molecular regulatory mechanism in which key residues of the bifunctional regulator NprR are directly and alternatively involved in its two functions. NprX binding switches NprR from a dimeric inhibitor of sporulation to a tetrameric transcriptional activator involved in the necrotrophic lifestyle of B. thuringiensis. NprR thus tightly coordinates sporulation and necrotrophism, ensuring survival and dissemination of the bacteria during host infection. PMID:27483473

  7. How Quorum Sensing Connects Sporulation to Necrotrophism in Bacillus thuringiensis.

    Science.gov (United States)

    Perchat, Stéphane; Talagas, Antoine; Poncet, Sandrine; Lazar, Noureddine; Li de la Sierra-Gallay, Inès; Gohar, Michel; Lereclus, Didier; Nessler, Sylvie

    2016-08-01

    Bacteria use quorum sensing to coordinate adaptation properties, cell fate or commitment to sporulation. The infectious cycle of Bacillus thuringiensis in the insect host is a powerful model to investigate the role of quorum sensing in natural conditions. It is tuned by communication systems regulators belonging to the RNPP family and directly regulated by re-internalized signaling peptides. One such RNPP regulator, NprR, acts in the presence of its cognate signaling peptide NprX as a transcription factor, regulating a set of genes involved in the survival of these bacteria in the insect cadaver. Here, we demonstrate that, in the absence of NprX and independently of its transcriptional activator function, NprR negatively controls sporulation. NprR inhibits expression of Spo0A-regulated genes by preventing the KinA-dependent phosphorylation of the phosphotransferase Spo0F, thus delaying initiation of the sporulation process. This NprR function displays striking similarities with the Rap proteins, which also belong to the RNPP family, but are devoid of DNA-binding domain and indirectly control gene expression via protein-protein interactions in Bacilli. Conservation of the Rap residues directly interacting with Spo0F further suggests a common inhibition of the sporulation phosphorelay. The crystal structure of apo NprR confirms that NprR displays a highly flexible Rap-like structure. We propose a molecular regulatory mechanism in which key residues of the bifunctional regulator NprR are directly and alternatively involved in its two functions. NprX binding switches NprR from a dimeric inhibitor of sporulation to a tetrameric transcriptional activator involved in the necrotrophic lifestyle of B. thuringiensis. NprR thus tightly coordinates sporulation and necrotrophism, ensuring survival and dissemination of the bacteria during host infection.

  8. Spider mite infestations reduce Bacillus thuringiensis toxin concentration in corn leaves and predators avoid spider mites that have fed on Bacillus thuringiensis corn

    Science.gov (United States)

    Transgenic crops containing pyramid-stacked genes for Bacillus thuringiensis derived toxins for controlling coleopteran and lepidopteran pests are increasingly common. As part of environmental risk assessments, these crops are evaluated for toxicity against non-target organisms, and for their poten...

  9. Environmental Distribution and Diversity of Insecticidal Proteins of Bacillus thuringiensis Berliner

    Directory of Open Access Journals (Sweden)

    Xavier, R.

    2007-01-01

    Full Text Available Bacillus thuringiensis Berliner based biopesticides have been successfully used world over for the control of agricultural pests and vectors of human diseases. Currently there are more than 200 B. thuringiensis strains with differing insecticidal activities are available as biocontrol agents and for developing transgenic plants. However, two major disadvantages are the development of insect resistance and high target specificity (narrow host range. Globally there is a continuous search for new B. thuringiensis strains with novel insecticidal activities. The present study aims to study the environmental distribution of B. thuringiensis and their toxic potential against insect pests. Soil and grain samples were collected from different environments and were processed by a modified acetate selection method. Initially B. thuringiensis isolates were screened on the basis of colony morphology and phase contrast microscopy for the presence of parasporal crystal inclusions. The population dynamics showed that B. thuringiensis is abundant in sericulture environment compared to other niches. Relative abundance of B. thuringiensis strains in sericulture environment shows the persistent association of B. thuringiensis with Bombyx mori (silk worm as insect pathogen. The protein profiles of the selected strains were studied by SDS-PAGE. The protein profiles of majority of B. thuringiensis isolates from grain storage facilities predominantly showing the 130 kDa and 68 kDa proteins, which is characteristics of lepidopteran active B. thuringiensis. However, one isolate BTRX-4 has 80-85 kDa protein, which is novel in that, this strain also exhibits antilepidopteran activity, which is normally presented by B. thuringiensis strains having 130 kDa and 68 kDa proteins. The protein profile of B. thuringiensis isolates from sericulture environment shows two different protein profiles. B. thuringiensis isolates BTRX-16 to BTRX-22 predominantly show 130 kDa protein

  10. Comparative genomics analysis of the companion mechanisms of Bacillus thuringiensis Bc601 and Bacillus endophyticus Hbe603 in bacterial consortium.

    Science.gov (United States)

    Jia, Nan; Ding, Ming-Zhu; Gao, Feng; Yuan, Ying-Jin

    2016-01-01

    Bacillus thuringiensis and Bacillus endophyticus both act as the companion bacteria, which cooperate with Ketogulonigenium vulgare in vitamin C two-step fermentation. Two Bacillus species have different morphologies, swarming motility and 2-keto-L-gulonic acid productivities when they co-culture with K. vulgare. Here, we report the complete genome sequencing of B. thuringiensis Bc601 and eight plasmids of B. endophyticus Hbe603, and carry out the comparative genomics analysis. Consequently, B. thuringiensis Bc601, with greater ability of response to the external environment, has been found more two-component system, sporulation coat and peptidoglycan biosynthesis related proteins than B. endophyticus Hbe603, and B. endophyticus Hbe603, with greater ability of nutrients biosynthesis, has been found more alpha-galactosidase, propanoate, glutathione and inositol phosphate metabolism, and amino acid degradation related proteins than B. thuringiensis Bc601. Different ability of swarming motility, response to the external environment and nutrients biosynthesis may reflect different companion mechanisms of two Bacillus species. Comparative genomic analysis of B. endophyticus and B. thuringiensis enables us to further understand the cooperative mechanism with K. vulgare, and facilitate the optimization of bacterial consortium. PMID:27353048

  11. Comparative genomics analysis of the companion mechanisms of Bacillus thuringiensis Bc601 and Bacillus endophyticus Hbe603 in bacterial consortium.

    Science.gov (United States)

    Jia, Nan; Ding, Ming-Zhu; Gao, Feng; Yuan, Ying-Jin

    2016-06-29

    Bacillus thuringiensis and Bacillus endophyticus both act as the companion bacteria, which cooperate with Ketogulonigenium vulgare in vitamin C two-step fermentation. Two Bacillus species have different morphologies, swarming motility and 2-keto-L-gulonic acid productivities when they co-culture with K. vulgare. Here, we report the complete genome sequencing of B. thuringiensis Bc601 and eight plasmids of B. endophyticus Hbe603, and carry out the comparative genomics analysis. Consequently, B. thuringiensis Bc601, with greater ability of response to the external environment, has been found more two-component system, sporulation coat and peptidoglycan biosynthesis related proteins than B. endophyticus Hbe603, and B. endophyticus Hbe603, with greater ability of nutrients biosynthesis, has been found more alpha-galactosidase, propanoate, glutathione and inositol phosphate metabolism, and amino acid degradation related proteins than B. thuringiensis Bc601. Different ability of swarming motility, response to the external environment and nutrients biosynthesis may reflect different companion mechanisms of two Bacillus species. Comparative genomic analysis of B. endophyticus and B. thuringiensis enables us to further understand the cooperative mechanism with K. vulgare, and facilitate the optimization of bacterial consortium.

  12. Instruction for evaluating deposit of bacillus thuringiensis formulas during aerial treatments. Information report No. LAU-X-54

    Energy Technology Data Exchange (ETDEWEB)

    Smirnoff, W.A.

    1982-01-01

    Studies carried out form many years revealed that the methods used for deposit assessment of chemical insecticides could not be used with Bacillus thuringiensis. A new method was developed giving the quantity of viable spores dispersed per surface unit. Details of this method are concisely described in this document. It specifically provides instructions for evaluating deposit of Bacillus thuringiensis formulas during aerial treatments.

  13. Draft Genome Sequence of Bacillus thuringiensis var. thuringiensis Strain T01-328, a Brazilian Isolate That Produces a Soluble Pesticide Protein, Cry1Ia

    OpenAIRE

    Varani, Alessandro M; Lemos, Manoel V.F.; Fernandes, Camila C.; Eliana G. M. Lemos; Alves, Eliane C. C.; Desidério, Janete A.

    2013-01-01

    Bacillus thuringiensis var. thuringiensis strain T01-328, isolated from Cubatão county (São Paulo State, Brazil), produces a soluble pesticide protein, Cry1Ia, during vegetative growth. Here, we report the 7.089-Mbp draft genome sequence, composed of a 5.5-Mb chromosome and 14 plasmids, which is the largest B. thuringiensis genome sequenced to date.

  14. Germination and conjugation of Bacillus thuringiensis subsp. israelensis in the intestine of gnotobiotic rats

    DEFF Research Database (Denmark)

    Wilcks, Andrea; Ørum-Smidt, Lasse; Bahl, Martin Iain;

    2008-01-01

    Aims: To study the ability of Bacillus thuringiensis subsp. israelensis spores to germinate and subsequently transfer a conjugative plasmid in the intestinal tract of gnotobiotic rats. Methods and Results: Germination was studied by feeding germ-free rats with spores of a B. thuringiensis strain...... the conjugative plasmid pXO16 was introduced. Both strains were given as spores and transfer of pXO16 was observed from the donor to the recipient strain. Conclusions: Bacillus thuringiensis is able to have a full life cycle in the intestine of gnotobiotic rats including germination of spores, several cycles...... harbouring a plasmid encoding green fluorescent protein (GFP), which enabled quantification of germinated bacteria by flow cytometry. To study in vivo conjugation, germ-free rats were first associated with a B. thuringiensis recipient strain and after 1 week an isogenic donor strain harbouring...

  15. Extended genetic analysis of Brazilian isolates of Bacillus cereus and Bacillus thuringiensis

    Science.gov (United States)

    Zahner, Viviane; Silva, Ana Carolina Telles de Carvalho e; de Moraes, Gabriela Pinhel; McIntosh, Douglas; de Filippis, Ivano

    2013-01-01

    Multiple locus sequence typing (MLST) was undertaken to extend the genetic characterization of 29 isolates of Bacillus cereus and Bacillus thuringiensis previously characterized in terms of presence/absence of sequences encoding virulence factors and via variable number tandem repeat (VNTR). Additional analysis involved polymerase chain reaction for the presence of sequences (be, cytK, inA, pag, lef, cya and cap), encoding putative virulence factors, not investigated in the earlier study. MLST analysis ascribed novel and unique sequence types to each of the isolates. A phylogenetic tree was constructed from a single sequence of 2,838 bp of concatenated loci sequences. The strains were not monophyletic by analysis of any specific housekeeping gene or virulence characteristic. No clear association in relation to source of isolation or to genotypic profile based on the presence or absence of putative virulence genes could be identified. Comparison of VNTR profiling with MLST data suggested a correlation between these two methods of genetic analysis. In common with the majority of previous studies, MLST was unable to provide clarification of the basis for pathogenicity among members of the B. cereus complex. Nevertheless, our application of MLST served to reinforce the notion that B. cereus and B. thuringiensis should be considered as the same species. PMID:23440117

  16. Extended genetic analysis of Brazilian isolates of Bacillus cereus and Bacillus thuringiensis

    Directory of Open Access Journals (Sweden)

    Viviane Zahner

    2013-02-01

    Full Text Available Multiple locus sequence typing (MLST was undertaken to extend the genetic characterization of 29 isolates of Bacillus cereus and Bacillus thuringiensis previously characterized in terms of presence/absence of sequences encoding virulence factors and via variable number tandem repeat (VNTR. Additional analysis involved polymerase chain reaction for the presence of sequences (be, cytK, inA, pag, lef, cya and cap, encoding putative virulence factors, not investigated in the earlier study. MLST analysis ascribed novel and unique sequence types to each of the isolates. A phylogenetic tree was constructed from a single sequence of 2,838 bp of concatenated loci sequences. The strains were not monophyletic by analysis of any specific housekeeping gene or virulence characteristic. No clear association in relation to source of isolation or to genotypic profile based on the presence or absence of putative virulence genes could be identified. Comparison of VNTR profiling with MLST data suggested a correlation between these two methods of genetic analysis. In common with the majority of previous studies, MLST was unable to provide clarification of the basis for pathogenicity among members of the B. cereus complex. Nevertheless, our application of MLST served to reinforce the notion that B. cereus and B. thuringiensis should be considered as the same species.

  17. Isolation and identification of some Bacillus thuringiensis strains with insecticidal activity against Ceratitis capitata

    International Nuclear Information System (INIS)

    The aims of the present work is to study the effect of toxins (delta-endotoxins), extracted from different strains of Bacillus thuringiensis on Ceratitis capitata, a devastating of citrus and fruit trees. Strains of B. thuringiensis were isolated from the mud of Sebket Sejoumi. Among 70 isolates tested, 15 showed a significant identicalness activity in which 5 isolates led to mortality rates ≥ 90 pour cent . These mortality rates are caused by endotoxins of B. thuringiensis. Analysis of proteins profiles of different isolates of B. thuringiensis revealed variability between them. The preliminary results of this study encourage us towards the characterization of the insecticidal activity produced by B. thuringiensis strains for large scale application.

  18. Persistence of Bacillus thuringiensis bioinsecticides in the gut of human-flora-associated rats

    DEFF Research Database (Denmark)

    Wilcks, Andrea; Hansen, Bjarne Munk; Hendriksen, Niels Bohse;

    2006-01-01

    The capability of two bioinsecticide strains of Bacillus thuringiensis (ssp. israelensis and ssp. kurstaki) to germinate and persist in vivo in the gastrointestinal tract of human-flora-associated rats was studied. Rats were dosed either with vegetative cells or spores of the bacteria for 4...... consecutive days. In animals fed spores, B. thuringiensis cells were detected in faecal and intestinal samples of all animals, whereas vegetative cells only poorly survived the gastric passage. Heat-treatment of intestinal samples, which kills vegetative cells, revealed that B. thuringiensis spores were...... capable of germination in the gastrointestinal tract. In one animal fed spores of B. thuringiensis ssp. kurstaki, these bacteria were detected at high density (10(3)-10(4) CFU g(-1) faecal and intestinal samples) even 2 weeks after the last dosage. In the same animal, passage of B. thuringiensis ssp...

  19. IS231A from Bacillus thuringiensis is functional in Escherichia coli: transposition and insertion specificity.

    OpenAIRE

    Hallet, Bernard; Rezsohazy, René; Delcour, Jean

    1991-01-01

    A kanamycin resistance gene was introduced within the insertion sequence IS231A from Bacillus thuringiensis, and transposition of the element was demonstrated in Escherichia coli. DNA sequencing at the target sites showed that IS231A transposition results in direct repeats of variable lengths (10, 11, and 12 bp). These target sequences resemble the terminal inverted repeats of the transposon Tn4430, which are the preferred natural insertion sites of IS231 in B. thuringiensis.

  20. Incorporation of Specific Fatty Acid Precursors During Spore Germination and Outgrowth in Bacillus thuringiensis

    OpenAIRE

    Nickerson, Kenneth W.; Bulla, Lee A

    1980-01-01

    The selective incorporation of precursors specific for individual fatty acids in germinating and outgrowing spores of Bacillus thuringiensis is described. The specific precursors utilized were [14C]butyrate, -isobutyrate, -valerate, and -isovalerate, which were incorporated into even-numbered normal-chain isomers, even-numbered iso-isomers, odd-numbered normal-chain acids, and odd-numbered isohomologs, respectively. This preferential incorporation by B. thuringiensis allows the terminal carbo...

  1. Binding of Bacillus thuringiensis proteins to a laboratory-selected line of Heliothis virescens.

    OpenAIRE

    MacIntosh, S C; Stone, T B; Jokerst, R S; Fuchs, R L

    1991-01-01

    A laboratory-selected colony of Heliothis virescens displaying a 20- to 70-fold level of resistance to Bacillus thuringiensis proteins was evaluated to identify mechanism(s) of resistance. Brush-border membrane vesicles were isolated from larval midgut epithelium from the susceptible and resistant strains of H. virescens. Two B. thuringiensis proteins, CryIA(b) and CryIA(c), were iodinated and shown to specifically bind to brush-border membrane vesicles of both insect strains. Multiple change...

  2. Shared Binding Sites in Lepidoptera for Bacillus thuringiensis Cry1Ja and Cry1A Toxins

    OpenAIRE

    Herrero, Salvador; González-Cabrera, Joel; Tabashnik, Bruce E; Ferré, Juan

    2001-01-01

    Bacillus thuringiensis toxins act by binding to specific target sites in the insect midgut epithelial membrane. The best-known mechanism of resistance to B. thuringiensis toxins is reduced binding to target sites. Because alteration of a binding site shared by several toxins may cause resistance to all of them, knowledge of which toxins share binding sites is useful for predicting cross-resistance. Conversely, cross-resistance among toxins suggests that the toxins share a binding site. At lea...

  3. The ecological roles of Bacillus thuringiensis within phyllosphere environments.

    Science.gov (United States)

    Wang, Xiaoxian; Xue, Yarong; Han, Meizhe; Bu, Yuanqing; Liu, Changhong

    2014-08-01

    Bacillus thuringiensis (Bt) is one of the most used bio-control agents to control plant insects, but little is known about its effect on the microbial population and communities on plant leaves. With the culture dependent method, it has been observed that the dynamics of Bt within the phyllosphere varied dependent on both the doses of Bt sprayed on the leaves and the plant species, however, Bt's population size kept stable at about 1000 cfu g(-1) after 15 d since inoculation. By comparing the bacterial abundances and community structures within the phyllosphere of three plant species, we confirmed that Bt at the doses of 1.5×10(7) and 1.5×10(9) cfu mL(-1) respectively did not significantly influence the natural bacterial population size on the leaf surfaces based on culture dependent assay. However, based on culture independent denaturing gradient gel electrophoresis (DGGE), Shannon-Wiener index (H') and Unweighted Pair Group Method with Arithmetic Mean (UPGMA) analysis, Bt has a significant influence on the bacterial communities within the phyllosphere of amaranth and cotton, but not rice. These results indicate that Bt exhibits different behaviors and ecological roles on the microbial diversity within the phyllosphere, and its environmental safety has to be concerned and evaluated in the future. PMID:24534157

  4. Bacillus thuringiensis: fermentation process and risk assessment: a short review

    Directory of Open Access Journals (Sweden)

    Deise M. F Capalbo

    1995-02-01

    Full Text Available Several factors make the local production of Bacillus thuringiensis (Bt highly appropriate for pest control in developing nations. Bt can be cheaply produced on a wide variety of low cost, organic substrates. Local production results in considerable savings in hard currency which otherwise would be spent on importation of chemical and biological insecticides. The use of Bt in Brazil has been limited in comparison with chemical insecticides. Although Bt is imported, some Brazilian researchers have been working on its development and production. Fermentation processes (submerged and semi-solid were applied, using by-products from agro-industries. As the semi-solid fermentation process demonstrated to be interesting for Bt endotoxins production, it could be adopted for small scale local production. Although promising results had been achieved, national products have not been registered due to the absence of a specific legislation for biological products. Effective actions are being developed in order to solve this gap. Regardless of the biocontrol agents being considered atoxic and harmless to the environment, information related to direct and indirect effects of microbials are still insufficient in many cases. The risk analysis of the use of microbial control agents is of upmost importance nowadays, and is also discussed.

  5. Continuous evolution of Bacillus thuringiensis toxins overcomes insect resistance.

    Science.gov (United States)

    Badran, Ahmed H; Guzov, Victor M; Huai, Qing; Kemp, Melissa M; Vishwanath, Prashanth; Kain, Wendy; Nance, Autumn M; Evdokimov, Artem; Moshiri, Farhad; Turner, Keith H; Wang, Ping; Malvar, Thomas; Liu, David R

    2016-05-01

    The Bacillus thuringiensis δ-endotoxins (Bt toxins) are widely used insecticidal proteins in engineered crops that provide agricultural, economic, and environmental benefits. The development of insect resistance to Bt toxins endangers their long-term effectiveness. Here we have developed a phage-assisted continuous evolution selection that rapidly evolves high-affinity protein-protein interactions, and applied this system to evolve variants of the Bt toxin Cry1Ac that bind a cadherin-like receptor from the insect pest Trichoplusia ni (TnCAD) that is not natively bound by wild-type Cry1Ac. The resulting evolved Cry1Ac variants bind TnCAD with high affinity (dissociation constant Kd = 11-41 nM), kill TnCAD-expressing insect cells that are not susceptible to wild-type Cry1Ac, and kill Cry1Ac-resistant T. ni insects up to 335-fold more potently than wild-type Cry1Ac. Our findings establish that the evolution of Bt toxins with novel insect cell receptor affinity can overcome insect Bt toxin resistance and confer lethality approaching that of the wild-type Bt toxin against non-resistant insects. PMID:27120167

  6. Role of receptors in Bacillus thuringiensis crystal toxin activity.

    Science.gov (United States)

    Pigott, Craig R; Ellar, David J

    2007-06-01

    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. PMID:17554045

  7. Continuous evolution of Bacillus thuringiensis toxins overcomes insect resistance.

    Science.gov (United States)

    Badran, Ahmed H; Guzov, Victor M; Huai, Qing; Kemp, Melissa M; Vishwanath, Prashanth; Kain, Wendy; Nance, Autumn M; Evdokimov, Artem; Moshiri, Farhad; Turner, Keith H; Wang, Ping; Malvar, Thomas; Liu, David R

    2016-05-01

    The Bacillus thuringiensis δ-endotoxins (Bt toxins) are widely used insecticidal proteins in engineered crops that provide agricultural, economic, and environmental benefits. The development of insect resistance to Bt toxins endangers their long-term effectiveness. Here we have developed a phage-assisted continuous evolution selection that rapidly evolves high-affinity protein-protein interactions, and applied this system to evolve variants of the Bt toxin Cry1Ac that bind a cadherin-like receptor from the insect pest Trichoplusia ni (TnCAD) that is not natively bound by wild-type Cry1Ac. The resulting evolved Cry1Ac variants bind TnCAD with high affinity (dissociation constant Kd = 11-41 nM), kill TnCAD-expressing insect cells that are not susceptible to wild-type Cry1Ac, and kill Cry1Ac-resistant T. ni insects up to 335-fold more potently than wild-type Cry1Ac. Our findings establish that the evolution of Bt toxins with novel insect cell receptor affinity can overcome insect Bt toxin resistance and confer lethality approaching that of the wild-type Bt toxin against non-resistant insects.

  8. Bacillus thuringiensis Toxins: An Overview of Their Biocidal Activity

    Science.gov (United States)

    Palma, Leopoldo; Muñoz, Delia; Berry, Colin; Murillo, Jesús; Caballero, Primitivo

    2014-01-01

    Bacillus thuringiensis (Bt) is a Gram positive, spore-forming bacterium that synthesizes parasporal crystalline inclusions containing Cry and Cyt proteins, some of which are toxic against a wide range of insect orders, nematodes and human-cancer cells. These toxins have been successfully used as bioinsecticides against caterpillars, beetles, and flies, including mosquitoes and blackflies. Bt also synthesizes insecticidal proteins during the vegetative growth phase, which are subsequently secreted into the growth medium. These proteins are commonly known as vegetative insecticidal proteins (Vips) and hold insecticidal activity against lepidopteran, coleopteran and some homopteran pests. A less well characterized secretory protein with no amino acid similarity to Vip proteins has shown insecticidal activity against coleopteran pests and is termed Sip (secreted insecticidal protein). Bin-like and ETX_MTX2-family proteins (Pfam PF03318), which share amino acid similarities with mosquitocidal binary (Bin) and Mtx2 toxins, respectively, from Lysinibacillus sphaericus, are also produced by some Bt strains. In addition, vast numbers of Bt isolates naturally present in the soil and the phylloplane also synthesize crystal proteins whose biological activity is still unknown. In this review, we provide an updated overview of the known active Bt toxins to date and discuss their activities. PMID:25514092

  9. Raman spectroscopy of Bacillus thuringiensis physiology and inactivation

    Science.gov (United States)

    Morrow, J. B.; Almeida, J.; Cole, K. D.; Reipa, V.

    2012-12-01

    The ability to detect spore contamination and inactivation is relevant to developing and determining decontamination strategy success for food and water safety. This study was conducted to develop a systematic comparison of nondestructive vibrational spectroscopy techniques (Surface-Enhanced Raman Spectroscopy, SERS, and normal Raman) to determine indicators of Bacillus thuringiensis physiology (spore, vegetative, outgrown, germinated and inactivated spore forms). SERS was found to provide better resolution of commonly utilized signatures of spore physiology (dipicolinic acid at 1006 cm-1 and 1387 cm-1) compared to normal Raman and native fluorescence indigenous to vegetative and outgrown cell samples was quenched in SERS experiment. New features including carotenoid pigments (Raman features at 1142 cm-1, 1512 cm-1) were identified for spore cell forms. Pronounced changes in the low frequency region (300 cm-1 to 500 cm-1) in spore spectra occurred upon germination and inactivation (with both free chlorine and by autoclaving) which is relevant to guiding decontamination and detection strategies using Raman techniques.

  10. Adhesion of Spores of Bacillus thuringiensis on a Planar Surface

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Eunhyea [Georgia Institute of Technology; Kweon, Hyojin [Georgia Institute of Technology; Yiacoumi, Sotira [Georgia Institute of Technology; Lee, Ida [University of Tennessee, Knoxville (UTK); Joy, David Charles [ORNL; Palumbo, Anthony Vito [ORNL; Tsouris, Costas [ORNL

    2010-01-01

    Adhesion of spores of Bacillus thuringiensis (Bt) and spherical silica particles on surfaces was experimentally and theoretically investigated in this study. Topography analysis via atomic force microscopy (AFM) and electron microscopy indicates that Bt spores are rod shaped, {approx}1.3 {mu}m in length and {approx}0.8 {mu}m in diameter. The adhesion force of Bt spores and silica particles on gold-coated glass was measured at various relative humidity (RH) levels by AFM. It was expected that the adhesion force would vary with RH because the individual force components contributing to the adhesion force depend on RH. The adhesion force between a particle and a planar surface in atmospheric environments was modeled as the contribution of three major force components: capillary, van der Waals, and electrostatic interaction forces. Adhesion force measurements for Bt spore (silica particle) and the gold surface system were comparable with calculations. Modeling results show that there is a critical RH value, which depends on the hydrophobicity of the materials involved, below which the water meniscus does not form and the contribution of the capillary force is zero. As RH increases, the van der Waals force decreases while the capillary force increases to a maximum value.

  11. PROFILIN ACTIVATES BACILLUS THURINGIENSIS PHOSPHOINOSITIDE SPECIFIC PHOSPHOLIPASE C

    Directory of Open Access Journals (Sweden)

    Sandeepta Burgula

    2012-08-01

    Full Text Available Many extracellular signaling molecules including hormones, growth factors, neurotransmitters andimmunoglobulins elicit intracellular responses by activating phosphatidylinositol-specific phospholipase C (PI-PLCupon binding to their cell surface receptors. Activated PLC catalyses the hydrolysis of Phosphotidylinositol 4,5-bisphosphate (PIP2 to generate DAG and IP3 , which act as signaling molecules that control various cellular processes.Exploring the mechanism of regulation of PLC activity may lead to understanding various signaling events thatregulate cell growth and differentiation. One of the dramatic effects of profilin is inhibition of PIP2 hydrolysis by PLC-γ in eukaryotic cells. In the present study, the effect of profilin on Phosphotidylinositol specific phospholipase C (PI-PLC purified from Bacillus thuringiensis (Bt was examined. Assay of PI-PLC activity indicated that Bovine profilinactivated the hydrolysis of phosphotidylinositol (PI by BtPI-PLC in a concentration dependent manner under in vitroconditions. A 250 % increase in activity was noted in the presence of profilin but not in presence of phosphoprofilin. Inthe presence of profilin more proteins are observed in the soluble fraction. In conclusion it can be stated that thatprofilin activates bacterial PLC activity towards PI hydrolysis

  12. The impact of secondary pests on Bacillus thuringiensis (Bt) crops.

    Science.gov (United States)

    Catarino, Rui; Ceddia, Graziano; Areal, Francisco J; Park, Julian

    2015-06-01

    The intensification of agriculture and the development of synthetic insecticides enabled worldwide grain production to more than double in the last third of the 20th century. However, the heavy dependence and, in some cases, overuse of insecticides has been responsible for negative environmental and ecological impacts across the globe, such as a reduction in biodiversity, insect resistance to insecticides, negative effects on nontarget species (e.g. natural enemies) and the development of secondary pests. The use of recombinant DNA technology to develop genetically engineered insect-resistant crops could mitigate many of the negative side effects of insecticides. One such genetic alteration enables crops to express toxic crystalline (Cry) proteins from the soil bacteria Bacillus thuringiensis (Bt). Despite the widespread adoption of Bt crops, there are still a range of unanswered questions concerning longer term agro-ecosystem interactions. For instance, insect species that are not susceptible to the expressed toxin can develop into secondary pests and cause significant damage to the crop. Here, we review the main causes surrounding secondary pest dynamics in Bt crops and the impact of such outbreaks. Regardless of the causes, if nonsusceptible secondary pest populations exceed economic thresholds, insecticide spraying could become the immediate solution at farmers' disposal, and the sustainable use of this genetic modification technology may be in jeopardy. Based on the literature, recommendations for future research are outlined that will help to improve the knowledge of the possible long-term ecological trophic interactions of employing this technology. PMID:25832330

  13. The complete genome sequence of Bacillus thuringiensis serovar Hailuosis YWC2-8.

    Science.gov (United States)

    Zhu, Jun; Zhang, Qinbin; Cao, Ye; Li, Qiao; Zhu, Zizhong; Wang, Linxia; Li, Ping

    2016-02-10

    Bacillus thuringiensis, a typical aerobic, Gram-positive, spore-forming bacterium, is an important microbial insecticide widely used in the control of agricultural pests. B. thuringiensis serovar Hailuosis YWC2-8 with high insecticidal activity against Diptera and Lepidoptera insects has three insecticidal crystal protein genes, such as cry4Cb2, cry30Ea2, and cry56Aa1. In this study, the complete genome sequence of B. thuringiensis YWC2-8 was analyzed, which contains one circular gapless chromosome and six circular plasmids.

  14. Microcalorimetric Study of the Biological Effects of Zn+ on Bacillus thuringiensis Growth

    Institute of Scientific and Technical Information of China (English)

    姚俊; 刘义; 等

    2002-01-01

    A microcalorimetric technique was used to investigate the influence of Zn2+ on the growth metabolism of Bacillus thuringiensis .LKB-2277 Bioactivity Monitor was employed to obtain the power-time curves,from which the maximum peak-heat output power(Pmax) in the log phase,the growth rate constants(k), the inhibitory ratios(I) ,the generational time(tG) and the total heat effect (Qtotal) in 23 h for the growth metabolism of Bacillus thuringiensis at 28℃ can be evaluated,The results indicate that the concentration of Zn2+ affects its growth obviously,Low concentration (0-50μg/mL) of Zn2+ promotes the growth of Bacillus thuringiensis while high concentration (50-500μg/mL) of Zn2+ inhibits its growth .When the concentration reached up to 600μg/mL,it can not grow at all.

  15. Microcalorimetric Study of the Biological Effects of Zn2+ on Bacillus thuringiensis Growth

    Institute of Scientific and Technical Information of China (English)

    YAO,Jun(姚俊); LIU,Yi(刘义); GAO,Zhen-Ting(高振霆); LIU,Peng(刘鹏); SUN,Ming(孙明); ZOU,xueb(邹雪); QU,Song-Sheng(屈松生); YU,Zi-Niu(喻子牛)

    2002-01-01

    A microcalorimetric technique was used to investigate the influence of Zn2 + on the growth metabolism of Bacillus thuringiensis. LKB-2277 Bioaciivity Monitor was employed to obtain the power-iime curves, from which the maximum peak-heat output power(Pmax) in the log phase, the growth rate constants (k),the inhibitory raiios (Ⅰ), the generational time (tG) and the total heat effect (Qtotal) in 23 h for the growth metabolism of Bacillus thuringiensis at 28 ℃ can be evaluated. The results indicate that the concentration of Zn2+ affects its growth obviously. Low concentration (0-50 μg/mL) of Zn2 + promotes the growth of Bacillus thuringiensis while high concentration (50-500 μg/mL) of Zn2 + inhibits its growth. When the concentration reached up to 600 μg/mL, it can not grow at all.

  16. Study of Thermokinetic Properties of Sodium Selenite on Bacillus thuringiensis Cry B by Microcalorimetry

    Institute of Scientific and Technical Information of China (English)

    LI,Xi; LIU,Yi; ZHAO,Ru-Ming; YU,Zi-Niu; QU Song-Sheng

    2001-01-01

    By using an LKB2277 Bioactivity Monitor, the power-time curves of Bacillus thuringiensis Cry B at 28℃ effected by Na2SeO3 were determined. Some paarameters, such as growh rate constant k, inhibitory ratio I, the maximum heat production rate Pmax, heat output Q, were obtained. Considering both the growth rate constant k and heat output Q, it was found that a low concentration of Na2SeO3 had a promoting action on the growth of Bacillus thuringiensis Cry B, but a high concentration of Na2SeO3 had an inhibitory action.

  17. Spatio-Temporal Evolution of Sporulation in Bacillus thuringiensis Biofilm.

    Science.gov (United States)

    El-Khoury, Nay; Majed, Racha; Perchat, Stéphane; Kallassy, Mireille; Lereclus, Didier; Gohar, Michel

    2016-01-01

    Bacillus thuringiensis can produce a floating biofilm which includes two parts: a ring and a pellicle. The ring is a thick structure which sticks to the culture container, while the pellicle extends over the whole liquid surface and joins the ring. We have followed over time, from 16 to 96 h, sporulation in the two biofilm parts. Sporulation was followed in situ in 48-wells polystyrene microtiterplates with a fluorescence binocular stereomicroscope and a spoIID-yfp transcriptional fusion. Sporulation took place much earlier in the ring than in the pellicle. In 20 h-aged biofilms, spoIID was expressed only in the ring, which could be seen as a green fluorescent circle surrounding the non-fluorescent pellicle. However, after 48 h of culture, the pellicle started to express spoIID in specific area corresponding to protrusions, and after 96 h both the ring and the whole pellicle expressed spoIID. Spore counts and microscopy observations of the ring and the pellicle harvested separately confirmed these results and revealed that sporulation occured 24 h-later in the pellicle comparatively to the ring, although both structures contained nearly 100% spores after 96 h of culture. We hypothesize that two mechanisms, due to microenvironments in the biofilm, can explain this difference. First, the ring experiences a decreased concentration of nutrients earlier than the pellicle, because of a lower exchange area with the culture medium. An second, the ring is exposed to partial dryness. Both reasons could speed up sporulation in this biofilm structure. Our results also suggest that spores in the biofilm display a phenotypic heterogeneity. These observations might be of particular significance for the food industry, since the biofilm part sticking to container walls - the ring - is likely to contain spores and will therefore resist both to washing and to cleaning procedures, and will be able to restart a new biofilm when food production has resumed.

  18. Spatio-Temporal Evolution of Sporulation in Bacillus thuringiensis Biofilm.

    Science.gov (United States)

    El-Khoury, Nay; Majed, Racha; Perchat, Stéphane; Kallassy, Mireille; Lereclus, Didier; Gohar, Michel

    2016-01-01

    Bacillus thuringiensis can produce a floating biofilm which includes two parts: a ring and a pellicle. The ring is a thick structure which sticks to the culture container, while the pellicle extends over the whole liquid surface and joins the ring. We have followed over time, from 16 to 96 h, sporulation in the two biofilm parts. Sporulation was followed in situ in 48-wells polystyrene microtiterplates with a fluorescence binocular stereomicroscope and a spoIID-yfp transcriptional fusion. Sporulation took place much earlier in the ring than in the pellicle. In 20 h-aged biofilms, spoIID was expressed only in the ring, which could be seen as a green fluorescent circle surrounding the non-fluorescent pellicle. However, after 48 h of culture, the pellicle started to express spoIID in specific area corresponding to protrusions, and after 96 h both the ring and the whole pellicle expressed spoIID. Spore counts and microscopy observations of the ring and the pellicle harvested separately confirmed these results and revealed that sporulation occured 24 h-later in the pellicle comparatively to the ring, although both structures contained nearly 100% spores after 96 h of culture. We hypothesize that two mechanisms, due to microenvironments in the biofilm, can explain this difference. First, the ring experiences a decreased concentration of nutrients earlier than the pellicle, because of a lower exchange area with the culture medium. An second, the ring is exposed to partial dryness. Both reasons could speed up sporulation in this biofilm structure. Our results also suggest that spores in the biofilm display a phenotypic heterogeneity. These observations might be of particular significance for the food industry, since the biofilm part sticking to container walls - the ring - is likely to contain spores and will therefore resist both to washing and to cleaning procedures, and will be able to restart a new biofilm when food production has resumed. PMID:27536298

  19. Screeninq on Synergist of Bacillus thuringiensis Wettable Powder

    Institute of Scientific and Technical Information of China (English)

    Donghua GE; Xiaohong ZHANG; Ziyan NANGONG; Ping SONG; Qinying WANG; Keqiang CAO

    2012-01-01

    [Objective] This study aimed to screen the best synergistic material for Bt wettable powder and evaluate their synergistic effect. [Method] The synergism of six different kinds of additives for Bacillus thuringiensis wettable powder (Bt WP) on the 2^nd instar larvae of Plutella xylostella was tested by method of leaf dipping in labora- tory. [Result] The mixtures of Bt with 0.1% ZnCl2, 0.5% ZnCl2, 1.0% ZnCl2, 1.0% MgCI2, 0.5% boric acid, 1.0% boric acid, 0.5% citric acid or 1.0% citric acid all ex- hibited synergistic effect, in which the synergistic effect of mixture containing 0.5% boric acid was the highest, with 17.2 synergistic ratio; followed by the mixture containing 1.0% ZnCl2, with 15.6 synergistic ratio. Moreover, addition of 0.5% boric acid could shorten the median lethal time of Bt wettable powder by about 10 h. After the mixtures of Bt with 0.5% boracic acid or 1.0% ZnCl2 was stored for 15 d at room temperature, toxicities of the two mixtures did not change significantly. [Conclusion] Boracic acid as the synergist of Bt wettable powder could not only increase insecti- cidal effect of Bt, but also accelerate its insecticidal rate. So, boracic acid could improve the disadvantages of Bt wettable powder such as poor insecticidal effect and slow insecticidal speed in a certain degree.

  20. Spatio-Temporal Evolution of Sporulation in Bacillus thuringiensis Biofilm

    Science.gov (United States)

    El-Khoury, Nay; Majed, Racha; Perchat, Stéphane; Kallassy, Mireille; Lereclus, Didier; Gohar, Michel

    2016-01-01

    Bacillus thuringiensis can produce a floating biofilm which includes two parts: a ring and a pellicle. The ring is a thick structure which sticks to the culture container, while the pellicle extends over the whole liquid surface and joins the ring. We have followed over time, from 16 to 96 h, sporulation in the two biofilm parts. Sporulation was followed in situ in 48-wells polystyrene microtiterplates with a fluorescence binocular stereomicroscope and a spoIID-yfp transcriptional fusion. Sporulation took place much earlier in the ring than in the pellicle. In 20 h-aged biofilms, spoIID was expressed only in the ring, which could be seen as a green fluorescent circle surrounding the non-fluorescent pellicle. However, after 48 h of culture, the pellicle started to express spoIID in specific area corresponding to protrusions, and after 96 h both the ring and the whole pellicle expressed spoIID. Spore counts and microscopy observations of the ring and the pellicle harvested separately confirmed these results and revealed that sporulation occured 24 h-later in the pellicle comparatively to the ring, although both structures contained nearly 100% spores after 96 h of culture. We hypothesize that two mechanisms, due to microenvironments in the biofilm, can explain this difference. First, the ring experiences a decreased concentration of nutrients earlier than the pellicle, because of a lower exchange area with the culture medium. An second, the ring is exposed to partial dryness. Both reasons could speed up sporulation in this biofilm structure. Our results also suggest that spores in the biofilm display a phenotypic heterogeneity. These observations might be of particular significance for the food industry, since the biofilm part sticking to container walls – the ring – is likely to contain spores and will therefore resist both to washing and to cleaning procedures, and will be able to restart a new biofilm when food production has resumed. PMID:27536298

  1. Potencial de Bacillus thuringiensis israelensis Berliner no controle de Aedes aegypti Potential of Bacillus thuringiensis israelensis Berliner for controlling Aedes aegypti

    Directory of Open Access Journals (Sweden)

    Ricardo Antonio Polanczyk

    2003-12-01

    Full Text Available Relata-se a importância da bactéria entomopatogênica Bacillus thuringiensis israelensis para o controle de Aedes aegypti. São abordados a utilização e potencial de B. thuringiensis israelensis contra o mosquito vetor da dengue. Outros aspectos são discutidos como a evolução da resistência dos insetos em relação aos inseticidas químicos e as vantagens e desvantagens do controle microbiano como estratégia de controle. É dada ênfase à importância da utilização desta bactéria no Brasil como alternativa para resolver o problema em questão sem afetar o ambiente, o homem e outros vertebrados nas áreas de risco.The importance of the entomopathogenic bacterium Bacillus thuringiensis israelensis in the control of Aedes aegypti is presented. The use and potential of B. thuringiensis israelensis against the mosquito vector of dengue fever is described. Other aspects such as insect's resistance development against chemicals and advantages and constraints of using microbial control are discussed. Emphasis is given to the importance of the use of this bacterium in Brazil, which could contribute significantly to solving the mosquito problem without affecting the environment, humans and others invertebrate organisms in critical regions.

  2. Effect of Bacillus thuringiensis on microbial functional groups in sorghum rhizosphere Efeito do Bacillus thuringiensis sobre grupos funcionais de microrganismos na rizosfera de sorgo

    Directory of Open Access Journals (Sweden)

    Carlos Brasil

    2006-05-01

    Full Text Available The objective of this work was to assess the effect of two strains of Bacillus thuringiensis var. kurstaki on sorghum rhizosphere microorganisms. The strains were HD1, that produces the bioinsecticidal protein, and 407, that is a mutant non-producer. The strains do not influence microbial population, but reduce plant growth and improve mycorrhizal colonization and free living fixing N2 community.O objetivo deste trabalho foi avaliar o efeito de duas cepas de Bacillus thuringiensis var. kurstaki sobre microrganismos na rizosfera do sorgo. As cepas foram a HD1, produtora do cristal bioinseticida, e a 407, uma mutante não-produtora. As duas cepas não influenciam a comunidade microbiana, mas reduzem o crescimento da planta. A colonização micorrízica e a população de fixadores de N2 de vida livre aumentaram.

  3. Estructura tridimensional de las toxinas de Bacillus thuringiensis: revisión Three dimensional structure of Bacillus thuringiensis toxins: a review

    Directory of Open Access Journals (Sweden)

    Cerón Salamanca JA.

    2007-08-01

    Full Text Available La ingeniería de proteínas de las d-endotoxinas de Bacillus thuringiensis puede orientar la búsqueda de variantes con un espectro mayor de especies susceptibles, potencia optimizada, y estabilidad apropiada. Aquí, nosotros revisamos las características más importantes de la estructura tridimensional de las proteínas Cry y Cyt. Es posible concluir que existe un modelo general obvio con propiedades específicas de acuerdo a su función y organismo susceptible.Structure-based protein engineering of Bacillus thuringiensis d-endotoxins may direct the search for variants with broader susceptible species spectra, optimal potency, and stability properties. Here, we revised the more important characteristics of the Cry and Cyt proteins three-dimensional structure; it is possible to conclude that an obvious general model exists with specific properties according to its function and target organism.

  4. Contributions of gut bacteria to Bacillus thuringiensis-induced mortality vary across a range of Lepidoptera

    Directory of Open Access Journals (Sweden)

    Holt Jonathan

    2009-03-01

    Full Text Available Abstract Background Gut microbiota contribute to the health of their hosts, and alterations in the composition of this microbiota can lead to disease. Previously, we demonstrated that indigenous gut bacteria were required for the insecticidal toxin of Bacillus thuringiensis to kill the gypsy moth, Lymantria dispar. B. thuringiensis and its associated insecticidal toxins are commonly used for the control of lepidopteran pests. A variety of factors associated with the insect host, B. thuringiensis strain, and environment affect the wide range of susceptibilities among Lepidoptera, but the interaction of gut bacteria with these factors is not understood. To assess the contribution of gut bacteria to B. thuringiensis susceptibility across a range of Lepidoptera we examined larval mortality of six species in the presence and absence of their indigenous gut bacteria. We then assessed the effect of feeding an enteric bacterium isolated from L. dispar on larval mortality following ingestion of B. thuringiensis toxin. Results Oral administration of antibiotics reduced larval mortality due to B. thuringiensis in five of six species tested. These included Vanessa cardui (L., Manduca sexta (L., Pieris rapae (L. and Heliothis virescens (F. treated with a formulation composed of B. thuringiensis cells and toxins (DiPel, and Lymantria dispar (L. treated with a cell-free formulation of B. thuringiensis toxin (MVPII. Antibiotics eliminated populations of gut bacteria below detectable levels in each of the insects, with the exception of H. virescens, which did not have detectable gut bacteria prior to treatment. Oral administration of the Gram-negative Enterobacter sp. NAB3, an indigenous gut resident of L. dispar, restored larval mortality in all four of the species in which antibiotics both reduced susceptibility to B. thuringiensis and eliminated gut bacteria, but not in H. virescens. In contrast, ingestion of B. thuringiensis toxin (MVPII following antibiotic

  5. Analysis of opportunities and challenges in patenting of Bacillus thuringiensis insecticidal crystal protein genes.

    Science.gov (United States)

    Swamy, H M Mahadeva; Asokan, R; Rajasekaran, P E; Mahmood, Riaz; Nagesha, S N; Arora, D K

    2012-04-01

    Bacillus thuringiensis (Bt) is the most widely used microbial control agent. The broad spectrum of susceptible hosts, production on artificial media and ease of application has caused the widespread use of this bacterium against several pests in agriculture, forest and vectors of human diseases. B.thuringiensis toxins are highly species specific which provide economic, environmental benefits, potential for future control and spread of the technology worldwide. This makes the B. thuringiensis crystal proteins an interesting tool for the implementation in integrated pest management programs. It has gained importance over the last 100 years for its biocontrol properties which is used in this review as a case study and analysis of the patents granted on B. thuringiensis was carried out. This study categorizes a number of patents related to B.thuringiensis insecticidal crystal proteins, application of B.thuringiensis insecticidal crystal proteins and the development of patentable technologies. The analyses were done using various criteria like patenting trends over the years, assignees playing a major role, comparison of the technology used in different patents and the patenting activity across the insect orders. Patent documents related to bacterium B.thuringiensis contain a trove of technical and commercial information and thus, patent analysis is considered as a useful tool for R management and techno economical development. Patent analysis also helps identifying and evaluating new and alternate technologies, keeping abreast with latest technologies for business interests, finding solutions to technical problems and ideas for new innovative trends.

  6. Analysis of opportunities and challenges in patenting of Bacillus thuringiensis insecticidal crystal protein genes.

    Science.gov (United States)

    Swamy, H M Mahadeva; Asokan, R; Rajasekaran, P E; Mahmood, Riaz; Nagesha, S N; Arora, D K

    2012-04-01

    Bacillus thuringiensis (Bt) is the most widely used microbial control agent. The broad spectrum of susceptible hosts, production on artificial media and ease of application has caused the widespread use of this bacterium against several pests in agriculture, forest and vectors of human diseases. B.thuringiensis toxins are highly species specific which provide economic, environmental benefits, potential for future control and spread of the technology worldwide. This makes the B. thuringiensis crystal proteins an interesting tool for the implementation in integrated pest management programs. It has gained importance over the last 100 years for its biocontrol properties which is used in this review as a case study and analysis of the patents granted on B. thuringiensis was carried out. This study categorizes a number of patents related to B.thuringiensis insecticidal crystal proteins, application of B.thuringiensis insecticidal crystal proteins and the development of patentable technologies. The analyses were done using various criteria like patenting trends over the years, assignees playing a major role, comparison of the technology used in different patents and the patenting activity across the insect orders. Patent documents related to bacterium B.thuringiensis contain a trove of technical and commercial information and thus, patent analysis is considered as a useful tool for R management and techno economical development. Patent analysis also helps identifying and evaluating new and alternate technologies, keeping abreast with latest technologies for business interests, finding solutions to technical problems and ideas for new innovative trends. PMID:22239684

  7. Isolation and partial characterization of a mutant of Bacillus thuringiensis producing melanin Isolamento e caracterização parcial de um mutante de Bacillus thuringiensis produtor de melanina

    Directory of Open Access Journals (Sweden)

    Gislayne T. Vilas-Bôas

    2005-09-01

    Full Text Available A mutant (407-P of Bacillus thuringiensis subsp. thuringiensis strain 407 producing a melanin was obtained after treatment with the mutagenic agent ethyl-methane-sulfonate. Several microbiological and biochemical properties of the two strains were analyzed and the results were similar. The mutant 407-P was also incorporated into non-sterilized soil samples, recovered, easily identified, and quantified, what enables its use in ecology of B. thuringiensis.Um mutante (407-P da linhagem Bacillus thuringiensis subsp. thuringiensis 407 produtor de melanina foi obtido após tratamento com o agente mutagênico etil-metano-sulfonato. Diversas propriedades microbiológicas e bioquímicas das duas linhagens foram analisadas e os resultados foram similares. O mutante 407-P foi incorporado em amostras de solo não esterilizado, recuperado, facilmente identificado e quantificado, possibilitando seu uso em estudos de ecologia de B. thuringiensis.

  8. A Novel Tenebrio molitor Cadherin is a Functional Receptor for Bacillus thuringiensis Toxin Cry3Aa

    Science.gov (United States)

    Cry toxins produced by the bacterium Bacillus thuringiensis (Bt) are effective biological insecticides. Cadherin-like proteins have been reported as functional Cry1A toxin receptors in Lepidoptera. We present the first report demonstrating a functional interaction between the coleopteran-specific ...

  9. Transcriptome of the gypsy moth (Lymantria dispar) larval midgut in response to infection by Bacillus thuringiensis

    Science.gov (United States)

    Transcriptomic profiles of the lepidopteran insect pest Lymantria dispar (gypsy moth) were characterized in the larval midgut in response to infection by the biopesticide Bacillus thuringiensis kurstaki. RNA-Seq approaches were used to define a set of 49,613 assembled transcript sequences, of which...

  10. The occurrence of Photorhabdus-like toxin complexes in Bacillus thuringiensis

    Science.gov (United States)

    Recently, genomic sequencing of a Bacillus thuringiensis (Bt) isolate from our collection revealed the presence of an apparent operon encoding an insecticidal toxin complex (Tca) similar to that first described from the entomopathogen Photorhabdus luminescens. To determine whether these genes are w...

  11. 40 CFR 180.1011 - Viable spores of the microorganism Bacillus thuringiensis Berliner; exemption from the...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Viable spores of the microorganism Bacillus thuringiensis Berliner; exemption from the requirement of a tolerance. 180.1011 Section 180.1011 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL...

  12. INGESTION AND ADSORPTION OF 'BACILLUS THURINGIENSIS' SUBSP. 'ISRAELENSIS' BY 'GAMMARUS LACUSTRIS' IN THE LABORATORY

    Science.gov (United States)

    Several groups of Gammarus lacustris adults were exposed to solutions containing 0.5 and 5.0 mg of Bacillus thuringiensis subsp. israelensis per liter for 1- or 24-hour periods by using traditional static bioassay exposure procedures. The experiments verified that traditional exp...

  13. Recovery of Bacillus thuringiensis and insect toxic related strains from forest soil

    Science.gov (United States)

    We attempted to recover Bacillus thuringiensis (Bt) from soil that had been sprayed two years prior with Bt for gypsy moth control. By amplifying the bacteria found in the soil on bacterial agar and feeding this diverse microbial population to tobacco hornworm larvae, 15 spore-forming bacteria from ...

  14. Screening Bacillus thuringiensis strains for toxicity against Manduca sexta and Plutella xylostella

    Science.gov (United States)

    Screening Bacillus thuringiensis (Bt) isolates or strains for toxicity has traditionally been performed with one bacterial isolate at time versus a specific insect. By testing of Bt strains in groups, we identified 28 of 147 Bt isolates as toxic to either diamondback moth, Plutella xylostella (L.),...

  15. BACILLUS THURINGIENSIS VAR. KURSTAKI AFFECTS A BENEFICIAL INSECT, THE CINNABAR MOTH (LEPIDOPTERA: ARCTIIDAE)

    Science.gov (United States)

    The microbial insecticide bacillus thuringiensis Berliner var. kurstaki is used to control forest pests in regions where tansy ragwort, Senecio jacobaea L. occurs. iological control of this noxious weed may be compromised if the cinnabar moth, Tyria jacobaeae (L), is susceptible ...

  16. 40 CFR 180.1107 - Delta endotoxin of Bacillus thuringiensis variety kurstaki encapsulated into killed Pseudomonas...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Delta endotoxin of Bacillus thuringiensis variety kurstaki encapsulated into killed Pseudomonas fluorescens; exemption from the requirement of a tolerance. 180.1107 Section 180.1107 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES...

  17. IMPACT OF BT ( BACILLUS THURINGIENSIS ) CROPS ON BAT ACTIVITY IN SOUTH TEXAS AGROECOSYSTEMS

    Science.gov (United States)

    The widespread adoption of transgenic insecticidal crops raises concerns that nontarget species may be harmed and food webs disrupted. The goal of this research is to determine how transgenic Bt (Bacillus thuringiensis) crops impact the activity of Brazilian freetailed bats (Tada...

  18. Investigation of Cytocidal Activity of Bacillus Thuringiensis Parasporal Toxin on CCRF-CEM Cell Line

    Directory of Open Access Journals (Sweden)

    Elham Moazamian

    2013-03-01

    Full Text Available Background & Objective: Parasporin is a parasporal protein of Bacillus thuringiensis and exhibits special cytocidal activity against human cancer cells. Similar to other insecticidal Bacillus thuringiensis crystal toxins, parasporin shows target specificity and damages the cellular membrane. In this study, different strains of Bacillus thuringiensis isolated from various regions of Iran and their cytocidal activity against CCRF-CEM cell line and human erythrocyte were investigated.   Materials & Methods: Fifty soil samples were collected from different Iranian provinces, and characterization was performed based on protein crystal morphology by phase-contrast microscope and variations of Cry protein toxin using SDS-PAGE. After parasporin was processed with proteinase K, the active form was produced and protein activity on the cell line was evaluated. Results: Parasporal inclusion proteins showed different cytotoxicity against acute lymphoblastic leukemia cells (ALL, but not against normal lymphocyte. Isolated parasporin demonstrated no hemolytic activity against human erythrocyte. It appears that these proteins have the ability to differentiate between normal lymphocytes and leukemia cells and have specific receptors on specific cancer cell lines. Conclusion: Our results provide evidence that the parasporin-producing organism is a common member in Bacillus thuringiensis populations occurring in the natural environments of Iran.

  19. Sub-chronic lung inflammation after airway exposures to Bacillus thuringiensis biopesticides in mice

    DEFF Research Database (Denmark)

    Barfod, Kenneth K; Poulsen, Steen Seier; Hammer, Maria;

    2010-01-01

    The aim of the present study was to assess possible health effects of airway exposures to Bacillus thuringiensis (Bt) based biopesticides in mice. Endpoints were lung inflammation evaluated by presence of inflammatory cells in bronchoalveolar lavage fluid (BALF), clearance of bacteria from the lung...

  20. Solubilization, Activation, and Insecticidal Activity of Bacillus thuringiensis Serovar thompsoni HD542 Crystal Proteins

    NARCIS (Netherlands)

    Naimov, S.; Boncheva, R.; Karlova, R.B.; Dukiandjiev, S.; Minkov, I.; Maagd, de R.A.

    2008-01-01

    Cry15Aa protein, produced by Bacillus thuringiensis serovar thompsoni HD542 in a crystal together with a 40 kDa accompanying protein is one of a small group of non-typical, less well-studied members of the Cry family of insecticidal proteins, and may provide an alternative for the more commonly used

  1. Chemical modulators of the innate immune response alter gypsy moth larval susceptibility to Bacillus thuringiensis

    Directory of Open Access Journals (Sweden)

    Broderick Nichole A

    2010-04-01

    Full Text Available Abstract Background The gut comprises an essential barrier that protects both invertebrate and vertebrate animals from invasion by microorganisms. Disruption of the balanced relationship between indigenous gut microbiota and their host can result in gut bacteria eliciting host responses similar to those caused by invasive pathogens. For example, ingestion of Bacillus thuringiensis by larvae of some species of susceptible Lepidoptera can result in normally benign enteric bacteria exerting pathogenic effects. Results We explored the potential role of the insect immune response in mortality caused by B. thuringiensis in conjunction with gut bacteria. Two lines of evidence support such a role. First, ingestion of B. thuringiensis by gypsy moth larvae led to the depletion of their hemocytes. Second, pharmacological agents that are known to modulate innate immune responses of invertebrates and vertebrates altered larval mortality induced by B. thuringiensis. Specifically, Gram-negative peptidoglycan pre-treated with lysozyme accelerated B. thuringiensis-induced killing of larvae previously made less susceptible due to treatment with antibiotics. Conversely, several inhibitors of the innate immune response (eicosanoid inhibitors and antioxidants increased the host's survival time following ingestion of B. thuringiensis. Conclusions This study demonstrates that B. thuringiensis infection provokes changes in the cellular immune response of gypsy moth larvae. The effects of chemicals known to modulate the innate immune response of many invertebrates and vertebrates, including Lepidoptera, also indicate a role of this response in B. thuringiensis killing. Interactions among B. thuringiensis toxin, enteric bacteria, and aspects of the gypsy moth immune response may provide a novel model to decipher mechanisms of sepsis associated with bacteria of gut origin.

  2. Effect of Cry1Ab protein on rhizobacterial communities of Bt-maize over a four-year cultivation period.

    Directory of Open Access Journals (Sweden)

    Jorge Barriuso

    Full Text Available BACKGROUND: Bt-maize is a transgenic variety of maize expressing the Cry toxin from Bacillus turingiensis. The potential accumulation of the relative effect of the transgenic modification and the cry toxin on the rhizobacterial communities of Bt-maize has been monitored over a period of four years. METHODOLOGY/PRINCIPAL FINDINGS: The accumulative effects of the cultivation of this transgenic plant have been monitored by means of high throughput DNA pyrosequencing of the bacterial DNA coding for the 16S rRNA hypervariable V6 region from rhizobacterial communities. The obtained sequences were subjected to taxonomic, phylogenetic and taxonomic-independent diversity studies. The results obtained were consistent, indicating that variations detected in the rhizobacterial community structure were possibly due to climatic factors rather than to the presence of the Bt-gene. No variations were observed in the diversity estimates between non-Bt and Bt-maize. CONCLUSIONS/SIGNIFICANCE: The cultivation of Bt-maize during the four-year period did not change the maize rhizobacterial communities when compared to those of the non-Bt maize. This is the first study to be conducted with Bt-maize during such a long cultivation period and the first evaluation of rhizobacterial communities to be performed in this transgenic plant using Next Generation Sequencing.

  3. Sensitivity of the bacterium Bacillus Thuringiensis as an insect disease agent to gamma-rays

    International Nuclear Information System (INIS)

    The effect of gamma radiation on the viability of the entomopathogenic spore-forming bacterium, Bacillus thuringiensis, was tested. The different gamma doses varied much in their effect on such bacterium. All irradiated Bacillus suspensions with doses below 85 krad showed different degrees of inhibitory activity. However, bacterial suspensions irradiated at a dose of 90 krad. proved to promote spore germination. Changes in the physiological, and morphological characters of the irradiated Bacillus at these levels were detected. The new observed characters were induced at a particular dose level of 90 krad. These new characters are assumed to be due to genetic changes induced at this particular gamma dose

  4. Genome Sequence of the Acrystalliferous Bacillus thuringiensis Serovar Israelensis Strain 4Q7, Widely Used as a Recombination Host

    OpenAIRE

    Jeong, Haeyoung; Park, Seung-Hwan; Choi, Soo-Keun

    2014-01-01

    Bacillus thuringiensis serovar israelensis is well known for its mosquitocidal activity and has long been used as a biopesticide. Herein, we present the genome sequence of B. thuringiensis serovar israelensis strain 4Q7, a plasmid-cured derivative with higher transformation efficiency than wild types.

  5. Analysis of Bacillus thuringiensis Population Dynamics and Its Interaction With Pseudomonas fluorescens in Soil

    Science.gov (United States)

    Rojas-Ruiz, Norma Elena; Sansinenea-Royano, Estibaliz; Cedillo-Ramirez, Maria Lilia; Marsch-Moreno, Rodolfo; Sanchez-Alonso, Patricia; Vazquez-Cruz, Candelario

    2015-01-01

    Background: Bacillus thuringiensis is the most successful biological control agent, however, studies so far have shown that B. thuringiensis is very sensitive to environmental factors such as soil moisture and pH. Ultraviolet light from the sun had been considered as the main limiting factor for its persistence in soil and it has recently been shown that the antagonism exerted by other native soil organisms, such as Pseudomonas fluorescens, is a determining factor in the persistence of this bacterium under in vitro culture conditions. Objectives: The aim of the present investigation was to analyze the population dynamics of B. thuringiensis and its interaction with P. fluorescens using microbiological and molecular methods in soil, under different conditions, and to determinate the effect of nutrients and moisture on its interaction. Materials and Methods: The monitoring was performed by microbiological methods, such as viable count of bacteria, and molecular methods such as Polymerase Chain Reaction (PCR) and hybridization, using the direct extraction of DNA from populations of inoculated soil. Results: The analysis of the interaction between B. thuringiensis and P. fluorescens in soil indicated that the disappearance of B. thuringiensis IPS82 is not dependent on the moisture but the composition of nutrients that may be affecting the secretion of toxic compounds in the environment of P. fluorescens. The results showed that the recovered cells were mostly spores and not vegetative cells in all proved treatments. The molecular methods were effective for monitoring bacterial population inoculated in soil. Conclusions: Bacillus thuringiensis is very sensitive to the interaction of P. fluorescens, however is capable to survive in soil due to its capacity of sporulate. Some of the cells in the form of spores germinated and folded slightly and remained in a constant cycle of sporulation and germination. This confirms that B. thuringiensis IPS82 can germinate, grow and

  6. A novel metalloproteinase virulence factor is involved in Bacillus thuringiensis pathogenesis in nematodes and insects.

    Science.gov (United States)

    Peng, Donghai; Lin, Jian; Huang, Qiong; Zheng, Wen; Liu, Guoqiang; Zheng, Jinshui; Zhu, Lei; Sun, Ming

    2016-03-01

    The Gram-positive soil bacterium Bacillus thuringiensis has been developed as the leading microbial insecticide for years. The pathogenesis of B. thuringiensis requires common extracellular factors that depend on the PlcR regulon, which regulates a large number of virulence factors; however, the precise role of many of these proteins is not known. In this study, we describe the complete lifecycle of a nematicidal B. thuringiensis strain in the free living nematode Caenorhabditis elegans using in vitro and in vivo molecular techniques to follow host and bacterial effectors during the infection process. We then focus on the metalloproteinase ColB, a collagenase, which was found highly important for destruction of the intestine thereby facilitates the adaptation and colonization of B. thuringiensis in C. elegans. In vivo green fluorescent protein (GFP) reporter-gene studies showed that ColB expression is highly induced and regulated by the global activator PlcR. Finally, we demonstrated that ColB also takes part in B. thuringiensis virulence in an insect model following injection and oral infection. Indeed, addition of purified ColB accelerates the action of Cry toxin proteins in insects, too. These results give novel insights into host adaptation for B. thuringiensis and other B. cereus group bacteria and highlight the role of collagenase metalloproteases to synergize infection process.

  7. A novel metalloproteinase virulence factor is involved in Bacillus thuringiensis pathogenesis in nematodes and insects.

    Science.gov (United States)

    Peng, Donghai; Lin, Jian; Huang, Qiong; Zheng, Wen; Liu, Guoqiang; Zheng, Jinshui; Zhu, Lei; Sun, Ming

    2016-03-01

    The Gram-positive soil bacterium Bacillus thuringiensis has been developed as the leading microbial insecticide for years. The pathogenesis of B. thuringiensis requires common extracellular factors that depend on the PlcR regulon, which regulates a large number of virulence factors; however, the precise role of many of these proteins is not known. In this study, we describe the complete lifecycle of a nematicidal B. thuringiensis strain in the free living nematode Caenorhabditis elegans using in vitro and in vivo molecular techniques to follow host and bacterial effectors during the infection process. We then focus on the metalloproteinase ColB, a collagenase, which was found highly important for destruction of the intestine thereby facilitates the adaptation and colonization of B. thuringiensis in C. elegans. In vivo green fluorescent protein (GFP) reporter-gene studies showed that ColB expression is highly induced and regulated by the global activator PlcR. Finally, we demonstrated that ColB also takes part in B. thuringiensis virulence in an insect model following injection and oral infection. Indeed, addition of purified ColB accelerates the action of Cry toxin proteins in insects, too. These results give novel insights into host adaptation for B. thuringiensis and other B. cereus group bacteria and highlight the role of collagenase metalloproteases to synergize infection process. PMID:26995589

  8. Identification of beta-exotoxin production, plasmids encoding beta-exotoxin, and a new exotoxin in Bacillus thuringiensis by using high-performance liquid chromatography.

    OpenAIRE

    Levinson, B L; Kasyan, K J; Chiu, S S; Currier, T C; González, J M

    1990-01-01

    An improved high-performance liquid chromatography separation was developed to detect and quantify beta-exotoxin production in Bacillus thuringiensis culture supernatants. Exotoxin production was assigned to a plasmid in five strains, from three subspecies (B. thuringiensis subsp. thuringiensis serotype 1, B. thuringiensis subsp. tolworthi serotype 9, and B. thuringiensis subsp. darmstadiensis serotype 10). A new exotoxin, called type II beta-exotoxin in this report, was discovered in B. thur...

  9. Estudio de la ecología de Bacillus thuringiensis en la hoja

    OpenAIRE

    Maduell Soler, Pau

    2008-01-01

    La ecología de Bacillus thuringiensis, un bioinsecticida muy común, es poco conocida. Nuestro principal objetivo era investigar acerca de la ecología de esta bacteria en la filosfera. En un primer estudio se recogieron 35 muestras de hojas del género Piper de bosques andinos colombianos. Se obtuvieron 256 aislamientos de B. thuringiensis del 74% de las muestras estudiadas. Los aislamientos fueron caracterizados según la morfología del cristal, la presencia de genes cry por PCR y la toxicidad ...

  10. Ubiquity of parasporin-1 producers in Bacillus thuringiensis natural populations of Japan

    Science.gov (United States)

    Uemori, Akiko; Maeda, Minoru; Yasutake, Koichi; Ohgushi, Akira; Kagoshima, Kumiko; Mizuki, Eiichi; Ohba, Michio

    2007-01-01

    Parasporin, a Bacillus thuringiensis parasporal protein, is unique in having a strong cytocidal activity preferential for human cancer cells. In this study, we characterized parasporin activities associated with three novel geographical isolates of B. thuringiensis. Parasporal inclusion proteins of the three isolates were highly toxic to human uterus cervix cancer cells (HeLa), but not to non-cancer uterine smooth muscle cells (UtSMC). Inclusions of the isolates lacked insect toxicity and hemolytic activity against sheep erythrocytes. Ouchterlony immunodiffusion tests revealed that the proteins of the three isolates are immunologically closely related to parasporin-1 (Cry31A), but dissimilar to the three other existing parasporin groups. Our results provide evidence that the parasporin-1-producing organism is a common member in B. thuringiensis populations occurring in natural environments of Japan.

  11. Structural Insights into Bacillus thuringiensis Cry, Cyt and Parasporin Toxins

    Directory of Open Access Journals (Sweden)

    Chengchen Xu

    2014-09-01

    Full Text Available Since the first X-ray structure of Cry3Aa was revealed in 1991, numerous structures of B. thuringiensis toxins have been determined and published. In recent years, functional studies on the mode of action and resistance mechanism have been proposed, which notably promoted the developments of biological insecticides and insect-resistant transgenic crops. With the exploration of known pore-forming toxins (PFTs structures, similarities between PFTs and B. thuringiensis toxins have provided great insights into receptor binding interactions and conformational changes from water-soluble to membrane pore-forming state of B. thuringiensis toxins. This review mainly focuses on the latest discoveries of the toxin working mechanism, with the emphasis on structural related progress. Based on the structural features, B. thuringiensis Cry, Cyt and parasporin toxins could be divided into three categories: three-domain type α-PFTs, Cyt toxin type β-PFTs and aerolysin type β-PFTs. Structures from each group are elucidated and discussed in relation to the latest data, respectively.

  12. Structural Insights into Bacillus thuringiensis Cry, Cyt and Parasporin Toxins

    Science.gov (United States)

    Xu, Chengchen; Wang, Bi-Cheng; Yu, Ziniu; Sun, Ming

    2014-01-01

    Since the first X-ray structure of Cry3Aa was revealed in 1991, numerous structures of B. thuringiensis toxins have been determined and published. In recent years, functional studies on the mode of action and resistance mechanism have been proposed, which notably promoted the developments of biological insecticides and insect-resistant transgenic crops. With the exploration of known pore-forming toxins (PFTs) structures, similarities between PFTs and B. thuringiensis toxins have provided great insights into receptor binding interactions and conformational changes from water-soluble to membrane pore-forming state of B. thuringiensis toxins. This review mainly focuses on the latest discoveries of the toxin working mechanism, with the emphasis on structural related progress. Based on the structural features, B. thuringiensis Cry, Cyt and parasporin toxins could be divided into three categories: three-domain type α-PFTs, Cyt toxin type β-PFTs and aerolysin type β-PFTs. Structures from each group are elucidated and discussed in relation to the latest data, respectively. PMID:25229189

  13. Genome characteristics of a novel phage from Bacillus thuringiensis showing high similarity with phage from Bacillus cereus.

    Directory of Open Access Journals (Sweden)

    Yihui Yuan

    Full Text Available Bacillus thuringiensis is an important entomopathogenic bacterium belongs to the Bacillus cereus group, which also includes B. anthracis and B. cereus. Several genomes of phages originating from this group had been sequenced, but no genome of Siphoviridae phage from B. thuringiensis has been reported. We recently sequenced and analyzed the genome of a novel phage, BtCS33, from a B. thuringiensis strain, subsp. kurstaki CS33, and compared the gneome of this phage to other phages of the B. cereus group. BtCS33 was the first Siphoviridae phage among the sequenced B. thuringiensis phages. It produced small, turbid plaques on bacterial plates and had a narrow host range. BtCS33 possessed a linear, double-stranded DNA genome of 41,992 bp with 57 putative open reading frames (ORFs. It had a typical genome structure consisting of three modules: the "late" region, the "lysogeny-lysis" region and the "early" region. BtCS33 exhibited high similarity with several phages, B. cereus phage Wβ and some variants of Wβ, in genome organization and the amino acid sequences of structural proteins. There were two ORFs, ORF22 and ORF35, in the genome of BtCS33 that were also found in the genomes of B. cereus phage Wβ and may be involved in regulating sporulation of the host cell. Based on these observations and analysis of phylogenetic trees, we deduced that B. thuringiensis phage BtCS33 and B. cereus phage Wβ may have a common distant ancestor.

  14. Biological characteristics of Bacillus thuringiensis strain Btll and identification of its cry-type genes

    Institute of Scientific and Technical Information of China (English)

    Tinghui LIU; Wei GUO; Weiming SUN; Yongxiang SUN

    2009-01-01

    A novel strain of Bacillus thuringiensis Bt11, isolated from soil samples in China, was classified and characterized in terms of its crystal proteins, cry genes content. The Bt11 strain showed high toxicity against Spodoptera exigua and Helicoverpa armigera neonates. Btll strain shares morphological and biochemical characteristics with the previously described Bacillus thuringiensis subsp. kurstaki. SDS-polyacrylamide gel electrophoresis revealed that crystals were composed of several polypeptides ranging from 20 to 130 kDa, of which the 35, 80, and 130 kDa proteins were the major components. PCR-RFLP with total DNA from strain Btll and specific primers for cryl, cry2, cry3, cry4/10, cry7, cry8, cry9, and cryll genes revealed that crylAa, crylAb, crylla, and cry9Ea genes were present.

  15. Laser He-Ne effect on bacillus thuringiensis var. kurstaki strain LBT-24

    International Nuclear Information System (INIS)

    Bacillus thuringiensis toxin is one of the world widely used entomopathogen. It presents an strong insecticide activity on Lepidoptera, Coleoptera and Diptera. It was studied the effect of Laser He-Ne on Bacillus thuringiensis var. kurstaki strain LBT-24. Growing curves were made and were calculated the duplication time and the specific growing speed of each one. The curves were statistically compared. It was also analysed the phage induction with and without Laser red light influence. Also, it was observed the presence of the d-endotoxin crystal with this treatment. The red Laser He-Ne enhanced the growth of this micro-organism under laboratory conditions and didn't have any effect over the other characteristics analysed

  16. Enhancement of virulence of bacillus thuringiensis and serratia marcescens by chemicals

    International Nuclear Information System (INIS)

    Studies were conducted on the enhancement of pathogenicity of Bacillus thuringiensis by 1% boric acid against various species of termites. The increase in virulence of Serratia marcescens by 1% potassium chloride or 1% Sodium citrate against the workers of M. championi has also been established. The increase in virulence is confirmed by the enhancement ratio, which are ranging from about 1.5 to 1.8 for Bacillus thuringiensis and 1.3 to 1.6 for Serratia marcescens. It was also noted that 1% boric acid alone was found toxic to various species of termites. However, Potassium chloride and Sodium citrate in a concentration of 1% were non-toxic to the workers of M. championi. (author)

  17. The Pathogenomic Sequence Analysis of B. cereus and B. Thuringiensis isolates closely related to Bacillus anthracis

    Energy Technology Data Exchange (ETDEWEB)

    Han, C S; Xie, G; Challacombe, J F; Altherr, M R; Bhotika, S S; Bruce, D; Campbell, C S; Campbell, M L; Chen, J; Chertkov, O; Cleland, C; Dimitrijevic-Bussod, M; Doggett, N A; Fawcett, J J; Glavina, T; Goodwin, L A; Hill, K K; Hitchcock, P; Jackson, P J; Keim, P; Kewalramani, A R; Longmire, J; Lucas, S; Malfatti, S; McMurry, K; Meincke, L J; Misra, M; Moseman, B L; Mundt, M; Munk, A C; Okinaka, R T; Parson-Quintana, B; Reilly, L P; Richardson, P; Robinson, D L; Rubin, E; Saunders, E; Tapia, R; Tesmer, J G; Thayer, N; Thompson, L S; Tice, H; Ticknor, L O; Wills, P L; Gilna, P; Brettin, T S

    2005-10-12

    The sequencing and analysis of two close relatives of Bacillus anthracis are reported. AFLP analysis of over 300 isolates of B. cereus, B. thuringiensis and B. anthracis identified two isolates as being very closely related to B. anthracis. One, a B. cereus, BcE33L, was isolated from a zebra carcass in Nambia; the second, a B. thuringiensis, 97-27, was isolated from a necrotic human wound. The B. cereus appears to be the closest anthracis relative sequenced to date. A core genome of over 3,900 genes was compiled for the Bacillus cereus group, including B anthracis. Comparative analysis of these two genomes with other members of the B. cereus group provides insight into the evolutionary relationships among these organisms. Evidence is presented that differential regulation modulates virulence, rather than simple acquisition of virulence factors. These genome sequences provide insight into the molecular mechanisms contributing to the host range and virulence of this group of organisms.

  18. Occurrence of natural Bacillus thuringiensis contaminants and residues of Bacillus thuringiensis-based insecticides on fresh fruits and vegetables

    DEFF Research Database (Denmark)

    Frederiksen, Kristine; Rosenquist, Hanne; Jørgensen, Kirsten;

    2006-01-01

    . kurstaki HD1 present in the products Dipel, Biobit, and Foray, and nine isolates grouped with B. thuringiensis subsp. aizawai present in Turex. The commercial strains were primarily isolated from samples of tomatoes, cucumbers, and peppers. A multiplex PCR method was developed to simultaneously detect all...

  19. Susceptibility of Aedes albopictus from dengue outbreak areas to temephos and Bacillus thuringiensis subsp. israelensis

    OpenAIRE

    Ahmad Mohiddin; Asmalia Md Lasim; Wan Fatma Zuharah

    2016-01-01

    Objective: To monitor the current duration of the application rates in vector programme and the level of Aedes albopictus larvae susceptibility from three selected areas in northeast district of Penang on two selected larvicides, temephos and Bacillus thuringiensis subsp. israelensis (Bti) which are commonly used by Penang Health Department for vector control. Methods: The mosquito larvae were tested against two types of larvicides: (1) temephos (Abate®) with diagnostic dosage (0.012 mg/L)...

  20. Genetical and radiobiological characteristics of phage Tg13 of Bacillus thuringiensis

    International Nuclear Information System (INIS)

    The radiation-genetical aspects of interrelations between phages and cells of the spore-forming bacteria Bacillus thurin-giensis were studied. The phage Tg13 liberates C-mutants, forming transparent negative colonies, both spontaneously and under the effect of UV irradiation. UV-radiation increases reliably the level of C-mutants in the population. The phenotype of the observed mutants is, evidently, caused by the specific features of interaction in the system: preudolysogenic culture -phage Tg13

  1. Mode of action of Bacillus thuringiensis Cry and Cyt toxins and their potential for insect control

    OpenAIRE

    Bravo, Alejandra; Gill, Sarjeet S.; Soberón, Mario

    2006-01-01

    Bacillus thuringiensis Cry and Cyt protein families are a diverse group of proteins with activity against insects of different orders - Lepidoptera, Coleoptera, Diptera and also against other invertebrates such as nematodes. Their primary action is to lyse midgut epithelial cells by inserting into the target membrane and forming pores. Among this group of proteins, members of the 3-Domain Cry family are used worldwide for insect control, and their mode of action has been characterized in some...

  2. Selection of high-yield strain of entomopathogenic bacteria Bacillus thuringiensis ppomising for nature protection

    Directory of Open Access Journals (Sweden)

    N. S. Dyrda

    2011-07-01

    means of the ultraviolet irradiation of the В-2 strain Bacillus thuringiensis spores. Insecticidal activity of the obtained variation is characterized by the deaths of 64.3 % of the great brown twist Archips podana at the 3rd day and 97 % at the 10th day after the treatment, which is 20.4 % higher than B-2 strain activity. Possibility of the obtained variation implementation for the natural plants protection against the leaf-eating insects is under discussion.

  3. Tn5401 disruption of the spo0F gene, identified by direct chromosomal sequencing, results in CryIIIA overproduction in Bacillus thuringiensis.

    OpenAIRE

    Malvar, T.; Baum, J A

    1994-01-01

    The Bacillus thuringiensis spo0F gene was identified by chromosomal DNA sequencing of sporulation mutants derived from a B. thuringiensis transposon insertion library. A spo0F defect in B. thuringiensis, which was suppressed by multicopy hknA or kinA, resulted in the overproduction of the CryIIIA insecticidal crystal protein.

  4. Oxygen mass transfer in fermentation of bacillus thuringiensis

    Directory of Open Access Journals (Sweden)

    R. Ríos

    2011-12-01

    Full Text Available The purpose of this work was to obtain a correlation based on literature, depicting the relationships betwen the physical oxygen transfer rate (OTR and microbial oxygen uptake rate (OUR in order to determine the conditions (mass transfer coefficient, resulting on diferents combinations of aereations and agitations rates, under which growth will not be limited by oxygen. This correlation was adapted to culture with B. thuringiensis in order to estimate what biomass concentration are feasible for the physical limits set by operations conditions before microbial activity becomes limited by oxygen.

  5. Dark fermentative bioconversion of glycerol to hydrogen by Bacillus thuringiensis.

    Science.gov (United States)

    Kumar, Prasun; Sharma, Rishi; Ray, Subhasree; Mehariya, Sanjeet; Patel, Sanjay K S; Lee, Jung-Kul; Kalia, Vipin C

    2015-04-01

    Biodiesel manufacturing units discharge effluents rich in glycerol. The need is to convert crude glycerol (CG) into useful products such as hydrogen (H2). Under batch culture, Bacillusthuringiensis EGU45 adapted on pure glycerol (PG, 2% v/v) resulted in an H2 yield of 0.646 mol/mol glycerol consumed on minimal media (250 mL) supplemented with 1% ammonium nitrate at 37°C over 4 days. Here, H2 constituted 67% of the total biogas. Under continuous culture, at 2 days of hydraulic retention time, B. thuringiensis immobilized on ligno-cellulosic materials (banana leaves - BL, 10% v/v) resulted in a H2 yield of 0.386 mol/mol PG consumed. On CG, the maximal H2 yield of 0.393 mol/mol feed consumed was recorded. In brief, B. thuringiensis could transform CG, on limited resources - minimal medium with sodium nitrate, by immobilizing them on cheap and easily available biowaste, which makes it a suitable candidate for H2 production on a large scale. PMID:25686722

  6. Altered protoxin activation by midgut enzymes from a Bacillus thuringiensis resistant strain of Plodia interpunctella.

    Science.gov (United States)

    Oppert, B; Kramer, K J; Johnson, D E; MacIntosh, S C; McGaughey, W H

    1994-02-15

    Processing of Bacillus thuringiensis protoxins to toxins by midgut proteinases from a strain of the Indianmeal moth, Plodia interpunctella (Hubner), resistant to B. thuringiensis subspecies entomocidus (HD-198) was slower than that by midgut proteinases from the susceptible parent strain or a strain resistant to B. thuringiensis subspecies kurstaki (HD-1, Dipel). Midgut extracts from entomocidus-resistant insects exhibited five-fold lower activity toward the synthetic substrate alpha-N-benzoyl-DL-arginine rho-nitroanilide than extracts from susceptible or kurstaki-resistant insects. Midgut enzymes from susceptible or kurstaki-resistant insects converted the 133 kDa CryIA(c) protoxin to 61-63 kDa proteins, while incubations with entomocidus-resistant enzymes resulted in predominantly products of intermediate size, even with increased amounts of midgut extract. The 61-63 kDa proteins were only produced by entomocidus-resistant midgut extracts after long term incubations with the protoxin. The data suggest that altered protoxin activation by midgut proteinases is involved in some types of insect resistance to B. thuringiensis.

  7. Bacillus thuringiensis metalloproteinase Bmp1 functions as a nematicidal virulence factor.

    Science.gov (United States)

    Luo, Xiaoxia; Chen, Ling; Huang, Qiong; Zheng, Jinshui; Zhou, Wei; Peng, Donghai; Ruan, Lifang; Sun, Ming

    2013-01-01

    Some Bacillus thuringiensis strains have high toxicity to nematodes. Nematicidal activity has been found in several families of crystal proteins, such as Cry5, Cry6, and Cry55. The B. thuringiensis strain YBT-1518 has three cry genes that have high nematicidal activity. The whole genome sequence of this strain contains multiple potential virulence factors. To evaluate the pathogenic potential of virulence factors, we focused on a metalloproteinase called Bmp1. It encompasses a consecutive N-terminal signal peptide, an FTP superfamily domain, an M4 neutral protease GluZincin superfamily, two Big-3 superfamily motifs, and a Gram-positive anchor superfamily motif as a C-terminal domain. Here, we showed that purified Bmp1 protein showed metalloproteinase activity and toxicity against Caenorhabditis elegans (the 50% lethal concentration is 610 ± 9.37 μg/ml). In addition, mixing Cry5Ba with Bmp1 protein enhanced the toxicity 7.9-fold (the expected toxicity of the two proteins calculated from their separate toxicities) against C. elegans. Confocal microscopic observation revealed that Bmp1 protein was detected from around the mouth and esophagus to the intestine. Striking microscopic images revealed that Bmp1 degrades intestine tissues, and the Cry5Ba causes intestinal shrinkage from the body wall. Thus, the B. thuringiensis Bmp1 metalloproteinase is a nematicidal virulence factor. These findings give a new insight into the relationship between B. thuringiensis and its host nematodes.

  8. Larvicidal activity of Bacillus thuringiensis var. israelensis Cry11Aa toxin against Haemonchus contortus.

    Science.gov (United States)

    DE Lara, Ana Paula DE Souza Stori; Lorenzon, Lucas Bigolin; Vianna, Ana Muñoz; Santos, Francisco Denis Souza; Pinto, Luciano Silva; Aires Berne, Maria Elisabeth; Leite, Fábio Pereira Leivas

    2016-10-01

    Effective control of gastrointestinal parasites is necessary in sheep production. The development of anthelmintics resistance is causing the available chemically based anthelmintics to become less effective. Biological control strategies present an alternative to this problem. In the current study, we tested the larvicidal effects of Bacillus thuringiensis var. israelensis Cry11Aa toxin against Haemonchus contortus larvae. Bacterial suspensions [2 × 108 colony-forming units (CFU) g-1 of the feces] of B. thuringiensis var. israelensis and recombinant Escherichia coli expressing Cry11Aa toxin were added to naturally H. contortus egg-contaminated feces. The larvae were quantified, and significant reductions of 62 and 81% (P < 0·001) were, respectively observed, compared with the control group. A 30 mL bacterial suspension (1 × 108 CFU mL-1) of B. thuringiensis var. israelensis and recombinant E. coli expressing Cry11Aa toxin were then orally administered to lambs naturally infected with H. contortus. Twelve hours after administration, feces were collected and submitted to coprocultures. Significant larvae reductions (P < 0·001) of 79 and 90% were observed respectively compared with the control group. The results suggest that the Cry11Aa toxin of B. thuringiensis var. israelensis is a promising new class of biological anthelmintics for treating sheep against H. contortus.

  9. Activity of bacteriocins synthesized by Bacillus thuringiensis against Staphylococcus aureus isolates associated to bovine mastitis.

    Science.gov (United States)

    Barboza-Corona, José Eleazar; de la Fuente-Salcido, Norma; Alva-Murillo, Nayeli; Ochoa-Zarzosa, Alejandra; López-Meza, Joel E

    2009-07-01

    Antimicrobial therapy is a useful tool to control bovine mastitis caused by Staphylococcus aureus, as consequence an increase in staphylococci resistant cases has been registered. Alternative strategies are desirable and bacteriocins represent attractive control agents to prevent bovine mastitis. The aim of this work was to evaluate the activity of five bacteriocins synthesized by Bacillus thuringiensis against S. aureus isolates associated to bovine mastitis. Fifty S. aureus isolates were recovered from milk composite samples of 26 Holstein lactating cows from one herd during September 2007 to February 2008 in México and susceptibility of those isolates to 12 antibiotics and 5 bacteriocins from B. thuringiensis was evaluated. S. aureus isolates were mainly resistant to penicillin (92%), dicloxacillin (86%), ampicillin (74%) and erythromycin (74%); whereas susceptibility to gentamicin, trimethoprim and tetracycline was detected at, respectively, 92%, 88%, and 72%. All S. aureus isolates showed susceptibility to the five bacteriocins synthesized by B. thuringiensis, mainly to morricin 269 and kurstacin 287 followed by kenyacin 404, entomocin 420 and tolworthcin 524. Our results showed that S. aureus isolates had differences in the antimicrobial resistance patterns and were susceptible to bacteriocins produced by B. thuringiensis, which could be useful as an alternative method to control bovine mastitis. PMID:19359107

  10. Binding of Bacillus thuringiensis proteins to a laboratory-selected line of Heliothis virescens.

    Science.gov (United States)

    MacIntosh, S C; Stone, T B; Jokerst, R S; Fuchs, R L

    1991-10-15

    A laboratory-selected colony of Heliothis virescens displaying a 20- to 70-fold level of resistance to Bacillus thuringiensis proteins was evaluated to identify mechanism(s) of resistance. Brush-border membrane vesicles were isolated from larval midgut epithelium from the susceptible and resistant strains of H. virescens. Two B. thuringiensis proteins, CryIA(b) and CryIA(c), were iodinated and shown to specifically bind to brush-border membrane vesicles of both insect strains. Multiple changes in the receptor-binding parameters were seen in the resistant strain as compared with the susceptible strain. A 2- to 4-fold reduction in binding affinity was accompanied by a 4- to 6-fold increase in binding-site concentration for both proteins. Although these two B. thuringiensis proteins competed for the same high-affinity binding site, competition experiments revealed different receptor specificity toward these proteins in the resistant H. virescens line. The H. virescens strains were not sensitive to a coleopteran-active protein, CryIIIA, nor did these proteins compete with the CryIA proteins for binding. Complexity of the mechanism of resistance is consistent with the complex mode of action of B. thuringiensis proteins. PMID:1924353

  11. 用合成多肽为半抗原制备Bt Cry1Ab的单克隆抗体%Preparation of the Monoclonal Antibody Against Bt Cry1Ab by Using Synthetic Peptide as Hapten

    Institute of Scientific and Technical Information of China (English)

    胡小元; 张岐蜀; 段伟; 姜国华; 李玲

    2013-01-01

    由于Bt Cry1Aa、Cry1Ab和Cry1Ac晶体蛋白之间具有很高的同源性(82%~90%),采用常规的单抗制备方法很难制取特异性强的Bt Cry1Ab单抗,为了制备抗Bt Cry1Ab蛋白的特异性单克隆抗体(MAB),本研究从NCBI获得了Bt Cry1Ab蛋白的氨基酸序列,根据ANTHEPORT和DNAStar软件对其抗原性、亲水性和表位性分析结果选定Bt Cry1Ab特异性肽段进行人工合成,并将其偶联于匙孔血蓝蛋白(KLH)免疫动物,应用细胞融合技术制备了抗该肽段的杂交瘤细胞22株.通过ELISA试验从中筛选出与Bt Cry1Ab天然蛋白产生特异性反应的单克隆抗体杂交瘤细胞株一株(3A10).经检测,其分泌的抗体亚类为IgG1型;轻链属κ型;杂交瘤细胞株染色体数目为89~108条;用其制作的腹水对Bt Cry1Ab合成肽的反应效价为1∶1×107;对Bt Cry1Ab天然蛋白的反应效价为1∶1×104;纯化后的抗体对Bt Cry1Ab合成肽的效价为1∶1×108;对Bt Cry1Ab天然蛋白的效价为1∶2×104.抗体的相对亲和力为0.5 μg/mL,对Bt Cry 1Ab蛋白的最低可检测值为10 ng/mL.ELISA结果显示,3A10杂交瘤细胞株所分泌的MAB能特异性识别合成肽和Bt Cry1Ab蛋白,而对同源的Cry1Ac和Cry1Aa蛋白无交叉反应;本研究所制备的Bt Cry1Ab单克隆抗体能够对常规棉和抗虫棉(Gossypium hirsutum L.)进行有效的区分,并且能特异性的识别其中的Bt Cry1Ab蛋白.%Because Bt Cry 1Aa, Cry 1Ab and Cry 1Ac share high sequence identity(82%~90%), it is difficult to prepare Bt Cry1 Ab monoclonal antibody that has highly specific by using conventional method. In order to prepare monoclonal antibody against Bt Cry1Ab, we acquired the amino acid sequence of Bt Cry1Ab protein from NCBI. According to the antigenicity, hydrophilicity and accessibility analyzed results by ANTHEPORT and DNAStar computer software, the specific peptide of Bt Cry1Ab was synthesized by a chemical process. The Bt Cry1Ab peptide was linked with carrier

  12. Effect of inherited sterility and bacillus thuringiensis on mortality and reproduction of phthorimaea opercullela zeller (lepidoptera: gelechidae)

    International Nuclear Information System (INIS)

    The effect of a commercial formulation of Bacillus thuringiensis (Dipel 2X) upon F1 progeny of irradiated and unirradiated phthorimaea operculella male parents was investigated. F1 progeny of irradiated parents was more susceptible to B. thuringiensis than that of unirradiated parents. A combination of irradiation and B. thuringiensis led to higher mortality in F1 progeny of P. operculella. The LC50 was 0.406 g/100ml for F1 progeny of unirradiated parents, but 0.199 g/100ml for those of irradiated parents. There was a great reduction in the pupal weight, fecundity and egg hatchability of F1 progeny of irradiated patents compared to those unirradiated parents. Such reduction was increased by applying higher concentration of B. thuringiensis. A combination between inherited sterility technique and B. thuringiensis application could give a good controlling result against P. operculella. (author)

  13. Are nematodes a missing link in the confounded ecology of the entomopathogen Bacillus thuringiensis?

    Science.gov (United States)

    Ruan, Lifang; Crickmore, Neil; Peng, Donghai; Sun, Ming

    2015-06-01

    Bacillus thuringiensis, which is well known as an entomopathogen, has been accepted by the public as a safe bioinsecticide. The natural ecology of this bacterium has never been particularly clear, with views ranging from it being an obligate pathogen to an opportunist pathogen that can otherwise exist as a soil saprophyte or a plant endophyte. This confusion has recently led to it being considered as an environmental pathogen that has evolved to occupy a diverse set of environmental niches in which it can thrive without needing a host. A significant driving force behind this classification is the fact that B. thuringiensis is found in high numbers in environments that are not occupied by the insect hosts to which it is pathogenic. It is our opinion that the ubiquitous presence of this bacterium in the environment is the result of a variety of vectoring systems, particularly those that include nematodes.

  14. U.v.-induced and N-methyl-N'-nitrosoguanidine-induced mutagenesis in Bacillus thuringiensis

    International Nuclear Information System (INIS)

    The lethal and mutagenic effects of u.v. light and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) on Bacillus thuringiensis were investigated. Lethality studies demonstrated that B. thuringiensis was relatively sensitive to these agents. This bacterium was mutated at the rifampicin resistance marker by u.v. light and to a lesser extent by the direct acting alkylating agent MNNG. One mutant selected for its greater sensitivity to u.v. light expressed a higher frequency of mutagenesis after u.v. light treatment and appeared to be defective in an excision repair pathway. However, this mutant was only slightly mutable by MNNG in comparison with the wild-type strain. This unusual phenotype does not yet have a parallel among the radiation sensitive mutants described in other bacterial species. (author)

  15. U. V. -induced and N-methyl-N'-nitrosoguanidine-induced mutagenesis in Bacillus thuringiensis

    Energy Technology Data Exchange (ETDEWEB)

    Auffray, Y.; Boutibonnes, P.

    1987-03-01

    The lethal and mutagenic effects of u.v. light and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) on Bacillus thuringiensis were investigated. Lethality studies demonstrated that B. thuringiensis was relatively sensitive to these agents. This bacterium was mutated at the rifampicin resistance marker by u.v. light and to a lesser extent by the direct acting alkylating agent MNNG. One mutant selected for its greater sensitivity to u.v. light expressed a higher frequency of mutagenesis after u.v. light treatment and appeared to be defective in an excision repair pathway. However, this mutant was only slightly mutable by MNNG in comparison with the wild-type strain. This unusual phenotype does not yet have a parallel among the radiation sensitive mutants described in other bacterial species.

  16. Potencial de Bacillus thuringiensis israelensis Berliner no controle de Aedes aegypti

    Directory of Open Access Journals (Sweden)

    Polanczyk Ricardo Antonio

    2003-01-01

    Full Text Available Relata-se a importância da bactéria entomopatogênica Bacillus thuringiensis israelensis para o controle de Aedes aegypti. São abordados a utilização e potencial de B. thuringiensis israelensis contra o mosquito vetor da dengue. Outros aspectos são discutidos como a evolução da resistência dos insetos em relação aos inseticidas químicos e as vantagens e desvantagens do controle microbiano como estratégia de controle. É dada ênfase à importância da utilização desta bactéria no Brasil como alternativa para resolver o problema em questão sem afetar o ambiente, o homem e outros vertebrados nas áreas de risco.

  17. Diagnostic properties of three conventional selective plating media for selection of Bacillus cereus, B. thuringiensis and B. weihenstephanensis

    DEFF Research Database (Denmark)

    Hendriksen, Niels Bohse; Hansen, Bjarne Munk

    2011-01-01

    The aim of this study was to assess the diagnostic properties of the two selective plating media and a chromogenic medium for identification of Bacillus cereus. The 324 isolates were B. cereus (37%), Bacillus weihenstephanensis (45%) or Bacillus thuringiensis (18%), as identified by a new...... combination of techniques. All isolates were growing on mannitol–egg yolk–polymyxin agar (MYP), and they did not form acid from mannitol. However, a significant lower number of B. thuringiensis isolates did not show lecithinase activity. All isolates were also growing on polymyxin–egg yolk...... recommended selective plating media MYP and PEMBA for detection of B. cereus group bacteria both have their limitations for identification of some B. cereus, B. weihenstephanensis or B. thuringiensis. However, MYP is preferable compared to PEMBA. The chromogenic medium has its own advantages and limitations...

  18. 固定化Bacillus thuringiensis ZJOU-010壳聚糖酶的研究%Immobilization and Enzymatic Properties of Chitosanase from Bacillus thuringiensis ZJOU-010

    Institute of Scientific and Technical Information of China (English)

    陈静; 陈余; 鹿刘奇; 陈小娥; 方旭波

    2010-01-01

    采用吸附交联技术,以DEAE-22纤维素为载体、戊二醛为交联剂,固定Bacillus thuringiensis ZJOU-010壳聚糖酶,考察固定化酶的制备条件,并研究固定化酶的性质.结果表明B.thuringiensis ZJOU-010壳聚糖酶的最佳固定化条件为:戊二醛体积分数3.0%、加酶量20mg、固定化时间10h;在此条件下制备的固定化壳聚糖酶的最适pH值和温度分别为4.83和50℃;与游离酶相比,该固定化酶的热稳定性较好,在40℃和50℃条件下的半衰期(t1/2)分别为36.3h和6.2h,动力学常数Km值为9.19g/L;该固定化酶重复使用10批后活力仍可保持初始活力的88.32%.

  19. Identification of distinct Bacillus thuringiensis 4A4 nematicidal factors using the model nematodes Pristionchus pacificus and Caenorhabditis elegans.

    Science.gov (United States)

    Iatsenko, Igor; Nikolov, Angel; Sommer, Ralf J

    2014-07-14

    Bacillus thuringiensis has been extensively used for the biological control of insect pests. Nematicidal B. thuringiensis strains have also been identified; however, virulence factors of such strains are poorly investigated. Here, we describe virulence factors of the nematicidal B. thuringiensis 4A4 strain, using the model nematodes Pristionchus pacificus and Caenorhabditis elegans. We show that B. thuringiensis 4A4 kills both nematodes via intestinal damage. Whole genome sequencing of B. thuringiensis 4A4 identified Cry21Ha, Cry1Ba, Vip1/Vip2 and β-exotoxin as potential nematicidal factors. Only Cry21Ha showed toxicity to C. elegans, while neither Cry nor Vip toxins were active against P. pacificus, when expressed in E. coli. Purified crystals also failed to intoxicate P. pacificus, while autoclaved spore-crystal mixture of B. thuringiensis 4A4 retained toxicity, suggesting that primary β-exotoxin is responsible for P. pacificus killing. In support of this, we found that a β-exotoxin-deficient variant of B. thuringiensis 4A4, generated by plasmid curing lost virulence to the nematodes. Thus, using two model nematodes we revealed virulence factors of the nematicidal strain B. thuringiensis 4A4 and showed the multifactorial nature of its virulence.

  20. Resistance of Trichoplusia ni Populations Selected by Bacillus thuringiensis Sprays to Cotton Plants Expressing Pyramided Bacillus thuringiensis Toxins Cry1Ac and Cry2Ab

    Science.gov (United States)

    Kain, Wendy; Song, Xiaozhao; Janmaat, Alida F.; Zhao, Jian-Zhou; Myers, Judith; Shelton, Anthony M.

    2014-01-01

    Two populations of Trichoplusia ni that had developed resistance to Bacillus thuringiensis sprays (Bt sprays) in commercial greenhouse vegetable production were tested for resistance to Bt cotton (BollGard II) plants expressing pyramided Cry1Ac and Cry2Ab. The T. ni colonies resistant to Bacillus thuringiensis serovar kurstaki formulations were not only resistant to the Bt toxin Cry1Ac, as previously reported, but also had a high frequency of Cry2Ab-resistant alleles, exhibiting ca. 20% survival on BollGard II foliage. BollGard II-resistant T. ni strains were established by selection with BollGard II foliage to further remove Cry2Ab-sensitive alleles in the T. ni populations. The BollGard II-resistant strains showed incomplete resistance to BollGard II, with adjusted survival values of 0.50 to 0.78 after 7 days. The resistance to the dual-toxin cotton plants was conferred by two genetically independent resistance mechanisms: one to Cry1Ac and one to Cry2Ab. The 50% lethal concentration of Cry2Ab for the resistant strain was at least 1,467-fold that for the susceptible T. ni strain. The resistance to Cry2Ab in resistant T. ni was an autosomally inherited, incompletely recessive monogenic trait. Results from this study indicate that insect populations under selection by Bt sprays in agriculture can be resistant to multiple Bt toxins and may potentially confer resistance to multitoxin Bt crops. PMID:25480752

  1. Toxicity studies for indigenous Bacillus thuringiensis isolates from Malang city, East Java on Aedes aegypti larvae

    Institute of Scientific and Technical Information of China (English)

    Zulfaidah Penata Gama; Nobukazu Nakagoshi; Suharjono; Faridah Setyowati

    2013-01-01

    Objective: To investigate the toxicity of indigenous Bacillus thuringiensis (B. thuringiensis) isolates from Malang City for controlling Aedes aegypti (Ae. aegypti) larvae. Methods: Soil samples were taken from Purwantoro and Sawojajar sub-districts. Bacterial isolation was performed using B. thuringiensis selective media. Phenotypic characteristics of the isolates were obtained with the simple matching method. The growth and prevalence of spores were determined by the Total Plate Count method, and toxicity tests were also performed on the third instar larval stage of Ae. aegypti. The percentage of larval mortality was analysed using probit regression. The LC50 was analysed by ANOVA, and the Tukey HSD interval was 95%. Results:Among the 33 selected bacterial isolates, six were obtained (PWR4-31, PWR4-32, SWJ4-2b, SWJ4-4b, SWJ-4k and SWJ5-1) that had a similar phenotype to reference B. thuringiensis. Based on the dendrogram, all of the bacterial isolates were 71%similar. Three isolates that had a higher prevalence of reference B. thuringiensis were PWR4-32, SWJ4-4b and SW5-1, of which the spore prevalence was 52.44%, 23.59%, 34.46%, respectively. These three indigenous isolates from Malang City successfully killed Ae. aegypti larvae. The PWR4-32 isolates were the most effective at killing the larvae. Conclusions:Six indigenous B. thuringiensis isolates among the 33 bacterial isolates found in the Sawojajar and Purwantoro sub-districts were toxic to the third instar larvae of Ae. aegypti. The PWR4-32 isolates were identical to the reference B. thuringiensis and had 88%phenotype similarity. The PWR4-32 isolates had the highest spore prevalence (52.44%), and the early stationary phase occurred at 36 h. The PWR4-32 isolates were the most effective at killing Ae. aegypti larvae (LC50-72 h=2.3í108 cells/mL).

  2. Isolation of strains of Bacillus thuringiensis insecticidal biological activity against Ceratitis capitata

    International Nuclear Information System (INIS)

    The present work is to study the effect of toxins (δ-endotoxins) extracted from strains of Bacillus thuringiensis isolated from the mud on the fly Sabkhat Dejoumi Ceratitis capitata, a pest of citrus and fruit trees. Among 51 isolated tested, 15 showed a very significant insecticidal activity, characterized by mortality rates exceeding 80 pour cent. These mortality rates are caused by endotoxins of Bt revealed variability between them. The preliminary results of this study encourage us towards the characterization of the insecticidal activity produced by strains of Bt for large scale application.

  3. Characterization of monoclonal antibodies to a crystal protein of Bacillus thuringiensis subsp. kurstaki.

    OpenAIRE

    Huber-Lukac, M; Jaquet, F; Luethy, P; Huetter, R; Braun, D G

    1986-01-01

    Ten monoclonal antibodies were produced against a k-1-type crystal protein of Bacillus thuringiensis subsp. kurstaki. Eight of the antibodies belong to the immunoglobulin G1 (IgG1) subclass, with pI values ranging from 5.5 to 8.6, one could be assigned to the IgG2b subclass, and one could be assigned to the IgM class. Competitive antibody-binding assays and analysis of antibody specificity indicated that the 10 antibodies recognized at least nine distinct antigenic determinants. Eight antibod...

  4. A Bacillus thuringiensis insecticidal crystal protein with a high activity against members of the family Noctuidae.

    OpenAIRE

    Lambert, B.; Buysse, L; Decock, C.; Jansens, S.; Piens, C; Saey, B; Seurinck, J; Van Audenhove, K; Van Rie, J.; A. van Vliet; Peferoen, M.

    1996-01-01

    The full characterization of a novel insecticidal crystal protein, named Cry9Ca1 according to the revised nomenclature for Cry proteins, from Bacillus thuringiensis serovar tolworthi is reported. The crystal protein has 1,157 amino acids and a molecular mass of 129.8 kDa. It has the typical features of the Lepidoptera-active crystal proteins such as five conserved sequence blocks. Also, it is truncated upon trypsin digestion to a toxic fragment of 68.7 kDa by removal of 43 amino acids at the ...

  5. Spatio-Temporal Evolution of Sporulation in Bacillus thuringiensis Biofilm

    Directory of Open Access Journals (Sweden)

    Nay El Khoury

    2016-08-01

    Full Text Available B. thuringiensis can produce a floating biofilm which includes two parts: a ring and a pellicle. The ring is a thick structure which sticks to the culture container, while the pellicle extends over the whole liquid surface and joins the ring. We have followed over time, from 16 h to 96 h, sporulation in the two biofilm parts. Sporulation was followed in situ in 48-wells polystyrene microtiterplates with a fluorescence binocular stereomicroscope and a spoIID-yfp transcriptional fusion. Sporulation took place much earlier in the ring than in the pellicle. In 20 h-aged biofilms, spoIID was expressed only in the ring, which could be seen as a green fluorescent circle surrounding the non-fluorescent pellicle. However, after 48 h of culture, the pellicle started to express spoIID in specific area corresponding to protrusions, and after 96 h both the ring and the whole pellicle expressed spoIID. Spore counts and microscopy observations of the ring and the pellicle harvested separately confirmed these results and revealed that sporulation occured 24 h-later in the pellicle comparatively to the ring, although both structures contained nearly 100% spores after 96 h of culture. We hypothesize that two mechanisms, due to microenvironments in the biofilm, can explain this difference. First, the ring experiences a decreased concentration of nutrients earlier than the pellicle, because of a lower exchange area with the culture medium. An second, the ring is exposed to partial dryness. Both reasons could speed up sporulation in this biofilm structure. Our results also suggest that spores in the biofilm display a phenotypic heterogeneity. These observations might be of particular significance for the food industry, since the biofilm part sticking to container walls - the ring - is likely to contain spores and will therefore resist both to washing and to cleaning procedures, and will be able to restart a new biofilm when food production has resumed.

  6. Effects of Bacillus thuringiensis var. kurstaki and medicinal plants on Hyphantria cunea Drury (Lepidoptera: Arctiidae

    Directory of Open Access Journals (Sweden)

    I Zibaee, AR Bandani, JJ Sendi, R Talaei-Hassanloei, B Kouchaki

    2010-11-01

    Full Text Available The fall armyworm, Hyphantria cunea Drury (Lepidoptera: Arctiidae is an insect native to NorthAmerica that was recently introduced into Iran resulting in severe damage to trees and agriculturalproduction. An experiment was conducted to examine potential effects of medicinal plants, Artemisiaannua and Lavandula stoechas and the insect pathogenic bacterium Bacillus thuringiensis var.kurstaki on activities of digestive enzymes (α-amylase, α- and β-glucosidase, lipase and proteasesand lactate dehydrogenase (LDH in H. cunea by using two hosts, mulberry and sycamore. Resultsshowed that B. thuringiensis var. kurstaki and plant extracts when administered orally, affected thedigestive enzyme profiles of H. cunea. Combined effect of B. thuringiensis, A. annua and L. stoechasextracts on mulberry decreased the activities of digestive enzymes in a dose-related manner, exceptfor β-glucosidase and lipase. When larvae were treated by different concentrations of the mentionedinsecticides, LDH activity increased i.e. the higher activity was obtained by B. thurengiensis alone andB. thurengiensis and L. stoechas extracts together. The least activity was observed in the case of L.stoechas extracts alone on both hosts. Physiological analysis would be particularly informative whenusing combination of biopesticides to enhance the efficiency of a safe management process.

  7. Heme sensing in Bacillus thuringiensis: a supplementary HssRS-regulated heme resistance system.

    Science.gov (United States)

    Schmidt, Rachel M; Carter, Micaela M; Chu, Michelle L; Latario, Casey J; Stadler, Sarah K; Stauff, Devin L

    2016-05-01

    Several Gram-positive pathogens scavenge host-derived heme to satisfy their nutritional iron requirement. However, heme is a toxic molecule capable of damaging the bacterial cell. Gram-positive pathogens within the phylum Firmicutes overcome heme toxicity by sensing heme through HssRS, a two-component system that regulates the heme detoxification transporter HrtAB. Here we show that heme sensing by HssRS and heme detoxification by HrtAB occur in the insect pathogen Bacillus thuringiensis We find that in B. thuringiensis, HssRS directly regulates an operon, hrmXY, encoding hypothetical membrane proteins that are not found in other Firmicutes with characterized HssRS and HrtAB systems. This novel HssRS-regulated operon or its orthologs BMB171_c3178 and BMB171_c3330 are required for maximal heme resistance. Furthermore, the activity of HrmXY is not dependent on expression of HrtAB. These results suggest that B. thuringiensis senses heme through HssRS and induces expression of separate membrane-localized systems capable of overcoming different aspects of heme toxicity.

  8. Effect of midgut proteolytic activity on susceptibility of lepidopteran larvae to Bacillus thuringiensis subsp. kurstaki

    Directory of Open Access Journals (Sweden)

    Reza eTalaei-Hassanloui

    2014-01-01

    Full Text Available Bacillus thuringiensis (Bt is the most effective microbial control agent for controlling numerous species from different insect orders. All subspecies and strains of B. thuringiensis can produce a spore and a crystalline parasporal body. This crystal which contains proteinaceous protoxins is dissolved in the alkaline midgut, the resulting molecule is then cleaved and activated by proteolytic enzymes and acts as a toxin. An interesting aspect of this activation process is that variations in midgut pH and protease activity have been shown to account for the spectrum of some Bt proteins activity. Thus, an important factor that could be a determinant of toxin activity is the presence of proteases in the midgut microenvironment of susceptible insects. Reciprocally, any alteration in the midgut protease composition of the host can result in resistance to Bt. Here in this paper, we reviewed this processes in general and presented our assays to reveal whether resistance mechanism to Bt in Diamondback Moth larvae could be due to the function of the midgut proteases? We estimated LC50 for both probable susceptible and resistant populations in laboratory and greenhouse tests. Then, the midgut protease activities of the B. thuringiensis ind

  9. Extraction of antibiotic zwittermicin A from Bacillus thuringiensis by macroporous resin and silica gel column chromatography.

    Science.gov (United States)

    Hao, Zaibin; Yan, Li; Liu, Jianguo; Song, Fuping; Zhang, Jie; Li, Xia

    2015-01-01

    To establish a production process capable of providing refined zwittermicin A (ZwA) on a large scale, the macroporous resin and silica gel column chromatography were used to separate and purify the antibiotic ZwA from the fermentation broth of Bacillus thuringiensis HD-1. The result of high-performance liquid chromatography-mass spectrometry after purification suggests that the samples of ZwA were of high purity, 89%, and the average yield was 20 mg L(-1). Erwinia herbicola LS005, Escherichia coli, Staphylococcus aureus, and Bacillus subtilis were used to assess the toxicity of ZwA. The antibiotic had strong antibacterial activity against E. herbicola LS005 and a color reaction with ninhydrin. PMID:25099664

  10. Identification and Distribution of Bacillus thuringiensis Isolates from Primeval Forests in Yunnan and Hainan Provinces and Northeast Region of China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ninety-two Bacillus thuringiensis isolates were screened from 683 soil samples collected from tropical and semitropical primeval forests in Yunnan and Hainan provinces of China. Several shapes of crystals, including bipyramidal, square,ovoid, spherical, and amorphous, were observed in the B. thuringiensis isolates. Twenty-six pairs of primers were used to identify 31 holotype cry genes at primary rank of the B. thuringiensis cry gene nomenclature system. The cry gene-types of 92 B. thuringiensis isolates and 33 B. thuringiensis isolates screened from Northeast region of China were identified by PCR-RFLP and SDS-PAGE methods. Fifty-eight isolates harbored cryl genes, 32 isolates cry2 genes, 12 isolates cry8 genes, 3 isolates cry9 genes, 12 isolates cry11 genes, and 13 isolates cry30 genes. Of the tested isolates, 42 produced no reaction product with 26 pairs of primers and also exhibited no toxicity against 8 insect species tested. The isolate Z2-34 harbored a novel cry30 gene, exhibited insecticidal activity against Aedes albopictus of Dipterans. The accession number of the novel genes in this study is AY916046. Isolation and identification of B. thuringiensis and cry gene are important for investigating the diversity of B. thuringiensis resources and cloning new cry gene.

  11. Cloning and characterization of an insecticidal crystal protein gene from Bacillus thuringiensis subspecies kenyae

    Indian Academy of Sciences (India)

    Hari S. Misra; Nivedita P. Khairnar; Manjula Mathur; N. Vijayalakshmi; Remesh S. Hire; T. K. Dongre; S. K. Mahajan

    2002-04-01

    A sporulating culture of Bacillus thuringiensis subsp. kenyae strain HD549 is toxic to larvae of lepidopteran insect species such as Spodoptera litura, Helicoverpa armigera and Phthorimaea operculella, and a dipteran insect, Culex fatigans. A 1.9-kb DNA fragment, PCR-amplified from HD549 using cryII-gene-specific primers, was cloned and expressed in E. coli. The recombinant protein produced 92% mortality in first-instar larvae of Spodoptera litura and 86% inhibition of adult emergence in Phthorimaea operculella, but showed very low toxicity against Helicoverpa armigera, and lower mortality against third-instar larvae of dipteran insects Culex fatigans, Anopheles stephensi and Aedes aegypti. The sequence of the cloned crystal protein gene showed almost complete homology with a mosquitocidal toxin gene from Bacillus thuringiensis var. kurstaki, with only five mutations scattered in different regions. Amino acid alignment with different insecticidal crystal proteins using the MUTALIN program suggested presence of the conserved block 3 region in the sequence of this protein. A mutation in codon 409 of this gene that changes a highly conserved phenylalanine residue to serine lies in this block.

  12. Cloning and characterization of an insecticidal crystal protein gene from Bacillus thuringiensis subspecies kenyae.

    Science.gov (United States)

    Misra, Hari S; Khairnar, Nivedita P; Mathur, Manjula; Vijayalakshmi, N; Hire, Ramesh S; Dongre, T K; Mahajan, S K

    2002-04-01

    A sporulating culture of Bacillus thuringiensis subsp. kenyae strain HD549 is toxic to larvae of lepidopteran insect species such as Spodoptera litura, Helicoverpa armigera and Phthorimaea operculella, and a dipteran insect, Culex fatigans. A 1.9-kb DNA fragment, PCR-amplified from HD549 using cryII-gene-specific primers, was cloned and expressed in E. coli. The recombinant protein produced 92% mortality in first-instar larvae of Spodoptera litura and 86% inhibition of adult emergence in Phthorimaea operculella, but showed very low toxicity against Helicoverpa armigera, and lower mortality against third-instar larvae of dipteran insects Culex fatigans, Anopheles stephensi and Aedes aegypti. The sequence of the cloned crystal protein gene showed almost complete homology with a mosquitocidal toxin gene from Bacillus thuringiensis var. kurstaki, with only five mutations scattered in different regions. Amino acid alignment with different insecticidal crystal proteins using the MUTALIN program suggested presence of the conserved block 3 region in the sequence of this protein. A mutation in codon 409 of this gene that changes a highly conserved phenylalanine residue to serine lies in this block. PMID:12357073

  13. Characterization of a Chitin-Binding Protein from Bacillus thuringiensis HD-1.

    Directory of Open Access Journals (Sweden)

    Naresh Arora

    Full Text Available Strains of Bacillus thuringiensis produce insecticidal proteins. These strains have been isolated from diverse ecological niches, such as soil, phylloplane, insect cadavers and grain dust. To effectively propagate, these strains produce a range of molecules that facilitate its multiplication in a competing environment. In this report, we have examined synthesis of a chitin-binding protein and evaluated its effect on fungi encountered in environment and its interaction with insecticidal proteins synthesized by B. thuringiensis. The gene encoding chitin-binding protein has been cloned and expressed. The purified protein has been demonstrated to interact with Cry insecticidal protein, Cry1Ac by Circular Dichrosim spectroscopy (CD and in vitro pull down assays. The chitin-binding protein potentiates insecticidal activity of bacillar insecticidal protein, Cry1Ac. Further, chitin-binding protein was fungistatic against several soil fungi. The chitin binding protein is expressed in spore mother cell and deposited along with insecticidal protein, Cry1Ac. It interacts with Cry1Ac to potentiate its insecticidal activity and facilitate propagation of Bacillus strain in environment by inhibiting growth of certain fungi.

  14. Optimization of process parameters for enhanced biodegradation of acid red 119 by Bacillus thuringiensis SRDD

    Directory of Open Access Journals (Sweden)

    Riddhi H. Dave

    2012-02-01

    Full Text Available Developed Bacillus thuringiensis SRDD showed degradation of C.I. Acid red 119 and growth under the extremecondition of temperature 70°C, pH 3-8, heavy metals concentration of 0.8 mM, NaCl up to 900 mM and 1000 ppm dye. Cottonseed, caster cake and corn cake powders were found to be better and cheaper nutrient supplements for the Bacillus thuringiensisSRDD for biodegradation as compared to molasses. After development of the culture and the process, more than99% degradation was achieved in less than 2 hrs of contact time even on 18th cycles of addition of 100 ppm AR-119 dye. Thedeveloped process showed AR-119 biodegradation rate as high as 220 mg L-1 h-1, which is found to be 130 times more ascompared to the reported data. U.V., FTIR, TLC and HPLC analysis data confirmed biodegradation ability of the Bacillusthuringiensis for AR-119.

  15. Cloning of the Bacillus thuringiensis serovar sotto chitinase (Schi gene and characterization of its protein

    Directory of Open Access Journals (Sweden)

    Wan-Fang Zhong

    2005-12-01

    Full Text Available Chitinase plays a positive role in the pathogenicity of Bacillus thuringiensis to insect pests. We used touchdown PCR to clone the chitinase (Schi gene from Bacillus thuringiensis serovar sotto (Bt sotto chromosomal DNA. Our DNA sequencing analysis revealed that the Bt sotto Schi gene consists of an open reading frame (ORF of 2067 nucleotides with codes for the chitinase precursor. We also found that the putative promoter consensus sequences (the -35 and -10 regions of the Bt soto Schi gene are identical to those of the chiA71 gene from Bt Pakistani, the chiA74 gene from Bt kenyae and the ichi gene from Bt israelensis. The Schi chitinase precursor is 688 amino acids long with an estimated molecular mass of 75.75 kDa and a theoretical isoelectric point of 5.74, and contains four domains, which are, in sequence, a signal peptide, an N-terminal catalytic domain, a fibronectin type III like domain and a C-terminal chitin-binding domain. Sequence comparison and the evolutionary relationship of the Bt sotto Schi chitinase to other chitinase and chitinase-like proteins are also discussed.

  16. Revision of the nomenclature for the Bacillus thuringiensis pesticidal crystal proteins.

    Science.gov (United States)

    Crickmore, N; Zeigler, D R; Feitelson, J; Schnepf, E; Van Rie, J; Lereclus, D; Baum, J; Dean, D H

    1998-09-01

    The crystal proteins of Bacillus thuringiensis have been extensively studied because of their pesticidal properties and their high natural levels of production. The increasingly rapid characterization of new crystal protein genes, triggered by an effort to discover proteins with new pesticidal properties, has resulted in a variety of sequences and activities that no longer fit the original nomenclature system proposed in 1989. Bacillus thuringiensis pesticidal crystal protein (Cry and Cyt) nomenclature was initially based on insecticidal activity for the primary ranking criterion. Many exceptions to this systematic arrangement have become apparent, however, making the nomenclature system inconsistent. Additionally, the original nomenclature, with four activity-based primary ranks for 13 genes, did not anticipate the current 73 holotype sequences that form many more than the original four subgroups. A new nomenclature, based on hierarchical clustering using amino acid sequence identity, is proposed. Roman numerals have been exchanged for Arabic numerals in the primary rank (e.g., Cry1Aa) to better accommodate the large number of expected new sequences. In this proposal, 133 crystal proteins comprising 24 primary ranks are systematically arranged. PMID:9729610

  17. Genetic Variation for Resistance to Bacillus thuringiensis Toxins in Helicoverpa zea (Lepidoptera: Noctuidae) in Eastern North Carolina

    Science.gov (United States)

    In order to evaluate resistance to Bacillus thuringiensis Berliner toxins, female bollworm moths, Helicoverpa zea (Boddie), were collected from four light trap locations in two eastern North Carolina counties from August-October during 2001 and 2002. Moths were allowed to oviposit, and upon hatch, ...

  18. Bacillus thuringiensis Cry3Aa protoxin intoxication of Tenebrio molitor induces widespread changes in the expression of serine peptidase transcripts

    Science.gov (United States)

    The yellow mealworm, Tenebrio molitor, is a pest of stored grain products and is sensitive to the coleopteran-specific Cry3Aa toxin from Bacillus thuringiensis (Bt). Larvae digest protein initially with cysteine peptidases in the anterior midgut and further with serine peptidases in middle and poste...

  19. A hybrid Bacillus thuringiensis delta-endotoxin gene gives resistance against a coleopteran and a lepidopteran pest in transgenic potato

    NARCIS (Netherlands)

    Naimov, S.; Dukiandjiev, S.; Maagd, de R.A.

    2003-01-01

    Expression of Bacillus thuringiensis delta-endotoxins has proven to be a successful strategy for obtaining insect resistance in transgenic plants. Drawbacks of expression of a single resistance gene are the limited target spectrum and the potential for rapid adaptation of the pest. Hybrid toxins wit

  20. Isolation of transcripts from Diabrotica virgifera virgifera LeConte responsive to the Bacillus thuringiensis toxin Cry3Bb1

    Science.gov (United States)

    Crystal proteins derived from Bacillus thuringiensis (Bt) have been widely used as a method of insect pest management for several decades. In recent years, a transgenic corn expressing the Cry3Bb1 toxin has been successfully used for protection against corn rootworm larvae (Genus...

  1. Bacillus thuringiensis Cry1Ca-resistant Spodoptera exigua lacks expression of one of four Aminopeptidase N genes

    NARCIS (Netherlands)

    Herrero, S.; Gechev, T.; Bakker, P.L.; Moar, W.; Maagd, de R.A.

    2005-01-01

    BACKGROUND: Insecticidal toxins from Bacillus thuringiensis bind to receptors on midgut epithelial cells of susceptible insect larvae. Aminopeptidases N (APNs) from several insect species have been shown to be putative receptors for these toxins. Here we report the cloning and expression analysis of

  2. 40 CFR 174.504 - Bacillus thuringiensis Cry1F protein in cotton; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bacillus thuringiensis Cry1F protein in cotton; exemption from the requirement of a tolerance. 174.504 Section 174.504 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS PROCEDURES AND REQUIREMENTS FOR PLANT-INCORPORATED PROTECTANTS Tolerances...

  3. 40 CFR 174.517 - Bacillus thuringiensis Cry9C protein in corn; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bacillus thuringiensis Cry9C protein in corn; exemption from the requirement of a tolerance. 174.517 Section 174.517 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS PROCEDURES AND REQUIREMENTS FOR PLANT-INCORPORATED PROTECTANTS Tolerances...

  4. 40 CFR 174.502 - Bacillus thuringiensis Cry1A.105 protein; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bacillus thuringiensis Cry1A.105 protein; exemption from the requirement of a tolerance. 174.502 Section 174.502 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS PROCEDURES AND REQUIREMENTS FOR PLANT-INCORPORATED PROTECTANTS Tolerances...

  5. 40 CFR 174.520 - Bacillus thuringiensis Cry1F protein in corn; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bacillus thuringiensis Cry1F protein in corn; exemption from the requirement of a tolerance. 174.520 Section 174.520 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS PROCEDURES AND REQUIREMENTS FOR PLANT-INCORPORATED PROTECTANTS Tolerances...

  6. Expression of Bacillus thuringiensis Cytolytic Toxin (Cyt2Ca1) in citrus roots to control Diaprepes abbreviatus larvae

    Science.gov (United States)

    Diaprepes abbreviatus (L.) is an important pest of citrus in the USA. Currently, no effective management strategies of Diaprepes abbreviatus exist in citriculture. To protect citrus against Diaprepes abbreviatus a transgenic citrus rootstock expressing Bacillus thuringiensis Cyt2Ca1, an insect toxin...

  7. The introduction of integrated pest management in the Ethiopian horticultural sector : Bacillus thuringiensis strains and its toxicity

    NARCIS (Netherlands)

    Belder, den E.; Elderson, J.

    2012-01-01

    1 Introduction As hazards of conventional broad acting pesticides are documented, researchers, poli cymakers and growers look for pesticides that are toxic only to the target pest, have no impact on other such as beneficial species, and have fewer environmental effects. Bacillus thuringiensis (Bt) i

  8. 40 CFR 180.1108 - Delta endotoxin of Bacillus thuringiensis variety San Diego encapsulated into killed Pseudomonas...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Delta endotoxin of Bacillus thuringiensis variety San Diego encapsulated into killed Pseudomonas fluorescens; exemption from the requirement of a tolerance. 180.1108 Section 180.1108 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES...

  9. 40 CFR 174.530 - Bacillus thuringiensis Cry2Ae protein in cotton; temporary exemption from the requirement of a...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bacillus thuringiensis Cry2Ae protein in cotton; temporary exemption from the requirement of a tolerance. 174.530 Section 174.530 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS PROCEDURES AND REQUIREMENTS FOR PLANT-INCORPORATED...

  10. 40 CFR 174.509 - Bacillus thuringiensis Cry3A protein; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bacillus thuringiensis Cry3A protein; exemption from the requirement of a tolerance. 174.509 Section 174.509 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS PROCEDURES AND REQUIREMENTS FOR PLANT-INCORPORATED PROTECTANTS Tolerances and...

  11. Spore prevalence and toxigenicity of Bacillus cereus and Bacillus thuringiensis isolates from U.S. retail spices.

    Science.gov (United States)

    Hariram, Upasana; Labbé, Ronald

    2015-03-01

    Recent incidents of foodborne illness associated with spices as the vehicle of transmission prompted this examination of U.S. retail spices with regard to Bacillus cereus. This study focused on the levels of aerobic-mesophilic spore-forming bacteria and B cereus spores associated with 247 retail spices purchased from five states in the United States. Samples contained a wide range of aerobic-mesophilic bacterial spore counts (spices had high levels of aerobic spores (> 10(7) CFU/g). Using a novel chromogenic agar, B. cereus and B. thuringiensis spores were isolated from 77 (31%) and 11 (4%) samples, respectively. Levels of B. cereus were spice isolates to form spores, produce diarrheal toxins, and grow at moderately abusive temperatures makes retail spices an important potential vehicle for foodborne illness caused by B. cereus strains, in particular those that produce diarrheal toxins.

  12. Identification of a Bacillus thuringiensis gene that positively regulates transcription of the phosphatidylinositol-specific phospholipase C gene at the onset of the stationary phase.

    OpenAIRE

    Lereclus, D.; Agaisse, H; Gominet, M; Salamitou, S; Sanchis, V

    1996-01-01

    A transcriptional analysis of the phosphatidylinositol-specific phospholipase C (plcA) gene of Bacillus thuringiensis indicated that its transcription was activated at the onset of the stationary phase in B. thuringiensis but was not activated in B. subtilis. The B. thuringiensis gene encoding a transcriptional activator required for plcA expression was cloned by using a B. subtilis strain carrying a chromosomal plcA'-'lacZ fusion as a heterologous host for selection. This trans activator (de...

  13. Natural phytosanitary products effects on Bacillus Thuringiensis SUBSP. Kurstaki (BerlinerEfeito de produtos fitossanitários naturais sobre Bacillus Thuringiensis subesp. Kurstaki (Berliner

    Directory of Open Access Journals (Sweden)

    Everton Ricardi Lozano da Silva

    2012-12-01

    Full Text Available This work aimed to evaluate the effect of natural phytossanitary products (NPP on spores and crystal toxicity of Bacillus thuringiensis subsp. kurstaki – HD1 (Btk. For this commercial products (Agromos, Biogermex, Bovemax, Bordeaux mixture, Ecolife®, Dalneen, Matan Plus, Pyronin and Stüble-Aid® were used at three different concentrations. The effect of NPP on spores was assessed by comparing a suspension of Btk + NPP with sterile distilled water (SDW and another suspension with nutrient broth (NB, inoculated on nutrient agar (NA in Petri dishes to quantify the number of CFU/mL, 18 h after inoculation and incubation. The effect of NPP on crystals was evaluated with a suspension of Btk+SDW+NPP added to the artificial diet supplied for Anticarsia gemmatalis Hub. (Lepidoptera: Noctuidae quantifying the number of dead larvae at 12, 24, 48 and 72 h. Matan Plus was the only natural product that did not present effect on spores. All other products, regardless of concentration, decreased significantly CFU/mL Regarding crystals, Bordeaux mixture was the only one that reduced significantly Btk insecticidal activity at three concentrations. Este trabalho objetivou avaliar o efeito dos produtos fitossanitários naturais (PFN sobre esporos e sobre a toxicidade dos cristais de Bacillus thuringiensis subespécie kurstaki – HD1 (Btk. Para tal foram usados os produtos comerciais (Agromos, Biogermex, Bovemax, Calda Bordalesa, Ecolife®, Dalneen, Matan Plus, Pironin e Stüble –Aid® em três diferentes concentrações. O efeito dos PFN sobre esporos foi avaliado comparando-se suspensões de Btk + PFN com água destilada esterelizada (ADE e suspensões com caldo nutriente (CB, inoculadas em agar nutriente (AN, em placas de Petri quantificando-se o número de unidades formadoras de colônias (UFC / mL, 18 h após a inoculação e incubação. O efeito dos PFN sobre cristais foi avaliado com suspensões de Btk + ADE + PFN adicionados à dieta artificial

  14. Influence of multi-year Bacillus thuringiensis subsp. israelensis on the abundance of B. cereus group populations in Swedish riparian wetland soils

    DEFF Research Database (Denmark)

    Hendriksen, Niels Bohse; Schneider, Salome; Tajrin, Tania;

    Bacillus thuringiensis subsp. israelensis (Bti) is a soil-born bacterium affiliated to the B. cereus group (Bcg, a group including the pathogens B. cereus, B. thuringiensis, and B. anthracis) and used in biocontrol products against nematoceran larvae. However, knowledge is limited on how long...

  15. Monitoring Bacillus thuringiensis-Susceptibility in Insect Pests That Occur in Large Geographies: How to Get the Best Information When Two Countries are Involved

    Science.gov (United States)

    The adoption of Bacillus thuringiensis-expressing cotton around the world has been proven to be beneficial for growers and the environment. The effectiveness of this important genetically-modified crop can be jeopardized by the development of B. thuringiensis-resistance in pests, with the possibilit...

  16. Lack of detrimental effects of Bacillus thuringiensis Cry toxins on the insect predator Chrysoperla carnea: a toxicological, histopathological, and biochemical analysis

    NARCIS (Netherlands)

    Rodrigo-Simón, A.; Maagd, de R.A.; Avilla, C.; Bakker, P.L.; Molthoff, J.W.; González-Zamora, J.; Ferré, J.

    2006-01-01

    The effect of Cry proteins of Bacillus thuringiensis on the green lacewing (Chrysoperla carnea) was studied by using a holistic approach which consisted of independent, complementary experimental strategies. Tritrophic experiments were performed, in which lacewing larvae were fed Helicoverpa armiger

  17. Produccion por tecnologia de fermentacion de bacillus thuringiensis utilizando medios alternativos

    Directory of Open Access Journals (Sweden)

    Yaneth Amparo Muñoz-Peñalosa

    2000-01-01

    Full Text Available In the production by fermentation technology Bacillus thuringiensis of five alternative methods they were studied. The results of cell growth, working-level 100ml in static culture and temperature of 28 ° C, mostraronque the optimal substrate corresponded to the environment in which molasses and rice powder was added (alternative Medium No. 1] The cell development using 100 ml of substrate was studied with reciprocating shaking 110 rpm. in this test was determined filter curve creciemiento medio.The inoculum, allowed tiempode set the process in 6 hours. For the development of fermentations, are counted with the experimental equipment, glass bioreactor in two liters of capacity and aeration devices, mechanical stirring, sampling and output gases.The fermentation in the production of Bacillus thuringiensis is the type discontinuous submerged aerobic process and growth into account .Teniendo bibliographic information and preliminary results of the study, fixed working parameters were determined for production by fermentation of Bacillus thuringiensis, being alternative means No. 1, volume 1 liter temperature 28 ° C and cell concentration of the inoculum. To determine the optimum parameters of fermantacion was used a factorial design of experiments of the type 22, (two variables at two levels, with aeration (3.2-0.5 VVM and agitation (110-210 rpm .The fermentations performed 7, 4 design and 3 the average level of the variables. For monitoring fermentation sample was taken every 12 hours and cell concentration (Chamber of Neuvauer and pH was analyzed. The results of cell concentration measurement for fermentations at 60 hours shows that optimum working conditions and limitations correspond to the values ​​of the variable, 3.2 VVM aeration and agitation 210 Variable rpm.Significant was the aeration of pH in the fermentation media change neutral to acid and ended as a staple. A fermentations I were efectuo controlde microbiological quality, Gram

  18. Toxicidad biológica de cepas nativas de Bacillus thuringiensis Berliner en larvas de Tecia solanivora Povolny

    OpenAIRE

    Paola Martínez; Wilson Martínez

    2011-01-01

    La biodiversidad microbiológica de los suelos del departamento de Boyacá aún no ha sido explorada en toda su magnitud y existen microorganismos, como en el caso de Bacillus thuringiensis Berliner (Bt), que pueden emplearse para el desarrollo de estrategias biológicas de control de plagas en el futuro. Por lo anterior, el presente trabajo evaluó la actividad biológica, expresada como  toxicidad, de cepas nativas de B. thuringiensis en la Polilla Guatemalteca  de  la  papa  Tecia  solanivora Po...

  19. Experimental evolution in silico: a custom-designed mathematical model for virulence evolution of Bacillus thuringiensis.

    Science.gov (United States)

    Strauß, Jakob Friedrich; Crain, Philip; Schulenburg, Hinrich; Telschow, Arndt

    2016-08-01

    Most mathematical models on the evolution of virulence are based on epidemiological models that assume parasite transmission follows the mass action principle. In experimental evolution, however, mass action is often violated due to controlled infection protocols. This "theory-experiment mismatch" raises the question whether there is a need for new mathematical models to accommodate the particular characteristics of experimental evolution. Here, we explore the experimental evolution model system of Bacillus thuringiensis as a parasite and Caenorhabditis elegans as a host. Recent experimental studies with strict control of parasite transmission revealed that one-sided adaptation of B. thuringiensis with non-evolving hosts selects for intermediate or no virulence, sometimes coupled with parasite extinction. In contrast, host-parasite coevolution selects for high virulence and for hosts with strong resistance against B. thuringiensis. In order to explain the empirical results, we propose a new mathematical model that mimics the basic experimental set-up. The key assumptions are: (i) controlled parasite transmission (no mass action), (ii) discrete host generations, and (iii) context-dependent cost of toxin production. Our model analysis revealed the same basic trends as found in the experiments. Especially, we could show that resistant hosts select for highly virulent bacterial strains. Moreover, we found (i) that the evolved level of virulence is independent of the initial level of virulence, and (ii) that the average amount of bacteria ingested significantly affects the evolution of virulence with fewer bacteria ingested selecting for highly virulent strains. These predictions can be tested in future experiments. This study highlights the usefulness of custom-designed mathematical models in the analysis and interpretation of empirical results from experimental evolution.

  20. Isolation and characterization of a new Bacillus thuringiensis strain with a promising toxicity against Lepidopteran pests.

    Science.gov (United States)

    Boukedi, Hanen; Sellami, Sameh; Ktari, Sonia; Belguith-Ben Hassan, Najeh; Sellami-Boudawara, Tahya; Tounsi, Slim; Abdelkefi-Mesrati, Lobna

    2016-01-01

    Insecticides derived from Bacillus thuringiensis are gaining worldwide importance as environmentally desirable alternatives to chemicals for the control of pests in public health and agriculture. Isolation and characterization of new strains with higher and broader spectrum of activity is an ever growing field. In the present work, a novel Tunisian B. thuringiensis isolate named BLB459 was characterized and electrophoresis assay showed that among a collection of 200 B. thuringiensis strains, the plasmid profile of BLB459 was distinctive. SmaI-PFGE typing confirmed the uniqueness of the DNA pattern of this strain, compared with BUPM95 and HD1 reference strains. PCR and sequencing assays revealed that BLB459 harbored three cry genes (cry30, cry40 and cry54) corresponding to the obtained molecular sizes in the protein pattern. Interestingly, PCR-RFLP assay demonstrated the originality of the BLB459 cry30-type gene compared to the other published cry30 genes. Insecticidal bioassays showed that BLB459 spore-crystal suspension was highly toxic to both Ephestia kuehniella and Spodoptera littoralis with LC50 values of about 64 (53-75) and 80 (69-91) μg of toxin cm(-2), respectively, comparing with that of the commercial strain HD1 used as reference. Important histopathological effects of BLB459 δ-endotoxins on the two tested larvae midguts were detected, traduced by the vacuolization of the apical cells, the damage of microvilli, and the disruption of epithelial cells. These results proved that BLB459 strain could be of a great interest for lepidopteran biocontrol. PMID:27242138

  1. Efficiency of Intergeneric Recombinants Between Bacillus Thuringiensis and Bacillus Subtilis for Increasing Mortality Rate in Cotten Leaf Worm

    Science.gov (United States)

    AlOtaibi, Saad Aied

    2012-12-01

    In this study , two strains of Bacillus belonging to two serotypes and four of their transconjugants were screened with respect to their toxicity against lepidopterous cotton pest. . Bacterial transconjugants isolated from conjugation between both strains were evaluated for their transconjugant efficiency caused mortality in Spodoptera littoralis larvae . Two groups of bioinsecticides ; crystals , crystals and spores have been isolated from Bacillusstrains and their transconjugants . Insecticidal crystal protein ( ICP ) was specific for lepidopteran insects because of the toxin sufficient both for insect specificity and toxicity . The toxicities of these two groups against larvae of Spodoptera littoralis was expressed as transconjugant efficiency , which related to the mean number of larvae died expressed as mortality percentage . The results showed transconjugant efficiency in reducing the mean number of Spodoptera littoralis larvae feeding on leaves of Ricinus communis sprayed with bioinsecticides of Bt transconjugants. Most values of positive transconjugant efficiency related to increasing mortality percentage are due to toxicological effects appeared in response to the treatments with crystals + endospores than that of crystals alone .This indicated that crystals + endospores was more effective for increasing mortality percentage than that resulted by crystals . Higher positive transconjugant efficiency in relation to the mid parents and better parent was appeared at 168 h of treatment . The results indicated that recombinant Bacillus thuringiensis are important control agents for lepidopteran pests , as well as , susceptibility decreased with larval development . The results also suggested a potential for the deployment of these recominant entomopathogens in the management of Spodoptera. littoralis larvae .

  2. Synthetic cryIIIA gene from Bacillus thuringiensis improved for high expression in plants.

    Science.gov (United States)

    Sutton, D W; Havstad, P K; Kemp, J D

    1992-09-01

    A 1974 bp synthetic gene was constructed from chemically synthesized oligonucleotides in order to improve transgenic protein expression of the cryIIIA gene from Bacillus thuringiensis var. tenebrionis in transgenic tobacco. The crystal toxin genes (cry) from B. thuringiensis are difficult to express in plants even when under the control of efficient plant regulatory sequences. We identified and eliminated five classes of sequence found throughout the cryIIIA gene that mimic eukaryotic processing signals and which may be responsible for the low levels of transcription and translation. Furthermore, the GC content of the gene was raised from 36% to 49% and the codon usage was changed to be more plant-like. When the synthetic gene was placed behind the cauliflower mosaic virus 35S promoter and the alfalfa mosaic virus translational enhancer, up to 0.6% of the total protein in transgenic tobacco plants was cryIIIA as measured from immunoblot analysis. Bioassay data using potato beetle larvae confirmed this estimate. PMID:1301214

  3. Novel toxicity of Bacillus thuringiensis strains against the melon fruit fly, Bactrocera cucurbitae (Diptera: Tephritidae).

    Science.gov (United States)

    Shishir, Md Asaduzzaman; Akter, Asma; Bodiuzzaman, Md; Hossain, M Aftab; Alam, Md Musfiqul; Khan, Shakil Ahmed; Khan, Shakila Nargis; Hoq, M Mozammel

    2015-01-01

    Bactrocera cucurbitae (melon fruit fly) is one of the most detrimental vegetable-damaging pests in Bangladesh. The toxicity of Bacillus thuringiensis (Bt) has been reported against a few genera of Bactrocera in addition to numerous other insect species. Bt strains, harbouring cry1A-type genes were, therefore, assayed in vivo against the 3(rd) instar larvae of B. cucurbitae in this study. The biotype-based prevalence of cry1 and cry1A genes was calculated to be 30.8% and 11.16%, respectively, of the test strains (n=224) while their prevalence was greatest in biotype kurstaki. Though three indigenous Bt strains from biotype kurstaki with close genetic relationship exhibited higher toxicity, maximum mortalities were recorded for Btk HD-73 (96%) and the indigenous Bt JSc1 (93%). LC50 and LC99 values were determined to be 6.81 and 8.32 for Bt JSc1, 7.30 and 7.92 for Bt SSc2, and 6.99 and 7.67 for Btk HD-73, respectively. The cause of toxicity and its variation among the strains was found to be correlated with the synergistic toxic effects of cry1, cry2, cry3 and cry9 gene products, i.e. relevant Cry proteins. The novel toxicity of the B. thuringiensis strains against B. cucurbitae revealed in the present study thus will help in developing efficient and eco-friendly control measures such as Bt biopesticides and transgenic Bt cucurbits.

  4. Beta-glucosidase enzymatic activity of crystal polypeptide of the Bacillus thuringiensis strain 1.1.

    Science.gov (United States)

    Papalazaridou, A; Charitidou, L; Sivropoulou, A

    2003-01-01

    The crystals of Bacillus thuringiensis strain 1.1 consist of the 140 kDa delta-endotoxin, which exhibits beta-glucosidase enzymatic activity, based on the following data. (i) Purified crystals exhibit beta-glucosidase enzymatic activity. When the crystals are reacted with specific antibodies directed either against the commercial (almond purified) beta-glucosidase or against the 140 kDa polypeptide, then considerable reduction of enzymatic activity is observed almost at the same level with both antibodies. (ii) Commercial beta-glucosidase and the 140 kDa crystal polypeptide share antigenic similarities; in Western immunoblots, the 140 kDa crystal polypeptide is recognized by anti-beta-glucosidase antibodies, and commercial beta-glucosidase is recognized by anti-140-kDa antibodies. (iii) The enzymatic properties of commercial beta-glucosidase and that resident in the crystals of B. thuringiensis strain 1.1 are very similar. Thus, both enzymes hydrolyze a wide range of substrates (aryl-beta-glucosides, disaccharides with alpha- or beta-linkage polysaccharides) and have an optimum activity at 40 degrees C and pH 5. Both enzymes are relatively thermostable and are resistant to end-product inhibition by glucose. Additionally, they show the same pattern of inhibition or activation by several chemical compounds. (iv) The crystals and commercial beta-glucosidase show almost equivalent levels of insecticidal activity against Drosophila melanogaster larvae and, furthermore, cause reduction in adult flies that emerge from larvae surviving treatment.

  5. Intravital imaging of Bacillus thuringiensis Cry1A toxin binding sites in the midgut of silkworm.

    Science.gov (United States)

    Li, Na; Wang, Jing; Han, Heyou; Huang, Liang; Shao, Feng; Li, Xuepu

    2014-02-15

    Identification of the resistance mechanism of insects against Bacillus thuringiensis Cry1A toxin is becoming an increasingly challenging task. This fact highlights the need for establishing new methods to further explore the molecular interactions of Cry1A toxin with insects and the receptor-binding region of Cry1A toxins for their wider application as biopesticides and a gene source for gene-modified crops. In this contribution, a quantum dot-based near-infrared fluorescence imaging method has been applied for direct dynamic tracking of the specific binding of Cry1A toxins, CrylAa and CrylAc, to the midgut tissue of silkworm. The in vitro fluorescence imaging displayed the higher binding specificity of CrylAa-QD probes compared to CrylAc-QD to the brush border membrane vesicles of midgut from silkworm. The in vivo imaging demonstrated that more CrylAa-QDs binding to silkworm midgut could be effectively and distinctly monitored in living silkworms. Furthermore, frozen section analysis clearly indicated the broader receptor-binding region of Cry1Aa compared to that of Cry1Ac in the midgut part. These observations suggest that the insecticidal activity of Cry toxins may depend on the receptor-binding sites, and this scatheless and visual near-infrared fluorescence imaging could provide a new avenue to study the resistance mechanism to maintain the insecticidal activity of B. thuringiensis toxins. PMID:24252542

  6. Anthelmintic Effect of Bacillus thuringiensis Strains against the Gill Fish Trematode Centrocestus formosanus

    Science.gov (United States)

    Mendoza-Estrada, Luis Javier; Hernández-Velázquez, Víctor Manuel; Arenas-Sosa, Iván; Flores-Pérez, Fernando Iván; Morales-Montor, Jorge; Peña-Chora, Guadalupe

    2016-01-01

    Parasitic agents, such as helminths, are the most important biotic factors affecting aquaculture, and the fluke Centrocestus formosanus is considered to be highly pathogenic in various fish species. There have been efforts to control this parasite with chemical helminthicides, but these efforts have had unsuccessful results. We evaluated the anthelmintic effect of 37 strains of Bacillus thuringiensis against C. formosanus metacercariae in vitro using two concentrations of total protein, and only six strains produced high mortality. The virulence (CL50) on matacercariae of three strains was obtained: the GP308, GP526, and ME1 strains exhibited a LC50 of 146.2 μg/mL, 289.2 μg/mL, and 1721.9 μg/mL, respectively. Additionally, these six B. thuringiensis strains were evaluated against the cercariae of C. formosanus; the LC50 obtained from the GP526 strain with solubilized protein was 83.8 μg/mL, and it could be considered as an alternative control of the metacercariae and cercariae of this parasite in the productivity systems of ornamental fishes. PMID:27294137

  7. An overview of the safety and biological effects of Bacillus thuringiensis Cry toxins in mammals.

    Science.gov (United States)

    Rubio-Infante, Néstor; Moreno-Fierros, Leticia

    2016-05-01

    Crystal proteins (Cry) produced during the growth and sporulation phases of Bacillus thuringiensis (Bt) bacterium are known as delta endotoxins. These toxins are being used worldwide as bioinsecticides to control pests in agriculture, and some Cry toxins are used against mosquitoes to control vector transmission. This review summarizes the relevant information currently available regarding the biosafety and biological effects that Bt and its insecticidal Cry proteins elicit in mammals. This work was performed because of concerns regarding the possible health impact of Cry toxins on vertebrates, particularly because Bt toxins might be associated with immune-activating or allergic responses. The controversial data published to date are discussed in this review considering earlier toxicological studies of B. thuringiensis, spores, toxins and Bt crops. We discussed the experimental studies performed in humans, mice, rats and sheep as well as in diverse mammalian cell lines. Although the term 'toxic' is not appropriate for defining the effects these toxins have on mammals, they cannot be considered innocuous, as they have some physiological effects that may become pathological; thus, trials that are more comprehensive are necessary to determine their effects on mammals because knowledge in this field remains limited.

  8. Anthelmintic Effect of Bacillus thuringiensis Strains against the Gill Fish Trematode Centrocestus formosanus

    Directory of Open Access Journals (Sweden)

    Luis Javier Mendoza-Estrada

    2016-01-01

    Full Text Available Parasitic agents, such as helminths, are the most important biotic factors affecting aquaculture, and the fluke Centrocestus formosanus is considered to be highly pathogenic in various fish species. There have been efforts to control this parasite with chemical helminthicides, but these efforts have had unsuccessful results. We evaluated the anthelmintic effect of 37 strains of Bacillus thuringiensis against C. formosanus metacercariae in vitro using two concentrations of total protein, and only six strains produced high mortality. The virulence (CL50 on matacercariae of three strains was obtained: the GP308, GP526, and ME1 strains exhibited a LC50 of 146.2 μg/mL, 289.2 μg/mL, and 1721.9 μg/mL, respectively. Additionally, these six B. thuringiensis strains were evaluated against the cercariae of C. formosanus; the LC50 obtained from the GP526 strain with solubilized protein was 83.8 μg/mL, and it could be considered as an alternative control of the metacercariae and cercariae of this parasite in the productivity systems of ornamental fishes.

  9. Anthelmintic Effect of Bacillus thuringiensis Strains against the Gill Fish Trematode Centrocestus formosanus.

    Science.gov (United States)

    Mendoza-Estrada, Luis Javier; Hernández-Velázquez, Víctor Manuel; Arenas-Sosa, Iván; Flores-Pérez, Fernando Iván; Morales-Montor, Jorge; Peña-Chora, Guadalupe

    2016-01-01

    Parasitic agents, such as helminths, are the most important biotic factors affecting aquaculture, and the fluke Centrocestus formosanus is considered to be highly pathogenic in various fish species. There have been efforts to control this parasite with chemical helminthicides, but these efforts have had unsuccessful results. We evaluated the anthelmintic effect of 37 strains of Bacillus thuringiensis against C. formosanus metacercariae in vitro using two concentrations of total protein, and only six strains produced high mortality. The virulence (CL50) on matacercariae of three strains was obtained: the GP308, GP526, and ME1 strains exhibited a LC50 of 146.2 μg/mL, 289.2 μg/mL, and 1721.9 μg/mL, respectively. Additionally, these six B. thuringiensis strains were evaluated against the cercariae of C. formosanus; the LC50 obtained from the GP526 strain with solubilized protein was 83.8 μg/mL, and it could be considered as an alternative control of the metacercariae and cercariae of this parasite in the productivity systems of ornamental fishes. PMID:27294137

  10. High instability of a nematicidal Cry toxin plasmid in Bacillus thuringiensis.

    Science.gov (United States)

    Sheppard, Anna E; Nakad, Rania; Saebelfeld, Manja; Masche, Anna C; Dierking, Katja; Schulenburg, Hinrich

    2016-01-01

    In bacterial pathogens, virulence factors are often carried on plasmids and other mobile genetic elements, and as such, plasmid evolution is central in understanding pathogenicity. Bacillus thuringiensis is an invertebrate pathogen that uses plasmid-encoded crystal (Cry) toxins to establish infections inside the host. Our study aimed to quantify stability of two Cry toxin-encoding plasmids, BTI_23p and BTI_16p, under standard laboratory culturing conditions. These two plasmids are part of the genome of the B. thuringiensis strain MYBT18679, which is of particular interest because of its high pathogenicity towards nematodes. One of the plasmids, BTI_23p, was found to be highly unstable, with substantial loss occurring within a single growth cycle. Nevertheless, longer term experimental evolution in the absence of a host revealed maintenance of the plasmid at low levels in the bacterial populations. BTI_23p encodes two nematicidal Cry toxins, Cry21Aa2 and Cry14Aa1. Consistent with previous findings, loss of the plasmid abolished pathogenicity towards the nematode Caenorhabditis elegans, which could be rescued by addition of Cry21Aa2-expressing Escherichia coli. These results implicate BTI_23p as a plasmid that is required for successful infection, yet unstable when present at high frequency in the population, consistent with the role of Cry toxins as public goods. PMID:26592941

  11. An overview of the safety and biological effects of Bacillus thuringiensis Cry toxins in mammals.

    Science.gov (United States)

    Rubio-Infante, Néstor; Moreno-Fierros, Leticia

    2016-05-01

    Crystal proteins (Cry) produced during the growth and sporulation phases of Bacillus thuringiensis (Bt) bacterium are known as delta endotoxins. These toxins are being used worldwide as bioinsecticides to control pests in agriculture, and some Cry toxins are used against mosquitoes to control vector transmission. This review summarizes the relevant information currently available regarding the biosafety and biological effects that Bt and its insecticidal Cry proteins elicit in mammals. This work was performed because of concerns regarding the possible health impact of Cry toxins on vertebrates, particularly because Bt toxins might be associated with immune-activating or allergic responses. The controversial data published to date are discussed in this review considering earlier toxicological studies of B. thuringiensis, spores, toxins and Bt crops. We discussed the experimental studies performed in humans, mice, rats and sheep as well as in diverse mammalian cell lines. Although the term 'toxic' is not appropriate for defining the effects these toxins have on mammals, they cannot be considered innocuous, as they have some physiological effects that may become pathological; thus, trials that are more comprehensive are necessary to determine their effects on mammals because knowledge in this field remains limited. PMID:26537666

  12. Decolorization of dyehouse effluent and biodegradation of Congo red by Bacillus thuringiensis RUN1.

    Science.gov (United States)

    Olukanni, Olumide David; Osuntoki, Akinniyi A; Awotula, Ayodeji Olushola; Kalyani, Dayanand C; Gbenle, George Olabode; Govindwar, Sanjay P

    2013-06-28

    A dye-decolorizing bacterium was isolated from a soil sample and identified as Bacillus thuringiensis using 16S rRNA sequencing. The bacterium was able to decolorize three different textile dyes, namely, Reactive blue 13, Reactive red 58, and Reactive yellow 42, and a real dyehouse effluent up to 80-95% within 6 h. Some non-textile industrially important dyes were also decolorized to different extents. Fourier transform infrared spectroscopy and gas chromatography-mass spectrometer analysis of the ethyl acetate extract of Congo red dye and its metabolites showed that the bacterium could degrade it by the asymmetric cleavage of the azo bonds to yield sodium (4- amino-3-diazenylnaphthalene-1-sulfonate) and phenylbenzene. Sodium (4-amino-3-diazenylnaphthalene-1-sulfonate) was further oxidized by the ortho-cleavage pathway to yield 2- (1-amino-2-diazenyl-2-formylvinyl) benzoic acid. There was induction of the activities of laccase and azoreductase during the decolorization of Congo red, which suggests their probable role in the biodegradation. B. thuringiensis was found to be versatile and could be used for industrial effluent biodegradation.

  13. Shared binding sites in Lepidoptera for Bacillus thuringiensis Cry1Ja and Cry1A toxins.

    Science.gov (United States)

    Herrero, S; González-Cabrera, J; Tabashnik, B E; Ferré, J

    2001-12-01

    Bacillus thuringiensis toxins act by binding to specific target sites in the insect midgut epithelial membrane. The best-known mechanism of resistance to B. thuringiensis toxins is reduced binding to target sites. Because alteration of a binding site shared by several toxins may cause resistance to all of them, knowledge of which toxins share binding sites is useful for predicting cross-resistance. Conversely, cross-resistance among toxins suggests that the toxins share a binding site. At least two strains of diamondback moth (Plutella xylostella) with resistance to Cry1A toxins and reduced binding of Cry1A toxins have strong cross-resistance to Cry1Ja. Thus, we hypothesized that Cry1Ja shares binding sites with Cry1A toxins. We tested this hypothesis in six moth and butterfly species, each from a different family: Cacyreus marshalli (Lycaenidae), Lobesia botrana (Tortricidae), Manduca sexta (Sphingidae), Pectinophora gossypiella (Gelechiidae), P. xylostella (Plutellidae), and Spodoptera exigua (Noctuidae). Although the extent of competition varied among species, experiments with biotinylated Cry1Ja and radiolabeled Cry1Ac showed that Cry1Ja and Cry1Ac competed for binding sites in all six species. A recent report also indicates shared binding sites for Cry1Ja and Cry1A toxins in Heliothis virescens (Noctuidae). Thus, shared binding sites for Cry1Ja and Cry1A occur in all lepidopteran species tested so far. PMID:11722929

  14. Combining Hexanoic Acid Plant Priming with Bacillus thuringiensis Insecticidal Activity against Colorado Potato Beetle

    Directory of Open Access Journals (Sweden)

    Carolina Rausell

    2013-06-01

    Full Text Available Interaction between insect herbivores and host plants can be modulated by endogenous and exogenous compounds present in the source of food and might be successfully exploited in Colorado potato beetle (CPB pest management. Feeding tests with CPB larvae reared on three solanaceous plants (potato, eggplant and tomato resulted in variable larval growth rates and differential susceptibility to Bacillus thuringiensis Cry3Aa toxin as a function of the host plant. An inverse correlation with toxicity was observed in Cry3Aa proteolytic patterns generated by CPB midgut brush-border membrane vesicles (BBMV from Solanaceae-fed larvae, being the toxin most extensively proteolyzed on potato, followed by eggplant and tomato. We found that CPB cysteine proteases intestains may interact with Cry3Aa toxin and, in CPB BBMV from larvae fed all three Solanaceae, the toxin was able to compete for the hydrolysis of a papain substrate. In response to treatment with the JA-dependent plant inducer Hexanoic acid (Hx, we showed that eggplant reduced OPDA basal levels and both, potato and eggplant induced JA-Ile. CPB larvae feeding on Hx-induced plants exhibited enhanced Cry3Aa toxicity, which correlated with altered papain activity. Results indicated host-mediated effects on B. thuringiensis efficacy against CPB that can be enhanced in combination with Hx plant induction.

  15. Luminal proteinases from Plodia interpunctella and the hydrolysis of Bacillus thuringiensis CryIA(c) protoxin.

    Science.gov (United States)

    Oppert, B; Kramer, K J; Johnson, D; Upton, S J; Mcgaughey, W H

    1996-06-01

    The ability of proteinases in gut extracts of the Indianmeal moth, Plodia interpunctella, to hydrolyze Bacillus thuringiensis (Bt) protoxin, casein, and rho-nitroanilide substrates was investigated. A polyclonal antiserum to protoxin CryIA(c) was used in Western blots to demonstrate slower protoxin processing by gut enzymes from Bt subspecies entomocidus-resistant larvae than enzymes from susceptible or kurstaki-resistant strains. Enzymes from all three strains hydrolyzed N-alpha-benzoyl-L-arginine rho-nitroanilide, N-succinyl-ala-ala-pro-phenylalanine rho-nitroanilide, and N-succinyl-ala-ala-pro-leucine rho-nitroanilide. Zymograms and activity blots were used to estimate the apparent molecular masses, number of enzymes, and relative activities in each strain. Several serine proteinase inhibitors reduced gut enzyme activities, with two soybean trypsin inhibitors, two potato inhibitors, and chymostatin the most effective in preventing protoxin hydrolysis.

  16. Effect of Bacillus thuringiensis on Habrobracon hebetor during combined biological control of Plodia interpunctella

    Institute of Scientific and Technical Information of China (English)

    Akinkurolere Rotimi Oluwafemi; Qiong Rao; Xi-Qiao Wang; Hong-Yu Zhang

    2009-01-01

    The suitability of combining microbial pesticides and an insect parasitoid for pest management of stored cereal in China was evaluated using laboratory assays.For this purpose,interactions between Bacillus thuringiensis (Bt),Bt-intoxicated host larvae and the parasitoid Habrobracon hebetor (Say) (Hymenoptera:Braconidae) were alone caused 41.67% and 35.35% P.interpunctella larval mortality respectively.The Btparasitoid combined treatment significantly increased mortality of P.interpunctella (86%).Progeny development of H.hebetor was dependent upon its susceptibility to Bt.Fewer parasitoids emerged from Bt-parasitoid combined treatment than in non-Bt treatments.However,since Bt did not prevent parasitoid development,a combined treatment with Bt and parasitoid release could produce better protection against P.interpunctella than either treatments when used singly,because their lethal effects were additive to each other.

  17. Structure and distribution of the Bacillus thuringiensis Cry4Ba toxin in lipid membranes

    International Nuclear Information System (INIS)

    Bacillus thuringiensis Cry δ-endotoxins cause death of susceptible insect larvae by forming lytic pores in the midgut epithelial cell membranes. The 65 kDa trypsin activated Cry4Ba toxin was previously shown to be capable of permeabilizing liposomes and forming ionic channels in receptor-free planar lipid bilayers. Here, magnetic ACmode (MACmode) atomic force microscopy (AFM) was used to characterize the lateral distribution and the native molecular structure of the Cry4Ba toxin in the membrane. Liposome fusion and the Langmuir-Blodgett technique were employed for supported lipid bilayer preparations. The toxin preferentially inserted in a self-assembled structure, rather than as a single monomeric molecule. In addition, the spontaneous insertion into receptor-free lipid bilayers lead to formation of characteristic pore-like structures with four-fold symmetry, suggesting that tetramers are the preferred oligomerization state of this toxin

  18. Toxicity of radiation-resistant strains of Bacillus thuringiensis (Berl.) to larval Plutella xylostella (L.)

    International Nuclear Information System (INIS)

    A total of 24 isolates of Bacillus thuringiensis (Berliner), resistant to a γ-radiation dose of 100 krad, were screened for their toxicity to larval silkworms, Bombyxmori(L.), and 15 of them were subsequently tested for their toxicity to larval diamond-back moth, Plutella xylostella(L.). The LC50's of these isolates to B. mori ranged from 1.6 X 105 to 6.0 X 103 spores/mL or from 5.9 to 0.3 μg cellular protein/mL. The irradiation treatment produced isolates which were significantly more toxic to P. xylostella (LC50 4 spores/mL or 3.7 μg cellular protein/mL) and/ or less toxic to B. mori (LC50 > 2.3 X 104 spores/mL or 1.0 μg cellular protein/mL) than the parent commercial strain

  19. Diversity among Bacillus thuringiensis active against the Mediterranean fruit fly, Ceratitis capitata

    International Nuclear Information System (INIS)

    Procedures were developed to screen rapidly isolates of the entomopathogen Bacillus thuringiensis against adults of the Mediterranean fruit fly, Ceratitis capitata, and simultaneously characterize its active agents on the basis of their water solubility and heat stability. Fermentation products in solution, in suspension or dried were bioassayed. Heat stable, soluble exotoxins were the most frequently found active agents; some strains produced exotoxins that precipitated and their activity was found in the sediment fraction of fermentation beers. Insoluble heat labile agents were found that upon subsequent preparation were identified as active spores. The activity of spores from different isolates was different. One isolate produced endotoxin that, although inactive when bioassayed alone, had synergistic activity when combined with spores. (author). 6 refs, 5 figs, 3 tabs

  20. Friction and Adhesion Forces of Bacillus thuringiensis Spores on Planar Surfaces in Atmospheric Systems

    Energy Technology Data Exchange (ETDEWEB)

    Kweon, Hyojin [Georgia Institute of Technology; Yiacoumi, Sotira [Georgia Institute of Technology; Tsouris, Costas [ORNL

    2011-01-01

    The kinetic friction force and the adhesion force of Bacillus thuringiensis spores on planar surfaces in atmospheric systems were studied using atomic force microscopy. The influence of relative humidity (RH) on these forces varied for different surface properties including hydrophobicity, roughness, and surface charge. The friction force of the spore was greater on a rougher surface than on mica, which is atomically flat. As RH increases, the friction force of the spores decreases on mica whereas it increases on rough surfaces. The influence of RH on the interaction forces between hydrophobic surfaces is not as strong as for hydrophilic surfaces. The friction force of the spore is linear to the sum of the adhesion force and normal load on the hydrophobic surface. The poorly defined surface structure of the spore and the adsorption of contaminants from the surrounding atmosphere are believed to cause a discrepancy between the calculated and measured adhesion forces.

  1. A structured model for vegetative growth and sporulation in Bacillus thuringiensis

    Energy Technology Data Exchange (ETDEWEB)

    Starzak, M.; Bajpai, R.K. [Univ. of Missouri, Columbia, MO (United States)

    1991-12-31

    A mathematical model has been developed for the 6-endotoxin producing Bacillus thuringiensis. The structure of the model involves the processes taking place during vegetative growth, those leading to the initiation of sporulation under conditions of carbon and/or nitrogen limitation, and the sporulation events. The key features in the model are the pools of compounds, such as PRPP, IMP, ADP/ATP, GDP/GTP, pyrimidine nucleotides, NAD/NADH{sub 2}, amino acids, nucleic acids, cell wall, and vegetative and sporulation proteins. These, along with a-factors that control the nature of RNA-polymerase during the different phases, effectively stimulate the vegetative growth and sporulation. The initiation of sporulation is controlled by the intracellular concentration of GTP. Results of simulation of vegetative growth, initiation of sporulation, spore protein formation, and production of {delta}-endotoxin under C- or N-limitation are presented.

  2. Parasporal Proteins from Bacillus thuringiensis and Their Cytotoxicity on Human Cancer Cells

    Institute of Scientific and Technical Information of China (English)

    WANG Lei; LV Yuan; YI Yin-sha; YI Shang-hui; LI Lin

    2015-01-01

    Parasporins(PSs) represent a novel functional category of crystal proteins (Cry) produced by non-insecticidal Bacillus thuringiensisA distinct feature for PSs is their specific cytotoxicity against human cancer cells from diverse origins, other than hemolytic or insecticidal activityAs structurally/functionally Cry proteins, parasporins are expressed as protoxins that require protease cleavage for activationCurrently, identified PSs is classified into 6 groups:PS1, PS2, PS3, PS4, PS5 and PS6, which are heterogeneous in cytotoxic spectrum and activity levelSome PSs have been explored for their mode of anticancer activities, reports mainly include pore formation induced by binding to putative receptors on cell membrane and apoptosis by intracellular Ca 2+concentrationFurther work should focus on the identification of new PS or PS homologs and better understanding of their anticancer mechanism before possible application in cancer therapy.

  3. Influence of Formate on Bioactivity Material-thuringiensin Synthesized by Bacillus thuringiensis YBT-032

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi; CHEN Xiong; CHEN Shouwen; SUN Ming; YU Ziniu

    2008-01-01

    The biological method to synthesize thuringiensin and the influence of formate on thuringiensin biosynthesis were investigated. Addition of 1.00 g/L formate to growth medium of bacillus thuringiensis YBT-032 resulted in significant enhancements in productions of citrate, a-ketoglutarate, intracellular adenine and thuringiensin. These results demonstrate that added formate attends metabolism of cell, facilitates carbon metabolic flux in tricarboxylic acid cycle and hexose monophosphate pathway. As a carbon source, formate facilitates cell growth, increases glucose consumption and enhances the ability of cell to synthesis adenine analogues, and subsequently thuringiensin. Thuringiensin production rate significantly enhanced from 6.44 to 8.46 mg·g-1·h-1 and transformation ratio from glucose to thuringiensin increased by 43.30%.

  4. 苏云金杆菌的研究%Study on Bacillus thuringiensis

    Institute of Scientific and Technical Information of China (English)

    黄自云

    2012-01-01

    苏云杆菌(Bacillus thuringiensis)制剂是目前广泛应用的一种微生物杀虫剂.本文介绍了苏云金芽孢杆菌的菌体形态,制剂的理化性质、毒性、作用原理及生产使用方法,不能与有机磷类杀虫、杀菌剂及碱性农药混用,对蚕毒性高,建议与其他作用机制不同的杀虫剂轮换使用,以延缓抗性产生.最后分析了苏云金杆菌在遗传工程上的应用.

  5. Structure and distribution of the Bacillus thuringiensis Cry4Ba toxin in lipid membranes

    Energy Technology Data Exchange (ETDEWEB)

    Puntheeranurak, Theeraporn [Institute for Biophysics, Johannes Kepler University of Linz, Altenbergerstr. 69, A-4040 Linz (Austria); Laboratory of Molecular Biophysics, Institute of Molecular Biology and Genetics, Mahidol University, Salaya Campus, Nakornpathom 73170 (Thailand); Stroh, Cordula [Institute for Biophysics, Johannes Kepler University of Linz, Altenbergerstr. 69, A-4040 Linz (Austria); Zhu Rong [Institute for Biophysics, Johannes Kepler University of Linz, Altenbergerstr. 69, A-4040 Linz (Austria); Angsuthanasombat, Chanan [Laboratory of Molecular Biophysics, Institute of Molecular Biology and Genetics, Mahidol University, Salaya Campus, Nakornpathom 73170 (Thailand); Hinterdorfer, Peter [Institute for Biophysics, Johannes Kepler University of Linz, Altenbergerstr. 69, A-4040 Linz (Austria)]. E-mail: peter.hinterdorfer@jku.at

    2005-11-15

    Bacillus thuringiensis Cry {delta}-endotoxins cause death of susceptible insect larvae by forming lytic pores in the midgut epithelial cell membranes. The 65 kDa trypsin activated Cry4Ba toxin was previously shown to be capable of permeabilizing liposomes and forming ionic channels in receptor-free planar lipid bilayers. Here, magnetic ACmode (MACmode) atomic force microscopy (AFM) was used to characterize the lateral distribution and the native molecular structure of the Cry4Ba toxin in the membrane. Liposome fusion and the Langmuir-Blodgett technique were employed for supported lipid bilayer preparations. The toxin preferentially inserted in a self-assembled structure, rather than as a single monomeric molecule. In addition, the spontaneous insertion into receptor-free lipid bilayers lead to formation of characteristic pore-like structures with four-fold symmetry, suggesting that tetramers are the preferred oligomerization state of this toxin.

  6. Comparison of biomass estimation techniques for a Bacillus thuringiensis fed-batch culture

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, C.C.F. [University of Newcastle upon Tyne (United Kingdom). Dept. of Chemical and Process Engineering]. E-mail: C.C.F.Cunha@newcastle.ac.uk; Souza Junior, M.B. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Escola de Quimica]. E-mail: mbsj@h2o.eq.ufrj.br

    2001-03-01

    In this work, the ability of artificial neural nets was investigated for the on-line biomass prediction of the simulated growth of a strain of Bacillus thuringiensis in fed-batch mode. For this purpose, multilayered backpropagation nets with sigmoid nodes were trained. The patterns were composed of input data on current values of biomass concentration, limiting substrate concentration and dilution rate, and output data on prediction of biomass concentration for the following step. The dilution rate was disturbed by a PRBS input, and simulations were conducted using a phenomenological experimentally validated model. The nets were able to predict the biomass concentration for different feeding techniques, and they were also compared with the variable estimation technique using the extended Kalman filter. (author)

  7. Bacillus thuringiensis Cry1Aa toxin-binding region of Bombyx mori aminopeptidase N.

    Science.gov (United States)

    Yaoi, K; Nakanishi, K; Kadotani, T; Imamura, M; Koizumi, N; Iwahana, H; Sato, R

    1999-12-17

    The Bacillus thuringiensis Cry1Aa toxin-binding region of Bombyx mori aminopeptidase N (APN) was analyzed, to better understand the molecular mechanism of susceptibility to the toxin and the development of resistance in insects. APN was digested with lysylendopeptidase and the ability of the resulting fragments to bind to Cry1Aa and 1Ac toxins was examined. The binding abilities of the two toxins to these fragments were different. The Cry1Aa toxin bound to the fragment containing 40-Asp to 313-Lys, suggesting that the Cry1Aa toxin-binding site is located in the region between 40-Asp and 313-Lys, while Cry1Ac toxin bound exclusively to mature APN. Next, recombinant APN of various lengths was expressed in Escherichia coli cells and its ability to bind to Cry1Aa toxin was examined. The results localized the Cry1Aa toxin binding to the region between 135-Ile and 198-Pro. PMID:10606725

  8. Isolation and characterization of radioresistant mutants in Bacillus subtilis and Bacillus thuringiensis

    International Nuclear Information System (INIS)

    Vegetative cells of Bac. thuringiensis var. galleriae (the wild-type strain 351) are much more sensitive to lethal effects of UV light and 60Co-γ-rays than those of Bac. subtilis (the wild-type strain 168). This difference is less pronounced for spores of these strains. By means of repeated γ-irradiation-regrowth cycles radioresistant mutants Bac. thuringiensis Gamsup(r) 14 and Bac. subtilis Gamsup(r) 9 were selected. The vegetative cells of these mutants are correspondingly 19 times and 3.9 times more resistant to lethal effects of γ-radiation than the cells of the parental strains. The resistance of the Gamsup(r) mutant cells to lethal effects of UV light and H2O2 is also increased. The spores of the Gamsup(r) 14 mutant are 1.5-1.7 times more resistant to γ-radiation and UV light than the wild-type spores. The radioresistant mutants and the parental strains do not vary in their capacity for host-cell reactivation of UV- or γ-irradiated phages Tg13 and 105

  9. Isolation and characterization of radioresistant mutants in Bacillus subtilis and Bacillus thuringiensis

    Energy Technology Data Exchange (ETDEWEB)

    Kalinin, V.L.; Petrov, V.N.; Petrova, T.M. (AN SSSR, Leningrad. Inst. Yadernoj Fiziki)

    Vegetative cells of Bac. thuringiensis var. galleriae (the wild-type strain 351) are much more sensitive to lethal effects of UV light and /sup 60/Co-..gamma..-rays than those of Bac. subtilis (the wild-type strain 168). This difference is less pronounced for spores of these strains. By means of repeated ..gamma..-irradiation-regrowth cycles radioresistant mutants of Bac. thuringiensis Gamsup(r) 14 and Bac. subtilis Gamsup(r) 9 were selected. The vegetative cells of these mutants are correspondingly 19 times and 3.9 times more resistant to lethal effects of ..gamma..-radiation than the cells of the parental strains. The resistance of the Gamsup(r) mutant cells to lethal effects of UV light and H/sub 2/O/sub 2/ is also increased. The spores of the Gamsup(r) 14 mutant are 1.5-1.7 times more resistant to ..gamma..-radiation and UV light than the wild-type spores. The radioresistant mutants and the parental strains do not vary in their capacity for host-cell reactivation of UV- or ..gamma..-irradiated phages Tg13 and 105.

  10. Invertebrate pathogenicity and toxin-producing potential of strains of Bacillus thuringiensis endemic to Antarctica.

    Science.gov (United States)

    Prabhakar, A; Bishop, A H

    2011-06-01

    Several strains of Bacillus thuringiensis were previously isolated from soil in Antarctica and appeared to have physiological adaptations to this cold, nutrient-poor environment. In spite of this they could produce abnormally large, parasporal crystals under laboratory conditions. Here, they have been further characterised for toxin genes and invertebrate pathogenicity. All of the strains were positive in PCR assays for the cry1Aa and cry2 genes. This was confirmed by sequence analysis and the parasporal crystals of all strains contained polypeptides of about 130kDa. This potential for lepidopteran toxicity was borne out in bioassays of purified δ-endotoxins against larvae of Pieris brassicae: the LD(50) values of B2408 (288μg) were comparable to that of the reference strain, HD-12 (201μg). There was no activity against the nematode Caenorhabditis elegans in spite of the fact that all strains appeared to possess the cry6 gene. PCR screening for genes encoding other nematode-toxic classes of toxins (Cry5, 4 and 21) was negative. B. thuringiensis has never previously been shown to be toxic to Collembola (springtails) but the purified δ-endotoxins of one of the Antarctic strains showed some activity against Folsomia candida and Seira domestica (224μg and 238μg, respectively). It seems unlikely that the level of toxicity demonstrated against springtails would support a pathogenic life-style in nature. All of the strains were positive for genes encoding Bacillus cereus-type enterotoxins. In the absence of higher insects and mammals the ecological value of retaining the toxic capability demonstrated here is uncertain. PMID:21457716

  11. Identification of metabolism pathways directly regulated by Sigma54 factor in Bacillus thuringiensis

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    Qi ePeng

    2015-05-01

    Full Text Available Sigma54 (σ54 normally regulates nitrogen and carbon utilization in bacteria. Promoters that are σ54-dependent are highly conserved and contain short sequences located at the −24 and −12 positions upstream of the transcription initiation site. σ54 requires regulatory proteins known as bacterial enhancer-binding proteins (bEBPs to activate gene transcription. We show that σ54 regulates the capacity to grow on various nitrogen sources using a Bacillus thuringiensis HD73 mutant lacking the sigL gene encoding σ54 (ΔsigL. A 2-fold-change cutoff and a false discovery rate cutoff of P < 0.05 were used to analyze the DNA microarray data, which revealed 255 genes that were downregulated and 121 that were upregulated in the ΔsigL mutant relative to the wild-type HD73 strain. The σ54 regulon (stationary phase was characterized by DNA microarray, bioinformatics, and functional assay; 16 operons containing 47 genes were identified whose promoter regions contain the conserved −12/−24 element and whose transcriptional activities were abolished or reduced in the ΔsigL mutant. Eight σ54-dependent transcriptional bEBPs were found in the Bt HD73 genome, and they regulated night σ54-dependent promoters.The metabolic pathways activated by σ54 in this process have yet to be identified in Bacillus thuringiensis; nonetheless, the present analysis of the σ54 regulon provides a better understanding of the physiological roles of σ factors in bacteria.

  12. RESIDUAL TOXICITY OF BACILLUS THURINGIENSIS H-14 (VCRC B17 IN SOME TYPES OF BREEDING PLACES OF AEDES AEGYPTI

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    Salamun Salamun

    2012-09-01

    Full Text Available Bacillus thuringiensis H-14, adalah agensia mikrobial yang sangat spesifik terhadap serangga sasaran, aman terhadap golongan mamalia, dan tidak mencemari lingkungan, sehingga dapat dikembangkan sebagai agensia untuk pengendalian vektor, khususnya vektor demam berdarah dengue di Indonesia. Toksisitas residual B. thuringiensis H-14 (VCRC B17 terhadap larva instar III Aedes aegypti pada beberapa tipe tempat penampung air telah dievaluasi di dalam laboratorium. Hasil evaluasi menunjukkan bahwa angka kematian larva uji lebih dari 80% oleh pengaruh B. thuringiensis H-14 (VCRC B17 pada konsentrasi antara 1 sampai 25 mg/l di dalam tipe tempat penampung air dari semen, tanah liat, dan plastik masing-masing adalah 16 sampai 60 hari, 18 sampai 36 hari, dan 12 sampai 42 hari.

  13. Selection of optimum conditions of medium acidity and aeration for submerget cultivation of Bacillus thuringiensis and Beauveria bassiana

    Directory of Open Access Journals (Sweden)

    O. A. Dregval

    2010-06-01

    Full Text Available The paper deals with the influence of medium pH and aeration rate on growth and sporulation of Bacillus thuringiensis and Вeauveria bassiana, which are main constituents of the complex microbial insecticide. It was established optimal medium pH for B. thuringiensis – 6.0 and for В. bassiana – 6.0–7.0. The maximum productivity of the studied microorganisms was observed in the same range of aeration – 7– 14 mmol O2/l/h. The selected conditions of cultivation are necessary for the production of complex biological insecticide based on the association of B. thuringiensis and B. bassiana.

  14. Tribolium castaneum Apolipophorin-III acts as an immune response protein against Bacillus thuringiensis Cry3Ba toxic activity.

    Science.gov (United States)

    Contreras, Estefanía; Rausell, Carolina; Real, M Dolores

    2013-07-01

    In this study, a 2.1-fold Apolipophorin-III mRNA up-regulation was found in Tribolium castaneum larvae challenged with Bacillus thuringiensis Cry3Ba spore-crystal mixture. Knockdown of Apolipophorin-III by RNAi resulted in increased T. castaneum larvae susceptibility following Cry3Ba spore-crystal treatment, demonstrating Apolipophorin-III involvement in insect defense against B. thuringiensis. We showed that Apolipophorin-III participates in T. castaneum immune response to B. thuringiensis activating the prophenoloxidase cascade since: (i) phenoloxidase activity significantly increased after Cry3Ba spore-crystal treatment compared to untreated or Cry1Ac spore-crystal treated larvae and (ii) phenoloxidase activity in Cry3Ba spore-crystal treated Apolipophorin-III silenced larvae was 71±14% lower than that of non-silenced intoxicated larvae.

  15. Isolation of Bacillus thuringiensis from the state of Amazonas, in Brazil, and screening against Aedes aegypti (Diptera, Culicidae

    Directory of Open Access Journals (Sweden)

    Joelma Soares-da-Silva

    2015-03-01

    Full Text Available We investigated the use of Bacillus thuringiensis isolated in the state of Amazonas, in Brazil, for the biological control of the dengue vector Aedes aegypti. From 25 soil samples collected in nine municipalities, 484 bacterial colonies were obtained, 57 (11.78% of which were identified as B. thuringiensis. Six isolates, IBt-03, IBt-06, IBt-07, IBt-28, IBt-30, and BtAM-27 showed insecticidal activity, and only BtAM-27 presents the five genes investigated cry4Aa, cry4Ba, cry10Aa, cry11Aa, and cry11Ba. The IBt-07 and IBt- 28, with lower LC50 values, showed equal toxicity compared to the standards. The isolates of B. thuringiensis from Amazonas constitute potential new means of biological control for A. aegypti, because of their larvicidal activity and the possibility that they may also contain new combinations of toxins.

  16. Screening and analysis of insecticidal activity of protein from Bacillus thuringiensis against Mythimna separata%对黏虫具有杀虫活性的Bt蛋白筛选及分析

    Institute of Scientific and Technical Information of China (English)

    杨素娟; 黄闽忠; 李艳秋; 周子珊; 江幸福; 高继国; 程云霞; 张杰

    2016-01-01

    In order to investigate the insecticidal activity of some Bacillus thuringiensis proteins against Mythimna separata (Walker),11 proteins of Cry1,Cry2,Cry9 and Vip3A were extracted and used for bioassay against M. separata by feeding artificial diet.The bioassay results showed that Cry1Ac,Cry1Ab,Cry2Ab,Cry1Be and Cry1Bb had insecticidal activity against M.separata larvae,with a LC50 value of 5.09 μg/g,17.71 μg/g, 26.75 μg/g,27.42 μg/g and 43.93 μg/g,respectively.Cry9Aa,Cry9Eb and Cry9Ee only inhibited growth of M. separata ,with a growth inhibition rate of 78.4%,79.0% and 86.9% at the concentration of 10 μg/g,and with an inhibition rate of 92.8%,95.7% and 96.7%,respectively,at the concentration of 100 μg/g.However, Cry1Ba,Cry1Ca and Vip3Aa showed no apparent toxicity to M.separata larvae.It lays the foundation for bio-logical control of M.separata ,and may provide some excellent candidate genes for insect-resistant genetically modified crops.%为筛选对黏虫[Mythimna separata (Walker)]具有毒杀作用的苏云金芽胞杆菌杀虫蛋白,本研究提取 Cry1类、Cry2类、Cry9类及 Vip3A 类等11种蛋白,通过人工饲料喂毒方法对黏虫进行生物活性测定。结果表明, Cry1Ac、Cry1Ab、Cry2Ab、Cry1Be 及 Cry1Bb 蛋白对黏虫具有杀虫活性,其致死中浓度依次为5.09、17.71、26.75、27.42及43.93μg/g;Cry9Aa、Cry9Eb、Cry9Ee 蛋白对黏虫生长具有抑制作用,其浓度为10μg/g 时的体重抑制率分别为78.4%、79.0%、86.9%,浓度为100μg/g 时的体重抑制率分别为92.8%、95.7%、96.7%;Cry1Ba、Cry1Ca和 Vip3Aa 蛋白对黏虫无显著活性。本研究为黏虫的生物防治奠定了基础,并为抗虫转基因作物的研究提供优良的候选基因。

  17. Susceptibility of Aedes aegypti larvae to temephos and Bacillus thuringiensis var israelensis in integrated control Susceptibilidade de larvas de Aedes aegypti ao tratamento integrado com temephos e Bacillus thuringiensis var israelensis

    OpenAIRE

    Carlos Fernando S. de Andrande; Maurício Modolo

    1991-01-01

    The susceptibility of field collected Aedes aegypti larvae was evaluated in terms of median lethal time (LT50) and final mortality, when treated with temephos, Bacillus thuringiensis var israelensis as well as mixtures of these two agents. Third instar larvae were shown to be more susceptible than early and late fourth instar ones to the entomopathogen. Survival of some individuals when exposed to temephos suggest possible resistance. Temporal synergism in early fourth instar larvae was detec...

  18. Prokaryotic Expression of the Soluble Cry2Ab Protein from Bacillus thuringiensis and Preparation of the Polyclonal Antibody Against Cry2Ab%苏云金杆菌Cry2Ab可溶蛋白的原核表达及多克隆抗体的制备

    Institute of Scientific and Technical Information of China (English)

    邵恩斯; 林莉; 关雄

    2013-01-01

    Cry2Ab toxin of Bacillus thuringiensis is a toxic protein, which is wildly used in controlling lepidopteran pest in agricultural production. In this research, the cry2A b gene (1 914 bp) was amplified from total DNA of B. Thuringiensis WB9 strain by a pair of primer designed by the full-length sequence of published crylAb gene. Then, cry2Ab was ligated with linearized pGEX-KG vector by restriction enzyme BamH Ⅰ and Xho Ⅰ for the construction of cry2Ab-pk expression vector. The soluble Cry2Ab-GST fusion protein (approximately 90 kD) was obtained after transferring Cry2Ab-PK expression vector into Escherichia coli BL21 (DE3) and then inducing by 0.8 mmol/L IPTG at 16℃ for 36 h. Total soluble protein was purified by batch purification and GST tag was removed by the use of prescission protease to obtain soluble Cry2Ab protein (approximately 65 kD). Polyclonal antibody against Cry2Ab was produced by immunizing the purified Cry2Ab to New Zealand white rabbit (Oryctolagus cuniculus) after three times of intramuscular injection and one time of intravenous injection. The titter of antibody was over 1:150 000, measured by indirect ELISA. Specificity of the prepared antibody was determined by Western blot, showing that the polyclonal antibody against the Cry2Aa or Cry2Ab protein was positive and the antibody against Cry1Ab or Cry3Aa protein was negative. These results indicated that antibody against Cry2Ab protein can specifically identify Cry2A protein but cannot identify other three domains Cry protein including CrylAb and Cry3Aa. These results will provide technical support for further study of Cry2A toxins mechanism and the interaction between Cry2A toxins and its receptors.%苏云金杆菌Cry2Ab蛋白是一类对鳞翅目昆虫有特异性毒性作用的毒素蛋白,已广泛应用于针对鳞翅目害虫的防治之中.依据苏云金杆菌cry2Ab基因序列设计一对全长引物,从苏云金杆菌(Bacillus thuringiensis WB9菌株总DNA中克隆出cry2Ab

  19. Bacillus cereus and Bacillus thuringiensis spores in Korean rice: prevalence and toxin production as affected by production area and degree of milling.

    Science.gov (United States)

    Kim, Booyoung; Bang, Jihyun; Kim, Hoikyung; Kim, Yoonsook; Kim, Byeong-Sam; Beuchat, Larry R; Ryu, Jee-Hoon

    2014-09-01

    We determined the prevalence of and toxin production by Bacillus cereus and Bacillus thuringiensis in Korean rice as affected by production area and degree of milling. Rough rice was collected from 64 farms in 22 agricultural areas and polished to produce brown and white rice. In total, rice samples were broadly contaminated with B. cereus spores, with no effect of production area. The prevalence and counts of B. cereus spores declined as milling progressed. Frequencies of hemolysin BL (HBL) production by isolates were significantly (P ≤ 0.01) reduced as milling progressed. This pattern corresponded with the presence of genes encoding the diarrheal enterotoxins. The frequency of B. cereus isolates positive for hblC, hblD, or nheB genes decreased as milling progressed. Because most B. cereus isolates from rice samples contained six enterotoxin genes, we concluded that B. cereus in rice produced in Korea is predominantly of the diarrheagenic type. The prevalence of B. thuringiensis in rice was significantly lower than that of B. cereus and not correlated with production area. All B. thuringiensis isolates were of the diarrheagenic type. This study provides information useful for predicting safety risks associated with B. cereus and B. thuringiensis in rough and processed Korean rice.

  20. Advances in developing Bacillus thuringiensis-based insecticde formulations Avances en el desarrollo de formulaciones insecticidas a base de Bacillus thuringiensis

    Directory of Open Access Journals (Sweden)

    Rosas-García Ninfa María

    2008-07-01

    Full Text Available Developing Bacillus thuringiensis-based formulations is an old technology which has been revived during recent decades. The spore-crystal complex (being the main ingredient in these preparations has been the main objective of this research, involving the search for new or improved strains. The type of materials used included a wide variety of completely biodegradable ingredients which could have been leaves, stems or fruit which when dried and ground could serve as feeding stimulants, as well as molasses and sugars. Sticky material such as gum providing adherence or starches working as encapsulating agents can both avoid dispersion by wind and wash-off by rain. Dyes and optical brighteners initially offer active protection against UV radiation and some other agents work as toxic activity enhancers. All of them are environmentally-friendly materials, completely harmless for human beings, other vertebrates, plants and even for beneficial insects so that the formulation is fully acceptable and ingested, thereby ensuring that it is highly effective. The foregoing has led to the manufacturing of a wide variety of commercial products whose effectiveness has positioned them in international markets; however, ongoing research provides specific solutions against new pests or is aimed at already-known ones avoiding resistance. Key words: Biological control; entomopathogen; toxic activity; feeding stimulants; residual activityEl desarrollo de las formulaciones insecticidas elaboradas a base de la bacteria Bacillus thuringiensis es una tecnología centenaria que ha recibido un fuerte impacto en décadas recientes. La mezcla de esporas y cristales, que es el principio activo de estas preparaciones, ha sido objeto de estudio constante y en ello se destaca la búsqueda de cepas cada vez más potentes o mejoradas. Así mismo, los materiales utilizados incluyen una amplia variedad de ingredientes completamente biodegradables como pueden ser partes de las

  1. The Pathogenomic Sequence Analysis of B. cereus and B.thuringiensis Isolates Closely Related to Bacillus anthracis

    Energy Technology Data Exchange (ETDEWEB)

    Han, Cliff S.; Xie, Gary; Challacombe, Jean F.; Altherr, MichaelR.; Smriti, B.; Bruce, David; Campbell, Connie S.; Campbell, Mary L.; Chen, Jin; Chertkov, Olga; Cleland, Cathy; Dimitrijevic-Bussod, M.; Doggett, Norman A.; Fawcett, John J.; Glavina, Tijana; Goodwin, Lynne A.; Hill, Karen K.; Hitchcock, Penny; Jackson, Paul J.; Keim, Paul; Kewalramani, Avinash Ramesh; Longmire, Jon; Lucas, Susan; Malfatti,Stephanie; McMurry, Kim; Meincke, Linda J.; Misra, Monica; Moseman,Bernice L.; Mundt, Mark; Munk, A. Christine; Okinaka, Richard T.; Parson-Quintana, B.; Reilly, Lee P.; Richardson, Paul; Robinson, DonnaL.; Rubin, Eddy; Saunders, Elizabeth; Tapia, Roxanne; Tesmer, Judith G.; Thayer, Nina; Thompson, Linda S.; Tice, Hope; Ticknor, Lawrence O.; Wills, Patti L.; Gilna, Payl; Brettin, Thomas S.

    2005-08-18

    The sequencing and analysis of two close relatives of Bacillus anthracis are reported. AFLP analysis of over 300 isolates of B.cereus, B. thuringiensis and B. anthracis identified two isolates as being very closely related to B. anthracis. One, a B. cereus, BcE33L, was isolated from a zebra carcass in Nambia; the second, a B. thuringiensis, 97-27, was isolated from a necrotic human wound. The B. cereus appears to be the closest anthracis relative sequenced to date. A core genome of over 3,900 genes was compiled for the Bacillus cereus group, including Banthracis. Comparative analysis of these two genomes with other members of the B. cereus group provides insight into the evolutionary relationships among these organisms. Evidence is presented that differential regulation modulates virulence, rather than simple acquisition of virulence factors. These genome sequences provide insight into the molecular mechanisms contributing to the host range and virulence of this group of organisms.

  2. Identification of a Bacillus thuringiensis Cry11Ba toxin-binding aminopeptidase from the mosquito, Anopheles quadrimaculatus

    Directory of Open Access Journals (Sweden)

    Abdullah Mohd

    2006-05-01

    Full Text Available Abstract Background Aminopeptidase N (APN type proteins isolated from several species of lepidopteran insects have been implicated as Bacillus thuringiensis (Bt toxin-binding proteins (receptors for Cry toxins. We examined brush border membrane vesicle (BBMV proteins from the mosquito Anopheles quadrimaculatus to determine if APNs from this organism would bind mosquitocidal Cry toxins that are active to it. Results A 100-kDa protein with APN activity (APNAnq 100 was isolated from the brush border membrane of Anopheles quadrimaculatus. Native state binding analysis by surface plasmon resonance shows that APNAnq 100 forms tight binding to a mosquitocidal Bt toxin, Cry11Ba, but not to Cry2Aa, Cry4Ba or Cry11Aa. Conclusion An aminopeptidase from Anopheles quadrimaculatus mosquitoes is a specific binding protein for Bacillus thuringiensis Cry11Ba.

  3. In Vitro Ovicidal and Cestocidal Effects of Toxins from Bacillus thuringiensis on the Canine and Human Parasite Dipylidium caninum

    Directory of Open Access Journals (Sweden)

    Guadalupe Peña

    2013-01-01

    Full Text Available Bacillus thuringiensis is a gram-positive soil-dwelling bacterium that is commonly used as a biological pesticide. This bacterium may also be used for biological control of helminth parasites in domestic animals. In this study, we evaluated the possible ovicidal and cestocidal effects of a total protein extract of B. thuringiensis native strains on the zoonotic cestode parasite of dogs, Dipylidium caninum (D. caninum. Dose and time response curves were determined by coincubating B. thuringiensis proteins at concentration ranging from 100 to 1000 μg/mL along with 4000 egg capsules of D. caninum. Egg viability was evaluated using the trypan blue exclusion test. The lethal concentration of toxins on eggs was 600 μg/ml, and the best incubation time to produce this effect was 3 h. In the adult stage, the motility and the thickness of the tegument were used as indicators of damage. The motility was inhibited by 100% after 8 hours of culture compared to the control group, while the thickness of the cestode was reduced by 34%. Conclusively, proteins of the strain GP526 of B. thuringiensis directly act upon D. caninum showing ovicidal and cestocidal effects. Thus, B. thuringiensis is proposed as a potential biological control agent against this zoonosis.

  4. Evidence of two mechanisms involved in Bacillus thuringiensis israelensis decreased toxicity against mosquito larvae: Genome dynamic and toxins stability.

    Science.gov (United States)

    Elleuch, Jihen; Zribi Zghal, Raida; Lacoix, Marie Noël; Chandre, Fabrice; Tounsi, Slim; Jaoua, Samir

    2015-07-01

    Biopesticides based on Bacillus thuringiensis israelensis are the most used and most successful around the world. This bacterium is characterized by a dynamic genome able to win or lose genetic materials which leads to a decrease in its effectiveness. The detection of such phenomena is of great importance to monitor the stability of B. thuringiensis strains in industrial production processes of biopesticides. New local B. thuringiensis israelensis isolates were investigated. They present variable levels of delta-endotoxins production and insecticidal activities against Aedes aegypti larvae. Searching on the origin of this variability, molecular and biochemical analyses were performed. The obtained results describe two main reasons of the decrease of B. thuringiensis israelensis insecticidal activity. The first reason was the deletion of cry4Aa and cry10Aa genes from the 128-kb pBtoxis plasmid as evidenced in three strains (BLB124, BLB199 and BLB506) among five. The second was the early degradation of Cry toxins by proteases in larvae midgut mainly due to some amino acids substitutions evidenced in Cry4Ba and Cry11Aa δ-endotoxins detected in BLB356. Before biological treatment based on B. thuringiensis israelensis, the studies of microflore in each ecosystem have a great importance to succeed pest management programs. PMID:26070692

  5. The susceptibility of Aedes aegypti populations displaying temephos resistance to Bacillus thuringiensis israelensis: a basis for management

    OpenAIRE

    Araújo, Ana Paula; Araujo Diniz, Diego Felipe; Helvecio, Elisama; de Barros, Rosineide Arruda; de Oliveira, Cláudia Maria Fontes; Ayres, Constância Flávia Junqueira; de Melo-Santos, Maria Alice Varjal; Regis, Lêda Narcisa; Silva-Filha, Maria Helena Neves Lobo

    2013-01-01

    Background Aedes aegypti is the vector of dengue virus, and its control is essential to prevent disease transmission. Among the agents available to control this species, biolarvicides based on Bacillus thuringiensis serovar israelensis (Bti) are an effective alternative to replace the organophosphate temephos for controlling populations that display resistance to this insecticide. The major goal of this study was to determine the baseline susceptibility of Brazilian Ae. aegypti populations to...

  6. Effect of ultraviolet and gamma rays on the activity of delta-endotoxin protein crystals of Bacillus thuringiensis

    International Nuclear Information System (INIS)

    Sensitive bioassays with larvae of Pieris brassicae revealed no reduction of insecticidal activity as a result of severe gamma or ultraviolet irradiation of crystals of Bacillus thuringiensis (serotype V). The measured response was the inhibition of larval feeding by the crystals over exposure periods short enough for the presence of live spores not to influence feeding. The results were analyzed using a logistic model. (U.S.)

  7. Thuringiensin: A Thermostable Secondary Metabolite from Bacillus thuringiensis with Insecticidal Activity against a Wide Range of Insects

    OpenAIRE

    Xiaoyan Liu; Lifang Ruan; Donghai Peng; Lin Li; Ming Sun; Ziniu Yu

    2014-01-01

    Thuringiensin (Thu), also known as β-exotoxin, is a thermostable secondary metabolite secreted by Bacillus thuringiensis. It has insecticidal activity against a wide range of insects, including species belonging to the orders Diptera, Coleoptera, Lepidoptera, Hymenoptera, Orthoptera, and Isoptera, and several nematode species. The chemical formula of Thu is C22H32O19N5P, and it is composed of adenosine, glucose, phosphoric acid, and gluconic diacid. In contrast to the more frequently studied ...

  8. [The effect of a soil extract on the development of Bacillus thuringiensis and on its synthesis of an insecticidal endotoxin].

    Science.gov (United States)

    Dregval', O A; Cherevach, N V; Andrienko, O E; Vinnikov, A I

    1999-01-01

    Selection of effective and inexpensive nutrient medium for cultivation of entomopathogenic bacteria Bacillus thuringiensis was carried out. The medium with molasses [correction of patoka], corn extract and mineral salts has been chosen. Addition of a soil extract to the medium enhanced growth of microorganisms, increased the rate of culture development, the yield of spore-crystalline material and quantity of synthesized endotoxin. Apparently the strengthening effect belongs to humic substances contained in the soil extract. PMID:10565149

  9. Concurrent use of transgenic plants expressing a single and two Bacillus thuringiensis genes speeds insect adaptation to pyramided plants

    OpenAIRE

    Zhao, Jian-Zhou; Cao, Jun; Collins, Hilda L.; Bates, Sarah L.; Roush, Richard T.; Earle, Elizabeth D.; Anthony M Shelton

    2005-01-01

    Transgenic plants expressing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) were grown on over 13 million ha in the United States and 22.4 million ha worldwide in 2004. Preventing or slowing the evolution of resistance by insects (“resistance management”) is critical for the sustainable use of Bt crops. Plants containing two dissimilar Bt toxin genes in the same plant (“pyramided”) have the potential to delay insect resistance. However, the advantage of pyramided Bt plan...

  10. Complete genome sequence of Bacillus thuringiensis CTC-A typical strain with high production of S-layer proteins.

    Science.gov (United States)

    Dong, Zhaoxia; Li, Junhua; Zheng, Jinshui; Geng, Ce; Peng, Donghai; Sun, Ming

    2016-02-20

    Bacillus thuringiensis CTC, which is identified as serotype H2, serovar. finitimus, is high production of S-layer protein. Due to the property of forming isoporous lattices on the whole cell surface, S-layer protein has been widely used in (nano) biotechnology, biomimetics, biomedicine, especially been employed for displaying many important active proteins. Here, we report the complete genome of strain CTC, which contains one circular chromosome and one linear plasmid.

  11. Bacillus thuringiensis Cry34Ab1/Cry35Ab1 Interactions with Western Corn Rootworm Midgut Membrane Binding Sites

    OpenAIRE

    Huarong Li; Monica Olson; Gaofeng Lin; Timothy Hey; Sek Yee Tan; Narva, Kenneth E.

    2013-01-01

    BACKGROUND: Bacillus thuringiensis (Bt) Cry34Ab1/Cry35Ab1 are binary insecticidal proteins that are co-expressed in transgenic corn hybrids for control of western corn rootworm, Diabrotica virgifera virgifera LeConte. Bt crystal (Cry) proteins with limited potential for field-relevant cross-resistance are used in combination, along with non-transgenic corn refuges, as a strategy to delay development of resistant rootworm populations. Differences in insect midgut membrane binding site interact...

  12. Bacillus thuringiensis Crystal Protein Cry6Aa Triggers Caenorhabditis elegans Necrosis Pathway Mediated by Aspartic Protease (ASP-1)

    OpenAIRE

    Fengjuan Zhang; Donghai Peng; Chunsheng Cheng; Wei Zhou; Shouyong Ju; Danfeng Wan; Ziquan Yu; Jianwei Shi; Yaoyao Deng; Fenshan Wang; Xiaobo Ye; Zhenfei Hu; Jian Lin; Lifang Ruan; Ming Sun

    2016-01-01

    Cell death plays an important role in host-pathogen interactions. Crystal proteins (toxins) are essential components of Bacillus thuringiensis (Bt) biological pesticides because of their specific toxicity against insects and nematodes. However, the mode of action by which crystal toxins to induce cell death is not completely understood. Here we show that crystal toxin triggers cell death by necrosis signaling pathway using crystal toxin Cry6Aa-Caenorhabditis elegans toxin-host interaction sys...

  13. Transcriptional cellular responses in midgut tissue of Aedes aegypti larvae following intoxication with Cry11Aa toxin from Bacillus thuringiensis

    OpenAIRE

    Canton, Pablo Emiliano; Cancino-Rodezno, Angeles; Gill, Sarjeet S.; Soberón, Mario; Bravo, Alejandra

    2015-01-01

    Background Although much is known about the mechanism of action of Bacillus thuringiensis Cry toxins, the target tissue cellular responses to toxin activity is less understood. Previous transcriptomic studies indicated that significant changes in gene expression occurred during intoxication. However, most of these studies were done in organisms without a sequenced and annotated reference genome. A reference genome and transcriptome is available for the mosquito Aedes aegypti, and its importan...

  14. Low translocation of Bacillus thuringiensis israelensis to inner organs in mice after pulmonary exposure to commercial biopesticide

    DEFF Research Database (Denmark)

    Barfod, Kenneth Klingenberg; Ørum-Smidt, Lasse; Krogfelt, Karen A.;

    2010-01-01

    Translocation of viable cells from a Bacillus thuringiensis israelensis-based biopesticide to inner organs in a mouse model was studied. Mice were exposed to the originally formulated product through the lungs and gastrointestinal tract by intratracheal instillation. Colony forming units (CFU) were...... grown from lungs, caecum, spleen and liver on Bacillus cereus-specific agar (BCSA) after 24 h and finally determined to be biopesticide strain B. t. israelensis by large plasmid profile. No CFU were found in spleen or liver of the control mice or in any aerosol background or material. We have shown...

  15. Application of statistical experimental design for optimisation of bioinsecticides production by sporeless Bacillus thuringiensis strain on cheap medium

    Directory of Open Access Journals (Sweden)

    Saoussen Ben Khedher

    2013-09-01

    Full Text Available In order to overproduce bioinsecticides production by a sporeless Bacillus thuringiensis strain, an optimal composition of a cheap medium was defined using a response surface methodology. In a first step, a Plackett-Burman design used to evaluate the effects of eight medium components on delta-endotoxin production showed that starch, soya bean and sodium chloride exhibited significant effects on bioinsecticides production. In a second step, these parameters were selected for further optimisation by central composite design. The obtained results revealed that the optimum culture medium for delta-endotoxin production consists of 30 g L-1 starch, 30 g L-1 soya bean and 9g L-1 sodium chloride. When compared to the basal production medium, an improvement in delta-endotoxin production up to 50% was noted. Moreover, relative toxin yield of sporeless Bacillus thuringiensis S22 was improved markedly by using optimised cheap medium (148.5 mg delta-endotoxins per g starch when compared to the yield obtained in the basal medium (94.46 mg delta-endotoxins per g starch. Therefore, the use of optimised culture cheap medium appeared to be a good alternative for a low cost production of sporeless Bacillus thuringiensis bioinsecticides at industrial scale which is of great importance in practical point of view.

  16. Mutually exclusive distribution of the sap and eag S-layer genes and the lytB/lytA cell wall hydrolase genes in Bacillus thuringiensis.

    Science.gov (United States)

    Soufiane, Brahim; Sirois, Marc; Côté, Jean-Charles

    2011-10-01

    Recently, two Bacillus thuringiensis strains were reported to synthesize parasporal inclusion bodies made not of the expected crystal (Cry) proteins but rather of the surface layer proteins (SLP) Sap (encoded by sap) and EA1 (encoded by eag), respectively. Whether the presence of the sap and eag genes is restricted to these two B. thuringiensis strains or ubiquitous in B. thuringiensis is unknown. We report here the distribution of the sap and eag genes in B. thuringiensis. Strains in the Bacillus cereus group were added for comparison purposes. We show that sap and eag are either present in tandem in 35% of the B. thuringiensis strains analysed and absent in 65% of the strains. When absent, a different tandem, the lytB/lytA cell wall hydrolase genes, is present. The distribution of the sap and eag S-layer and the lytB/lytA cell wall hydrolase genes is not species-specific in B. thuringiensis, B. cereus and Bacillus weihenstephanensis. Bacillus anthracis and Bacillus mycoides harbor sap and eag but not lytB/lytA. The sap, eag and lytB/lytA genes were absent in Bacillus pseudomycoides. Clearly, the distribution of the sap and eag S-layer and the lytB/lytA cell wall hydrolase genes in B. thuringiensis and in the Bacillus cereus group is mutually exclusive. We also showed that two genes involved in cell wall metabolism, csaA and csaB, are present not only upstream of the sap and eag S-layer genes, but also upstream of the lytB/lytA tandem in strains where sap and eag are absent. Bootstrapped neighbor-joining trees were inferred from the translated amino acid sequences of sap, eag and the tandem lytB/lytA, respectively.

  17. Structural studies of δ-endotoxin Cry 1 C from Bacillus thuringiensis

    International Nuclear Information System (INIS)

    Full text. The δ-endotoxins are a family of crystal protein by a soil bacterium, Bacillus thuringiensis. The study of these proteins has been of great interest due to their highly specific activity against insects of the orders Lepidoptera, Diptera and Coleoptera. Thus, the δa-endotoxins have been used for more than two decades as biological insecticides to control agricultural pests and, more recently, insects vectors of some diseases. The knowledge of their three-dimensional structures is very important to understand their mechanism of action and their high specificity. To date, the structure of only three proteins of the δ-endotoxins family have been reported: Cry3A, a coleopteran-specific toxin (beetle toxin)1, Cry1Aa, a lepidopteran-specific toxin (butterfly toxin)2 and CytB, a dipteran-specific toxin (mosquito toxin)3 Our work is aimed at the determination of the crystallographic structure by X-ray diffraction of δ-endotoxin Cry1C, also toxic to insects of the Lepidoptera order but towards families other than those affected by Cry1Aa. A comparison between these structures may lead to important conclusions about the reasons for the specificity and would allow the planning of mutants with more efficient activity. The cry1C gene was cloned into an adequate vector and expressed in an acrystalliferous B. thuringiensis strain. After cell culture and sporulation the microcrystals of Cry1C were separated by ultra-centrifugation in sacharose. The protoxin inclusion bodies were activated by commercial trpsin and the protease-resistant core was purified by anion-exchange chromatography. Crystallization experiments are being conducted in order to obtain single crystals suitable for diffraction measurements. We intend to use the Protein Crystallograph Station of the LNLS to collect data as soon as it is available and we have suitable crystals. (author)

  18. Gamma Radiation to Increase Efficiency of Bacillus thuringiensis Thai Strain for Insect Pets Control

    International Nuclear Information System (INIS)

    Bacillus thuringiensis (Bt) isolates JCPT16 and JCPT68 were gamma-irradiated at 2, 4, 6 and 8 kGy. The efficiency of these Bt isolates on S. litura control was also undertaken. It was found that the 4 kGy irradiated JCPT16 isolate had lowest LC50 of 6.6x103 spore/ml while the non-irradiated JCPT 16 isolate had LC50 of 6.2x103 spore/ml. Whereas the irradiated JCPT68 isolate at 8 kGy was noticed to have the lowest LC50 of 2.7 x 103 spores/ml, the non-irradiated JCPT68 had LC50 of 1.8x103 spores/ml. The efficiency test of B. thuringiensis isolate on S. exigua showed that the 2 kGy irradiated JCPT16 isolate had the lowest LC50 of 2.52x104 spores/ml while the non-irradiated JCPT16 isolate had LC50 of 6.04x103 spores/ml. The irradiated JCPT68 isolate at 4 kGy had the lowest LC50 of 5.41x104 spores/ml, the non irradiated JCPT68 had LC50 of 1.51x104 spores/ml. According to LC50 values, there were no significant differences of efficiency on S. litura and S. exigua control among Bt isolates irradiated at various concentrations. The isolate JCPT16, JCPT35, JCPT50 and JCPT68 irradiated at dose of 10 kGy showed higher UV tolerance. After expose by UV ray, most of irradiated isolates still displayed high efficiency of controlling S. litura, S. exigua and Plutella xylostell.

  19. Structural studies of {delta}-endotoxin Cry 1 C from Bacillus thuringiensis

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, B.G.; Garratt, R.C.; Oliva, G. [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Fisica; Lemos, M.V.F. [UNESP, Jaboticabal, SP (Brazil). Dept. de Biologia Aplicada Agropecuaria; Arantes, O.M.N. [Universidade Estadual de Londrina, PR (Brazil). Dept. de Biologia Geral

    1996-12-31

    Full text. The {delta}-endotoxins are a family of crystal protein by a soil bacterium, Bacillus thuringiensis. The study of these proteins has been of great interest due to their highly specific activity against insects of the orders Lepidoptera, Diptera and Coleoptera. Thus, the {delta}a-endotoxins have been used for more than two decades as biological insecticides to control agricultural pests and, more recently, insects vectors of some diseases. The knowledge of their three-dimensional structures is very important to understand their mechanism of action and their high specificity. To date, the structure of only three proteins of the {delta}-endotoxins family have been reported: Cry3A, a coleopteran-specific toxin (beetle toxin){sup 1}, Cry1Aa, a lepidopteran-specific toxin (butterfly toxin){sup 2} and CytB, a dipteran-specific toxin (mosquito toxin){sup 3} Our work is aimed at the determination of the crystallographic structure by X-ray diffraction of {delta}-endotoxin Cry1C, also toxic to insects of the Lepidoptera order but towards families other than those affected by Cry1Aa. A comparison between these structures may lead to important conclusions about the reasons for the specificity and would allow the planning of mutants with more efficient activity. The cry1C gene was cloned into an adequate vector and expressed in an acrystalliferous B. thuringiensis strain. After cell culture and sporulation the microcrystals of Cry1C were separated by ultra-centrifugation in sacharose. The protoxin inclusion bodies were activated by commercial trpsin and the protease-resistant core was purified by anion-exchange chromatography. Crystallization experiments are being conducted in order to obtain single crystals suitable for diffraction measurements. We intend to use the Protein Crystallograph Station of the LNLS to collect data as soon as it is available and we have suitable crystals. (author) 3 refs.

  20. Long lasting persistence of Bacillus thuringiensis Subsp. israelensis (Bti in mosquito natural habitats.

    Directory of Open Access Journals (Sweden)

    Mathieu Tilquin

    Full Text Available BACKGROUND: The detrimental effects of chemical insecticides on the environment and human health have lead to the call for biological alternatives. Today, one of the most promising solutions is the use of spray formulations based on Bacillus thuringiensis subsp. israelensis (Bti in insect control programs. As a result, the amounts of Bti spread in the environment are expected to increase worldwide, whilst the common belief that commercial Bti is easily cleared from the ecosystem has not yet been clearly established. METHODOLOGY/MAIN FINDINGS: In this study, we aimed to determine the nature and origin of the high toxicity toward mosquito larvae found in decaying leaf litter collected in several natural mosquito breeding sites in the Rhône-Alpes region. From the toxic fraction of the leaf litter, we isolated B. cereus-like bacteria that were further characterized as B. thuringiensis subsp. israelensis using PCR amplification of specific toxin genes. Immunological analysis of these Bti strains showed that they belong to the H14 group. We finally used amplified length polymorphism (AFLP markers to show that the strains isolated from the leaf litter were closely related to those present in the commercial insecticide used for field application, and differed from natural worldwide genotypes. CONCLUSIONS/SIGNIFICANCE: Our results raise the issue of the persistence, potential proliferation and environmental accumulation of human-spread Bti in natural mosquito habitats. Such Bti environmental persistence may lengthen the exposure time of insects to this bio-insecticide, thereby increasing the risk of resistance acquisition in target insects, and of a negative impact on non-target insects.

  1. A Bacillus thuringiensis isolation method utilizing a novel stain, low selection and high throughput produced atypical results

    Directory of Open Access Journals (Sweden)

    Ammons David

    2005-09-01

    Full Text Available Abstract Background Bacillus thuringiensis is a bacterium known for producing protein crystals with insecticidal properties. These toxins are widely sought after for controlling agricultural pests due to both their specificity and their applicability in transgenic plants. There is great interest in isolating strains with improved or novel toxin characteristics, however isolating B. thuringiensis from the environment is time consuming and yields relatively few isolates of interest. New approaches to B. thuringiensis isolation have been, and continue to be sought. In this report, candidate B. thuringiensis isolates were recovered from environmental samples using a combination of a novel stain, high throughput and reduced selection. Isolates were further characterized by SDS-PAGE, light microscopy, PCR, probe hybridization, and with selected isolates, DNA sequencing, bioassay or Electron Microscopy. Results Based on SDS-PAGE patterns and the presence of cry genes or a crystal, 79 candidate, non-clonal isolates of B. thuringiensis were identified from 84 samples and over 10,000 colonies. Although only 16/79 (20% of the isolates showed DNA homology by Probe Hybridization or PCR to common cry genes, initial characterization revealed a surprisingly rich library that included a putative nematocidal gene, a novel filamentous structure associated with a crystal, a spore with spikes originating from a very small parasporal body and isolates with unusually small crystals. When compared to reports of other screens, this screen was also atypical in that only 3/79 isolates (3.8% produced a bipyramidal crystal and 24/79 (30% of the isolates' spores possessed an attached, dark-staining body. Conclusion Results suggest that the screening methodology adopted in this study might deliver a vastly richer and potentially more useful library of B. thuringiensis isolates as compared to that obtained with commonly reported methodologies, and that by extension

  2. Leaf morphology and ultrastructure responses to elevated O3 in transgenic Bt (cry1Ab/cry1Ac rice and conventional rice under fully open-air field conditions.

    Directory of Open Access Journals (Sweden)

    Chunyan Li

    Full Text Available BACKGROUND: Elevated tropospheric ozone severely affects not only yield but also the morphology, structure and physiological functions of plants. Because of concerns regarding the potential environmental risk of transgenic crops, it is important to monitor changes in transgenic insect-resistant rice under the projected high tropospheric ozone before its commercial release. METHODOLOGY/PRINCIPAL FINDINGS: Using a free-air concentration enrichment (FACE system, we investigated the changes in leaf morphology and leaf ultrastructure of two rice varieties grown in plastic pots, transgenic Bt Shanyou 63 (Bt-SY63, carrying a fusion gene of cry1Ab and cry1Ac and its non-transgenic counterpart (SY63, in elevated O3 (E-O3 versus ambient O3 (A-O3 after 64-DAS (Days after seeding, 85-DAS and 102-DAS. Our results indicated that E-O3 had no significant effects on leaf length, leaf width, leaf area, stomatal length and stomatal density for both Bt-SY63 and SY63. E-O3 increased the leaf thickness of Bt-SY63, but decreased that of SY63. O3 stress caused early swelling of the thylakoids of chloroplasts, a significant increase in the proportion of total plastoglobule area in the entire cell area (PCAP and a significant decrease in the proportion of total starch grain area in the entire cell area (SCAP, suggesting that E-O3 accelerated the leaf senescence of the two rice genotypes. Compared with SY63, E-O3 caused early swelling of the thylakoids of chloroplasts and more substantial breakdown of chloroplasts in Bt-SY63. CONCLUSIONS/SIGNIFICANCE: Our results suggest that the incorporation of cry1Ab/Ac into SY63 could induce unintentional changes in some parts of plant morphology and that O3 stress results in greater leaf damage to Bt-SY63 than to SY63, with the former coupled with higher O3 sensitivity in CCAP (the proportions of total chloroplast area in the entire cell area, PCAP and SCAP. This study provides valuable baseline information for the prospective

  3. Comparative analysis of two-component signal transduction systems of Bacillus cereus, Bacillus thuringiensis and Bacillus anthracis

    NARCIS (Netherlands)

    Been, M.W.H.J. de; Francke, C.; Moezelaar, R.; Abee, T.; Siezen, R.J.

    2006-01-01

    Members of the Bacillus cereus group are ubiquitously present in the environment and can adapt to a wide range of environmental fluctuations. In bacteria, these adaptive responses are generally mediated by two-component signal transduction systems (TCSs), which consist of a histidine kinase (HK) and

  4. Resistance to Bacillus thuringiensis by the Indian meal moth, Plodia interpunctella: comparison of midgut proteinases from susceptible and resistant larvae.

    Science.gov (United States)

    Johnson, D E; Brookhart, G L; Kramer, K J; Barnett, B D; McGaughey, W H

    1990-03-01

    Midgut homogenates from susceptible and resistant strains of the Indian meal moth, Plodia interpunctella, were compared for their ability to activate the entomocidal parasporal crystal protein from Bacillus thuringiensis. The properties of midgut proteinases from both types of larvae were also examined. Electrophoretic patterns of crystal protein from B. thuringiensis subspecies kurstaki (HD-1) and aizawai (HD-133 and HD-144) were virtually unchanged following digestion by either type of midgut homogenate. Changes in pH (9.5 to 11.5) or midgut homogenate concentration during digestion failed to substantially alter protein electrophoretic patterns of B. thuringiensis HD-1 crystal toxin. In vitro toxicity of crystal protein activated by either type of midgut preparation was equal toward cultured insect cells from either Manduca sexta or Choristoneura fumiferana. Electrophoresis of midgut extracts in polyacrylamide gels containing gelatin as substrate also yielded matching mobility patterns of proteinases from both types of midguts. Quantitation of midgut proteolytic activity using tritiated casein as a substrate revealed variation between midgut preparations, but no statistically significant differences between proteolytic activities from susceptible and resistant Indian meal moth larvae. Inhibition studies indicated that a trypsin-like proteinase with maximal activity at pH 10 is a major constituent of Indian meal moth midguts. The results demonstrated that midguts from susceptible and resistant strains of P. interpunctella are similar both in their ability to activate B. thuringiensis protoxin and in their proteolytic activity.

  5. Avaliação de produtos à base de Bacillus thuringiensis no controle da traça-das-crucíferas Evaluation of insecticides based on Bacillus thuringiensis in the control of the diamondback moth

    Directory of Open Access Journals (Sweden)

    Patrícia T Medeiros

    2006-06-01

    Full Text Available Avaliou-se em dois experimentos a suscetibilidade da traça-das-crucíferas a inseticidas à base de Bacillus thuringiensis em repolho cv. Itiban. O delineamento do primeiro experimento (de julho a setembro/03, em área de plantio comercial em Brazlândia (DF, foi de blocos casualizados, com seis tratamentos e dez repetições; os bioinseticidas utilizados foram B. thuringiensis kurstaki (S1450CO, B. thuringiensis aizawai comercial (Bta e três produtos formulados com as estirpes S1450BB, S811BB, S845BB de B. thuringiensis pertencentes ao Banco de Bacillus spp. da Embrapa Recursos Genéticos e Biotecnologia. No segundo experimento, realizado no campo experimental da Embrapa (DF, de outubro/03 a janeiro/04, o delineamento foi de blocos casualizados, com seis tratamentos e quatro repetições; os inseticidas utilizados foram os mesmos do primeiro experimento, com a adição de Spinosad, e retirado o tratamento S811BB. Os produtos foram aplicados quando foi atingido o nível de dano de seis furos nas quatro folhas centrais do repolho. O Bta comercial foi o produto mais eficaz no primeiro experimento, tendo sido aplicado cinco vezes e diferiu estaticamente dos demais produtos. Os formulados S845BB e S1450BB não apresentaram diferenças quando comparados ao produto comercial S1450 e foram aplicados seis vezes. O produto S811BB também foi aplicado seis vezes, mas sua eficácia foi inferior aos demais produtos e não diferiu da testemunha. Já no segundo experimento, o S1450 comercial foi aplicado cinco vezes e os demais produtos à base de Bt, seis vezes. Todos os produtos utilizados não diferiram entre si, diferindo apenas no número de aplicações.Two experiments were performed to evaluate the susceptibility of the diamondback moth to insecticides based on Bacillus thuringiensis in cabbage cv. Itiban. The first experiment was carried out from July to September 2003, in a production area in Brazlândia (DF, Brazil. Randomized blocks with six

  6. Elucidation of the mechanisms of CryIIIA overproduction in a mutagenized strain of Bacillus thuringiensis var. tenebrionis

    International Nuclear Information System (INIS)

    NB176 is a Bacillus thuringiensis mutant derived by λ-irradiation of NB125 Bacillus thuringiensis var. tenebrionis (Krieg). It exhibits two interesting phenotypes: (i) oligosporogeny and (ii) twofold to threefold overproduction of the CryIIIA protein. Southern profiles of the NB176 strain showed an additional copy(s) of the cryIIIA gene located on a 4 kb HindIII fragment, in addition to the expected cryIIIA gene on a 3 kb HindIII fragment. Each cryIIIA gene-bearing HindIII fragment was cloned from NB176. The restriction map of the 3 kb HindIII fragment was identical to that published by Donovan and coworkers. Sequencing of the 4 kb HindIII fragment showed no alterations in the promoter region of the cryIIIA gene but did show replacement of the region immediately following the cryIIIA open reading frame with a sequence encoding a transposase with 50% amino acid homology to that of Tn 1000. These findings suggest that the overproduction phenotype of NB176 results from extra copies of the cryIIIA gene produced from a transposition event(s) induced or stabilized by γ-irradiation. Integration of additional copies of the cryIIIA gene into the native 90MDa plasmid of the wild-type B. thuringiensis var. tenebrionis strain resulted in strains that made enormous crystals, many possessing greatly enhanced insecticidal activity

  7. Transcriptome analysis of Bacillus thuringiensis spore life, germination and cell outgrowth in a vegetable-based food model.

    Science.gov (United States)

    Bassi, Daniela; Colla, Francesca; Gazzola, Simona; Puglisi, Edoardo; Delledonne, Massimo; Cocconcelli, Pier Sandro

    2016-05-01

    Toxigenic species belonging to Bacillus cereus sensu lato, including Bacillus thuringiensis, cause foodborne outbreaks thanks to their capacity to survive as spores and to grow in food matrixes. The goal of this work was to assess by means of a genome-wide transcriptional assay, in the food isolate B. thuringiensis UC10070, the gene expression behind the process of spore germination and consequent outgrowth in a vegetable-based food model. Scanning electron microscopy and Energy Dispersive X-ray microanalysis were applied to select the key steps of B. thuringiensis UC10070 cell cycle to be analyzed with DNA-microarrays. At only 40 min from heat activation, germination started rapidly and in less than two hours spores transformed in active growing cells. A total of 1646 genes were found to be differentially expressed and modulated during the entire B. cereus life cycle in the food model, with most of the significant genes belonging to transport, transcriptional regulation and protein synthesis, cell wall and motility and DNA repair groups. Gene expression studies revealed that toxin-coding genes nheC, cytK and hblC were found to be expressed in vegetative cells growing in the food model.

  8. Adaptive Evolution of cry Genes in Bacillus thuringiensis:Implications for Their Specificity Determination

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The cry gene family, produced during the late exponential phase of growth in Bacillus thuringiensis, is a large, still-growing family of homologous genes, in which each gene encodes a protein with strong specific activity against only one or a few insect species. Extensive studies are mostly focusing on the structural and functional relationships of Cry proteins, and have revealed several residues or domains that are important for the target recognition and receptor attachment. In this study,we have employed a maximum likelihood method to detect evidence of adaptive evolution in Cry proteins, and have identified 24 positively selected residues, which are all located in Domain Ⅱ or Ⅲ. Combined with known data from mutagenesis studies, the majority of these residues, at the molecular level, contribute much to the insect specificity determination. We postulate that the potential pressures driving the diversification of Cry proteins may be in an attempt to adapt for the "arm race" between δ-endotoxins and the targeted insects, or to enlarge their target spectra, hence result in the functional divergence. The sites identified to be under positive selection would provide targets for further structural and functional analyses on Cry proteins.

  9. Response Surface Methodology: Optimisation of Antifungal Bioemulsifier from Novel Bacillus thuringiensis

    Directory of Open Access Journals (Sweden)

    Deepak Rajendran

    2014-01-01

    Full Text Available An antifungal bioemulsifier compound was produced from a novel strain of Bacillus thuringiensis pak2310. To accentuate the production and as the first step to improve the yield, a central composite design (CCD was used to study the effect of various factors like minimal salts (1X and 3X, glycerol concentration (2% and 4%, beef extract concentration (1% and 3%, and sunflower oil concentration (2% and 4% on the production of bioemulsifier molecule and to optimize the conditions to increase the production. The E24 emulsification index was used as the response variable as the increase in surfactant production was seen to be proportional to increased emulsification. A quadratic equation was employed to express the response variable in terms of the independent variables. Statistical tools like student’s t-test, F-test, and ANOVA were employed to identify the important factors and to test the adequacy of the model. Under optimum conditions (1X concentration of minimal salts (MS, 2.6% glycerol (v/v, 1% beef extract (w/v, and 2% sunflower oil (v/v a 65% increase in yield was produced.

  10. Response surface methodology: optimisation of antifungal bioemulsifier from novel Bacillus thuringiensis.

    Science.gov (United States)

    Rajendran, Deepak; Venkatachalam, Ponnusami; Ramakrishnan, Jayapradha

    2014-01-01

    An antifungal bioemulsifier compound was produced from a novel strain of Bacillus thuringiensis pak2310. To accentuate the production and as the first step to improve the yield, a central composite design (CCD) was used to study the effect of various factors like minimal salts (1X and 3X), glycerol concentration (2% and 4%), beef extract concentration (1% and 3%), and sunflower oil concentration (2% and 4%) on the production of bioemulsifier molecule and to optimize the conditions to increase the production. The E 24 emulsification index was used as the response variable as the increase in surfactant production was seen to be proportional to increased emulsification. A quadratic equation was employed to express the response variable in terms of the independent variables. Statistical tools like student's t-test, F-test, and ANOVA were employed to identify the important factors and to test the adequacy of the model. Under optimum conditions (1X concentration of minimal salts (MS), 2.6% glycerol (v/v), 1% beef extract (w/v), and 2% sunflower oil (v/v)) a 65% increase in yield was produced. PMID:25379529

  11. Acute, sublethal, and combination effects of azadirachtin and Bacillus thuringiensis on the cotton bollworm, Helicoverpa armigera.

    Science.gov (United States)

    Abedi, Zahra; Saber, Moosa; Vojoudi, Samad; Mahdavi, Vahid; Parsaeyan, Ehsan

    2014-01-01

    The cotton bollworm, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) is a polyphagous and cosmopolitan insect pest that causes damage to various plants. In this study, the lethal and sublethal effects of azadirachtin and Bacillus thuringiensis Berliner sub sp . kurstaki (Bacillales: Bacillaceae) were evaluated on third instar H. armigera under laboratory conditions. The LC50 values of azadirachtin and Bt were 12.95 and 96.8 µg a.i./mL, respectively. A total mortality of 56.7% was caused on third instar larvae when LC20 values of the insecticides were applied in combination with each other. The LT50 values of azadirachtin and Bt were 4.8 and 3.6 days, respectively. The results of the sublethal study showed that the application of LC30 value of azadirachtin and Bt reduced the larval and pupal weight and increased larval and pupal duration of H. armigera. The longevity and fecundity of female adults were affected significantly by the insecticides. Female fecundity was reduced by the treatments, respectively. The lowest adult emergence ratio and pupation ratio were observed in the azadirachtin treatment. The results indicated that both insecticides have high potential for controlling of the pest. PMID:25373177

  12. Three cadherin alleles associated with resistance to Bacillus thuringiensis in pink bollworm

    Science.gov (United States)

    Morin, Shai; Biggs, Robert W.; Sisterson, Mark S.; Shriver, Laura; Ellers-Kirk, Christa; Higginson, Dawn; Holley, Daniel; Gahan, Linda J.; Heckel, David G.; Carrière, Yves; Dennehy, Timothy J.; Brown, Judith K.; Tabashnik, Bruce E.

    2003-01-01

    Evolution of resistance by pests is the main threat to long-term insect control by transgenic crops that produce Bacillus thuringiensis (Bt) toxins. Because inheritance of resistance to the Bt toxins in transgenic crops is typically recessive, DNA-based screening for resistance alleles in heterozygotes is potentially much more efficient than detection of resistant homozygotes with bioassays. Such screening, however, requires knowledge of the resistance alleles in field populations of pests that are associated with survival on Bt crops. Here we report that field populations of pink bollworm (Pectinophora gossypiella), a major cotton pest, harbored three mutant alleles of a cadherin-encoding gene linked with resistance to Bt toxin Cry1Ac and survival on transgenic Bt cotton. Each of the three resistance alleles has a deletion expected to eliminate at least eight amino acids upstream of the putative toxin-binding region of the cadherin protein. Larvae with two resistance alleles in any combination were resistant, whereas those with one or none were susceptible to Cry1Ac. Together with previous evidence, the results reported here identify the cadherin gene as a leading target for DNA-based screening of resistance to Bt crops in lepidopteran pests. PMID:12695565

  13. Risk assessment and ecological effects of transgenic Bacillus thuringiensis crops on non-target organisms.

    Science.gov (United States)

    Yu, Hui-Lin; Li, Yun-He; Wu, Kong-Ming

    2011-07-01

    The application of recombinant DNA technology has resulted in many insect-resistant varieties by genetic engineering (GE). Crops expressing Cry toxins derived from Bacillus thuringiensis (Bt) have been planted worldwide, and are an effective tool for pest control. However, one ecological concern regarding the potential effects of insect-resistant GE plants on non-target organisms (NTOs) has been continually debated. In the present study, we briefly summarize the data regarding the development and commercial use of transgenic Bt varieties, elaborate on the procedure and methods for assessing the non-target effects of insect-resistant GE plants, and synthetically analyze the related research results, mostly those published between 2005 and 2010. A mass of laboratory and field studies have shown that the currently available Bt crops have no direct detrimental effects on NTOs due to their narrow spectrum of activity, and Bt crops are increasing the abundance of some beneficial insects and improving the natural control of specific pests. The use of Bt crops, such as Bt maize and Bt cotton, results in significant reductions of insecticide application and clear benefits on the environment and farmer health. Consequently, Bt crops can be a useful component of integrated pest management systems to protect the crop from targeted pests.

  14. Risk Assessment and Ecological Effects of Transgenic Bacillus thuringiensis Crops on Non-Target Organisms

    Institute of Scientific and Technical Information of China (English)

    Hui-Lin Yu; Yun-He Li; Kong-Ming Wu

    2011-01-01

    The application of recombinant DNA technology has resulted in many insect-resistant varieties by genetic engineering (GE). Crops expressing Cry toxins derived from Bacillus thuringiensis (Bt) have been planted worldwide, and are an effective tool for pest control. However, one ecological concern regarding the potential effects of insect-resistant GE plants on non-target organisms (NTOs) has been continually debated.In the present study, we briefly summarize the data regarding the development and commercial use of transgenic Bt varieties, elaborate on the procedure and methods for assessing the non-target effects of insect-resistant GE plants, and synthetically analyze the related research results, mostly those published between 2005 and 2010. A mass of laboratory and field studies have shown that the currently available Bt crops have no direct detrimental effects on NTOs due to their narrow spectrum of activity, and Bt crops are increasing the abundance of some beneficial insects and improving the natural control of specific pests. The use of Bt crops, such as Bt maize and Bt cotton, results in significant reductions of insecticide application and clear benefits on the environment and farmer health. Consequently, Bt crops can be a useful component of integrated pest management systems to protect the crop from targeted pests.

  15. Characterization of Bacillus thuringiensis soil isolates from Cuba, with insecticidal activity against mosquitoes.

    Science.gov (United States)

    González, Aileen; Díaz, Raúl; Díaz, Manuel; Borrero, Yainais; Bruzón, Rosa Y; Carreras, Bertha; Gato, René

    2011-09-01

    Chemical insecticides may be toxic and cause environmental degradation. Consequently, biological control for insects represents an alternative with low ecological impact. In this work, three soil isolates (A21, A51 and C17) from different regions of the Cuban archipelago were identified, characterized and evaluated against Aedes aegypti and Culex quinquefasciatus. The new isolates were compared with reference IPS82 strain and two strains isolated from biolarvicides Bactivec and Bactoculicida, respectively. The differentiation was done by morphological, biochemical, bioassays activity and molecular methods (SDS-PAGE, plasmid profile and random amplified polymorphic analysis). All isolates were identified as Bacillus thuringiensis. The A21, A51 and C17 isolates showed higher larvicide activity than Bactivec's isolated reference strain, against both A. aegypti and C. quinquefasciatus. A21 isolate had a protein profile similar to IPS82 and Bactivec strain. A51 and C17 isolates produced a characteristic proteins pattern. A21 and A51 isolates had plasmid patterns similar to IPS82 standard strain, while C17 isolate had different both plasmid profile and protein bands. All the studied isolates showed a diverse RAPD patterns and were different from the strains previously used in biological control in Cuba.

  16. Biosynthesis of silver nanoparticles using Bacillus thuringiensis against dengue vector, Aedes aegypti (Diptera: Culicidae).

    Science.gov (United States)

    Banu, A Najitha; Balasubramanian, C; Moorthi, P Vinayaga

    2014-01-01

    The present study reveals the larvicidal activity of silver nanoparticles (AgNPs) synthesized by Bacillus thuringiensis (Bt) against Aedes aegypti responsible for the diseases of public health importance. The Bt-AgNPs were characterized by using UV-visible spectrophotometer followed by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy. A surface plasmon resonance spectrum of AgNps was obtained at 420 nm. The particle sizes were measured through SEM imaging ranging from 43.52 to 142.97 nm. The Bt-AgNPs has also given a characteristic peak at 3 keV in EDX image. Interestingly, the mortality rendered by Bt-AgNPs was comparatively high than that of the control against third-instar larvae of A. aegypti (LC50 0.10 ppm and LC90 0.39 ppm) in all the tested concentrations, viz. 0.03, 0.06, 0.09, 0.12, and 0.15 ppm. Hence, Bt-AgNPs would be significantly used as a potent mosquito larvicide against A. aegypti.

  17. Bacillus thuringiensis endotoxins active against Chilo partellus and Glossina morsitans morsitans

    International Nuclear Information System (INIS)

    Bacillus thuringiensis crystal endotoxins were isolated by centrifugation on linear sucrose gradients. Analysis of the crystals by gel electrophoresis revealed that the major component of the Chilo partellus active crystal endotoxin was a protein of Mr ∼ 130 kilodalton. The Glossina morsitans morsitans active crystal endotoxin gave a major protein band of Mr ∼ 120 kilodalton. Upon solubilization under alkaline pH and reducing conditions, the C. partellus and G. m. morsitans crystal endotoxin yielded protoxins of Mr ∼ 63 and Mr ∼ 64 kilodalton, respectively. Activation of the C. partellus protoxin with bovine trypsin resulted in no apparent change in the molecular weight. However, treatment with bovine chymotrypsin or C. partellus midgut homogenate resulted in a shift in the molecular weight of the protoxin to a toxin of Mr ∼ 60 kilodalton. Similarly, treatment of G.m. morsitans protoxin with bovine trypsin gave a toxin of Mr ∼ 62 kilodalton, but bovine chymotrypsin gave a toxin of Mr ∼ 60 kilodalton. Staining with periodic acid Schiff reagent revealed that both the crystal endotoxins were glycosylated. The carbohydrate moieties were of the high mannose type, as shown by staining with fluorescein isothiocyanate conjugated-concanavalin A. Rabbit antibodies against C. partellus protoxin cross-reacted with the G. m. morsitans toxin. (author). 19 refs, 5 figs

  18. Construction of an environmental safe Bacillus thuringiensis engineered strain against Coleoptera.

    Science.gov (United States)

    Yu, Yajun; Yuan, Yihui; Gao, Meiying

    2016-05-01

    Cloning of new toxic genes from Bacillus thuringiensis (Bt) and construction of Bt engineered strains are two key strategies for bio-control of coleopteran pests in agriculture and forestry. In this study, we cloned a new cry3Aa-type gene, cry3Aa8, from wild Bt strain YC-03 against coleopteran, and constructed a Bt engineered strain, ACE-38, containing insecticidal protein-encoding gene cry3Aa8. The engineered strain, with almost four times of Cry3Aa yield compared with strain YC-03, was an antibiotic marker-free strain. Though no selective pressure was presented in the medium, cry3Aa8 in the engineered strain ACE-38 remained stable. The yield of Cry3Aa by strain ACE-38 reached 2.09 mg/ml in the optimized fermentation medium. The activity of strain ACE-38 against Plagiodera versicolora was tested, and the LC50 of ACE-38 cultures in the optimized fermentation medium was 1.13 μl/ml. Strain ACE-38 is a non-antibiotic Bt engineered strain with high Chrysomelidae toxicity and exhibits good fermentation property. The modified indigenous site-specific recombination system constructed in this study might be useful for the construction of Bt engineered strains containing genes that cannot be expressed in the indigenous site-specific recombination system using plasmid pBMB1205R. PMID:26767987

  19. Occurrence, characterization and insecticidal activity of Bacillus thuringiensis strains isolated from argan fields in Morocco.

    Science.gov (United States)

    Aboussaid, H; Vidal-Quist, J C; Oufdou, K; El Messoussi, S; Castañera, P; González-Cabrera, J

    2011-01-01

    Soils collected from five locations in the argan forest (an endemic plant) in Morocco were used to form the first collection of Bacillus thuringiensis (Bt) strains from this area (58 strains). Here we found that the argan forest is a major source of Bt, as 90.62% of the samples contained Bt strains. These strains produced mainly spherical or irregular crystals that in some cases remained adhered to the spore after cell lysis. There was no strain producing bipyramidal crystals, suggesting the absence of strains bearing crv1 genes. This was confirmed by PCR analysis using eight primer pairs that can potentially detect 13 different groups of cry and cyt genes. Strains containing cry7/8 were the most abundant (25.53%), followed by strains harbouring cry9A (14.89%), cry11 (8.51%) and cry4 (4.25%). The mixtures of spores and crystals as well as culture supernatants were assayed for toxicity towards Ceratitis capitata (Medfly), showing up to 30% mortality. Our findings suggest that the argan region is a suitable target for future and wider screening programmes looking for strains bearing toxins or combinations of them to develop more efficient Bt-based formulates. PMID:21970180

  20. Persistence of detectable insecticidal proteins from Bacillus thuringiensis (Cry) and toxicity after adsorption on contrasting soils.

    Science.gov (United States)

    Hung, T P; Truong, L V; Binh, N D; Frutos, R; Quiquampoix, H; Staunton, S

    2016-01-01

    Insecticidal Cry, or Bt, proteins are produced by the soil-endemic bacterium, Bacillus thuringiensis and some genetically modified crops. Their environmental fate depends on interactions with soil. Little is known about the toxicity of adsorbed proteins and the change in toxicity over time. We incubated Cry1Ac and Cry2A in contrasting soils subjected to different treatments to inhibit microbial activity. The toxin was chemically extracted and immunoassayed. Manduca sexta was the target insect for biotests. Extractable toxin decreased during incubation for up to four weeks. Toxicity of Cry1Ac was maintained in the adsorbed state, but lost after 2 weeks incubation at 25 °C. The decline in extractable protein and toxicity were much slower at 4 °C with no significant effect of soil sterilization. The major driving force for decline may be time-dependent fixation of adsorbed protein, leading to a decrease in the extraction yield in vitro, paralleled by decreasing solubilisation in the larval gut. PMID:26549751

  1. Characterization of Bacillus thuringiensis soil isolates from Cuba, with insecticidal activity against mosquitoes.

    Science.gov (United States)

    González, Aileen; Díaz, Raúl; Díaz, Manuel; Borrero, Yainais; Bruzón, Rosa Y; Carreras, Bertha; Gato, René

    2011-09-01

    Chemical insecticides may be toxic and cause environmental degradation. Consequently, biological control for insects represents an alternative with low ecological impact. In this work, three soil isolates (A21, A51 and C17) from different regions of the Cuban archipelago were identified, characterized and evaluated against Aedes aegypti and Culex quinquefasciatus. The new isolates were compared with reference IPS82 strain and two strains isolated from biolarvicides Bactivec and Bactoculicida, respectively. The differentiation was done by morphological, biochemical, bioassays activity and molecular methods (SDS-PAGE, plasmid profile and random amplified polymorphic analysis). All isolates were identified as Bacillus thuringiensis. The A21, A51 and C17 isolates showed higher larvicide activity than Bactivec's isolated reference strain, against both A. aegypti and C. quinquefasciatus. A21 isolate had a protein profile similar to IPS82 and Bactivec strain. A51 and C17 isolates produced a characteristic proteins pattern. A21 and A51 isolates had plasmid patterns similar to IPS82 standard strain, while C17 isolate had different both plasmid profile and protein bands. All the studied isolates showed a diverse RAPD patterns and were different from the strains previously used in biological control in Cuba. PMID:22017108

  2. Microcalorimetric Studies on Influence of Sm3+, Dy3+ on Growth and Sporulation of Bacillus thuringiensis

    Institute of Scientific and Technical Information of China (English)

    赵儒铭; 刘义; 杨昌英; 谢志雄; 沈萍; 屈松生

    2004-01-01

    By using an LKB-2277 Bioactivity Monitor and cycle-flow method, the thermogenic curves of aerobic growth for Bacillus thuringiensis cry Ⅱ strain at 28 ℃ have been obtained. The metabolic thermogenic curves of Bt cry Ⅱ contain two distinct parts: the first part reflects the changes of bacterial growth phase and the second part corresponds to sporulation phase. From these thermogenic curves in the absence or presence of Sm3+, Dy3+ ions, the thermokinetic parameters such as the growth rate constants k, the interval time τI, the maximum power PMAxl and heat-output QLoG for log phase, the maximum power PMAX2 and heat-output QSTAT for stationary phase, the heat-output QSPOR for sporulation phase and total heat effects QT were calculated. Sm3+ and Dy3+ ions have promoting action on the growth of Bt cry Ⅱ in their lower concentration range, on the other hand, they have inhibitory action on the sporulation of Bt in their higher concentration range. It has also been found that the effects of Sm3+ and Dy3+ ions on Bt during the sporulation phase were far greater than those during the bacterial growth phase. It was concluded that the application of Bt for controlling insecticide could not be affected by the presence of the rare-earth elements in the environmental ecosystem.

  3. Mode of action of Bacillus thuringiensis Cry and Cyt toxins and their potential for insect control.

    Science.gov (United States)

    Bravo, Alejandra; Gill, Sarjeet S; Soberón, Mario

    2007-03-15

    Bacillus thuringiensis Crystal (Cry) and Cytolitic (Cyt) protein families are a diverse group of proteins with activity against insects of different orders--Lepidoptera, Coleoptera, Diptera and also against other invertebrates such as nematodes. Their primary action is to lyse midgut epithelial cells by inserting into the target membrane and forming pores. Among this group of proteins, members of the 3-Domain Cry family are used worldwide for insect control, and their mode of action has been characterized in some detail. Phylogenetic analyses established that the diversity of the 3-Domain Cry family evolved by the independent evolution of the three domains and by swapping of domain III among toxins. Like other pore-forming toxins (PFT) that affect mammals, Cry toxins interact with specific receptors located on the host cell surface and are activated by host proteases following receptor binding resulting in the formation of a pre-pore oligomeric structure that is insertion competent. In contrast, Cyt toxins directly interact with membrane lipids and insert into the membrane. Recent evidence suggests that Cyt synergize or overcome resistance to mosquitocidal-Cry proteins by functioning as a Cry-membrane bound receptor. In this review we summarize recent findings on the mode of action of Cry and Cyt toxins, and compare them to the mode of action of other bacterial PFT. Also, we discuss their use in the control of agricultural insect pests and insect vectors of human diseases. PMID:17198720

  4. Bacillus thuringiensis peptidoglycan hydrolase SleB171 involved in daughter cell separation during cell division.

    Science.gov (United States)

    Li, Hua; Hu, Penggao; Zhao, Xiuyun; Yu, Ziniu; Li, Lin

    2016-04-01

    Whole-genome analyses have revealed a putative cell wall hydrolase gene (sleB171) that constitutes an operon with two other genes (ypeBandyhcN) of unknown function inBacillus thuringiensisBMB171. The putative SleB171 protein consists of 259 amino acids and has a molecular weight of 28.3 kDa. Gene disruption ofsleB171in the BMB171 genome causes the formation of long cell chains during the vegetative growth phase and delays spore formation and spore release, although it has no significant effect on cell growth and the ultimate release of the spores. The inseparable vegetative cells were nearly restored through the complementation ofsleB171expression. Real-time quantitative polymerase chain reaction analysis revealed thatsleB171is mainly active in the vegetative growth phase, with a maximum activity at the early stationary growth phase. Western blot analysis also confirmed thatsleB171is preferentially expressed during the vegetative growth phase. These results demonstrated that SleB171 plays an essential role in the daughter cell separation during cell division.

  5. Response Surface Methodology: Optimisation of Antifungal Bioemulsifier from Novel Bacillus thuringiensis

    Science.gov (United States)

    Venkatachalam, Ponnusami

    2014-01-01

    An antifungal bioemulsifier compound was produced from a novel strain of Bacillus thuringiensis pak2310. To accentuate the production and as the first step to improve the yield, a central composite design (CCD) was used to study the effect of various factors like minimal salts (1X and 3X), glycerol concentration (2% and 4%), beef extract concentration (1% and 3%), and sunflower oil concentration (2% and 4%) on the production of bioemulsifier molecule and to optimize the conditions to increase the production. The E24 emulsification index was used as the response variable as the increase in surfactant production was seen to be proportional to increased emulsification. A quadratic equation was employed to express the response variable in terms of the independent variables. Statistical tools like student's t-test, F-test, and ANOVA were employed to identify the important factors and to test the adequacy of the model. Under optimum conditions (1X concentration of minimal salts (MS), 2.6% glycerol (v/v), 1% beef extract (w/v), and 2% sunflower oil (v/v)) a 65% increase in yield was produced. PMID:25379529

  6. Novel actin filaments from Bacillus thuringiensis form nanotubules for plasmid DNA segregation.

    Science.gov (United States)

    Jiang, Shimin; Narita, Akihiro; Popp, David; Ghoshdastider, Umesh; Lee, Lin Jie; Srinivasan, Ramanujam; Balasubramanian, Mohan K; Oda, Toshiro; Koh, Fujiet; Larsson, Mårten; Robinson, Robert C

    2016-03-01

    Here we report the discovery of a bacterial DNA-segregating actin-like protein (BtParM) from Bacillus thuringiensis, which forms novel antiparallel, two-stranded, supercoiled, nonpolar helical filaments, as determined by electron microscopy. The BtParM filament features of supercoiling and forming antiparallel double-strands are unique within the actin fold superfamily, and entirely different to the straight, double-stranded, polar helical filaments of all other known ParMs and of eukaryotic F-actin. The BtParM polymers show dynamic assembly and subsequent disassembly in the presence of ATP. BtParR, the DNA-BtParM linking protein, stimulated ATP hydrolysis/phosphate release by BtParM and paired two supercoiled BtParM filaments to form a cylinder, comprised of four strands with inner and outer diameters of 57 Å and 145 Å, respectively. Thus, in this prokaryote, the actin fold has evolved to produce a filament system with comparable features to the eukaryotic chromosome-segregating microtubule.

  7. Adsorption and Insecticidal Activity of Toxin from Bacillus thuringiensis on Rectorite

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xue-Yong; HUANG Qiao-Yun; CAI Peng; YU Zi-Niu

    2007-01-01

    The adsorption and desorption of the toxin from Bacillus thuringiensis strain WG-001 on rectorite were studied at different toxin and/or rectorite concentrations, pH values and temperatures. The insecticidal activity of the adsorbed toxin was evaluated by determining the lethal concentration to kill 50% of the larvae of Heliothis armigera (Lcso). The adsorption of the toxin on rectorite in sodium carbonate buffer (pH 9) reached equilibrium within 0.5-1.0 h and the adsorption isotherm of the toxin followed the Langmuir equation (R2>0.99). In the pH range from 9 to 11 (carbonate buffer), the adsorbed toxin decreased with increasing pH. The adsorption amounts decreased with increasing rectoritettoxin ratio. The adsorption was not significantly affected by the temperature between 10 and 50 °C. The X-ray diffraction analysis indicated occurrence of the intercalation of the rectorite by the toxin. The infrared absorption spectrum showed that the binding of the toxin did not alter its structure. The Lcgo values of the adsorbed toxin were smaller than those of the free toxin. The rectorite protected the toxin from ultraviolet irradiation damage. The desorption of the adsorbed toxin in water ranged from 37.5% to 56.4% and from 27.4% to 41.8% in a carbonate buffer. The desorption percentage also decreased with increasing rectorite:toxin ratio.

  8. LARVICICAL ACTIVITY OF BACILLUS THURINGIENSIS H-14 (TEKNAR ON MOSQUITO LARVAE IN RICEFIELDS, SOUTHERN IRAN

    Directory of Open Access Journals (Sweden)

    M.Motabar

    1986-12-01

    Full Text Available An investigation was conducted to study the larvicidal activity of Teknar (San-402-I-Bacillus thuringiensis, serotype H-14, Sandoz, 600 ITU/mg on mosquitolarvaein Kazeroun, Fars Province, southern Iran. Five experimental plots were selected randomly in a rice field and three concentrations of Teknar: .0003, .0006 and .0012 cc/1 was used. Maximum larval mortality usually occurred during the first 24 hours of exposure. Culicinae larvae were more susceptible than the anophelines. Also, the first and second instars showed greater mortality than the third and fourth instars. The percent larval vortality were 71.8 to 81.5 in anophelines and 82.1 to 100 in culicinae at.0003 cc/1, 89.4 to 100 in anophelinae and 97.2 to 100 in culicinae at.0006 cc/1and 98.4 to 98.6 in anophelinae and 100 in culicinae at.0012 cc/1 concentrations respectively. No mortality was detected in the control plots. It was concluded that.0006 and .0003 cc/1 were the concentrations of choice for the proper mosquito larval control in the area.

  9. Broad-spectrum resistance to Bacillus thuringiensis toxins by western corn rootworm (Diabrotica virgifera virgifera).

    Science.gov (United States)

    Jakka, Siva R K; Shrestha, Ram B; Gassmann, Aaron J

    2016-06-14

    The evolution of resistance and cross-resistance threaten the sustainability of genetically engineered crops that produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt). Western corn rootworm, Diabrotica virgifera virgifera LeConte, is a serious pest of maize and has been managed with Bt maize since 2003. We conducted laboratory bioassays with maize hybrids producing Bt toxins Cry3Bb1, mCry3A, eCry3.1Ab, and Cry34/35Ab1, which represent all commercialized Bt toxins for management of western corn rootworm. We tested populations from fields where severe injury to Cry3Bb1 maize was observed, and populations that had never been exposed to Bt maize. Consistent with past studies, bioassays indicated that field populations were resistant to Cry3Bb1 maize and mCry3A maize, and that cross-resistance was present between these two types of Bt maize. Additionally, bioassays revealed resistance to eCry3.1Ab maize and cross-resistance among Cry3Bb1, mCry3A and eCry3.1Ab. However, no resistance or cross-resistance was detected for Cry34/35Ab1 maize. This broad-spectrum resistance illustrates the potential for insect pests to develop resistance rapidly to multiple Bt toxins when structural similarities are present among toxins, and raises concerns about the long-term durability of Bt crops for management of some insect pests.

  10. Quantitative spectral light scattering polarimetry for monitoring fractal growth pattern of Bacillus thuringiensis bacterial colonies

    Science.gov (United States)

    Banerjee, Paromita; Soni, Jalpa; Ghosh, Nirmalya; Sengupta, Tapas K.

    2013-02-01

    It is of considerable current interest to develop various methods which help to understand and quantify the cellular association in growing bacterial colonies and is also important in terms of detection and identification of a bacterial species. A novel approach is used here to probe the morphological structural changes occurring during the growth of the bacterial colony of Bacillus thuringiensis under different environmental conditions (in normal nutrient agar, in presence of glucose - acting as additional nutrient and additional 3mM arsenate as additional toxic material). This approach combines the quantitative Mueller matrix polarimetry to extract intrinsic polarization properties and inverse analysis of the polarization preserving part of the light scattering spectra to determine the fractal parameter H (Hurst exponent) using Born approximation. Interesting differences are observed in the intrinsic polarization parameters and also in the Hurst exponent, which is a measurement of the fractality of a pattern formed by bacteria while growing as a colony. These findings are further confirmed with optical microscopic studies of the same sample and the results indicate a very strong and distinct dependence on the environmental conditions during growth, which can be exploited to quantify different bacterial species and their growth patterns.

  11. Construction of an environmental safe Bacillus thuringiensis engineered strain against Coleoptera.

    Science.gov (United States)

    Yu, Yajun; Yuan, Yihui; Gao, Meiying

    2016-05-01

    Cloning of new toxic genes from Bacillus thuringiensis (Bt) and construction of Bt engineered strains are two key strategies for bio-control of coleopteran pests in agriculture and forestry. In this study, we cloned a new cry3Aa-type gene, cry3Aa8, from wild Bt strain YC-03 against coleopteran, and constructed a Bt engineered strain, ACE-38, containing insecticidal protein-encoding gene cry3Aa8. The engineered strain, with almost four times of Cry3Aa yield compared with strain YC-03, was an antibiotic marker-free strain. Though no selective pressure was presented in the medium, cry3Aa8 in the engineered strain ACE-38 remained stable. The yield of Cry3Aa by strain ACE-38 reached 2.09 mg/ml in the optimized fermentation medium. The activity of strain ACE-38 against Plagiodera versicolora was tested, and the LC50 of ACE-38 cultures in the optimized fermentation medium was 1.13 μl/ml. Strain ACE-38 is a non-antibiotic Bt engineered strain with high Chrysomelidae toxicity and exhibits good fermentation property. The modified indigenous site-specific recombination system constructed in this study might be useful for the construction of Bt engineered strains containing genes that cannot be expressed in the indigenous site-specific recombination system using plasmid pBMB1205R.

  12. Proteolytic Activation of Bacillus thuringiensis Cry2Ab through a Belt-and-Braces Approach.

    Science.gov (United States)

    Xu, Lian; Pan, Zhi-Zhen; Zhang, Jing; Liu, Bo; Zhu, Yu-Jing; Chen, Qing-Xi

    2016-09-28

    Proteolytic processing of Bacillus thuringiensis (Bt) crystal toxins by insect midgut proteases plays an essential role in their insecticidal toxicities against target insects. In the present study, proteolysis of Bt crystal toxin Cry2Ab by Plutella xylostella L. midgut proteases (PxMJ) was evaluated. Both trypsin and chymotrypsin were identified involving the proteolytic activation of Cry2Ab and cleaving Cry2Ab at Arg(139) and Leu(144), respectively. Three Cry2Ab mutants (R139A, L144A, and R139A-L144A) were constructed by replacing residues Arg(139), Leu(144), and Arg(139)-Leu(144) with alanine. Proteolysis assays revealed that mutants R139A and L144A but not R139A-L144A could be cleaved into 50 kDa activated toxins by PxMJ. Bioassays showed that mutants R139A and L144A were highly toxic against P. xylostella larvae, while mutant R139A-L144A was almost non-insecticidal. Those results demonstrated that proteolysis by PxMJ was associated with the toxicity of Cry2Ab against P. xylostella. It also revealed that either trypsin or chymotrypsin was enough to activate Cry2Ab protoxin. This characteristic was regarded as a belt-and-braces approach and might contribute to the control of resistance development in target insects. Our studies characterized the proteolytic processing of Cry2Ab and provided new insight into the activation of this Bt toxin.

  13. Toxicity of radiation-resistant strains of Bacillus thuringiensis (Berl. ) to larval Plutella xylostella (L. )

    Energy Technology Data Exchange (ETDEWEB)

    Jangi, M.S.; Ibrahim, H. (Faculty of Health Sciences, Universiti Kebangsaan, Malysia, Bangi, Selangor)

    1983-05-01

    A total of 24 isolates of Bacillus thuringiensis (Berliner), resistant to a ..gamma..-radiation dose of 100 krad, were screened for their toxicity to larval silkworms, Bombyxmori(L.), and 15 of them were subsequently tested for their toxicity to larval diamond-back moth, Plutella xylostella(L.). The LC/sub 50/'s of these isolates to B. mori ranged from 1.6 X 10/sup 5/ to 6.0 X 10/sup 3/ spores/mL or from 5.9 to 0.3 ..mu..g cellular protein/mL. The irradiation treatment produced isolates which were significantly more toxic to P. xylostella (LC/sub 50/ < 8.1 X 10/sup 4/ spores/mL or 3.7 ..mu..g cellular protein/mL) and/ or less toxic to B. mori (LC/sub 50/ > 2.3 X 10/sup 4/ spores/mL or 1.0 ..mu..g cellular protein/mL) than the parent commercial strain.

  14. Crystallization and preliminary crystallographic analysis of poly(3-hydroxybutyrate) depolymerase from Bacillus thuringiensis

    Science.gov (United States)

    Wang, Yung-Lin; Lin, Yi-Ting; Chen, Chia-Lin; Shaw, Gwo-Chyuan; Liaw, Shwu-Huey

    2014-01-01

    Poly[(R)-3-hydroxybutyrate] (PHB) is a microbial biopolymer that has been commercialized as biodegradable plastics. The key enzyme for the degradation is PHB depolymerase (PhaZ). A new intracellular PhaZ from Bacillus thuringiensis (BtPhaZ) has been screened for potential applications in polymer biodegradation. Recombinant BtPhaZ was crystallized using 25% polyethylene glycol 3350, 0.2 M ammonium acetate, 0.1 M bis-tris pH 6.5 at 288 K. The crystals belonged to space group P1, with unit-cell parameters a = 42.97, b = 83.23, c = 85.50 Å, α = 73.45, β = 82.83, γ = 83.49°. An X-ray diffraction data set was collected to 1.42 Å resolution with an R merge of 6.4%. Unexpectedly, a molecular-replacement solution was obtained using the crystal structure of Streptomyces lividans chloroperoxidase as a template, which shares 24% sequence identity to BtPhaZ. This is the first crystal structure of an intracellular poly(3-hydroxybutyrate) depolymerase. PMID:25286954

  15. Proteomic Analysis of Bacillus thuringiensis Strain 4.0718 at Different Growth Phases

    Directory of Open Access Journals (Sweden)

    Xiaohui Li

    2012-01-01

    Full Text Available The growth process of Bacillus thuringiensis Bt4.0718 strain was studied using proteomic technologies. The proteins of Bt whole cells at three phases—middle vegetative, early sporulation, and late sporulation—were extracted with lysis buffer, followed with separation by 2-DE and identified by MALDI-TOF/TOF MS. Bioactive factors such as insecticidal crystal proteins (ICPs including Cry1Ac(3, Cry2Aa, and BTRX28, immune inhibitor (InhA, and InhA precursor were identified. InhA started to express at the middle vegetative phase, suggesting its contribution to the survival of Bt in the host body. At the early sporulation phase, ICPs started their expression. CotJC, OppA, ORF1, and SpoIVA related to the formation of crystals and spores were identified, the expression characteristics of which ensured the stable formation of crystals and spores. This study provides an important foundation for further exploration of the stable expression of ICPs, the smooth formation of crystals, and the construction of recombinant strains.

  16. No adjuvant effect of Bacillus thuringiensis-maize on allergic responses in mice.

    Directory of Open Access Journals (Sweden)

    Daniela Reiner

    Full Text Available Genetically modified (GM foods are evaluated carefully for their ability to induce allergic disease. However, few studies have tested the capacity of a GM food to act as an adjuvant, i.e. influencing allergic responses to other unrelated allergens at acute onset and in individuals with pre-existing allergy. We sought to evaluate the effect of short-term feeding of GM Bacillus thuringiensis (Bt-maize (MON810 on the initiation and relapse of allergic asthma in mice. BALB/c mice were provided a diet containing 33% GM or non-GM maize for up to 34 days either before ovalbumin (OVA-induced experimental allergic asthma or disease relapse in mice with pre-existing allergy. We observed that GM-maize feeding did not affect OVA-induced eosinophilic airway and lung inflammation, mucus hypersecretion or OVA-specific antibody production at initiation or relapse of allergic asthma. There was no adjuvant effect upon GM-maize consumption on the onset or severity of allergic responses in a mouse model of allergic asthma.

  17. Host-Pathogen Coevolution: The Selective Advantage of Bacillus thuringiensis Virulence and Its Cry Toxin Genes.

    Science.gov (United States)

    Masri, Leila; Branca, Antoine; Sheppard, Anna E; Papkou, Andrei; Laehnemann, David; Guenther, Patrick S; Prahl, Swantje; Saebelfeld, Manja; Hollensteiner, Jacqueline; Liesegang, Heiko; Brzuszkiewicz, Elzbieta; Daniel, Rolf; Michiels, Nicolaas K; Schulte, Rebecca D; Kurtz, Joachim; Rosenstiel, Philip; Telschow, Arndt; Bornberg-Bauer, Erich; Schulenburg, Hinrich

    2015-06-01

    Reciprocal coevolution between host and pathogen is widely seen as a major driver of evolution and biological innovation. Yet, to date, the underlying genetic mechanisms and associated trait functions that are unique to rapid coevolutionary change are generally unknown. We here combined experimental evolution of the bacterial biocontrol agent Bacillus thuringiensis and its nematode host Caenorhabditis elegans with large-scale phenotyping, whole genome analysis, and functional genetics to demonstrate the selective benefit of pathogen virulence and the underlying toxin genes during the adaptation process. We show that: (i) high virulence was specifically favoured during pathogen-host coevolution rather than pathogen one-sided adaptation to a nonchanging host or to an environment without host; (ii) the pathogen genotype BT-679 with known nematocidal toxin genes and high virulence specifically swept to fixation in all of the independent replicate populations under coevolution but only some under one-sided adaptation; (iii) high virulence in the BT-679-dominated populations correlated with elevated copy numbers of the plasmid containing the nematocidal toxin genes; (iv) loss of virulence in a toxin-plasmid lacking BT-679 isolate was reconstituted by genetic reintroduction or external addition of the toxins. We conclude that sustained coevolution is distinct from unidirectional selection in shaping the pathogen's genome and life history characteristics. To our knowledge, this study is the first to characterize the pathogen genes involved in coevolutionary adaptation in an animal host-pathogen interaction system. PMID:26042786

  18. Host-Pathogen Coevolution: The Selective Advantage of Bacillus thuringiensis Virulence and Its Cry Toxin Genes.

    Directory of Open Access Journals (Sweden)

    Leila Masri

    2015-06-01

    Full Text Available Reciprocal coevolution between host and pathogen is widely seen as a major driver of evolution and biological innovation. Yet, to date, the underlying genetic mechanisms and associated trait functions that are unique to rapid coevolutionary change are generally unknown. We here combined experimental evolution of the bacterial biocontrol agent Bacillus thuringiensis and its nematode host Caenorhabditis elegans with large-scale phenotyping, whole genome analysis, and functional genetics to demonstrate the selective benefit of pathogen virulence and the underlying toxin genes during the adaptation process. We show that: (i high virulence was specifically favoured during pathogen-host coevolution rather than pathogen one-sided adaptation to a nonchanging host or to an environment without host; (ii the pathogen genotype BT-679 with known nematocidal toxin genes and high virulence specifically swept to fixation in all of the independent replicate populations under coevolution but only some under one-sided adaptation; (iii high virulence in the BT-679-dominated populations correlated with elevated copy numbers of the plasmid containing the nematocidal toxin genes; (iv loss of virulence in a toxin-plasmid lacking BT-679 isolate was reconstituted by genetic reintroduction or external addition of the toxins. We conclude that sustained coevolution is distinct from unidirectional selection in shaping the pathogen's genome and life history characteristics. To our knowledge, this study is the first to characterize the pathogen genes involved in coevolutionary adaptation in an animal host-pathogen interaction system.

  19. Effects of algae on the efficacy of Bacillus thuringiensis var. israelensis against larval black flies.

    Science.gov (United States)

    Stephens, Marianne S; Overmyer, Jay P; Gray, Elmer W; Noblet, Ray

    2004-06-01

    Personnel from several black fly control programs have reported that the efficacy of Bacillus thuringiensis var. israelesis (Bti) is reduced during periods when algal concentrations are high in the waterways. Although the reduction in Bti-induced mortality in black fly larvae is presumed to be related to the presence of algae, no scientific data support this theory. In this study, 4 genera of algae (Microcytis, Scenedesmus, Dictrosphaerium, and Chlorella) commonly detected in Pennsylvania rivers where Bti-induced mortality in black fly larvae has been reduced were assessed to determine their respective effects on Bti-induced mortality by using an orbital shaker bioassay with laboratory-reared black fly larvae (Simulium vittatum cytospecies IS-7). A significant reduction in Bti-induced mortality was observed when Scenedesmus was present in the flasks at concentrations > or = 16,000 cells/ml. The Bti-induced mortality of larvae was not significantly reduced when Chlorella, Dictyosphaerium, or Microcytis was present in the flasks, even at concentrations > or = 250,000 cells/ml. These results indicate that the presence of certain types of algae can reduce the mortality of black flies exposed to Bti. Although not clearly defined, the mechanisms involved may be related to algal morphology due to overall size and structures associated with certain types of algae, and possible interference with feeding. PMID:15264627

  20. EFEKTIVITAS Bacillus thuringiensis H-14 STRAIN LOKAL DALAM BUAH KELAPA TERHADAP LARVA Anopheles sp dan Culex sp di KAMPUNG LAUT KABUPATEN CILACAP

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    Blondine Ch. P

    2013-07-01

    Full Text Available Abstrak Bacillus thuringiensis serotipe H-14 strain lokal adalah bakteri patogen bersifat target spesifiknya larva nyamuk, aman bagi mamalia dan lingkungan. Penelitian bertujuan menentukan efektivitas B. thuringiensis H-14 strain lokal yang dikembangbiakkan dalam buah kelapa untuk pengendalian larva Anopheles sp dan Culex sp. Rancangan eksperimental semu, terdiri dari kelompok perlakuan dan kontrol. Bacillus thuringiensis H-14 strain lokal dikembangbiakan dalam10 buah kelapa umur 6–8 bulan, dengan berat kira-kira 1 kg, telah berisi air kelapa sekitar 400-500 ml/buah kelapa yang diperoleh dari Desa Klaces, Kampung Laut, Kabupaten Cilacap. Diinkubasi selama 14 hari pada temperatur kamar dan ditebarkan di 6 kolam yang menjadi habitat perkembangbiakan larva nyamuk dengan luas berkisar 3–100 m2.Hasil yang diperoleh menunjukkan efektivitas B. thuringiensis H-14 strain lokal terhadap larva Anopheles sp dan Culex sp selama 1 hari sesudah penebaran kematian larva berturut-turut sebesar 80–100% dan 79,31–100%. Sedangkan pada hari ke-14 sebesar 69,30–76,71% dan 67,69–86,04%. Buah kelapa dapat digunakan sebagai media lokal alternatif untuk pengembangbiakan B. thuringiensis H-14 strain lokal Kata kunci: B. thuringiensis H-14,  strain  lokal, buah kelapa, pengendalian larva Abstract Bacillus thuringiensis serotype H-14 local strain is pathogenic bacteria which specific  target to mosquito larvae. It is safe for mammals and enviroment. The aims of this study was to determine the effectivity of B. thuringiensis H-14 local strain which culturing in thecoconut wates against Anopheles sp and Culex sp mosquito larvae. This research is quasi experiment which consist of treated  and control groups. Bacillus thuringiensis H-14 local strain was cultured in 10 coconuts with 6–8 months age with weight around 1 kg that contained were approximately 400-500 ml/coconut were taken from Klaces village, Kampung Laut. After that the coconuts incubated for 14

  1. Biological control of the spruce coneworm Dioryctria abietella: Spraying with Bacillus thuringiensis reduced damage in a seed orchard

    Energy Technology Data Exchange (ETDEWEB)

    Weslien, Jan [Forestry Research Inst. of Sweden, Uppsala (Sweden)

    1999-08-01

    Spraying of cones with Bacillus thuringiensis var. Kurstaki x Aizawa in a Norway spruce (Picea abies (L.) Karst.) seed orchard reduced damage by Dioryctria abietella Den. et Schiff. (Lepidoptera, Pyralidae). The incidence of D. abietella attacks was about 80% among unsprayed cones, but less than 15% showed attacks among cones that had been sprayed three times at 9-day intervals with a 0.2% suspension (weight/weight) of the B. thuringiensis preparation in water (Turex 50 WP, 25 000 IU/mg). Attacked, sprayed cones had fewer D. abietella larvae per cone than attacked, unsprayed cones. Spraying did not reduce the damage by Cydia strobilella (L.) (Lepidoptera, Tortricidae) or by Strobilomyia anthracina Czerny (Diptera, Anthomyiidae) 13 refs, 3 tabs

  2. Identification of new isolates of Bacillus thuringiensis using rep-PCR products and d-endotoxin electron microscopy

    Directory of Open Access Journals (Sweden)

    Lima A.S.G.

    2002-01-01

    Full Text Available PCR has been used to analyze the distribution of REP (Repetitive Extragenic Palindromic and ERIC (Enterobacterial Repetitive Intergenic Consensus sequences (rep-PCR found within the genome of the bacterium Bacillus thuringiensis, with the purpose to analyze the genetic similarities among 56 subspecies samples and 95 field isolates. The PCR products were analyzed by EB-AGE (ethidium bromide-agarose electrophoresis and then submitted to banding comparisons, based on the Phyllip software algorithm. When the banding similarities were considered for comparison purposes among all the strains, the phylogenic tree patterns varied according to the rep-PCR primers considered, but, from a broader point of view, the ERIC sequences produced better results, which, together with electron microscopy analysis of the released parasporal bodies and colony morphology characteristics, allowed to detect two possible new subspecies of B. thuringiensis.

  3. Identification of new isolates of Bacillus thuringiensis using rep-PCR products and delta-endotoxin electron microscopy

    Directory of Open Access Journals (Sweden)

    A.S.G. Lima

    2002-01-01

    Full Text Available PCR has been used to analyze the distribution of REP (Repetitive Extragenic Palindromic and ERIC (Enterobacterial Repetitive Intergenic Consensus sequences (rep-PCR found within the genome of the bacterium Bacillus thuringiensis, with the purpose to analyze the genetic similarities among 56 subspecies samples and 95 field isolates. The PCR products were analyzed by EB-AGE (ethidium bromide-agarose electrophoresis and then submitted to banding comparisons, based on the Phyllip software algorithm. When the banding similarities were considered for comparison purposes among all the strains, the phylogenic tree patterns varied according to the rep-PCR primers considered, but, from a broader point of view, the ERIC sequences produced better results, which, together with electron microscopy analysis of the released parasporal bodies and colony morphology characteristics, allowed to detect two possible new subspecies of B. thuringiensis.

  4. Molecular characterization of a DNA fragment harboring the replicon of pBMB165 from Bacillus thuringiensis subsp. tenebrionis

    Directory of Open Access Journals (Sweden)

    Yu Ziniu

    2006-10-01

    Full Text Available Abstract Background Bacillus thuringiensis belongs to the Bacillus cereus sensu lato group of Gram-positive and spore-forming bacteria. Most isolates of B. thuringiensis can bear many endogenous plasmids, and the number and size of these plasmids can vary widely among strains or subspecies. As far as we know, the replicon of the plasmid pBMB165 is the first instance of a plasmid replicon being isolated from subsp. tenebrionis and characterized. Results A 20 kb DNA fragment containing a plasmid replicon was isolated from B. thuringiensis subsp. tenebrionis YBT-1765 and characterized. By Southern blot analysis, this replicon region was determined to be located on pBMB165, the largest detected plasmid (about 82 kb of strain YBT-1765. Deletion analysis revealed that a replication initiation protein (Rep165, an origin of replication (ori165 and an iteron region were required for replication. In addition, two overlapping ORFs (orf6 and orf10 were found to be involved in stability control of plasmid. Sequence comparison showed that the replicon of pBMB165 was homologous to the pAMβ1 family replicons, indicating that the pBMB165 replicon belongs to this family. The presence of five transposable elements or remnants thereof in close proximity to and within the replicon control region led us to speculate that genetic exchange and recombination are potentially responsible for the divergence among the replicons of this plasmid family. Conclusion The replication and stability features of the pBMB165 from B. thuringiensis subsp. tenebrionis YBT-1765 were identified. Of particular interest is the homology and divergence shared between the pBMB165 replicon and other pAMβ1 family replicons.

  5. Susceptibility of Ostrinia furnacalis to Bacillus thuringiensis and Bt Corn Under Long-Term Laboratory Selection

    Institute of Scientific and Technical Information of China (English)

    WEN Li-ping; HE Kang-lai; WANG Zhen-ying; ZHOU Da-rong; BAI Shu-xiong

    2005-01-01

    The susceptibility of the Asian corn borer, Ostrinia furnacalis to Bacillus thuringiensis (Bt) formulation and Bt corn was evaluated using insect bioassays for 6 years. Four strains of O. furnacalis were developed by laboratory selection from the laboratory strain reared on a non-agar semi-artificial diet. The RR-1 strain was exposed to a commercial formulation of B. thuringiensis subsp. kurstaki (Btk) incorporated into the artificial diet, the RR-2 strain was exposed to Bt corn (MON810)tissue incorporated into the diet, and the SS-1 and SS-2 strains were reared on the standard diet with or without non-Bt corn tissues material. Decreasing susceptibility of O. furnacalis to Bt and to Bt corn were found in each selected strain although the ED50 and larval weight fluctuated from generation to generation. The resistance of Bt-exposed strain (RR-1)to Btk increased 48-fold by generation 39; the Bt corn-exposed strain (RR-2) increased its resistance 37-fold to Btk by generation 24. No larvae of SS-1 survived when they were exposed to the leaves of Bt corn, Bt1 1 and MON810. However,2-54% of the RR-1 (generation 46) and RR-2 (generation 20) larvae survived a 3 day-exposure to the leaves of Bt1 1 and MON810. The survival of both selected strains on Bt corn silk increased by 10-69%, and the larval weights after many generations selection were increased by 15-22% compared with the unselected susceptible strain. The young larvae were much more susceptible to Bt than older larvae. The highest mortality occurred when the larvae were exposed to Bt at the neonate stage. All of the results suggested that ACB could not only develop resistance to Bt preparation but also to Bt corn. Bt had significant effects on the growth and development of Asian corn borer than on the larval mortality. In order to maintain the long-term effectiveness of Bt pesticide and Bt corn, the resistance management should pay much attention to the larvae that may have opportunities to grow and developed on non

  6. Differentiation Between Bacillus thuringiensis and Bacillus cereus by 16S rDNA-PCR and ERIC-PCR

    Institute of Scientific and Technical Information of China (English)

    LI Haitao; LIU Dongming; GAO Jiguo

    2011-01-01

    16S rDNA and ERIC (Enterobacteia Repetitive Intergenic Consensus Sequences) based on PCR method were tested for the effectiveness of the differentiation of B. thuringiensis and B. cereus. 16S rDNA-PCR primers were designed based on the sequence difference in variable regions of B. cereus 16S rDNA and B. thuringiensis 16S rDNA, 16S rDNA-PCR showed no obvious difference between B. cereus and B. thuringiensis. The only difference was that one 1600-bp amplificon could be obtained from all the three B. Cereus strains, and none amplificon from any B. thuringiensis strains. ERIC was optimized based on previous reports. The genonlic DNA was used for the template of ER1C-PCR, and the following DNA fingerprints were analyzed by the agarose gel electrophoresis. The results showed that DNA fingerprint of three B. thuringiensis strains had a unique amplicon less than 100-bp, while DNA fingerprint of three B. cereus" strains had none. Moreover, DNA fingerprint of B. cereus showed a 700-bp amplicon, but didn't have any DNA fingerprints ofB. thuringiensis genome. Therefore, ERIC-PCR technique should be able to be used for the differentiation of B. thuringiensis and B. cereus.

  7. Estudio de las bases de la resistencia a las proteínas insecticidas de bacillus thuringiensis en ostrinia nubilalis

    OpenAIRE

    Crava, Maria C.

    2013-01-01

    Ostrinia nubilalis (Hübner) es una de las plagas más devastadoras de los cultivos de maíz de Europa y Norte América, y a nivel económico la obtención de un control eficaz de esta plaga es un logro fundamental. En 1996, se permitió la comercialización de las plantas transgénicas que llevan insertado en el genoma un gen procedente de Bacillus thuringiensis (Berliner) (Bt) y que codifica para una proteína insecticida de las que esta bacteria produce en forma de cristales paraesporales (proteínas...

  8. Enhancement of intrinsic antitumor activity in spore-endotoxin mixtures of Bacillus thuringiensis by exposure to ultraviolet radiation

    International Nuclear Information System (INIS)

    Irradiation of spore-endotoxin mixtures from Bacillus thuringiensis cultures at 254 nm (60 μW cm-2) enhances their intrinsic antitumor potency as well as that of either component. The extent of enhancement depends on the length of exposure (optimum: 35 min) and may thus be due to photochemical changes of the endotoxin protein or/and to photoproduction of additional compounds with antitumor activity. Antitumor effects, expressed as survival rates of C57BL/6 mice inoculated with Lewis' mouse lung carcinoma and subjected to treatments 24 h later, depended on the number of doses of preparations administered (mixture, separated components). (author)

  9. Cloning and Analysis of a Large Plasmid pBMB165 from Bacillus thuringiensis Revealed a Novel Plasmid Organization

    OpenAIRE

    Yueying Wang; Donghai Peng; Zhaoxia Dong; Lei Zhu; Suxia Guo; Ming Sun

    2013-01-01

    In this study, we report a rapid cloning strategy for large native plasmids via a contig linkage map by BAC libraries. Using this method, we cloned a large plasmid pBMB165 from Bacillus thuringiensis serovar tenebrionis strain YBT-1765. Complete sequencing showed that pBMB165 is 77,627 bp long with a GC-content of 35.36%, and contains 103 open reading frames (ORFs). Sequence analysis and comparison reveals that pBMB165 represents a novel plasmid organization: it mainly consists of a pXO2-like...

  10. Bacillus thuringiensis subsp. israelensis Cyt1Aa synergizes Cry11Aa toxin by functioning as a membrane-bound receptor

    OpenAIRE

    Pérez, Claudia; Fernandez, Luisa E.; Sun, Jianguang; Folch, Jorge Luis; Gill, Sarjeet S.; Soberón, Mario; Bravo, Alejandra

    2005-01-01

    Bacillus thuringiensis subsp. israelensis produces crystal proteins, Cry (4Aa, 4Ba, 10Aa, and 11Aa) and Cyt (1Aa and 2Ba) proteins, toxic to mosquito vectors of human diseases. Cyt1Aa overcomes insect resistance to Cry11Aa and Cry4 toxins and synergizes the toxicity of these toxins. However, the molecular mechanism of synergism remains unsolved. Here, we provide evidence that Cyt1Aa functions as a receptor of Cry11Aa. Sequential-binding analysis of Cyt1Aa and Cry11Aa revealed that Cyt1Aa bind...

  11. Characterization of native Bacillus thuringiensis strains and selection of an isolate active against Spodoptera frugiperda and Peridroma saucia.

    Science.gov (United States)

    Alvarez, Analía; Virla, Eduardo G; Pera, Licia M; Baigorí, Mario D

    2009-12-01

    Twelve Bacillus thuringiensis (Bt) strains, isolated from larvae and soil samples in Argentina, were molecularly and phenotypically characterized and their insecticidal activities against Spodoptera frugiperda and Peridroma saucia were determined. One isolate--Bt RT--produced more than 93% mortality on first instar larvae of both species, which was higher than that produced by the reference strain Bt 4D1. Bt RT carried a different cry gene profile than Bt 4D1. Scanning electron microscopy showed the presence of bipyramidal and cuboidal crystals. Phenotypic characterization revealed lytic enzymes that could contribute to Bt pathogenicity. PMID:19693442

  12. Enhancement of intrinsic antitumor activity in spore-endotoxin mixtures of Bacillus thuringiensis by exposure to ultraviolet radiation

    Energy Technology Data Exchange (ETDEWEB)

    Zamola, B.; Karminski-Zamola, G.; Fuks, Z.; Kubovic, M. (Zagreb Univ. (Yugoslavia)); Wrishcer, M. (Institut Rudjer Boskovic, Zagreb (Yugoslavia))

    1985-03-01

    Irradiation of spore-endotoxin mixtures from Bacillus thuringiensis cultures at 254 nm (60 ..mu..W cm/sup -2/) enhances their intrinsic antitumor potency as well as that of either component. The extent of enhancement depends on the length of exposure (optimum: 35 min) and may thus be due to photochemical changes of the endotoxin protein or/and to photoproduction of additional compounds with antitumor activity. Antitumor effects, expressed as survival rates of C57BL/6 mice inoculated with Lewis' mouse lung carcinoma and subjected to treatments 24 h later, depended on the number of doses of preparations administered (mixture, separated components).

  13. Aspectos economicos do controle de Thyrinteina arnobia (Stoll, 1782) (Lep.: Geometridae) com bacillus thuringiensis (Berliner) em povoamentos de Eucalyptus spp.

    OpenAIRE

    Branco, Edward Fagundes

    2013-01-01

    Resumo: Este trabalho foi desenvolvido com o objetivo básico de estudar aspectos econômicos do controle de lagartas desfolhadoras da espécie Thyrinteina arnobia, com esporos da bactéria Bacillus thuringiensis, em povoamentos de Eucalyptus grandis e Eucalyptus urophylla. As diferenças estatísticas entre os parâmetros dendrométricos utilizados também foram estudados. Trabalhou-se com levantamentos dendrométricos oriundos de 4 inventários contínuos, agrupados em três épocas distintas: anos antes...

  14. Resistance to Bacillus thuringiensis Toxin Cry2Ab in Trichoplusia ni Is Conferred by a Novel Genetic Mechanism

    OpenAIRE

    Song, Xiaozhao; Kain, Wendy; Cassidy, Douglas; Wang, Ping

    2015-01-01

    The resistance to the Bacillus thuringiensis (Bt) toxin Cry2Ab in a greenhouse-originated Trichoplusia ni strain resistant to both Bt toxins Cry1Ac and Cry2Ab was characterized. Biological assays determined that the Cry2Ab resistance in the T. ni strain was a monogenic recessive trait independent of Cry1Ac resistance, and there existed no significant cross-resistance between Cry1Ac and Cry2Ab in T. ni. From the dual-toxin-resistant T. ni strain, a strain resistant to Cry2Ab only was isolated,...

  15. Proteolytic Activation of Bacillus thuringiensis Cry2Ab through a Belt-and-Braces Approach.

    Science.gov (United States)

    Xu, Lian; Pan, Zhi-Zhen; Zhang, Jing; Liu, Bo; Zhu, Yu-Jing; Chen, Qing-Xi

    2016-09-28

    Proteolytic processing of Bacillus thuringiensis (Bt) crystal toxins by insect midgut proteases plays an essential role in their insecticidal toxicities against target insects. In the present study, proteolysis of Bt crystal toxin Cry2Ab by Plutella xylostella L. midgut proteases (PxMJ) was evaluated. Both trypsin and chymotrypsin were identified involving the proteolytic activation of Cry2Ab and cleaving Cry2Ab at Arg(139) and Leu(144), respectively. Three Cry2Ab mutants (R139A, L144A, and R139A-L144A) were constructed by replacing residues Arg(139), Leu(144), and Arg(139)-Leu(144) with alanine. Proteolysis assays revealed that mutants R139A and L144A but not R139A-L144A could be cleaved into 50 kDa activated toxins by PxMJ. Bioassays showed that mutants R139A and L144A were highly toxic against P. xylostella larvae, while mutant R139A-L144A was almost non-insecticidal. Those results demonstrated that proteolysis by PxMJ was associated with the toxicity of Cry2Ab against P. xylostella. It also revealed that either trypsin or chymotrypsin was enough to activate Cry2Ab protoxin. This characteristic was regarded as a belt-and-braces approach and might contribute to the control of resistance development in target insects. Our studies characterized the proteolytic processing of Cry2Ab and provided new insight into the activation of this Bt toxin. PMID:27598769

  16. Purification and Characterization of a Novel Cold Shock Protein-Like Bacteriocin Synthesized by Bacillus thuringiensis

    Science.gov (United States)

    Huang, Tianpei; Zhang, Xiaojuan; Pan, Jieru; Su, Xiaoyu; Jin, Xin; Guan, Xiong

    2016-01-01

    Bacillus thuringiensis (Bt), one of the most successful biopesticides, may expand its potential by producing bacteriocins (thuricins). The aim of this study was to investigate the antimicrobial potential of a novel Bt bacteriocin, thuricin BtCspB, produced by Bt BRC-ZYR2. The results showed that this bacteriocin has a high similarity with cold-shock protein B (CspB). BtCspB lost its activity after proteinase K treatment; however it was active at 60 °C for 30 min and was stable in the pH range 5–7. The partial loss of activity after the treatments of lipase II and catalase were likely due to the change in BtCspB structure and the partial degradation of BtCspB, respectively. The loss of activity at high temperatures and the activity variation at different pHs were not due to degradation or large conformational change. BtCspB did not inhibit four probiotics. It was only active against B. cereus strains 0938 and ATCC 10987 with MIC values of 3.125 μg/mL and 0.781 μg/mL, and MBC values of 12.5 μg/mL and 6.25 μg/mL, respectively. Taken together, these results provide new insights into a novel cold shock protein-like bacteriocin, BtCspB, which displayed promise for its use in food preservation and treatment of B. cereus-associated diseases. PMID:27762322

  17. Comparative analysis of genomics and proteomics in Bacillus thuringiensis 4.0718.

    Directory of Open Access Journals (Sweden)

    Jie Rang

    Full Text Available Bacillus thuringiensis is a widely used biopesticide that produced various insecticidal active substances during its life cycle. Separation and purification of numerous insecticide active substances have been difficult because of the relatively short half-life of such substances. On the other hand, substances can be synthetized at different times during development, so samples at different stages have to be studied, further complicating the analysis. A dual genomic and proteomic approach would enhance our ability to identify such substances, and particularily using mass spectrometry-based proteomic methods. The comparative analysis for genomic and proteomic data have showed that not all of the products deduced from the annotated genome could be identified among the proteomic data. For instance, genome annotation results showed that 39 coding sequences in the whole genome were related to insect pathogenicity, including five cry genes. However, Cry2Ab, Cry1Ia, Cytotoxin K, Bacteriocin, Exoenzyme C3 and Alveolysin could not be detected in the proteomic data obtained. The sporulation-related proteins were also compared analysis, results showed that the great majority sporulation-related proteins can be detected by mass spectrometry. This analysis revealed Spo0A~P, SigF, SigE(+, SigK(+ and SigG(+, all known to play an important role in the process of spore formation regulatory network, also were displayed in the proteomic data. Through the comparison of the two data sets, it was possible to infer that some genes were silenced or were expressed at very low levels. For instance, found that cry2Ab seems to lack a functional promoter while cry1Ia may not be expressed due to the presence of transposons. With this comparative study a relatively complete database can be constructed and used to transform hereditary material, thereby prompting the high expression of toxic proteins. A theoretical basis is provided for constructing highly virulent engineered

  18. Diversity and Toxicity of Bacillus thuringiensis from Shifting Cultivation (Jhum) Habitat.

    Science.gov (United States)

    Zothansanga, Ralte; Senthilkumar, Nachimuthu; Gurusubramanian, Guruswami

    2016-01-01

    Bacillus thuringiensis (Bt) strains were isolated from jhum-agriculture, jhum-forest, aquatic and fallow soil samples from Mizoram by acetate selection method. Isolates were characterized for biochemical typing, cry gene and protein profiling, growth curve study and toxicity against Culex tritaeniorhynchus. Bt frequency was high in jhum-agriculture land (69.56%) whereas low in jhum-forest soils (31.57%). Bt was found to be abundant in jhum shifting cultivation soil with an index ranging between 0.010 and 0.015. Majority of the isolates from jhum soils produced oval and spherical crystals and showed eleven types of crystal proteins groups. PCR analysis revealed predominance of dipteran-active cry genes (cry4 and cry9). The variations in crystal morphology, cry genes and Cry protein (s) from the isolates of Bt revealed molecular diversity. Higher mortality, lower lethal dose, and lesser time to kill were observed in Bt isolates from jhum soils than aquatic and fallow habitats. Based on the toxicity test, SC1 and HP7 isolates containing cry 4 and cry 9 genes showed higher activity. Growth curve analysis showed significant variations among Bt isolates to reach the sporulating stage. Higher growth index and lower mean generation time were observed in SC1 and HP7 Bt isolates. Bt strains express different endotoxin genes and crystal proteins and their harvesting time also varied from strain to strain. Significant variation was found in Bt isolates from jhum habitats in relation to the cry gene composition, protein profiling and toxicity. Results from this study suggest that novel Bt entomopathogens may complement for regulating mosquito vectors. PMID:27350428

  19. Effects of bacillus thuringiensis transgenic corn on corn earworm and fall armyworm (Lepidoptera: Noctuidae) densities.

    Science.gov (United States)

    Chilcutt, Charles F; Odvody, Gary N; Correa, J Carlos; Remmers, Jeff

    2007-04-01

    We examined 17 pairs of near-isogenic hybrids of Bacillus thuringiensis (Bt) (176, Mon810, and Bt11) and non-Bt corn, Zea mays L., to examine the effects of Bt on larval densities of Helicoverpa zea (Boddie) and Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) during 2 yr. During ear formation, instar densities of H. zea and S. frugiperda were recorded for each hybrid. We found that H. zea first, second, and fifth instar densities were each affected by Mon810 and Bt11 Bt corn but not by 176 corn. Surprisingly, first and second instars were found in higher numbers on ears of Mon810 and Bt11 corn than on non-Bt corn. Densities of third and fourth instars were equal on Bt and non-Bt hybrids, whereas densities of fifth instars were lower on Bt plants. S. frugiperda larval densities were only affected during 1 yr when second, and fourth to sixth instars were lower on ears of Mon810 and Bt11 hybrids compared with their non-Bt counterparts. Two likely explanations for early instar H. zea densities being higher on Bt corn than non-Bt corn are that (1) Bt toxins delay development, creating a greater abundance of early instars that eventually die, and (2) reduced survival of H. zea to later instars on Bt corn decreased the normal asymmetric cannibalism or H. zea-S. frugiperda intraguild predation of late instars on early instars. Either explanation could explain why differences between Bt and non-Bt plants were greater for H. zea than S. frugiperda, because H. zea is more strongly affected by Bt toxins and more cannibalistic.

  20. Field-evolved resistance by western corn rootworm to multiple Bacillus thuringiensis toxins in transgenic maize.

    Science.gov (United States)

    Gassmann, Aaron J; Petzold-Maxwell, Jennifer L; Clifton, Eric H; Dunbar, Mike W; Hoffmann, Amanda M; Ingber, David A; Keweshan, Ryan S

    2014-04-01

    The widespread planting of crops genetically engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) places intense selective pressure on pest populations to evolve resistance. Western corn rootworm is a key pest of maize, and in continuous maize fields it is often managed through planting of Bt maize. During 2009 and 2010, fields were identified in Iowa in which western corn rootworm imposed severe injury to maize producing Bt toxin Cry3Bb1. Subsequent bioassays revealed Cry3Bb1 resistance in these populations. Here, we report that, during 2011, injury to Bt maize in the field expanded to include mCry3A maize in addition to Cry3Bb1 maize and that laboratory analysis of western corn rootworm from these fields found resistance to Cry3Bb1 and mCry3A and cross-resistance between these toxins. Resistance to Bt maize has persisted in Iowa, with both the number of Bt fields identified with severe root injury and the ability western corn rootworm populations to survive on Cry3Bb1 maize increasing between 2009 and 2011. Additionally, Bt maize targeting western corn rootworm does not produce a high dose of Bt toxin, and the magnitude of resistance associated with feeding injury was less than that seen in a high-dose Bt crop. These first cases of resistance by western corn rootworm highlight the vulnerability of Bt maize to further evolution of resistance from this pest and, more broadly, point to the potential of insects to develop resistance rapidly when Bt crops do not achieve a high dose of Bt toxin.

  1. Improvement and efficient display of Bacillus thuringiensis toxins on M13 phages and ribosomes.

    Science.gov (United States)

    Pacheco, Sabino; Cantón, Emiliano; Zuñiga-Navarrete, Fernando; Pecorari, Frédéric; Bravo, Alejandra; Soberón, Mario

    2015-12-01

    Bacillus thuringiensis (Bt) produces insecticidal proteins that have been used worldwide in the control of insect-pests in crops and vectors of human diseases. However, different insect species are poorly controlled by the available Bt toxins or have evolved resistance to these toxins. Evolution of Bt toxicity could provide novel toxins to control insect pests. To this aim, efficient display systems to select toxins with increased binding to insect membranes or midgut proteins involved in toxicity are likely to be helpful. Here we describe two display systems, phage display and ribosome display, that allow the efficient display of two non-structurally related Bt toxins, Cry1Ac and Cyt1Aa. Improved display of Cry1Ac and Cyt1Aa on M13 phages was achieved by changing the commonly used peptide leader sequence of the coat pIII-fusion protein, that relies on the Sec translocation pathway, for a peptide leader sequence that relies on the signal recognition particle pathway (SRP) and by using a modified M13 helper phage (Phaberge) that has an amber mutation in its pIII genomic sequence and preferentially assembles using the pIII-fusion protein. Also, both Cry1Ac and Cyt1Aa were efficiently displayed on ribosomes, which could allow the construction of large libraries of variants. Furthermore, Cry1Ac or Cyt1Aa displayed on M13 phages or ribosomes were specifically selected from a mixture of both toxins depending on which antigen was immobilized for binding selection. These improved systems may allow the selection of Cry toxin variants with improved insecticidal activities that could counter insect resistances. PMID:26606918

  2. Broad-spectrum resistance to Bacillus thuringiensis toxins by western corn rootworm (Diabrotica virgifera virgifera).

    Science.gov (United States)

    Jakka, Siva R K; Shrestha, Ram B; Gassmann, Aaron J

    2016-01-01

    The evolution of resistance and cross-resistance threaten the sustainability of genetically engineered crops that produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt). Western corn rootworm, Diabrotica virgifera virgifera LeConte, is a serious pest of maize and has been managed with Bt maize since 2003. We conducted laboratory bioassays with maize hybrids producing Bt toxins Cry3Bb1, mCry3A, eCry3.1Ab, and Cry34/35Ab1, which represent all commercialized Bt toxins for management of western corn rootworm. We tested populations from fields where severe injury to Cry3Bb1 maize was observed, and populations that had never been exposed to Bt maize. Consistent with past studies, bioassays indicated that field populations were resistant to Cry3Bb1 maize and mCry3A maize, and that cross-resistance was present between these two types of Bt maize. Additionally, bioassays revealed resistance to eCry3.1Ab maize and cross-resistance among Cry3Bb1, mCry3A and eCry3.1Ab. However, no resistance or cross-resistance was detected for Cry34/35Ab1 maize. This broad-spectrum resistance illustrates the potential for insect pests to develop resistance rapidly to multiple Bt toxins when structural similarities are present among toxins, and raises concerns about the long-term durability of Bt crops for management of some insect pests. PMID:27297953

  3. pH-controlled Bacillus thuringiensis Cry1Ac protoxin loading and release from polyelectrolyte microcapsules.

    Directory of Open Access Journals (Sweden)

    Wenhui Yang

    Full Text Available Crystal proteins synthesized by Bacillus thuringiensis (Bt have been used as biopesticides because of their toxicity to the insect larval hosts. To protect the proteins from environmental stress to extend their activity, we have developed a new microcapsule formulation. Poly (acrylic acid (PAH and poly (styrene sulfonate (PSS were fabricated through layer-by-layer self-assembly based on a CaCO(3 core. Cry1Ac protoxins were loaded into microcapsules through layer-by-layer self-assembly at low pH, and the encapsulated product was stored in water at 4°C. Scanning electron microscopy (SEM was used to observe the morphology of the capsules. To confirm the successful encapsulation, the loading results were observed with a confocal laser scattering microscope (CLSM, using fluorescein-labeled Cry1Ac protoxin (FITC-Cry1Ac. The protoxins were released from the capsule under the alkaline condition corresponding to the midgut of certain insects, a condition which seldom exists elsewhere in the environment. The following bioassay experiment demonstrated that the microcapsules with Cry1Ac protoxins displayed approximately equivalent insecticidal activity to the Asian corn borer compared with free Cry1Ac protoxins, and empty capsules proved to have no effect on insects. Further result also indicated that the formulation could keep stable under the condition of heat and desiccation. These results suggest that this formulation provides a promising methodology that protects protoxins from the environment and releases them specifically in the target insects' midgut, which has shown potential as biopesticide in the field.

  4. In vivo fluorescence observation of parasporal inclusion formation in Bacillus thuringiensis

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A recombinant gene expressing a Cry1Ac-GFP fusion protein with a molecular mass of approximately 160 kD was constructed to investigate the expression of cry1Ac,the localization of its gene product Cry1Ac,and its role in crystal development in Bacillus thuringiensis.The cry1Ac-gfp fusion gene under the control of the cry1Ac promoter was cloned into the plasmid pHT304,and this construct was designated pHTcry1Ac-gfp.pHTcry1Ac-gfp was transformed into the crystal-negative strain,HD-73 cry-,and the resulting strain was named HD-73-(pHTcry1Ac-gfp).The gfp gene was then inserted into the large HD-73 endogenous plasmid pHT73 and fused with the 3’ terminal of the cry1Ac gene by homologous recombination,yielding HD-73Φ(cry1Ac-gfp)3534.Laser confocal microscopy and Western blot analyses showed for the first time that the Cry1Ac-GFP fusion proteins in both HD-73-(pHTcry1Ac-gfp) and HD-73Φ(cry1Ac-gfp)3534 were produced during asymmetric septum formation.Surprisingly,the Cry1Ac-GFP fusion protein showed polarity and was located near the septa in both strains.There was no significant difference between Cry1Ac-GFP and Cry1Ac in their toxicity to Plutella xylostella larvae.

  5. Cloning, Expression and Toxicity of a Mosquitocidal Toxin Gene of Bacillus thuringiensis subsp. medellin

    Directory of Open Access Journals (Sweden)

    Restrepo Nora

    1997-01-01

    Full Text Available Bacillus thuringiensis (Bt subsp. medellin (Btmed produces parasporal crystalline inclusions which are toxic to mosquito larvae. It has been shown that the inclusions of this bacterium contain mainly proteins of 94, 68 and 28-30 kDa. EcoRI partially digested total DNA of Btmed was cloned by using the Lambda Zap II cloning kit. Recombinant plaques were screened with a mouse policlonal antibody raised against the 94 kDa crystal protein of Btmed. One of the positive plaques was selected, and by in vivo excision, a recombinant pBluescript SK(- was obtained. The gene encoding the 94 kDa toxin of Btmed DNA was cloned in a 4.4 kb DNA fragment. Btmed DNA was then subcloned as a EcoRI/EcoRI fragment into the shuttle vector pBU4 producing the recombinant plasmid pBTM3 and used to transform by electroporation Bt subsp. israelensis (Bti crystal negative strain 4Q2-81. Toxicity to mosquito larvae was estimated by using first instar laboratory reared Aedes aegypti, and Culex quinquefasciatus larvae challenged with whole crystals. Toxicity results indicate that the purified inclusions from the recombinant Bti strain were toxic to all mosquito species tested, although the toxicity was not as high as the one produced by the crystal of the Btmed wild type strain. Poliacrylamide gel electrophoresis indicate that the inclusions produced by the recombinant strain Bti (pBTM3 were mainly composed of the 94 kDa protein of Btmed, as it was determined by Western blot

  6. Análisis exploratorio para la optimización de un medio de cultivo para la fermentación de Bacillus thuringiensis Exploratory analysis for the optimization of culture media for Bacillus thuringiensis fermentation

    Directory of Open Access Journals (Sweden)

    Escobar Jenny M.

    2004-12-01

    Full Text Available Los insecticidas químicos usados indiscriminadamente traen riesgos para la salud de quienes los aplican y de quienes consumen alimentos contaminados con éstos; además atacan insectos benéficos, aves, peces y mamí­feros. Como alternativa al uso de insecticidas químicos están los bioinsecticidas, como es el caso de Bacillus thuringiensis, que es específico para el insecto plaga que se desea controlar. Un factor clave en la producción por fermentación de biopesticidas basados en Bacillus thuringiensis es el diseño del medio de cultivo, el cual debe ser económico y contener todos los nutrientes necesarios para el crecimiento del microorganismo. Del cultivo se espera que rinda una alta producción de ingrediente activo conformado por los cristales que contie­nen las toxinas y por la espora del microorganismo, y que este ingrediente posea el valor de toxicidad requeri­do para la formulación del producto comercial. En este trabajo se estudiaron diferentes medios de cultivo, se seleccionó un medio promisorio y se optimizó para la fermentación con una cepa nativa de B. thuringiensis te­niendo en cuenta no sólo el ingrediente activo sino también los costos que éste genera en materias primas. Se lograron concentraciones finales de ingrediente activo entre 15 y 16 g/L con un costo aproximado por mate­rias primas de $650/kg producto (aproximadamente US$0,30/kg producto. Para esto se utilizó la metodología de superficies de respuesta en un diseño compuesto central (DCC para la fase de experimentación, y para la fase de optimización se utilizó el método desarrollado por Derringer y Suich (1980 para múltiples respuestas. Palabras clave: biopesticidas, medios de cultivo, superficie de respuesta, respuesta dual, gráficas de contorno, diseño compuesto central.Agrichemical involve health risks for producers and consumers; they can also affect beneficial insects, birds, fish and mammals. Bacillus thuringiensis-based biopesticides

  7. MORTALITY OF Spodoptera eridania (Cramer CATERPILLARS BY Bacillus thuringiensis (Berliner MORTALIDADE DE LAGARTAS DE Spodoptera eridania (Cramer PELA UTILIZAÇÃO DE Bacillus thuringiensis (Berliner

    Directory of Open Access Journals (Sweden)

    Carlos Brustolin

    2009-03-01

    Full Text Available

    This research evaluated the effects of two products based on Bacillus thuringiensis in the mortality rate of first and third instar caterpillars of Spodoptera eridania, in laboratory conditions, at 25±2°C, relative humidity 70±5%, and photoperiod of 12 hours. The treatments were B. thuringiensis kurstaki (Dipel SC, at 500 mL.ha-1

  8. Susceptibility of Aedes aegypti larvae to temephos and Bacillus thuringiensis var israelensis in integrated control Susceptibilidade de larvas de Aedes aegypti ao tratamento integrado com temephos e Bacillus thuringiensis var israelensis

    Directory of Open Access Journals (Sweden)

    Carlos Fernando S. de Andrande

    1991-06-01

    Full Text Available The susceptibility of field collected Aedes aegypti larvae was evaluated in terms of median lethal time (LT50 and final mortality, when treated with temephos, Bacillus thuringiensis var israelensis as well as mixtures of these two agents. Third instar larvae were shown to be more susceptible than early and late fourth instar ones to the entomopathogen. Survival of some individuals when exposed to temephos suggest possible resistance. Temporal synergism in early fourth instar larvae was detected when they were exposed to mixtures of Bti-temephos. The possibility of this integrated treatment is commented on.A susceptibilidade de larvas de Aedes aegypti coletadas no campo foi avaliada em termos do tempo letal mediano (TL50 e da mortalidade final, quando tratadas com temephos, Bacillus thuringiensis var israelensis ou misturas desses dois agentes. As larvas de terceiro estádio mostraram-se mais suceptíveis ao patógeno do que aquelas no início ou no fim do quarto estádio. A sobrevivência de alguns indivíduos aos tratamentos com temephos permite sugerir a possibilidade de resistência. Foi detectada a existência de sinergismo temporal, quando larvas no início do quarto estádio foram tratadas com as misturas do Bti com o temephos. A possibilidade do tratamento integrado é comentada.

  9. Cloning and Characterization of a Unique Cytotoxic Protein Parasporin-5 Produced by Bacillus thuringiensis A1100 Strain

    Directory of Open Access Journals (Sweden)

    Keisuke Ekino

    2014-06-01

    Full Text Available Parasporin is the cytocidal protein present in the parasporal inclusion of the non-insecticidal Bacillus thuringiensis strains, which has no hemolytic activity but has cytocidal activities, preferentially killing cancer cells. In this study, we characterized a cytocidal protein that belongs to this category, which was designated parasporin-5 (PS5. PS5 was purified from B. thuringiensis serovar tohokuensis strain A1100 based on its cytocidal activity against human leukemic T cells (MOLT-4. The 50% effective concentration (EC50 of PS5 to MOLT-4 cells was approximately 0.075 μg/mL. PS5 was expressed as a 33.8-kDa inactive precursor protein and exhibited cytocidal activity only when degraded by protease at the C-terminal into smaller molecules of 29.8 kDa. Although PS5 showed no significant homology with other known parasporins, a Position Specific Iterative-Basic Local Alignment Search Tool (PSI-BLAST search revealed that the protein showed slight homology to, not only some B. thuringiensis Cry toxins, but also to aerolysin-type β-pore-forming toxins (β-PFTs. The recombinant PS5 protein could be obtained as an active protein only when it was expressed in a precursor followed by processing with proteinase K. The cytotoxic activities of the protein against various mammalian cell lines were evaluated. PS5 showed strong cytocidal activity to seven of 18 mammalian cell lines tested, and low to no cytotoxicity to the others.

  10. Crystalline protein profiling and cry gene detection in Bacillus thuringiensis strains isolated during epizootics in Cydia pomonella L.

    Directory of Open Access Journals (Sweden)

    Konecka Edyta

    2014-12-01

    Full Text Available The composition of Bacillus thuringiensis crystalline inclusions was characterized in 18 strains: 12 isolates were obtained from the intestinal tract of Cydia pomonella larvae during epizootics, 2 isolates were cultured from Leucoma salicis larvae taken from their natural populations, and 4 reference strains. The number and molecular mass of B. thuringiensis crystalline proteins (Cry and Cyt was estimated by the sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE. The crystals contained 1-8 proteins with molecular masses of 36-155 kDa. The toxin profiles differed both quantatively and qualitatively. The B. thuringiensis MPU B9 isolate had the highest number and diversity of Cry toxins. The analysis of crystal composition by SDS-PAGE was insufficient to detect groups and subgroups of Cry proteins. We identified 20 groups and 3 subgroups of Cry and Cyt crystalline toxins. Only one epizootic strain harboured cry25. In single reference strains, the cry1H, cry10 and cry25 genes were found. We did not find any correlation between the occurrence of cry genes and electrophoretic protein profiles of crystalline toxins.

  11. Poly-β-hydroxybutyrate Metabolism Is Unrelated to the Sporulation and Parasporal Crystal Protein Formation in Bacillus thuringiensis.

    Science.gov (United States)

    Wang, Xun; Li, Zhou; Li, Xin; Qian, Hongliang; Cai, Xia; Li, Xinfeng; He, Jin

    2016-01-01

    Poly-3-hydroxybutyrate (PHB) is a natural polymer synthesized by many bacteria as a carbon-energy storage material. It was accumulated maximally prior to the spore formation but was degraded during the process of sporulation in Bacillus thuringiensis. Intriguingly, B. thuringiensis also accumulates large amounts of insecticidal crystal proteins (ICPs) during sporulation, which requires considerable input of carbon and energy sources. How PHB accumulation affects sporulation and ICP formation remains unclear to date. Intuitively, one would imagine that accumulated PHB provides the energy required for ICP formation. Yet our current data indicate that this is not the case. First, growth curves of the deletion mutants of phaC (encoding the PHB synthase) and phaZ (encoding the PHB depolymerase) were found to be similar to the parent strain BMB171; no difference in growth rate could be observed. In addition we further constructed the cry1Ac10 ICP gene overexpression strains of BMB171 (BMB171-cry), as well as its phaC and phaZ deletion mutants ΔphaC-cry and ΔphaZ-cry to compare their spore and ICP production rates. Again, not much change of ICP production was observed among these strains either. In fact, PHB was still degraded in most ΔphaZ-cry cells as observed by transmission electron microscopy. Together these results indicated that there is no direct association between the PHB accumulation and the sporulation and ICP formation in B. thuringiensis. Some other enzymes for PHB degradation or other energy source may be responsible for the sporulation and/or ICP formation in B. thuringiensis. PMID:27379025

  12. Poly-β-hydroxybutyrate Metabolism Is Unrelated to the Sporulation and Parasporal Crystal Protein Formation in Bacillus thuringiensis

    Science.gov (United States)

    Wang, Xun; Li, Zhou; Li, Xin; Qian, Hongliang; Cai, Xia; Li, Xinfeng; He, Jin

    2016-01-01

    Poly-3-hydroxybutyrate (PHB) is a natural polymer synthesized by many bacteria as a carbon-energy storage material. It was accumulated maximally prior to the spore formation but was degraded during the process of sporulation in Bacillus thuringiensis. Intriguingly, B. thuringiensis also accumulates large amounts of insecticidal crystal proteins (ICPs) during sporulation, which requires considerable input of carbon and energy sources. How PHB accumulation affects sporulation and ICP formation remains unclear to date. Intuitively, one would imagine that accumulated PHB provides the energy required for ICP formation. Yet our current data indicate that this is not the case. First, growth curves of the deletion mutants of phaC (encoding the PHB synthase) and phaZ (encoding the PHB depolymerase) were found to be similar to the parent strain BMB171; no difference in growth rate could be observed. In addition we further constructed the cry1Ac10 ICP gene overexpression strains of BMB171 (BMB171-cry), as well as its phaC and phaZ deletion mutants ΔphaC-cry and ΔphaZ-cry to compare their spore and ICP production rates. Again, not much change of ICP production was observed among these strains either. In fact, PHB was still degraded in most ΔphaZ-cry cells as observed by transmission electron microscopy. Together these results indicated that there is no direct association between the PHB accumulation and the sporulation and ICP formation in B. thuringiensis. Some other enzymes for PHB degradation or other energy source may be responsible for the sporulation and/or ICP formation in B. thuringiensis. PMID:27379025

  13. The mechanism of uranium transformation from U(VI) into nano-uramphite by two indigenous Bacillus thuringiensis strains

    International Nuclear Information System (INIS)

    Highlights: • Indigenous B. thuringiensis exhibited highly accumulation ability to U(VI) in the absence of additional nutrients. • The amorphous uranium compound would transformed into crystalline nano-uramphite by B. thuringiensis. • The chemical nature of formed U-species were monitored. • The cell-free extracts of B. thuringiensis had better uranium-immobilization ability than its cell debris. • Provided the understanding of the uranium transformation mechanism. - Abstract: The mechanism of uranium transformation from U(VI) into nano-uramphite by two indigenous Bacillus thuringiensis strains was investigated in the present work. Our data showed that the bacteria isolated from uranium mine possessed highly accumulation ability to U(VI), and the maximum accumulation capacity was around 400 mg U/g biomass (dry weight). X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) analyzes indicated that the U(VI) was adsorbed on the bacterial surface firstly through coordinating with phosphate, −CH2 and amide groups, and then needle-like amorphous uranium compounds were formed. With the extension of time, the extracellular crystalline substances were disappeared, but some particles were appeared in the intracellular region, and these particles were characterized as tetragonal-uramphite. Moreover, the disrupted experiment indicated that the cell-free extracts had better uranium-immobilization ability than cell debris. Our findings provided the understanding of the uranium transformation process from amorphous uranium to crystalline uramphite, which would be useful in the regulation of uranium immobilization process

  14. Isolation and Characterization of Gut Bacterial Proteases Involved in Inducing Pathogenicity of Bacillus thuringiensis Toxin in Cotton Bollworm, Helicoverpa armigera

    Science.gov (United States)

    Regode, Visweshwar; Kuruba, Sreeramulu; Mohammad, Akbar S.; Sharma, Hari C.

    2016-01-01

    Bacillus thuringiensis toxin proteins are deployed in transgenic plants for pest management. The present studies were aimed at characterization of gut bacterial proteases involved in activation of inactive Cry1Ac protoxin (pro-Cry1Ac) to active toxin in Helicoverpa armigera. Bacterial strains were isolated from H. armigera midgut and screened for their proteolytic activation toward pro-Cry1Ac. Among 12 gut bacterial isolates seven isolates showed proteolytic activity, and proteases from three isolates (IVS1, IVS2, and IVS3) were found to be involved in the proteolytic conversion of pro-Cry1Ac into active toxin. The proteases from IVS1, IVS2, and IVS3 isolates were purified to 11.90-, 15.50-, and 17.20-fold, respectively. The optimum pH and temperature for gut bacterial protease activity was 8.0 and 40°C. Maximum inhibition of total proteolytic activity was exerted by phenylmethane sulfonyl fluoride followed by EDTA. Fluorescence zymography revealed that proteases from IVS1, IVS2, and IVS3 were chymotrypsin-like and showing protease band at ~15, 65, and 15 kDa, respectively. Active Cry1Ac formed from processing pro-Cry1Ac by gut bacterial proteases exhibited toxicity toward H. armigera. The gut bacterial isolates IVS1, IVS2, and IVS3 showed homology with B. thuringiensis (CP003763.1), Vibrio fischeri (CP000020.2), and Escherichia coli (CP011342.1), respectively. Proteases produced by midgut bacteria are involved in proteolytic processing of B. thuringiensis protoxin and play a major role in inducing pathogenicity of B. thuringiensis toxins in H. armigera. PMID:27766093

  15. Poly-β-hydroxybutyrate Metabolism Is Unrelated to the Sporulation and Parasporal Crystal Protein Formation in Bacillus thuringiensis.

    Science.gov (United States)

    Wang, Xun; Li, Zhou; Li, Xin; Qian, Hongliang; Cai, Xia; Li, Xinfeng; He, Jin

    2016-01-01

    Poly-3-hydroxybutyrate (PHB) is a natural polymer synthesized by many bacteria as a carbon-energy storage material. It was accumulated maximally prior to the spore formation but was degraded during the process of sporulation in Bacillus thuringiensis. Intriguingly, B. thuringiensis also accumulates large amounts of insecticidal crystal proteins (ICPs) during sporulation, which requires considerable input of carbon and energy sources. How PHB accumulation affects sporulation and ICP formation remains unclear to date. Intuitively, one would imagine that accumulated PHB provides the energy required for ICP formation. Yet our current data indicate that this is not the case. First, growth curves of the deletion mutants of phaC (encoding the PHB synthase) and phaZ (encoding the PHB depolymerase) were found to be similar to the parent strain BMB171; no difference in growth rate could be observed. In addition we further constructed the cry1Ac10 ICP gene overexpression strains of BMB171 (BMB171-cry), as well as its phaC and phaZ deletion mutants ΔphaC-cry and ΔphaZ-cry to compare their spore and ICP production rates. Again, not much change of ICP production was observed among these strains either. In fact, PHB was still degraded in most ΔphaZ-cry cells as observed by transmission electron microscopy. Together these results indicated that there is no direct association between the PHB accumulation and the sporulation and ICP formation in B. thuringiensis. Some other enzymes for PHB degradation or other energy source may be responsible for the sporulation and/or ICP formation in B. thuringiensis.

  16. The mechanism of uranium transformation from U(VI) into nano-uramphite by two indigenous Bacillus thuringiensis strains

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Xiaohong; Chen, Zhi [Key Lab of Biopesticide and Chemical Biology, Fujian Agriculture and Forestry University, Ministry of Education & Fujian–Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian 350002 (China); Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Chen, Fanbing [Key Lab of Biopesticide and Chemical Biology, Fujian Agriculture and Forestry University, Ministry of Education & Fujian–Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian 350002 (China); Cheng, Yangjian [Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Lin, Zhang, E-mail: zlin@fjirsm.ac.cn [Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); School of Environment and Energy, South China University of Technology, Guangzhou 510006 (China); Guan, Xiong, E-mail: guanxfafu@126.com [Key Lab of Biopesticide and Chemical Biology, Fujian Agriculture and Forestry University, Ministry of Education & Fujian–Taiwan Joint Center for Ecological Control of Crop Pests, Fuzhou, Fujian 350002 (China)

    2015-10-30

    Highlights: • Indigenous B. thuringiensis exhibited highly accumulation ability to U(VI) in the absence of additional nutrients. • The amorphous uranium compound would transformed into crystalline nano-uramphite by B. thuringiensis. • The chemical nature of formed U-species were monitored. • The cell-free extracts of B. thuringiensis had better uranium-immobilization ability than its cell debris. • Provided the understanding of the uranium transformation mechanism. - Abstract: The mechanism of uranium transformation from U(VI) into nano-uramphite by two indigenous Bacillus thuringiensis strains was investigated in the present work. Our data showed that the bacteria isolated from uranium mine possessed highly accumulation ability to U(VI), and the maximum accumulation capacity was around 400 mg U/g biomass (dry weight). X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) analyzes indicated that the U(VI) was adsorbed on the bacterial surface firstly through coordinating with phosphate, −CH{sub 2} and amide groups, and then needle-like amorphous uranium compounds were formed. With the extension of time, the extracellular crystalline substances were disappeared, but some particles were appeared in the intracellular region, and these particles were characterized as tetragonal-uramphite. Moreover, the disrupted experiment indicated that the cell-free extracts had better uranium-immobilization ability than cell debris. Our findings provided the understanding of the uranium transformation process from amorphous uranium to crystalline uramphite, which would be useful in the regulation of uranium immobilization process.

  17. Microcalorimetric Investigation of Influence of Fungicide SYP-L190 on Growth Metabolism of Tetrahymena thermophila and Bacillus thuringiensis

    Institute of Scientific and Technical Information of China (English)

    LI Hui-Rong; KU Zong-Jun; QIN Cai-Qin; ZHANG Zhong-Hai; LIU Yi

    2007-01-01

    Flumorph (SYP-L190) is a new systemic fungicide with good protective,curative and antisporulant activities but no phytotoxicity to certain plants.Its performance on the environmental ecosystem is unknown.Tetrahymena thermophila and Bacillus thuringiensis are two of biological indicators for the aquatic and soil environmental ecosystem respectively.Microcalorimetric technique based on the heat output was applied to evaluate the influence of fungicide flumorph (SYP-L190) on the two microorganisms.The thermogenic curves and corresponding thermodynamic and thermokinetic parameters were obtained.SYP-L 190 at a concentration of 50-100 μg·mL-1 had 5%-10% inhibitory ratios aganist Tetrahymena thermophila and was used as a protection reagent,while at a concentration of 100-200 μg·mL-1 SYP-L190 had 10%-20% inhibitory ratios and was used as a therapy reagent.The metabolic thermogenic curves of Bacillus thuringiensis contained bacterial growth phase and sporulation phase.The SYP-L190 at a concentration of 0-200 μg·mL-1 had no influence on bacterial growth phase,but led to a little lag of the sporulation phase with a constant heat output.Hormesis was obviously observed in present study.

  18. Quorum Sensing in Bacillus thuringiensis Is Required for Completion of a Full Infectious Cycle in the Insect

    Directory of Open Access Journals (Sweden)

    Leyla Slamti

    2014-07-01

    Full Text Available Bacterial cell-cell communication or quorum sensing (QS is a biological process commonly described as allowing bacteria belonging to a same pherotype to coordinate gene expression to cell density. In Gram-positive bacteria, cell-cell communication mainly relies on cytoplasmic sensors regulated by secreted and re-imported signaling peptides. The Bacillus quorum sensors Rap, NprR, and PlcR were previously identified as the first members of a new protein family called RNPP. Except for the Rap proteins, these RNPP regulators are transcription factors that directly regulate gene expression. QS regulates important biological functions in bacteria of the Bacillus cereus group. PlcR was first characterized as the main regulator of virulence in B. thuringiensis and B. cereus. More recently, the PlcR-like regulator PlcRa was characterized for its role in cysteine metabolism and in resistance to oxidative stress. The NprR regulator controls the necrotrophic properties allowing the bacteria to survive in the infected host. The Rap proteins negatively affect sporulation via their interaction with a phosphorelay protein involved in the activation of Spo0A, the master regulator of this differentiation pathway. In this review we aim at providing a complete picture of the QS systems that are sequentially activated during the lifecycle of B. cereus and B. thuringiensis in an insect model of infection.

  19. Genome Sequence of the Mosquitocidal Bacillus thuringiensis Strain BR58, a Biopesticide Product Effective against the Coffee Berry Borer (Hypothenemus hampei)

    Science.gov (United States)

    Zorzetti, Janaina; Ricietto, Ana P. S.; da Silva, Carlos R. M.; Wolf, Ivan R.; Neves, Pedro M. O. J.; Meneguim, Ana M.; Vilas-Boas, Laurival A.

    2015-01-01

    Bacillus thuringiensis is an important microbial control agent against insect pests. The draft genome sequence of the Brazilian strain BR58 described here contains the insecticidal genes cry4A, cry4B, cry10A, cry11A, cry60A, cry60B, and cyt1A, which show toxicity to both Aedes aegypti and Hypothenemus hampei larvae. PMID:26659669

  20. Bacillus thuringiensis toxin resistance mechanisms among Lepidoptera: progress on genomic approaches to uncover causal mutations in the European corn borer, Ostrinia nubilalis

    Science.gov (United States)

    Transgenic plants that expressed Bacillus thuringiensis (Bt) crystalline (Cry) protein toxins can suffer feeding damage from a small number of lepidopteran insect species under field conditions, which has heightened concerns about the durability of pest control tactics. Genomics research has provid...