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Wang Y, Wang M, Zhang Y, Chen F, Sun M, Li S, Zhang J, Zhang F. Resistance to both aphids and nematodes in tobacco plants expressing a Bacillus thuringiensis crystal protein. PEST MANAGEMENT SCIENCE 2024; 80:3098-3106. [PMID: 38319036 DOI: 10.1002/ps.8013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 01/23/2024] [Accepted: 02/03/2024] [Indexed: 02/07/2024]
Abstract
BACKGROUND Bacillus thuringiensis (Bt) and its crystal toxin or δ-endotoxins (Cry) offer great potential for the efficient control of crop pests. A vast number of pests can potentially infect the same host plant, either simultaneously or sequentially. However, no effective Bt-Cry protein has been reported to control both aphids and plant parasitic nematodes due to its highly specific activity. RESULTS Our study indicated that the Cry5Ba2 protein was toxic to the green peach aphid Myzus persicae, which had a median lethal concentration (LC50) of 9.7 ng μL-1 and fiducial limits of 3.1-34.6 ng μL-1. Immunohistochemical localization of Cry5Ba2 revealed that it could bind to the apical tip of microvilli in midgut regions. Moreover, transgenic tobacco plants expressing Cry5Ba2 exhibited significant resistance to Myzus persicae, as evidenced by reduced insect survival and impaired fecundity, and also intoxicated the Meloidogyne incognita as indicated by a decrease in galls and progeny reproduction. CONCLUSION In sum, we identified a new aphicidal Bt toxin resource that could simultaneously control both aboveground and belowground pests, thus extending the application range of Bt-based strategy for crop protection. © 2024 Society of Chemical Industry.
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Affiliation(s)
- Yong Wang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Hubei Hongshan laboratory, Wuhan, China
| | - MengNan Wang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Hubei Hongshan laboratory, Wuhan, China
| | - Yali Zhang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Hubei Hongshan laboratory, Wuhan, China
| | - Feng Chen
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Ming Sun
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Shengchun Li
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Hubei Hongshan laboratory, Wuhan, China
| | - Jiang Zhang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Hubei Hongshan laboratory, Wuhan, China
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Fengjuan Zhang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Hubei Hongshan laboratory, Wuhan, China
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Díaz-Valerio S, Lev Hacohen A, Schöppe R, Liesegang H. IDOPS, a Profile HMM-Based Tool to Detect Pesticidal Sequences and Compare Their Genetic Context. Front Microbiol 2021; 12:664476. [PMID: 34276598 PMCID: PMC8279765 DOI: 10.3389/fmicb.2021.664476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 05/13/2021] [Indexed: 11/13/2022] Open
Abstract
Biopesticide-based crop protection is constantly challenged by insect resistance. Thus, expansion of available biopesticides is crucial for sustainable agriculture. Although Bacillus thuringiensis is the major agent for pesticide bioprotection, the number of bacteria species synthesizing proteins with biopesticidal potential is much higher. The Bacterial Pesticidal Protein Resource Center (BPPRC) offers a database of sequences for the control of insect pests, grouped in structural classes. Here we present IDOPS, a tool that detects novel biopesticidal sequences and analyzes them within their genetic environment. The backbone of the IDOPS detection unit is a curated collection of high-quality hidden Markov models that is in accordance with the BPPRC nomenclature. IDOPS was positively benchmarked with BtToxin_Digger and Cry_Processor. In addition, a scan of the UniProtKB database using the IDOPS models returned an abundance of new pesticidal protein candidates distributed across all of the structural groups. Gene expression depends on the genomic environment, therefore, IDOPS provides a comparative genomics module to investigate the genetic regions surrounding pesticidal genes. This feature enables the investigation of accessory elements and evolutionary traits relevant for optimal toxin expression and functional diversification. IDOPS contributes and expands our current arsenal of pesticidal proteins used for crop protection.
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Affiliation(s)
- Stefani Díaz-Valerio
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University of Göttingen, Göttingen, Germany
| | - Anat Lev Hacohen
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University of Göttingen, Göttingen, Germany
| | - Raphael Schöppe
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University of Göttingen, Göttingen, Germany
| | - Heiko Liesegang
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University of Göttingen, Göttingen, Germany
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3
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How Does Bacillus thuringiensis Crystallize Such a Large Diversity of Toxins? Toxins (Basel) 2021; 13:toxins13070443. [PMID: 34206796 PMCID: PMC8309854 DOI: 10.3390/toxins13070443] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 06/22/2021] [Accepted: 06/24/2021] [Indexed: 12/31/2022] Open
Abstract
Bacillus thuringiensis (Bt) is a natural crystal-making bacterium. Bt diversified into many subspecies that have evolved to produce crystals of hundreds of pesticidal proteins with radically different structures. Their crystalline form ensures stability and controlled release of these major virulence factors. They are responsible for the toxicity and host specificity of Bt, explaining its worldwide use as a biological insecticide. Most research has been devoted to understanding the mechanisms of toxicity of these toxins while the features driving their crystallization have long remained elusive, essentially due to technical limitations. The evolution of methods in structural biology, pushing back the limits in size of amenable protein crystals now allows access to be gained to structural information hidden within natural crystals of such toxins. In this review, we present the main parameters that have been identified as key drivers of toxin crystallization in Bt, notably in the light of recent discoveries driven by structural biology studies. Then, we develop how the future evolution of structural biology will hopefully unveil new mechanisms of Bt toxin crystallization, opening the door to their hijacking with the aim of developing a versatile in vivo crystallization platform of high academic and industrial interest.
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Ursino E, Albertini AM, Fiorentino G, Gabrieli P, Scoffone VC, Pellegrini A, Gasperi G, Di Cosimo A, Barbieri G. Bacillus subtilis as a host for mosquitocidal toxins production. Microb Biotechnol 2020; 13:1972-1982. [PMID: 32864888 PMCID: PMC7533320 DOI: 10.1111/1751-7915.13648] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 07/23/2020] [Indexed: 02/05/2023] Open
Abstract
Aedes albopictus transmits several arboviral infections. In the absence of vaccines, control of mosquito populations is the only strategy to prevent vector-borne diseases. As part of the search for novel, biological and environmentally friendly strategies for vector control, the isolation of new bacterial species with mosquitocidal activity represents a promising approach. However, new bacterial isolates may be difficult to grow and genetically manipulate. To overcome these limits, here we set up a system allowing the expression of mosquitocidal bacterial toxins in the well-known genetic background of Bacillus subtilis. As a proof of this concept, the ability of B. subtilis to express individual or combinations of toxins of Bacillus thuringiensis israelensis (Bti) was studied. Different expression systems in which toxin gene expression was driven by IPTG-inducible, auto-inducible or toxin gene-specific promoters were developed. The larvicidal activity of the resulting B. subtilis strains against second-instar Ae. albopictus larvae allowed studying the activity of individual toxins or the synergistic interaction among Cry and Cyt toxins. The expression systems here presented lay the foundation for a better improved system to be used in the future to characterize the larvicidal activity of toxin genes from new environmental isolates.
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Affiliation(s)
- Emanuela Ursino
- Department of Biology and BiotechnologyUniversità degli Studi di PaviaPaviaItaly
| | | | - Giulia Fiorentino
- Department of Biology and BiotechnologyUniversità degli Studi di PaviaPaviaItaly
| | - Paolo Gabrieli
- Department of Biology and BiotechnologyUniversità degli Studi di PaviaPaviaItaly
- Present address:
Department of BiosciencesUniversità degli Studi di MilanoMilanoItaly
| | | | - Angelica Pellegrini
- Department of Biology and BiotechnologyUniversità degli Studi di PaviaPaviaItaly
| | - Giuliano Gasperi
- Department of Biology and BiotechnologyUniversità degli Studi di PaviaPaviaItaly
| | - Alessandro Di Cosimo
- Department of Biology and BiotechnologyUniversità degli Studi di PaviaPaviaItaly
| | - Giulia Barbieri
- Department of Biology and BiotechnologyUniversità degli Studi di PaviaPaviaItaly
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5
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Shi J, Peng D, Zhang F, Ruan L, Sun M. The Caenorhabditis elegans CUB-like-domain containing protein RBT-1 functions as a receptor for Bacillus thuringiensis Cry6Aa toxin. PLoS Pathog 2020; 16:e1008501. [PMID: 32369532 PMCID: PMC7228132 DOI: 10.1371/journal.ppat.1008501] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 05/15/2020] [Accepted: 03/26/2020] [Indexed: 12/16/2022] Open
Abstract
Plant-parasitic nematodes cause huge agricultural economic losses. Two major families of Bacillus thuringiensis crystal proteins, Cry5 and Cry6, show nematicidal activity. Previous work showed that binding to midgut receptors is a limiting step in Cry toxin mode of action. In the case of Cry5Ba, certain Caenorhabditis elegans glycolipids were identified as receptors of this toxin. However, the receptors for Cry6 toxin remain unknown. In this study, the C. elegans CUB-like-domain containing protein RBT-1, released by phosphatidylinositol-specific phospholipase C (PI-PLC), was identified as a Cry6Aa binding protein by affinity chromatography. RBT-1 contained a predicted glycosylphosphatidylinositol (GPI) anchor site and was shown to locate in lipid rafts in the surface of the midgut cells. Western ligand blot assays and ELISA binding analysis confirmed the binding interaction between Cry6Aa and RBT-1 showing high affinity and specificity. In addition, the mutation of rbt-1 gene decreased the susceptibility of C. elegans to Cry6Aa but not that of Cry5Ba. Furthermore, RBT-1 mediated the uptake of Cry6Aa into C. elegans gut cells, and was shown to be involved in triggering pore-formation activity, indicating that RBT-1 is required for the interaction of Cry6Aa with the nematode midgut cells. These results support that RBT-1 is a functional receptor for Cry6Aa. Bacillus thuringiensis (Bt) crystal proteins belong to pore-forming toxins (PFTs), which display virulence against target hosts by forming holes in the cell membrane. Cry6A is a nematicidal PFT, which exhibits unique protein structure and different mode of action than Cry5B, another nematicidal PFT. However, little is known about the mode of action of Cry6A. Although an intracellular nematicidal necrosis pathway of Cry6A was reported, its extracellular mode of action remains unknown. We here demonstrate that the CUB-like-domain containing protein RBT-1 acts as a functional receptor of Cry6A, which mediates the intestinal cell interaction and nematicidal activity of this toxin. RBT-1 represents a new class of crystal protein receptors. RBT-1 is dispensable for Cry5B toxicity against nematodes, consistent with that Cry6A and Cry5B have different nematicidal mechanisms. We also find that Cry6A kills nematodes by complex mechanism since rbt-1 mutation did not affect Cry6A-mediated necrosis signaling pathway. This work not only enhances the understanding of Bt crystal protein-nematode mechanism, but is also in favor for the application of Cry6A in nematode control.
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Affiliation(s)
- Jianwei Shi
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Donghai Peng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
- * E-mail: (DP); (MS)
| | - Fengjuan Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Lifang Ruan
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Ming Sun
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
- * E-mail: (DP); (MS)
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Domínguez-Arrizabalaga M, Villanueva M, Fernandez AB, Caballero P. A Strain of Bacillus thuringiensis Containing a Novel cry7Aa2 Gene that Is Toxic to Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). INSECTS 2019; 10:E259. [PMID: 31438609 PMCID: PMC6780604 DOI: 10.3390/insects10090259] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 07/26/2019] [Accepted: 08/16/2019] [Indexed: 12/03/2022]
Abstract
The genome of the Bacillus thuringiensis BM311.1 strain was sequenced and assembled in 359 contigs containing a total of 6,390,221 bp. The plasmidic ORF of a putative cry gene from this strain was identified as a potential novel Cry protein of 1138 amino acid residues with a 98% identity compared to Cry7Aa1 and a predicted molecular mass of 129.4 kDa. The primary structure of Cry7Aa2, which had eight conserved blocks and the classical structure of three domains, differed in 28 amino acid residues from that of Cry7Aa1. The cry7Aa2 gene was amplified by PCR and then expressed in the acrystalliferous strain BMB171. SDS-PAGE analysis confirmed the predicted molecular mass for the Cry7Aa2 protein and revealed that after in vitro trypsin incubation, the protein was degraded to a toxin of 62 kDa. However, when treated with digestive fluids from Leptinotarsa decemlineata larvae, one major proteinase-resistant fragment of slightly smaller size was produced. The spore and crystal mixture produced by the wild-type BM311.1 strain against L. decemlineata neonate larvae resulted in a LC50 value of 18.8 μg/mL, which was statistically similar to the estimated LC50 of 20.8 μg/mL for the recombinant BMB17-Cry7Aa2 strain. In addition, when this novel toxin was activated in vitro with commercial trypsin, the LC50 value was reduced 3.8-fold to LC50 = 4.9 μg/mL. The potential advantages of Cry7Aa2 protoxin compared to Cry7Aa1 protoxin when used in the control of insect pests are discussed.
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Affiliation(s)
- Mikel Domínguez-Arrizabalaga
- Institute for Multidisciplinary Research in Applied Biology-IMAB, Universidad Pública de Navarra, 31192 Mutilva, Navarra, Spain
| | - Maite Villanueva
- Institute for Multidisciplinary Research in Applied Biology-IMAB, Universidad Pública de Navarra, 31192 Mutilva, Navarra, Spain
- Bioinsectis SL, Avda Pamplona 123, Mutilva, Navarra, Spain
| | - Ana Beatriz Fernandez
- Institute for Multidisciplinary Research in Applied Biology-IMAB, Universidad Pública de Navarra, 31192 Mutilva, Navarra, Spain
| | - Primitivo Caballero
- Institute for Multidisciplinary Research in Applied Biology-IMAB, Universidad Pública de Navarra, 31192 Mutilva, Navarra, Spain.
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7
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Peng D, Luo X, Zhang N, Guo S, Zheng J, Chen L, Sun M. Small RNA-mediated Cry toxin silencing allows Bacillus thuringiensis to evade Caenorhabditis elegans avoidance behavioral defenses. Nucleic Acids Res 2019; 46:159-173. [PMID: 29069426 PMCID: PMC5758910 DOI: 10.1093/nar/gkx959] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 10/09/2017] [Indexed: 11/14/2022] Open
Abstract
Pathogen avoidance behavior protects animal hosts against microbial pathogens. Pathogens have evolved specific strategies during coevolution in response to such host defenses. However, these strategies for combatting host avoidance behavioral defenses remain poorly understood. Here, we used Caenorhabditis elegans and its bacterial pathogen Bacillus thuringiensis as a model and determined that small RNA (sRNA)-mediated Cry toxin silencing allowed pathogens to evade host avoidance behavioral defenses. The B. thuringiensis strain YBT-1518, which encodes three nematicidal cry genes, is highly toxic to C. elegans. However, the expression of the most potent toxin, Cry5Ba, was silenced in this strain when YBT-1518 was outside the host. Cry5Ba silencing was due to the sRNA BtsR1, which bound to the RBS site of the cry5Ba transcript via direct base pairing and inhibited Cry5Ba expression. Upon ingestion by C. elegans, Cry5Ba was expressed in vivo by strain YBT-1518. Cry5Ba silencing may allow B. thuringiensis to avoid nematode behavioral defenses and then express toxins once ingested to kill the host and gain a survival advantage. Our work describes a novel model of sRNA-mediated regulation to aid pathogens in combating host avoidance behavioral defenses.
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Affiliation(s)
- Donghai Peng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Xiaoxia Luo
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Ni Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Suxia Guo
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Jinshui Zheng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Ling Chen
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Ming Sun
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
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Adalat R, Saleem F, Bashir A, Ahmad M, Zulfiqar S, Shakoori AR. Multiple upstream start codons (AUG) in 5' untranslated region enhance translation efficiency of cry2Ac11 without helper protein. J Cell Biochem 2019; 120:2236-2250. [PMID: 30242865 DOI: 10.1002/jcb.27534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 08/01/2018] [Indexed: 01/24/2023]
Abstract
Cry2Ac11, a 65 kDa insecticidal protein produced by Bacillus thuringiensis, shows toxicity against dipteran and lepidopteran larvae. It is encoded by cry2Ac11 gene ( orf3), which is part of an operon comprising orf1, orf2, and orf3. Orf2, a helper protein, helps in proper folding and prevents aberrant aggregation of newly produced molecules. In this study, we have elucidated the effect of different mutations in translation initiation region (TIR), particularly the ribosomal binding site and the start codon (RBS-ATG) on cry2Ac11 gene expression without helper protein. All recombinant constructs were expressed in acrystalliferous B. thuringiensis subsp israelensis 4Q7 under the control of strong chimeric promoter cyt1AP/STAB. Of all the mutants, mut/RBS2, with two consecutive AUGs after the spacer region in TIR, exhibited 89- and 2246-fold higher transcript levels compared with 4Q7-operSalI/RBS ( cry2Ac11 operon) and 4Q7-w-RBS ( cry2Ac11 gene), respectively. The analysis of mut/RBS2 messenger RNA (mRNA) structure in the RBS-AUG region showed the presence of RBS in the single-stranded part of the moderately stable hairpin loop. The high expression efficiency of Cry2Ac11 mutant without helper protein is a cumulative and cooperative result of chimeric promoter cyt1AP/STAB-SD with the optimal context of RBS-AUG region provided by multiple AUGs and stabilizer sequence at 3' ends.
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Affiliation(s)
- Rooma Adalat
- Department of Biotechnology, Lahore College for Women University, Lahore, Pakistan
| | - Faiza Saleem
- Department of Biotechnology, Lahore College for Women University, Lahore, Pakistan
| | - Aftab Bashir
- Department of Biological Sciences, Forman Christian College, Lahore, Pakistan
| | - Munir Ahmad
- School of Biological Sciences, Quaid-i-Azam Campus, University of the Punjab, Lahore, Pakistan
| | - Soumble Zulfiqar
- School of Biological Sciences, Quaid-i-Azam Campus, University of the Punjab, Lahore, Pakistan
| | - Abdul Rauf Shakoori
- School of Biological Sciences, Quaid-i-Azam Campus, University of the Punjab, Lahore, Pakistan.,Department of Biochemistry, Faculty of Life Sciences, University of Central Punjab, Lahore, Pakistan
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Adalat R, Saleem F, Crickmore N, Naz S, Shakoori AR. In Vivo Crystallization of Three-Domain Cry Toxins. Toxins (Basel) 2017; 9:toxins9030080. [PMID: 28282927 PMCID: PMC5371835 DOI: 10.3390/toxins9030080] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 02/10/2017] [Accepted: 02/23/2017] [Indexed: 12/13/2022] Open
Abstract
Bacillus thuringiensis (Bt) is the most successful, environmentally-friendly, and intensively studied microbial insecticide. The major characteristic of Bt is the production of proteinaceous crystals containing toxins with specific activity against many pests including dipteran, lepidopteran, and coleopteran insects, as well as nematodes, protozoa, flukes, and mites. These crystals allow large quantities of the protein toxins to remain stable in the environment until ingested by a susceptible host. It has been previously established that 135 kDa Cry proteins have a crystallization domain at their C-terminal end. In the absence of this domain, Cry proteins often need helper proteins or other factors for crystallization. In this review, we classify the Cry proteins based on their requirements for crystallization.
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Affiliation(s)
- Rooma Adalat
- Department of Biotechnology, Lahore College for Women University, Lahore 54590, Pakistan.
| | - Faiza Saleem
- Department of Biotechnology, Lahore College for Women University, Lahore 54590, Pakistan.
| | - Neil Crickmore
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RH, UK.
| | - Shagufta Naz
- Department of Biotechnology, Lahore College for Women University, Lahore 54590, Pakistan.
| | - Abdul Rauf Shakoori
- School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590, Pakistan.
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10
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Peralta C, Palma L. Is the Insect World Overcoming the Efficacy of Bacillus thuringiensis? Toxins (Basel) 2017; 9:toxins9010039. [PMID: 28106770 PMCID: PMC5308271 DOI: 10.3390/toxins9010039] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 01/05/2017] [Accepted: 01/10/2017] [Indexed: 12/20/2022] Open
Abstract
The use of chemical pesticides revolutionized agriculture with the introduction of DDT (Dichlorodiphenyltrichloroethane) as the first modern chemical insecticide. However, the effectiveness of DDT and other synthetic pesticides, together with their low cost and ease of use, have led to the generation of undesirable side effects, such as pollution of water and food sources, harm to non-target organisms and the generation of insect resistance. The alternative comes from biological control agents, which have taken an expanding share in the pesticide market over the last decades mainly promoted by the necessity to move towards more sustainable agriculture. Among such biological control agents, the bacterium Bacillus thuringiensis (Bt) and its insecticidal toxins have been the most studied and commercially used biological control agents over the last 40 years. However, some insect pests have acquired field-evolved resistance to the most commonly used Bt-based pesticides, threatening their efficacy, which necessitates the immediate search for novel strains and toxins exhibiting different modes of action and specificities in order to perpetuate the insecticidal potential of this bacterium.
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Affiliation(s)
- Cecilia Peralta
- Centro de Investigaciones y Transferencia de Villa María (CITVM-CONICET), Universidad Nacional de Villa María, 5900 Villa María, Córdoba, Argentina.
- Consejo Nacional de Investigaciones Científicas y Técnicas, C1 425FQB Ciudad Autónoma de Buenos Aires, Argentina.
| | - Leopoldo Palma
- Centro de Investigaciones y Transferencia de Villa María (CITVM-CONICET), Universidad Nacional de Villa María, 5900 Villa María, Córdoba, Argentina.
- Consejo Nacional de Investigaciones Científicas y Técnicas, C1 425FQB Ciudad Autónoma de Buenos Aires, Argentina.
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11
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Elleuch J, Jaoua S, Ginibre C, Chandre F, Tounsi S, Zghal RZ. Toxin stability improvement and toxicity increase against dipteran and lepidopteran larvae of Bacillus thuringiensis crystal protein Cry2Aa. PEST MANAGEMENT SCIENCE 2016; 72:2240-2246. [PMID: 26910489 DOI: 10.1002/ps.4261] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 01/24/2016] [Accepted: 02/17/2016] [Indexed: 06/05/2023]
Abstract
BACKGROUND Bacillus thuringiensis δ-endotoxins are the most widely used biopesticides for controlling economically important crop pests and disease vectors. Improving their efficacy is of great benefit. Here, an improvement in Cry2Aa δ-endotoxin toxicity was attempted via a cry gene over expression system using P20 from B. thuringiensis israelensis. RESULTS The coexpression of Cry2Aa with P20 resulted in a seven fold increase in its production yield in B. thuringiensis. Generated crystals proved to be significantly more toxic (505.207 µg g-1 , 1.99 mg L-1 and 1.49 mg L-1 ) than the P20-lacking control (720.78 µg g-1 , 705.69 mg L-1 and 508.51 mg L-1 ) against Ephestia kuehniella, Aedes aegypti and Culex pipiens larvae respectively. In vitro, processing experiments revealed a P20-mediated protection of Cry2Aa against degradation under larval gut conditions. Thus, P20 could promote the maintenance of a tightly packaged conformation of Cry2Aa toxins in the larval midgut upon correct activation and binding to its membrane receptors. CONCLUSION Based on their resistance against excessive proteolysis, Cry2Aa δ-endotoxins, produced in the presence of P20, could be considered as a successful control agent for E. kuehniella and an effective alternative for mosquito control, implying its possible exploitation in pest management programmes. © 2016 Society of Chemical Industry.
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Affiliation(s)
- Jihen Elleuch
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Samir Jaoua
- Department of Biological and Environmental Sciences, College of Arts Sciences, Qatar University, Doha, Qatar
| | - Carole Ginibre
- Institut de Recherche pour le Développement (IRD), UMR MIVEGEC (UM1-UM2-CNRS 5290-IRD 224) Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle, Laboratoire de Lutte contre les Insectes Nuisibles (LIN), Montpellier, France
| | - Fabrice Chandre
- Institut de Recherche pour le Développement (IRD), UMR MIVEGEC (UM1-UM2-CNRS 5290-IRD 224) Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle, Laboratoire de Lutte contre les Insectes Nuisibles (LIN), Montpellier, France
| | - Slim Tounsi
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Raida Z Zghal
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia.
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12
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Elleuch J, Jaoua S, Tounsi S, Zghal RZ. Cry1Ac toxicity enhancement towards lepidopteran pest Ephestia kuehniella through its protection against excessive proteolysis. Toxicon 2016; 120:42-8. [DOI: 10.1016/j.toxicon.2016.07.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 07/15/2016] [Accepted: 07/20/2016] [Indexed: 10/21/2022]
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13
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Wang P, Zhu Y, Zhang Y, Zhang C, Xu J, Deng Y, Peng D, Ruan L, Sun M. Mob/oriT, a mobilizable site-specific recombination system for unmarked genetic manipulation in Bacillus thuringiensis and Bacillus cereus. Microb Cell Fact 2016; 15:108. [PMID: 27286821 PMCID: PMC4902927 DOI: 10.1186/s12934-016-0492-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/23/2016] [Indexed: 11/29/2022] Open
Abstract
Background Bacillus thuringiensis and Bacillus cereus are two important species in B. cereus group. The intensive study of these strains at the molecular level and construction of genetically modified bacteria requires the development of efficient genetic tools. To insert genes into or delete genes from bacterial chromosomes, marker-less manipulation methods were employed. Results We present a novel genetic manipulation method for B. thuringiensis and B. cereus strains that does not leave selection markers. Our approach takes advantage of the relaxase Mob02281 encoded by plasmid pBMB0228 from Bacillus thuringiensis. In addition to its mobilization function, this Mob protein can mediate recombination between oriT sites. The Mob02281 mobilization module was associated with a spectinomycin-resistance gene to form a Mob-Spc cassette, which was flanked by the core 24-bp oriT sequences from pBMB0228. A strain in which the wild-type chromosome was replaced with the modified copy containing the Mob-Spc cassette at the target locus was obtained via homologous recombination. Thus, the spectinomycin-resistance gene can be used to screen for Mob-Spc cassette integration mutants. Recombination between the two oriT sequences mediated by Mob02281, encoded by the Mob-Spc cassette, resulted in the excision of the Mob-Spc cassette, producing the desired chromosomal alteration without introducing unwanted selection markers. We used this system to generate an in-frame deletion of a target gene in B. thuringiensis as well as a gene located in an operon of B. cereus. Moreover, we demonstrated that this system can be used to introduce a single gene or an expression cassette of interest in B. thuringiensis. Conclusion The Mob/oriT recombination system provides an efficient method for unmarked genetic manipulation and for constructing genetically modified bacteria of B. thuringiensis and B. cereus. Our method extends the available genetic tools for B. thuringiensis and B. cereus strains. Electronic supplementary material The online version of this article (doi:10.1186/s12934-016-0492-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Pengxia Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
| | - Yiguang Zhu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
| | - Yuyang Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
| | - Chunyi Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
| | - Jianyi Xu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
| | - Yun Deng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
| | - Donghai Peng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
| | - Lifang Ruan
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
| | - Ming Sun
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China.
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14
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Li H, Hu P, Zhao X, Yu Z, Li L. Bacillus thuringiensis peptidoglycan hydrolase SleB171 involved in daughter cell separation during cell division. Acta Biochim Biophys Sin (Shanghai) 2016; 48:354-62. [PMID: 26922318 DOI: 10.1093/abbs/gmw004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 12/02/2015] [Indexed: 01/05/2023] Open
Abstract
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.
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Affiliation(s)
- Hua Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Penggao Hu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Xiuyun Zhao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Ziniu Yu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Lin Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
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15
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Elleuch J, Zghal RZ, Ben Fguira I, Lacroix MN, Suissi J, Chandre F, Tounsi S, Jaoua S. Effects of the P20 protein from Bacillus thuringiensis israelensis on insecticidal crystal protein Cry4Ba. Int J Biol Macromol 2015; 79:174-9. [DOI: 10.1016/j.ijbiomac.2015.04.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 04/08/2015] [Accepted: 04/09/2015] [Indexed: 11/25/2022]
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16
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Ni H, Zeng S, Qin X, Sun X, Zhang S, Zhao X, Yu Z, Li L. Molecular docking and site-directed mutagenesis of a Bacillus thuringiensis chitinase to improve chitinolytic, synergistic lepidopteran-larvicidal and nematicidal activities. Int J Biol Sci 2015; 11:304-15. [PMID: 25678849 PMCID: PMC4323370 DOI: 10.7150/ijbs.10632] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 12/24/2014] [Indexed: 11/05/2022] Open
Abstract
Bacterial chitinases are useful in the biocontrol of agriculturally important pests and fungal pathogens. However, the utility of naturally occurring bacterial chitinases is often limited by their low enzyme activity. In this study, we constructed mutants of a Bacillus thuringiensis chitinase with enhanced activity based on homology modeling, molecular docking, and the site-directed mutagenesis of target residues to modify spatial positions, steric hindrances, or hydrophilicity/hydrophobicity. We first identified a gene from B. thuringiensis YBT-9602 that encodes a chitinase (Chi9602) belonging to glycosyl hydrolase family 18 with conserved substrate-binding and substrate-catalytic motifs. We constructed a structural model of a truncated version of Chi9602 (Chi960235-459) containing the substrate-binding domain using the homologous 1ITX protein of Bacillus circulans as the template. We performed molecular docking analysis of Chi960235-459 using di-N-acetyl-D-glucosamine as the ligand. We then selected 10 residues of interest from the docking area for the site-directed mutagenesis experiments and expression in Escherichia coli. Assays of the chitinolytic activity of the purified chitinases revealed that the three mutants exhibited increased chitinolytic activity. The ChiW50A mutant exhibited a greater than 60 % increase in chitinolytic activity, with similar pH, temperature and metal ion requirements, compared to wild-type Chi9602. Furthermore, ChiW50A exhibited pest-controlling activity and antifungal activity. Remarkable synergistic effects of this mutant with B. thuringiensis spore-crystal preparations against Helicoverpa armigera and Caenorhabditis elegans larvae and obvious activity against several plant-pathogenic fungi were observed.
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Affiliation(s)
- Hong Ni
- 1. State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, Hubei, China ; 2. Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Faculty of Life Science, Hubei University, Wuhan 430062, Hubei, China
| | - Siquan Zeng
- 2. Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Faculty of Life Science, Hubei University, Wuhan 430062, Hubei, China
| | - Xu Qin
- 1. State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Xiaowen Sun
- 2. Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Faculty of Life Science, Hubei University, Wuhan 430062, Hubei, China
| | - Shan Zhang
- 2. Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Faculty of Life Science, Hubei University, Wuhan 430062, Hubei, China
| | - Xiuyun Zhao
- 1. State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Ziniu Yu
- 1. State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Lin Li
- 1. State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, Hubei, China
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17
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Palma L, Muñoz D, Berry C, Murillo J, Caballero P. Bacillus thuringiensis toxins: an overview of their biocidal activity. Toxins (Basel) 2014; 6:3296-325. [PMID: 25514092 PMCID: PMC4280536 DOI: 10.3390/toxins6123296] [Citation(s) in RCA: 349] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 11/07/2014] [Accepted: 12/03/2014] [Indexed: 11/16/2022] Open
Abstract
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.
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Affiliation(s)
- Leopoldo Palma
- Instituto de Agrobiotecnología, CSIC-UPNA-Gobierno de Navarra, Campus Arrosadía, Mutilva Baja, 31192 Navarra, Spain.
| | - Delia Muñoz
- Grupo de Protección Cultivos, Departamento de Producción Agraria, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Pública de Navarra, Pamplona, 31006 Navarra, Spain.
| | - Colin Berry
- Cardiff School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AT, UK.
| | - Jesús Murillo
- Grupo de Protección Cultivos, Departamento de Producción Agraria, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Pública de Navarra, Pamplona, 31006 Navarra, Spain.
| | - Primitivo Caballero
- Instituto de Agrobiotecnología, CSIC-UPNA-Gobierno de Navarra, Campus Arrosadía, Mutilva Baja, 31192 Navarra, Spain.
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18
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Deng C, Peng Q, Song F, Lereclus D. Regulation of cry gene expression in Bacillus thuringiensis. Toxins (Basel) 2014; 6:2194-209. [PMID: 25055802 PMCID: PMC4113751 DOI: 10.3390/toxins6072194] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 07/11/2014] [Accepted: 07/15/2014] [Indexed: 02/02/2023] Open
Abstract
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-transcriptional, metabolic and post-translational levels.
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Affiliation(s)
- Chao Deng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Qi Peng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Fuping Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
| | - Didier Lereclus
- INRA, UMR1319 Micalis, La Minière, Guyancourt 78280, France.
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19
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Palma L, Muñoz D, Berry C, Murillo J, Caballero P. Draft genome sequences of two Bacillus thuringiensis strains and characterization of a putative 41.9-kDa insecticidal toxin. Toxins (Basel) 2014; 6:1490-504. [PMID: 24784323 PMCID: PMC4052248 DOI: 10.3390/toxins6051490] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 04/21/2014] [Accepted: 04/24/2014] [Indexed: 11/16/2022] Open
Abstract
In this work, we report the genome sequencing of two Bacillus thuringiensis strains using Illumina next-generation sequencing technology (NGS). Strain Hu4-2, toxic to many lepidopteran pest species and to some mosquitoes, encoded genes for two insecticidal crystal (Cry) proteins, cry1Ia and cry9Ea, and a vegetative insecticidal protein (Vip) gene, vip3Ca2. Strain Leapi01 contained genes coding for seven Cry proteins (cry1Aa, cry1Ca, cry1Da, cry2Ab, cry9Ea and two cry1Ia gene variants) and a vip3 gene (vip3Aa10). A putative novel insecticidal protein gene 1143 bp long was found in both strains, whose sequences exhibited 100% nucleotide identity. The predicted protein showed 57 and 100% pairwise identity to protein sequence 72 from a patented Bt strain (US8318900) and to a putative 41.9-kDa insecticidal toxin from Bacillus cereus, respectively. The 41.9-kDa protein, containing a C-terminal 6× HisTag fusion, was expressed in Escherichia coli and tested for the first time against four lepidopteran species (Mamestra brassicae, Ostrinia nubilalis, Spodoptera frugiperda and S. littoralis) and the green-peach aphid Myzus persicae at doses as high as 4.8 µg/cm2 and 1.5 mg/mL, respectively. At these protein concentrations, the recombinant 41.9-kDa protein caused no mortality or symptoms of impaired growth against any of the insects tested, suggesting that these species are outside the protein’s target range or that the protein may not, in fact, be toxic. While the use of the polymerase chain reaction has allowed a significant increase in the number of Bt insecticidal genes characterized to date, novel NGS technologies promise a much faster, cheaper and efficient screening of Bt pesticidal proteins.
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Affiliation(s)
- Leopoldo Palma
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas-Universidad Pública de Navarra-Gobierno de Navarra, Campus Arrosadía, Mutilva Baja, Navarra 31192, Spain.
| | - Delia Muñoz
- Grupo de Protección Cultivos, Departamento de Producción Agraria, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Pública de Navarra, Pamplona, Navarra 31006, Spain.
| | - Colin Berry
- Cardiff School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AT, UK.
| | - Jesús Murillo
- Grupo de Protección Cultivos, Departamento de Producción Agraria, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Pública de Navarra, Pamplona, Navarra 31006, Spain.
| | - Primitivo Caballero
- Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas-Universidad Pública de Navarra-Gobierno de Navarra, Campus Arrosadía, Mutilva Baja, Navarra 31192, Spain.
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20
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Elleuch J, Zghal RZ, Jemaà M, Azzouz H, Tounsi S, Jaoua S. New Bacillus thuringiensis toxin combinations for biological control of lepidopteran larvae. Int J Biol Macromol 2014; 65:148-54. [DOI: 10.1016/j.ijbiomac.2014.01.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 01/10/2014] [Accepted: 01/13/2014] [Indexed: 10/25/2022]
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21
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Bacillus thuringiensis metalloproteinase Bmp1 functions as a nematicidal virulence factor. Appl Environ Microbiol 2012; 79:460-8. [PMID: 23124228 DOI: 10.1128/aem.02551-12] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
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.
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22
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Improvement of crystal solubility and increasing toxicity against Caenorhabditis elegans by asparagine substitution in block 3 of Bacillus thuringiensis crystal protein Cry5Ba. Appl Environ Microbiol 2012; 78:7197-204. [PMID: 22865071 DOI: 10.1128/aem.01048-12] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The crystal proteins from Bacillus thuringiensis are widely used for their specific toxicity against insects and nematodes. The highly conserved sequence blocks play an important role in Cry protein stability and flexibility, the basis of toxicity. The block 3 in Cry5Ba subfamily has a shorter sequence (only 12 residues) and more asparagine residues than that of others which harbor about 48 residues but only one asparagine. Based on the theoretical structure model of Cry5Ba, all three asparagines in block 3 are closely located in the interface of putative three domains, implying their probable importance in structure and function. In this study, all three asparagines in Cry5Ba2 block 3 were individually substituted with alanine by site-directed mutagenesis. The wild-type and mutant proteins were overexpressed and crystallized in acrystalliferous B. thuringiensis strain BMB171. However, the crystals formed in one of the mutants, designated N586A, abnormally disappeared and dissolved into the culture supernatant once the sporulation cells lysed, whereas the Cry5Ba crystal and the other mutant crystals were stable. The mutant N586A crystal, isolated from sporulation cells by the ultrasonic process, was found to be easily dissolved at wide range of pH value (5.0 to 10.0). Moreover, the toxicity assays showed that the mutant N586A exhibited nearly 9-fold-higher activity against nematodes and damaged the host's intestine more efficiently than the native Cry5Ba2. These data support the presumption that the amide residue Asn586 at the interface of domains might adversely affect the protein flexibility, solubility and resultant toxicity of Cry5Ba.
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23
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Li WP, Xia LQ, Ding XZ, Lv Y, Luo YS, Hu SB, Yin J, Yan F. Expression and characterization of a recombinant Cry1Ac crystal protein fused with an insect-specific neurotoxin ω-ACTX-Hv1a in Bacillus thuringiensis. Gene 2012; 498:323-7. [PMID: 22548233 DOI: 10.1016/j.gene.2012.01.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
In order to assess possible enhancement of biopesticide activity, the fusion gene of crystal protein gene cry1Ac with the insect-specific neurotoxin ω-ACTX-Hv1a gene and egfp was expressed in Bacillus thuringiensis acrystalliferous strain Cry-B under the control of the native gene expression system. The fusion recombinant Cry-B(1Ac-ACTX-EGFP) generally produced two or three small crystal-like inclusion bodies in each cell and the GFP signal could be clearly observed. A 166 kDa full-length fusion protein was identified by immunoblot analysis. Virulence of the fusion inclusions was at least fivefold higher toward larvae of Spodoptera exigua. These results demonstrated that a foreign protein could be expressed and accumulate as parasporal inclusions in B. thuringiensis by C-terminal fusion with the native endotoxin while retaining partial insecticidal activity.
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Affiliation(s)
- W P Li
- College of Life Science, Hunan Normal University, State Key Laboratory of Breeding Base of Microbial Molecular Biology, Changsha 410081, PR China
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24
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Buasri W, Panbangred W. Large crystal toxin formation in chromosomally engineered Bacillus thuringiensis subsp. aizawai due to σE accumulation. Appl Environ Microbiol 2012; 78:1682-91. [PMID: 22267677 PMCID: PMC3298149 DOI: 10.1128/aem.06505-11] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 01/02/2012] [Indexed: 11/20/2022] Open
Abstract
Seven distinct Bacillus thuringiensis subsp. aizawai integrants were constructed that carried the chitinase (chiBlA) gene from B. licheniformis under the control of the cry11Aa promoter and terminator with and without p19 and p20 genes. The toxicity of B. thuringiensis subsp. aizawai integrants against second-instar Spodoptera litura larvae was increased 1.8- to 4.6-fold compared to that of the wild-type strain (BTA1). Surprisingly, the enhanced toxicity in some strains of B. thuringiensis subsp. aizawai integrants (BtaP19CS, BtaP19CSter, and BtaCAT) correlated with an increase in toxin formation. To investigate the role of these genes in toxin production, the expression profiles of the toxin genes, cry1Aa and chiBlA, as well as their transcriptional regulators (sigK and sigE), were analyzed by quantitative real-time RT-PCR (qPCR) from BTA1, BtaP19CS, and BtaCAT. Expression levels of cry1Aa in these two integrants increased about 2- to 3-fold compared to those of BTA1. The expression of the transcription factor sigK also was prolonged in the integrants compared to that of the wild type; however, sigE expression was unchanged. Western blot analysis of σ(E) and σ(K) showed the prolonged accumulation of σ(E) in the integrants compared to that of BTA1, resulting in the increased synthesis of pro-σ(K) up to T(17) after the onset of sporulation in both BtaP19CS and BtaCAT compared to that of T(13) in BTA1. The results from qPCR indicate clearly that the cry1Aa promoter activity was influenced most strongly by σ(E), whereas cry11Aa depended mostly on σ(K). These results on large-crystal toxin formation with enhanced toxicity should provide useful information for the generation of strains with improved insecticidal activity.
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Affiliation(s)
- Wasin Buasri
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Excellence for Agricultural Biotechnology (AG-BIO/PERDO-CHE), Bangkok, Thailand
| | - Watanalai Panbangred
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
- Center of Excellence for Agricultural Biotechnology (AG-BIO/PERDO-CHE), Bangkok, Thailand
- Mahidol University and Osaka University Collaborative Research Center of Bioscience and Biotechnology (MU-OU: CRC), Faculty of Science, Mahidol University, Bangkok, Thailand
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Zhu Y, Ji F, Shang H, Zhu Q, Wang P, Xu C, Deng Y, Peng D, Ruan L, Sun M. Gene clusters located on two large plasmids determine spore crystal association (SCA) in Bacillus thuringiensis subsp. finitimus strain YBT-020. PLoS One 2011; 6:e27164. [PMID: 22076131 PMCID: PMC3208593 DOI: 10.1371/journal.pone.0027164] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 10/11/2011] [Indexed: 11/23/2022] Open
Abstract
Crystals in Bacillus thuringiensis are usually formed in the mother cell compartment during sporulation and are separated from the spores after mother cell lysis. In a few strains, crystals are produced inside the exosporium and are associated with the spores after sporulation. This special phenotype, named ‘spore crystal association’ (SCA), typically occurs in B. thuringiensis subsp. finitimus. Our aim was to identify genes determining the SCA phenotype in B. thuringiensis subsp. finitimus strain YBT-020. Plasmid conjugation experiments indicated that the SCA phenotype in this strain was tightly linked with two large plasmids (pBMB26 and pBMB28). A shuttle bacterial artificial chromosome (BAC) library of strain YBT-020 was constructed. Six fragments from BAC clones were screened from this library and discovered to cover the full length of pBMB26; four others were found to cover pBMB28. Using fragment complementation testing, two fragments, each of approximately 35 kb and located on pBMB26 and pBMB28, were observed to recover the SCA phenotype in an acrystalliferous mutant, B. thuringiensis strain BMB171. Furthermore, deletion analysis indicated that the crystal protein gene cry26Aa from pBMB26, along with five genes from pBMB28, were indispensable to the SCA phenotype. Gene disruption and frame-shift mutation analyses revealed that two of the five genes from pBMB28, which showed low similarity to crystal proteins, determined the location of crystals inside the exosporium. Gene disruption revealed that the three remaining genes, similar to spore germination genes, contributed to the stability of the SCA phenotype in strain YBT-020. Our results thus identified the genes determining the SCA phenotype in B. thuringiensis subsp. finitimus.
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Affiliation(s)
- Yiguang Zhu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Beijing, People's Republic of China
| | - Fang Ji
- School of Medicine, Jianghan University, Wuhan, People's Republic of China
| | - Hui Shang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Beijing, People's Republic of China
| | - Qian Zhu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Beijing, People's Republic of China
| | - Pengxia Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Beijing, People's Republic of China
| | - Chengchen Xu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Beijing, People's Republic of China
| | - Yun Deng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Beijing, People's Republic of China
| | - Donghai Peng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Beijing, People's Republic of China
| | - Lifang Ruan
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Beijing, People's Republic of China
| | - Ming Sun
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Beijing, People's Republic of China
- * E-mail:
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Shao X, Ni H, Lu T, Jiang M, Li H, Huang X, Li L. An improved system for the surface immobilisation of proteins on Bacillus thuringiensis vegetative cells and spores through a new spore cortex-lytic enzyme anchor. N Biotechnol 2011; 29:302-10. [PMID: 21968393 DOI: 10.1016/j.nbt.2011.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 09/20/2011] [Accepted: 09/20/2011] [Indexed: 11/28/2022]
Abstract
An improved surface-immobilisation system was engineered to target heterologous proteins onto vegetative cells and spores of Bacillus thuringiensis plasmid-free recipient strain BMB171. The sporulation-dependent spore cortex-lytic enzyme from B. thuringiensis YBT-1520, SceA, was expressed in vegetative cells and used as the surface anchoring motif. Green fluorescent protein (GFP) and a Bacillus endo-β-1,3-1,4-glucanase (BglS) were used as the fusion partners to test the binding efficiency and the functional activities of immobilised surface proteins. The surface localisation of the SceA-GFP fusion protein on vegetative cells and spores was confirmed by Western blot, immunofluorescence microscopy and flow cytometry. The GFP fluorescence intensity from both vegetative cells and spores was measured and compared to a previously characterised surface display system using a peptidoglycan hydrolase anchor (Mbg). Results demonstrated comparable efficiency of SceA- and Mbg-mediated immobilisation on vegetative cells but a more efficient immobilisation on spores using the SceA anchor, suggesting SceA has greater potential for spore-based applications. The SceA protein was then applied to target BglS onto vegetative cells and spores, and the surface immobilisation was verified by the substantial whole-cell enzymatic activity and enhanced whole-spore enzymatic activity compared to vegetative cells. A dually active B. thuringiensis vegetative cell and spore display system could prove especially valuable for the development of regenerable and heat-stable biocatalysts that function under adverse environmental conditions, for example, an effective feed additive for improved digestion and nutrient absorption by livestock.
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Affiliation(s)
- Xiaohu Shao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
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Peng D, Wang F, Li N, Zhang Z, Song R, Zhu Z, Ruan L, Sun M. Single cysteine substitution in Bacillus thuringiensis Cry7Ba1 improves the crystal solubility and produces toxicity to Plutella xylostella larvae. Environ Microbiol 2011; 13:2820-31. [DOI: 10.1111/j.1462-2920.2011.02557.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Jiang M, Shao X, Ni H, Yu Z, Li L. In vivo and in vitro surface display of heterologous proteins on Bacillus thuringiensis vegetative cells and spores. Process Biochem 2011. [DOI: 10.1016/j.procbio.2011.05.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Novel Bacillus thuringiensis δ-endotoxin active against Locusta migratoria manilensis. Appl Environ Microbiol 2011; 77:3227-33. [PMID: 21441319 DOI: 10.1128/aem.02462-10] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel δ-endotoxin gene was cloned from a Bacillus thuringiensis strain with activity against Locusta migratoria manilensis by PCR-based genome walking. The sequence of the cry gene was 3,432 bp long, and it encoded a Cry protein of 1,144 amino acid residues with a molecular mass of 129,196.5 kDa, which exhibited 62% homology with Cry7Ba1 in the amino acid sequence. The δ-endotoxin with five conserved sequence blocks in the amino-terminal region was designated Cry7Ca1 (GenBank accession no. EF486523). Protein structure analysis suggested that the activated toxin of Cry7Ca1 has three domains: 227 residues forming 7 α-helices (domain I); 213 residues forming three antiparallel β-sheets (domain II); and 134 residues forming a β-sandwich (domain III). The three domains, respectively, exhibited 47, 44, and 34% sequence identity with corresponding domains of known Cry toxins. SDS-PAGE and Western blot analysis showed that Cry7Ca1, encoded by the full-length open reading frame of the cry gene, the activated toxin 1, which included three domains but without the N-terminal 54 amino acid residues and the C terminus, and the activated toxin 2, which included three domains and N-terminal 54 amino acid residues but without the C terminus, could be expressed in Escherichia coli. Bioassay results indicated that the expressed proteins of Cry7Ca1 and the activated toxins (toxins 1 and 2) showed significant activity against 2nd instar locusts, and after 7 days of infection, the estimated 50% lethal concentrations (LC₅₀s) were 8.98 μg/ml for the expressed Cry7Ca1, 0.87 μg/ml for the activated toxin 1, and 4.43 μg/ml for the activated toxin 2. The δ-endotoxin also induced histopathological changes in midgut epithelial cells of adult L. migratoria manilensis.
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Baig DN, Bukhari DA, Shakoori AR. Cry genes profiling and the toxicity of isolates of Bacillus thuringiensis from soil samples against American bollworm, Helicoverpa armigera. J Appl Microbiol 2011; 109:1967-78. [PMID: 20738439 DOI: 10.1111/j.1365-2672.2010.04826.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIMS The aim of this study was to search for Bacillus thuringiensis (Bt) harbouring cry1A gene which could effectively control cotton pest, American bollworm, Helicoverpa armigera. METHODS AND RESULTS cry gene profiling of 50 Bt isolates showed the presence of cry1, cry2, cry3, cry4, cry7, cry8 and cry9 genes. None of the isolates harboured cry1 gene alone. It was always found in combination with cry3. There was no isolate positive for cry10 gene. Considering isolates with single cry genes, the frequency of cry4 was predominant (22%) followed cry2 (6%), cry3 (4%) and cry8 (2%). Isolates having two cry genes in combination had 14% incidence for cry2 + cry4, 12% for cry3 + cry4 and 10% for cry1 + cry3. The most dominant three gene linkage was cry1 + cry3 + cry4. Further profiling of cry1 gene showed that cry1K gene was abundantly present in all combinations such as cry1A, cry1D, cry1F and cry1I. However, cry1C existed independent of other subtypes. Finally, the Bt isolates with cry1A were analyzed for 16S rRNA gene, which showed two distinct groups of isolates on the basis of sequence homology. Bioassays of spore-crystal mixtures of SBS-Bt4, 8, 17, 21 and 26 harbouring cry1 against neonate larvae of H. armigera showed LC(50) 1288, 1202, 467·7, 524·8 and 108·5 μg ml(-1) . The SBS-Bt26 showed fourfold higher toxicity than the cry 1Ac harbouring positive control, HD-73. CONCLUSIONS None of the isolates harboured single cry 1 gene. They were always in combination of two or three genes. A Bt isolate (Bt26) had fourfold higher toxicity against H. armigera larvae compared with the positive control HD 73 and hence can be commercially exploited to control insect pest. SIGNIFICANCE AND IMPACT OF THE STUDY The inter relationship between the cry genes content and the toxicity may allow better understanding of Bt ecology.
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Affiliation(s)
- D N Baig
- School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore, Pakistan
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Development of an efficient expression system for Flavobacterium strains. Gene 2010; 458:1-10. [PMID: 20206244 DOI: 10.1016/j.gene.2010.02.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 02/10/2010] [Accepted: 02/14/2010] [Indexed: 11/20/2022]
Abstract
Strong promoters were isolated from Flavobacterium johnsoniae in a promoter-trap vector incorporating a gfp reporter system, and were used to express fluorescent protein markers (including GFP, YFP, mOrange and mStrawberry) and insecticidal protein genes in Flavobacterium strains. Sequence analysis of trapped DNA fragments showed conserved Bacteroidetes promoter motifs (TTG-N(19)-TAnnTTTG) located upstream of putative open reading frames. Plasmids harboring these genomic DNA fragments from F. johnsoniae promoted strong production of fluorescent proteins in Flavobacterium hibernum but not in Escherichiacoli. The most potent promoter (PompA) identified in this work was cloned upstream of genes encoding fluorescent proteins, and these were co-expressed in Flavobacterium strains. The p42 and p51 genes (binary toxins from Bacillus sphaericus) when translationally fused to the 3'-end of gfp showed strong expression. Flavobacteria expressing these genes exhibited toxicity against larvae of the mosquitoes Culex quinquefasciatus, Anopheles gambiae, and Ochlerotatus triseriatus. However, transformants with the transcriptional fusion construct between cry11A with p20 from Bacillus thuringiensis did not express Cry11A protein indicating that constitutive expression of cry11A may be problematic in Flavobacterium.
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Ji F, Zhu Y, Ju S, Zhang R, Yu Z, Sun M. Promoters of crystal protein genes do not control crystal formation inside exosporium ofBacillus thuringiensisssp.finitimusstrain YBT-020. FEMS Microbiol Lett 2009; 300:11-7. [DOI: 10.1111/j.1574-6968.2009.01743.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Liu X, Peng D, Luo Y, Ruan L, Yu Z, Sun M. Construction of an Escherichia coli to Bacillus thuringiensis shuttle vector for large DNA fragments. Appl Microbiol Biotechnol 2009; 82:765-72. [DOI: 10.1007/s00253-008-1854-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 12/30/2008] [Accepted: 12/31/2008] [Indexed: 11/24/2022]
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Guo S, Liu M, Peng D, Ji S, Wang P, Yu Z, Sun M. New strategy for isolating novel nematicidal crystal protein genes from Bacillus thuringiensis strain YBT-1518. Appl Environ Microbiol 2008; 74:6997-7001. [PMID: 18820056 PMCID: PMC2583473 DOI: 10.1128/aem.01346-08] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Accepted: 09/19/2008] [Indexed: 11/20/2022] Open
Abstract
We have developed a strategy for isolating cry genes from Bacillus thuringiensis. The key steps are the construction of a DNA library in an acrystalliferous B. thuringiensis host strain and screening for the formation of crystal through optical microscopy observation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses. By this method, three cry genes--cry55Aa1, cry6Aa2, and cry5Ba2--were cloned from rice-shaped crystals, producing B. thuringiensis YBT-1518, which consists of 54- and 45-kDa crystal proteins. cry55Aa1 encoded a 45-kDa protein, cry6Aa2 encoded a 54-kDa protein, and cry5Ba2 remained cryptic in strain YBT-1518, as shown by SDS-PAGE or microscopic observation. Proteins encoded by these three genes are all toxic to the root knot nematode Meloidogyne hapla. The two genes cry55Aa1 and cry6Aa2 were found to be located on a plasmid with a rather small size of 17.7 kb, designated pBMB0228.
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Affiliation(s)
- Suxia Guo
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, People's Republic of China
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Song R, Peng D, Yu Z, Sun M. Carboxy-terminal half of Cry1C can help vegetative insecticidal protein to form inclusion bodies in the mother cell of Bacillus thuringiensis. Appl Microbiol Biotechnol 2008; 80:647-54. [DOI: 10.1007/s00253-008-1613-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 07/07/2008] [Accepted: 07/09/2008] [Indexed: 11/28/2022]
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Chaoyin Y, Wei S, Sun M, Lin L, Faju C, Zhengquan H, Ziniu Y. Comparative study on effect of different promoters on expression of cry1Ac in Bacillus thuringiensis chromosome. J Appl Microbiol 2007; 103:454-61. [PMID: 17650206 DOI: 10.1111/j.1365-2672.2006.03269.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS The aim of this work was to investigate the effect of cry3A promoter on the expression of cry1Ac in Bacillus thuringiensis chromosome and stably enhance the production of different cry genes under the control of cry3A promoter. METHODS AND RESULTS The cry1Ac gene, which is specific to Lepidopteran larvae, was integrated into the chromosome of a B. thuringiensis plasmid-free and acrystalliferous strain BMB171, under the control of cry3A promoter and cry1Ac promoter, respectively. The expression of cry1Ac genes in the chromosome of host strain was investigated. The results from sodium dodecyl sulfate-polyacrymide gel electrophoresis, crystal observation and bioassay showed that either integrated with cry3A promoter (cry3Apro-cry1Ac) or with its native promoter (cry1Acpro-cry1Ac), cry1Ac gene could efficiently and stably express in the chromosome. The production of cry3Apro-cry1Ac gene was higher than that of cry1Acpro-cry1Ac gene. CONCLUSIONS The cry3A promoter enhanced the expression of cry1Ac gene efficiently either on the chromosome or on the plasmid in B. thuringiensis strain. SIGNIFICANCE AND IMPACT OF THE STUDY So far, the comparative studies on cry3A promoter and other cry promoters were carried on B. thuringiensis plasmids. This system offers an additional method for potentially improving the efficacy of B. thuringiensis insecticidal proteins efficiently, stably and safely.
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Affiliation(s)
- Y Chaoyin
- Biotechnology Research Center, China Three Gorges University, Yichang, Hubei, China.
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Khasdan V, Sapojnik M, Zaritsky A, Horowitz AR, Boussiba S, Rippa M, Manasherob R, Ben-Dov E. Larvicidal activities against agricultural pests of transgenic Escherichia coli expressing combinations of four genes from Bacillus thuringiensis. Arch Microbiol 2007; 188:643-53. [PMID: 17665174 DOI: 10.1007/s00203-007-0285-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2007] [Revised: 06/19/2007] [Accepted: 07/11/2007] [Indexed: 10/23/2022]
Abstract
The genes cry1Ac and cry1Ca from Bacillus thuringiensis subsps. kurstaki HD-73 and aizawai 4J4, respectively, encoding delta-endotoxins against lepidopteran larvae were isolated, cloned and expressed in Escherichia coli, with and without cyt1Aa (encoding cytolytic protein) and p20 (accessory protein) from subsp. israelensis. Nine combinations of the genes under control of an early T7, P A1 inducible promoter, produced the encoding proteins. Toxicities were examined against larvae of three major agricultural pests: Pectinophora gossypiella, Helicoverpa armigera and Spodoptera littoralis. The clones expressing cyt1Aa, with or without p20, were not toxic. The clone expressing cry1Ac (pBt-1A) was the most toxic to P. gossypiella (LC50 of 0.27 x 10(8) cells g(-1)). Clone pBt-1CA expressing cry1Ca and cry1Ac displayed the highest toxicity (LC50 of 0.12 x 10(8) cells ml(-1)) against S. littoralis. Clone pBt-1CARCy expressing all four genes (cry1Ca, cry1Ac, p20, cyt1Aa) in tandem exhibited the highest toxicity to H. armigera (LC50 of 0.16 x 10(8) cells ml(-1)). Cyt1Aa failed to raise the toxicity of these Cry toxins against P. gossypiella and S. littoralis but significantly enhanced toxicity against H. armigera. Two additional clones expressing either cry1Ac or cry1Ca under tandem promoters, P A1 and P psbA (constitutive), displayed significantly higher toxicities (7.5- to 140-fold) than their counterparts with P A1 alone, reducing the LC50 values to below 10(7) cells ml(-1).
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Affiliation(s)
- Vadim Khasdan
- Department of Life Sciences, Ben-Gurion University of the Negev, PO Box 653, Be'er-Sheva 84105, Israel
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Park HW, Bideshi DK, Federici BA. The 20-kDa protein of Bacillus thuringiensis subsp. israelensis enhances Bacillus sphaericus 2362 bin toxin synthesis. Curr Microbiol 2007; 55:119-24. [PMID: 17597341 DOI: 10.1007/s00284-006-0359-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Accepted: 01/01/2007] [Indexed: 11/26/2022]
Abstract
Improving the amount of protein endotoxins synthesized by Bacillus thuringiensis and B. sphaericus per unit of culture medium is important because higher yields typically correlate with higher insecticidal activity per unit weight of spore/toxin mixtures. Higher levels of synthesis can also result in larger crystals that could persist for longer periods in the environment. Improving endotoxin production in B. thuringiensis can be achieved by manipulating genetic elements that regulate protein synthesis at the transcriptional, translational, and even posttranslational levels. In the present study, we used a combination of genetic elements to improve yields of B. sphaericus 2362 binary toxin (Bin) in B. thuringiensis. Our results show that a 20-kDa chaperone-like protein, which occurs as the third open-reading frame in the cry11Aa operon, improves Bin yields when expression of the genes encoding this binary toxin is driven by the native bin promoter, cyt1A promoters, or a novel cyt1A-p/STAB-SD expression system, the latter of which yields maximal levels of Bin synthesis. The 20-kDa helper protein increased Bin toxin levels in B. thuringiensis by as much as 53% and concomitant toxicity by at least 90% when Bin was produced using the cyt1A promoters.
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Affiliation(s)
- Hyun-Woo Park
- John A. Mulrennan, Sr., Public Health Entomology Research and Education Center, College of Engineering Sciences, Technology, and Agriculture, Florida A & M University, 4000 Frankford Avenue, Panama City, FL 32405, USA.
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Liang F, Shouwen C, Ming S, Ziniu Y. Expression of Vitreoscilla hemoglobin in Bacillus thuringiensis improve the cell density and insecticidal crystal proteins yield. Appl Microbiol Biotechnol 2007; 74:390-7. [PMID: 17089120 DOI: 10.1007/s00253-006-0676-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Revised: 09/09/2006] [Accepted: 09/12/2006] [Indexed: 11/26/2022]
Abstract
The Vitreoscilla hemoglobin (VHb) gene (vgb) was integrated into the chromosome of Bacillus thuringiensis BMB171 using integrative vector pEG491. The production of VHb was confirmed by CO-difference spectra analysis. Fermentation experiments results showed that with the production of VHb, the critical oxygen concentration (COC) of the host strain was reduced from 18 to 12%. The maximum viable cell counts of the VHb+ strain in high, middle, and low aeration/agitation fermentations were 0.94-, 1.23-, and 1.59-fold of those of the VHb- strain, respectively. Under the same conditions, the yields of insecticidal crystal proteins (ICP) by VHb+ strain were 1.22-, 1.63-, and 3.13-fold of those of the VHb- strain. The production of VHb also accelerated the formation of ICP and spores. These results indicated that the production of VHb could improve the cell density and ICP yield of B. thuringiensis, especially under low aeration/agitation condition.
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Affiliation(s)
- Feng Liang
- State Key Laboratory of Agricultural Microbiology, National Engineering Research Center for Microbial Pesticides, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
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Nisnevitch M, Cohen S, Ben-Dov E, Zaritsky A, Sofer Y, Cahan R. Cyt2Ba of Bacillus thuringiensis israelensis: activation by putative endogenous protease. Biochem Biophys Res Commun 2006; 344:99-105. [PMID: 16630537 DOI: 10.1016/j.bbrc.2006.03.134] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Accepted: 03/20/2006] [Indexed: 10/24/2022]
Abstract
The gene cyt2Ba of Bacillus thuringiensis subsp. israelensis was cloned for expression, together with p20, in an acrystalliferous strain. The large hexagonal crystals formed were composed of Cyt2Ba, which facilitated its purification. Crystal solubilization in the presence of endogenous proteases (with spores and cell debris) enabled quick and simple procedure to obtain rather pure and active toxin species by cleavage between amino acid residues 34 and 35, most likely by a camelysin-like protease that was discovered in association with activated Cyt2Ba. The product of this cleavage displayed haemolytic activity comparable to that of exogenously activated Cyt2Ba. The sequence of this putative protease shares high homology with the cell envelope-bound metalloprotease (camelysin) of the closely related species Bacillus cereus.
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Affiliation(s)
- Marina Nisnevitch
- Department of Chemical Engineering and Biotechnology, College of Judea and Samaria, Ariel 44837, Israel
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Yue C, Sun M, Yu Z. Improved production of insecticidal proteins inBacillus thuringiensis strains carrying an additionalcry1C gene in its chromosome. Biotechnol Bioeng 2005; 92:1-7. [PMID: 16116654 DOI: 10.1002/bit.20396] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A cryIC gene, whose product is active against Spodoptera exigua, was introduced into wildtype Bacillus thuringiensis kurstaki strain YBT1520 using an integrative and thermosensitive vector, pBMB-FLCE, which was developed based on B. thuringiensis transposon Tn4430 harboring a tnpI-tnpA gene. With the mediation of TnpI-TnpA, the cry1C gene was integrated into the chromosome of the host strain. To prevent secondary integration, the integrative vector was eliminated by moving recombinant cultures to 46 degrees C for generations. Two integrative recombinant B. thuringiensis strains BMB1520-E and BMB1520-F were obtained. In recombinant BMB1520-F, the cry1C gene was expressed stably at a significant level and did not reduce the expression of endogenous crystal protein genes. Bioassay results indicated that BMB1520-E and BMB1520-F showed a higher level of activity against S. exigua third-instar larvae than did their parent strains, in addition to the high toxicity to Plutella xylostella third-instar later larvae.
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Affiliation(s)
- Chaoyin Yue
- Biotechnology Research Center, China Three Gorges University, Yichang, 443002 Hubei, People's Republic of China
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Yue C, Sun M, Yu Z. Broadening the insecticidal spectrum of Lepidoptera-specificBacillus thuringiensis strains by chromosomal integration ofcry3A. Biotechnol Bioeng 2005; 91:296-303. [PMID: 15984034 DOI: 10.1002/bit.20493] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A TnpI-TnpIA-mediated and thermosensitive recombination system was developed to construct genetically modified Bacillus thuringiensis strains encoding a crystal protein particularly active against Coleopteran species. Based on B. thuringiensis transposon Tn4430, an integrative vector, pBMB-R14E, was constructed, by which the cry3A delta-endotoxin gene highly toxic to Lepidoptera was delivered into a wildtype B. thuringiensis subsp. kurstaki strain YBT1520. The cry3A gene was integrated into the chromosome of the host strain. Then the integrative vector was eliminated by moving recombinant cultures to 46 degrees C. Two recombinant B. thuringiensis strains, BMB1520-S and BMB1520-T, were obtained. In recombinant strains, the cry3A gene was stably expressed in measurable amounts and did not reduce the expression of endogenous crystal protein genes. Bioassay results showed that BMB1520-S and BMB1520-T, in addition to the activity against lepidopteran Plutella xylostella third-instar larvae present in the parental strains, exhibited a high level of activity against coleopteran Rhyllodecta vulgatissima third-instar larvae, absent from the parental strains.
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Affiliation(s)
- Chaoyin Yue
- Biotechnology Research Center, China Three Gorges University, Yichang, 443002 Hubei, People's Republic of China
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Xiaoyan L, Yi L, Peng L, Songsheng Q, Ziniu Y. Microcalorimetric investigation on the growth model and the protein yield of Bacillus thuringiensis. ACTA ACUST UNITED AC 2004; 59:267-74. [PMID: 15165757 DOI: 10.1016/j.jbbm.2004.03.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2003] [Revised: 03/04/2004] [Accepted: 03/09/2004] [Indexed: 10/26/2022]
Abstract
A novel microcalorimetric technique based on the bacterial heat output was applied to evaluate the special growth model, the protein expression and the generation time of Bacillus thuringiensis for the first time. The thermogenic curves of the aerobic metabolism of B. thuringiensis strains YBT-833, YBT-1520 and YBT-833-2-1 were determined by using an LKB-2277 BioActivity Monitor. The analysis of the thermogenic curves indicated both the mutant strain and the wild-type strains followed the same linear growth model during sporulation. The metabolism heat output revealed heat output was correlated to the yield of the insecticidal crystal proteins (ICPs) very well, the more protein product, and the less heat output. Based on the data acquired, we proposed that this method could be a useful tool in monitoring the fermentation of B. thuringiensis.
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Affiliation(s)
- Lin Xiaoyan
- Key Laboratory of Agricultural Microbiology of Chinese Agriculture Ministry, Life Science and Technology College, Huazhong Agriculture University, Wuhan 430070, Hubei, PR China.
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Yang CY, Pang JC, Kao SS, Tsen HY. Enterotoxigenicity and cytotoxicity of Bacillus thuringiensis strains and development of a process for Cry1Ac production. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2003; 51:100-105. [PMID: 12502392 DOI: 10.1021/jf025863l] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Bacillus thuringiensis is indistinguishable from Bacillus cereus except for the production of insecticidal crystal proteins (ICPs). B. thuringiensis strains may show enterotoxin profiles and toxin levels similar to those of B. cereus strains isolated from food-poisoning cases. It is important for the food industry and farmers to consider that with the application of B. thuringiensis strains to crops, their spores may be introduced into the human food chain. In this study, 59 B. thuringiensis strains were assayed for their hemolysin BL (HBL) using a BCET-RPLA kit and their cytotoxicity to Chinese hamster ovary (CHO) cells. The enterotoxin titer was as high as that of B. cereus diarrheal-type strain ATCC 49064. In an attempt to obtain a food safety strain for bioinsecticide use, in this study, a 3.5-kb cry1Ac DNA fragment was amplified with PCR from the total DNA of B. thuringiensis subsp. kurstaki CCRC 11502 and cloned into the Bacillus expression vector pHY300PLK. The alpha-amylase promoter, amyE, was then introduced into the promoter region and, afterward, the recombinant plasmid pHYe1Ac35 was introduced into a non-enterotoxigenic and non-cytotoxic B. thuringiensis subsp. kurstaki Tt14 strain. The transformant, without any detectable enterotoxigenicity or cytotoxicity, produced Cry1Ac toxin properly, and its insecticidal activity against Trichoplusia ni larvae was found to be satisfactory.
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Affiliation(s)
- Chi-Yea Yang
- Department of Food Science, National Chung-Hsing University, Taichung, Taiwan
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