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Cui S, Shen K, Xiong S, Li X, Wang Y, Geng X, Lu Y. Low-Frequency Ultrasound Assisted in Improvement in Cell Development and Production of Parasporal Crystals from Bacillus thuringiensis HD1. INSECTS 2025; 16:507. [PMID: 40429220 DOI: 10.3390/insects16050507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2025] [Revised: 04/17/2025] [Accepted: 05/01/2025] [Indexed: 05/29/2025]
Abstract
Bacillus thuringiensis is widely utilized as a microbial insecticide due to its production of parasporal crystals during the spore-forming stage. However, lower fermentation efficiency coupled with elevated production costs limit its broad application. Low-frequency ultrasound (LFU) has been employed in the fermentation industry to enhance microbial growth and metabolism. In this study, the effect of LFU on the growth of B. thuringiensis HD1 and the yields of parasporal crystals was investigated. The maximum biomass accumulation of Bacillus thuringiensis and parasporal crystal production yield were achieved following low-frequency ultrasonic (LFU) treatment applied during the logarithmic growth phase (18 h of cultivation) under optimized parameters: a frequency of 40 kHz, a power output of 176 W, and an irradiation duration of 45 min. Under optimal conditions, LFU significantly increased the cell membrane permeability and secretory inositol, favoring cell growth and parasporal crystal production. FESEM/CLSM and TEM analyses visually displayed the changes in cell morphology. In addition, the germination rate of spores was increased after LFU treatment, which further confirmed the positive effect of LFU on the growth of B. thuringiensis. Compared to the control, parasporal crystals harvested under LFU exhibited significant modifications in their physicochemical characteristics; the particle size increased, the surface electronegativity intensified, and there was a morphological transition from spherical to cubic geometry. Importantly, the parasporal crystals exhibited strong insecticidal activity against S. zeamais adults, a typical stored-product insect pest, with an LC50 of 10.795 mg/g on day 14 and a Kt50 of 4.855 days at a concentration of 30 mg/g. These findings will provide new insights into the product development and application of B. thuringiensis in the future.
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Affiliation(s)
- Sufen Cui
- School of Grain Science and Technology, Jiangsu University of Science and Technology, Zhenjiang 212004, China
| | - Kaihui Shen
- School of Grain Science and Technology, Jiangsu University of Science and Technology, Zhenjiang 212004, China
| | - Shiqi Xiong
- School of Grain Science and Technology, Jiangsu University of Science and Technology, Zhenjiang 212004, China
| | - Xiao Li
- School of Grain Science and Technology, Jiangsu University of Science and Technology, Zhenjiang 212004, China
| | - Yue Wang
- School of Grain Science and Technology, Jiangsu University of Science and Technology, Zhenjiang 212004, China
| | - Xueqing Geng
- Department of Resources and Environment, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yujie Lu
- School of Grain Science and Technology, Jiangsu University of Science and Technology, Zhenjiang 212004, China
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2
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Mohanty P, Rajadurai G, Mohankumar S, Balakrishnan N, Raghu R, Balasubramani V, Sivakumar U. Interactions between insecticidal cry toxins and their receptors. Curr Genet 2025; 71:9. [PMID: 40156649 DOI: 10.1007/s00294-025-01312-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2024] [Revised: 03/15/2025] [Accepted: 03/20/2025] [Indexed: 04/01/2025]
Abstract
Bacillus thuringiensis is a prominent, eco-friendly entomopathogenic bacterium used as a plant-incorporated toxin in genetically modified crops and as a stomach poison for insects in the form of spore formulations. Upon entering the alkaline environment of the insect gut, the toxin undergoes proteolytic breakdown, converting the protoxin into its activated form. The activated toxin then binds to receptors, forming pores that disrupt the ionic balance within the cell, ultimately leading to the insect's death. Alongside the four major receptors (Cadherin, ABCC, APN, and ALP), several other notable receptors are present on the Brush Border Membrane Vesicle of insects. Binding to these receptors plays a crucial role, and any mutations in these receptors can result in improper binding, leading to the development of resistant insect strains. This review explores the major receptors of insecticidal Cry toxins, the intricate interactions between toxins and receptors, receptor mutations, and strategies to overcome the resistance.
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Affiliation(s)
- Pravukalyan Mohanty
- Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, 641003, India
| | - G Rajadurai
- Department of Plant Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, 641003, India
| | - S Mohankumar
- Department of Plant Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, 641003, India.
| | - N Balakrishnan
- Directorate of Research, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, 641003, India
| | - R Raghu
- Department of Plant Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, 641003, India
| | - V Balasubramani
- Controller of Examinations, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, 641003, India
| | - U Sivakumar
- Department of Microbiology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, 641003, India
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3
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Zhu C, Qi L, Yu Y, Zhang X, Ying J, Ye Y, Shen Z. Molecular Characterization and Assessment of Insect Resistance of Transgenic Maize ZDRF-8. PLANTS (BASEL, SWITZERLAND) 2025; 14:901. [PMID: 40265875 PMCID: PMC11946635 DOI: 10.3390/plants14060901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2025] [Revised: 03/10/2025] [Accepted: 03/11/2025] [Indexed: 04/24/2025]
Abstract
ZDRF-8 is a transgenic maize event created via Agrobacterium-mediated transformation for insect resistance and glyphosate tolerance by expressing Cry1Ab, Cry2Ab, and G10evo-epsps. A Southern blot analysis suggested that it is a single-copy T-DNA insertion event. The flanking genomic sequences of the T-DNA insertion suggested that its T-DNA was inserted at the terminal region of the long arm of chromosome 7 without interrupting any known or predicted genes. Event-specific PCRs based on the flanking sequence were able to detect this event specifically. Laboratory bioassays and field trials of multiple generations demonstrated that ZDRF-8 is highly active against major corn pests in China, including Asian corn borers (ACB, Ostrinia furnacalis), cotton bollworms (CBW, Helicoverpa armigera), and oriental armyworm (OAW, Mythimna separata), and meanwhile confers glyphosate tolerance up to two times the recommended dose. The expression of the transgenes and the efficacy of insect resistance and glyphosate tolerance were stable over more than 10 generations. ZDRF-8 has been granted with a safety certificate in China, and its commercial release is expected in the coming years.
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Affiliation(s)
- Chengqi Zhu
- Institute of Insect Sciences, Zhejiang University, Hangzhou 310058, China; (C.Z.); (L.Q.); (Y.Y.)
| | - Liang Qi
- Institute of Insect Sciences, Zhejiang University, Hangzhou 310058, China; (C.Z.); (L.Q.); (Y.Y.)
| | - Yinfang Yu
- Institute of Insect Sciences, Zhejiang University, Hangzhou 310058, China; (C.Z.); (L.Q.); (Y.Y.)
| | - Xianwen Zhang
- Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China;
| | - Jifeng Ying
- Hangzhou LeadGene Biotech Co., Ltd., Hangzhou 310018, China;
| | - Yuxuan Ye
- The Rural Development Academy, Zhejiang University, Hangzhou 310058, China;
| | - Zhicheng Shen
- Institute of Insect Sciences, Zhejiang University, Hangzhou 310058, China; (C.Z.); (L.Q.); (Y.Y.)
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Lanzaro MD, Padilha I, Ramos LFC, Mendez APG, Menezes A, Silva YM, Martins MR, Junqueira M, Nogueira FCS, AnoBom CD, Dias GM, Gomes FM, Oliveira DMP. Cry1Ac toxin binding in the velvetbean caterpillar Anticarsia gemmatalis: study of midgut aminopeptidases N. Front Physiol 2024; 15:1484489. [PMID: 39534858 PMCID: PMC11554492 DOI: 10.3389/fphys.2024.1484489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2024] [Accepted: 10/09/2024] [Indexed: 11/16/2024] Open
Abstract
The velvetbean caterpillar Anticarsia gemmatalis is one of the main soybean defoliators in Brazil. Currently, the main biopesticide used to control insect pests worldwide is the bacteria Bacillus thuringiensis (Bt), which produces entomopathogenic Crystal toxins (Cry) that act in the midgut of susceptible insects, leading them to death. The mode of action of Cry toxins in the midgut involves binding to specific receptors present on the brush border of epithelial cells such as aminopeptidase N (APN), alkaline phosphatase (ALP), cadherin, and others. Mutations in these receptors, among other factors, may be involved in the development of resistance; identification of functional Cry receptors in the midgut of A. gemmatalis is crucial to develop effective strategies to overcome this possible scenario. This study's goal is to characterize APNs of A. gemmatalis and identify a receptor for Cry1Ac in the midgut. The interaction of Bt spores with the midgut epithelium was observed in situ by immunohistochemistry and total aminopeptidase activity was estimated in brush border membrane vesicle (BBMV) samples, presenting higher activity in challenged individuals than in control ones. Ten APN sequences were found in a A. gemmatalis' transcriptome and subjected to different in silico analysis, such as phylogenetic tree, multiple sequence alignment and identification of signal peptide, activity domains and GPI-anchor signal. BBMV proteins from 5th instar larvae were submitted to a ligand blotting using activated Cry1Ac toxin and a commercial anti-Cry polyclonal antibody; corresponding bands of proteins that showed binding to Cry toxin were excised from the SDS-PAGE gel and subjected to mass spectrometry analysis, which resulted in the identification of seven of those APNs. Quantitative PCR was realized to compare expression levels between individuals subjected to sublethal infection with Bt spores and control ones, presenting up- and downregulations upon Bt infection. From these results, we can infer that aminopeptidases N in A. gemmatalis could be involved in the mode of action of Cry toxins in its larval stage.
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Affiliation(s)
- M. D. Lanzaro
- Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - I. Padilha
- Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - L. F. C. Ramos
- Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - A. P. G. Mendez
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - A. Menezes
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Y. M. Silva
- Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - M. R. Martins
- Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - M. Junqueira
- Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - F. C. S. Nogueira
- Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - C. D. AnoBom
- Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - G. M. Dias
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - F. M. Gomes
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Instituto Nacional de Entomologia Molecular, Rio de Janeiro, Brazil
| | - D. M. P. Oliveira
- Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Prashar A, Kinkar OU, Kumar A, Hadapad AB, Makde RD, Hire RS. Crystal structures of PirA and PirB toxins from Photorhabdus akhurstii subsp. akhurstii K-1. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2023; 162:104014. [PMID: 37778713 DOI: 10.1016/j.ibmb.2023.104014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 08/08/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
PirAB binary toxin from Photorhabdus is toxic to the larvae of dipteran and lepidopteran insect pests. However, the 3-D structures and their toxicity mechanism are not yet fully understood. Here we report the crystal structures of PirA and PirB proteins from Photorhabdus akhurstii subsp. akhurstii K-1 at 1.6 and 2.1 Å, respectively. PirA comprises of eight β-strands depicting jelly-roll topology while PirB folds into two distinct domains, an N-terminal domain (PirB-N) made up of seven α-helices and a C-terminal domain (PirB-C) consists of ten β-strands. Despite the low sequence identity, PirA adopts similar architecture as domain III and PirB shared similar architecture as domain I/II of the Cry δ-endotoxin of Bacillus thuringiensis, respectively. However, PirA shows significant structural variations as compared to domain III of lepidopteran and dipteran specific Cry toxins (Cry1Aa and Cry11Ba) suggesting its role in virulence among range of insect pests and hence, in receptor binding. High structural resemblance between PirB-N and domain I of Cry toxin raises the possibility that the putative PirAB binary toxin may mimic the toxicity mechanism of the Cry protein, particularly its ability to perform pore formation. The mixture of independently purified PirA and PirB proteins are not toxic to insects. However, PirA-PirB protein complex purified from expression of pir operon with non-coding Enterobacterial Repetitive Intergenic Consensus (ERIC) sequences found toxic to Galleria mellonella larvae with LD50 value of 1.62 μg/larva. This suggests that toxic conformation of PirA and PirB are achieved in-vivo with the help of ERIC sequences.
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Affiliation(s)
- Arpit Prashar
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Omkar U Kinkar
- Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, Maharashtra, India; Beamline Development and Application Section, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Ashwani Kumar
- Beamline Development and Application Section, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Ashok B Hadapad
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Ravindra D Makde
- Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, Maharashtra, India; Beamline Development and Application Section, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Ramesh S Hire
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, Maharashtra, India.
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6
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Efficient and Scalable Process to Produce Novel and Highly Bioactive Purified Cytosolic Crystals from Bacillus thuringiensis. Microbiol Spectr 2022; 10:e0235622. [PMID: 35946940 PMCID: PMC9430767 DOI: 10.1128/spectrum.02356-22] [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] [Indexed: 11/22/2022] Open
Abstract
Bacillus thuringiensis (Bt) is a Gram-positive soil bacterium that is widely and safely applied in the environment as an insecticide for combatting insect pests that damage crops or are disease vectors. Dominant active ingredients made by Bt are insect-killing crystal (Cry) proteins released as crystalline inclusions upon bacterial sporulation. Some Bt Cry proteins, e.g., Cry5B (formally Cry5Ba1), target nematodes (roundworms) and show exceptional promise as anthelmintics (cures for parasitic nematode diseases). We have recently described inactivated bacteria with cytosolic crystal(s) (IBaCC) in which bioactive Bt Cry crystals (containing Cry5B) are fully contained within the cytosol of dead bacterial ghosts. Here, we demonstrate that these IBaCC-trapped Cry5B crystals can be liberated and purified away from cellular constituents, yielding purified cytosolic crystals (PCC). Cry5B PCC contains ~95% Cry5B protein out of the total protein content. Cry5B PCC is highly bioactive against parasitic nematode larvae and adults in vitro. Cry5B PCC is also highly active in vivo against experimental human hookworm and Ascaris infections in rodents. The process was scaled up to the 100-liter scale to produce PCC for a pilot study to treat two foals infected with the ascarid Parascaris spp. Single-dose Cry5B PCC brought the fecal egg counts of both foals to zero. These studies describe the process for the scalable production of purified Bt crystals and define a new and attractive pharmaceutical ingredient form of Bt Cry proteins. IMPORTANCEBacillus thuringiensis crystal proteins are widely and safely used as insecticides. Recent studies have shown they also can cure gastrointestinal parasitic worm (nematode) infections when ingested. However, reproducible, scalable, and practical techniques for purifying these proteins have been lacking. Here, we address this severe limitation and present scalable and practical methods for large-scale purification of potently bioactive B. thuringiensis crystals and crystal proteins. The resultant product, called purified cytosolic crystals (PCC), is highly compatible with ingestible drug delivery and formulation. Furthermore, there are growing applications in agriculture and insect control where access to large quantities of purified crystal proteins is desirable and where these methods will find great utility.
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Ye J, Guo J, Li T, Tian J, Yu M, Wang X, Majeed U, Song W, Xiao J, Luo Y, Yue T. Phage-based technologies for highly sensitive luminescent detection of foodborne pathogens and microbial toxins: A review. Compr Rev Food Sci Food Saf 2022; 21:1843-1867. [PMID: 35142431 DOI: 10.1111/1541-4337.12908] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 12/25/2021] [Accepted: 12/28/2021] [Indexed: 02/05/2023]
Abstract
Foodborne pathogens and microbial toxins are the main causes of foodborne illness. However, trace pathogens and toxins in foods are difficult to detect. Thus, techniques for their rapid and sensitive identification and quantification are urgently needed. Phages can specifically recognize and adhere to certain species of microbes or toxins due to molecular complementation between capsid proteins of phages and receptors on the host cell wall or toxins, and thus they have been successfully developed into a detection platform for pathogens and toxins. This review presents an update on phage-based luminescent detection technologies as well as their working principles and characteristics. Based on phage display techniques of temperate phages, reporter gene detection assays have been designed to sensitively detect trace pathogens by luminous intensity. By the host-specific lytic effects of virulent phages, enzyme-catalyzed chemiluminescent detection technologies for pathogens have been exploited. Notably, these phage-based luminescent detection technologies can discriminate viable versus dead microbes. Further, highly selective and sensitive immune-based assays have been developed to detect trace toxins qualitatively and quantitatively via antibody analogs displayed by phages, such as phage-ELISA (enzyme-linked immunosorbent assay) and phage-IPCR (immuno-polymerase chain reaction). This literature research may lead to novel and innocuous phage-based rapid detection technologies to ensure food safety.
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Affiliation(s)
- Jianming Ye
- College of Food Science and Technology, Northwest University, Xi'an, Shaanxi, China
| | - Jiaqing Guo
- College of Food Science and Technology, Northwest University, Xi'an, Shaanxi, China
| | - Tairan Li
- College of Food Science and Technology, Northwest University, Xi'an, Shaanxi, China
| | - Jiaxin Tian
- College of Food Science and Technology, Northwest University, Xi'an, Shaanxi, China
| | - Mengxi Yu
- College of Food Science and Technology, Northwest University, Xi'an, Shaanxi, China
| | - Xiaochen Wang
- College of Food Science and Technology, Northwest University, Xi'an, Shaanxi, China
| | - Usman Majeed
- College of Food Science and Technology, Northwest University, Xi'an, Shaanxi, China
| | - Wei Song
- College of Food Science and Technology, Northwest University, Xi'an, Shaanxi, China
| | - Jianbo Xiao
- Department of Analytical Chemistry and Food Science, Faculty of Food Science and Technology, University of Vigo-Ourense Campus, Ourense, Spain
| | - Yane Luo
- College of Food Science and Technology, Northwest University, Xi'an, Shaanxi, China
- Laboratory of Nutritional and Healthy Food-Individuation Manufacturing Engineering, Xi'an, Shaanxi, China
- Research Center of Food Safety Risk Assessment and Control, Xi'an, Shaanxi, China
| | - Tianli Yue
- College of Food Science and Technology, Northwest University, Xi'an, Shaanxi, China
- Laboratory of Nutritional and Healthy Food-Individuation Manufacturing Engineering, Xi'an, Shaanxi, China
- Research Center of Food Safety Risk Assessment and Control, Xi'an, Shaanxi, China
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Batool K, Alam I, Liu P, Shu Z, Zhao S, Yang W, Jie X, Gu J, Chen XG. Recombinant Mosquito Densovirus with Bti Toxins Significantly Improves Pathogenicity against Aedes albopictus. Toxins (Basel) 2022; 14:147. [PMID: 35202174 PMCID: PMC8879223 DOI: 10.3390/toxins14020147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 02/12/2022] [Accepted: 02/14/2022] [Indexed: 12/12/2022] Open
Abstract
Mosquito densoviruses (MDVs) are mosquito-specific viruses that are recommended as mosquito bio-control agents. The MDV Aedes aegypti densovirus (AeDNV) is a good candidate for controlling mosquitoes. However, the slow activity restricts their widespread use for vector control. In this study, we introduced the Bacillus thuringiensis (Bti) toxin Cry11Aa domain II loop α8 and Cyt1Aa loop β6-αE peptides into the AeDNV genome to improve its mosquitocidal efficiency; protein expression was confirmed using nanoscale liquid chromatography coupled to tandem mass spectrometry (nano LC-MS/MS). Recombinant plasmids were transfected into mosquito C6/36 cell lines, and the expression of specific peptides was detected through RT-PCR. A toxicity bioassay against the first instar Aedes albopictus larvae revealed that the pathogenic activity of recombinant AeDNV was significantly higher and faster than the wild-type (wt) viruses, and mortality increased in a dose-dependent manner. The recombinant viruses were genetically stable and displayed growth phenotype and virus proliferation ability, similar to wild-type AeDNV. Our novel results offer further insights by combining two mosquitocidal pathogens to improve viral toxicity for mosquito control.
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Affiliation(s)
- Khadija Batool
- Department of Pathogen Biology, Institute of Tropical Medicine, School of Public Health, Southern Medical University, Guangzhou 510515, China; (K.B.); (P.L.); (Z.S.); (S.Z.); (W.Y.); (X.J.); (J.G.)
| | - Intikhab Alam
- College of Life Sciences, South China Agricultural University, Guangzhou 510515, China;
| | - Peiwen Liu
- Department of Pathogen Biology, Institute of Tropical Medicine, School of Public Health, Southern Medical University, Guangzhou 510515, China; (K.B.); (P.L.); (Z.S.); (S.Z.); (W.Y.); (X.J.); (J.G.)
| | - Zeng Shu
- Department of Pathogen Biology, Institute of Tropical Medicine, School of Public Health, Southern Medical University, Guangzhou 510515, China; (K.B.); (P.L.); (Z.S.); (S.Z.); (W.Y.); (X.J.); (J.G.)
| | - Siyu Zhao
- Department of Pathogen Biology, Institute of Tropical Medicine, School of Public Health, Southern Medical University, Guangzhou 510515, China; (K.B.); (P.L.); (Z.S.); (S.Z.); (W.Y.); (X.J.); (J.G.)
| | - Wenqiang Yang
- Department of Pathogen Biology, Institute of Tropical Medicine, School of Public Health, Southern Medical University, Guangzhou 510515, China; (K.B.); (P.L.); (Z.S.); (S.Z.); (W.Y.); (X.J.); (J.G.)
| | - Xiao Jie
- Department of Pathogen Biology, Institute of Tropical Medicine, School of Public Health, Southern Medical University, Guangzhou 510515, China; (K.B.); (P.L.); (Z.S.); (S.Z.); (W.Y.); (X.J.); (J.G.)
| | - Jinbao Gu
- Department of Pathogen Biology, Institute of Tropical Medicine, School of Public Health, Southern Medical University, Guangzhou 510515, China; (K.B.); (P.L.); (Z.S.); (S.Z.); (W.Y.); (X.J.); (J.G.)
| | - Xiao-Guang Chen
- Department of Pathogen Biology, Institute of Tropical Medicine, School of Public Health, Southern Medical University, Guangzhou 510515, China; (K.B.); (P.L.); (Z.S.); (S.Z.); (W.Y.); (X.J.); (J.G.)
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Gonzalez-Vazquez MC, Vela-Sanchez RA, Rojas-Ruiz NE, Carabarin-Lima A. Importance of Cry Proteins in Biotechnology: Initially a Bioinsecticide, Now a Vaccine Adjuvant. Life (Basel) 2021; 11:999. [PMID: 34685371 PMCID: PMC8541582 DOI: 10.3390/life11100999] [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: 09/07/2021] [Revised: 09/19/2021] [Accepted: 09/19/2021] [Indexed: 11/21/2022] Open
Abstract
A hallmark of Bacillus thuringiensis bacteria is the formation of one or more parasporal crystal (Cry) proteins during sporulation. The toxicity of these proteins is highly specific to insect larvae, exerting lethal effects in different insect species but not in humans or other mammals. The aim of this review is to summarize previous findings on Bacillus thuringiensis, including the characteristics of the bacterium, its subsequent contribution to biotechnology as a bioinsecticide due to the presence of Cry proteins, and its potential application as an adjuvant. In several studies, Cry proteins have been administered together with specific antigens to immunize experimental animal models. The results have shown that these proteins can enhance immunogenicity by generating an adequate immune response capable of protecting the model against an experimental infectious challenge, whereas protection is decreased when the specific antigen is administered without the Cry protein. Therefore, based on previous results and the structural homology between Cry proteins, these molecules have arisen as potential adjuvants in the development of vaccines for both animals and humans. Finally, a model of the interaction of Cry proteins with different components of the immune response is proposed.
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Affiliation(s)
- Maria Cristina Gonzalez-Vazquez
- Centro de Investigaciones en Ciencias Microbiologicas, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla, Puebla 72000, PU, Mexico; (M.C.G.-V.); (N.E.R.-R.)
| | - Ruth Abril Vela-Sanchez
- Licenciatura en Biotecnología, Benemerita Universidad Autonoma de Puebla, Puebla 72000, PU, Mexico;
| | - Norma Elena Rojas-Ruiz
- Centro de Investigaciones en Ciencias Microbiologicas, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla, Puebla 72000, PU, Mexico; (M.C.G.-V.); (N.E.R.-R.)
- Licenciatura en Biotecnología, Benemerita Universidad Autonoma de Puebla, Puebla 72000, PU, Mexico;
| | - Alejandro Carabarin-Lima
- Centro de Investigaciones en Ciencias Microbiologicas, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla, Puebla 72000, PU, Mexico; (M.C.G.-V.); (N.E.R.-R.)
- Licenciatura en Biotecnología, Benemerita Universidad Autonoma de Puebla, Puebla 72000, PU, Mexico;
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Transition Phase Regulator AbrB Positively Regulates the sip1Ab1 Gene Expression in Bacillus thuringiensis. Microbiol Spectr 2021; 9:e0007521. [PMID: 34319140 PMCID: PMC8552724 DOI: 10.1128/spectrum.00075-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Bacillus thuringiensis secreted insecticidal proteins (Sip) are a secretion that is toxic to coleopteran pests. However, the transcriptional mechanism of sip genes is still unknown. The transcriptional regulation of the sip1Ab1 gene and the expression of the Sip1Ab1 protein were investigated in this study. The results demonstrated that the secretion of the Sip1Ab1 protein in HD73 was almost the same as that in the original QZL38 strain during the transition phase. Analysis of the β-galactosidase activities of sip1Ab1-lacZ in both the HD73 and abrB mutant strains indicated that the transcription of sip1Ab1 is dependent on AbrB. Electrophoretic mobility shift assays showed that AbrB could bind with the sip1Ab1 promoter, and two binding sites of AbrB in the region of the promoter of sip1Ab1 were determined by DNase I footprinting assays. All of the above-described results proved that AbrB positively regulates the sip1Ab1 gene. IMPORTANCEBacillus thuringiensis Sip proteins are secreted insecticidal toxins that are toxic to coleopteran pests. In this study, we investigated the transcriptional mechanism of the sip gene and showed strong evidence that Sip1Ab1 is secreted in the transition phase and that AbrB, a transition phase regulator that is usually a repressor, positively and directly regulates sip1Ab1. Reports of AbrB positive regulation are rare, even in Bacillus subtilis. To the best of our knowledge, no toxic gene has been reported to be positively regulated by AbrB in Bacillus species.
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Mastore M, Caramella S, Quadroni S, Brivio MF. Drosophila suzukii Susceptibility to the Oral Administration of Bacillus thuringiensis, Xenorhabdus nematophila and Its Secondary Metabolites. INSECTS 2021; 12:insects12070635. [PMID: 34357295 PMCID: PMC8305655 DOI: 10.3390/insects12070635] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/07/2021] [Accepted: 07/11/2021] [Indexed: 11/26/2022]
Abstract
Simple Summary In recent decades, climate change and the international fruit trade have favored the movement of allochthonous species such as harmful insects into new geographic areas. The settlement of phytophagous insects and vectors in new areas, where potential predators are often lacking, has increased the use of chemical insecticides for their control. The intensive use of these substances represents a serious problem for ecosystems and human health; a possible alternative to chemical control is biological control, i.e., the use of biological insecticides that are compatible with the environment. The aim of our work was to further improve biological control methods for the management of the dipteran Spotted Wing Drosophila, an insect recently introduced in America and Europe, which can damage thin-skinned fruit crops. The methodologies applied are based on the combined use of different entomopathogens, i.e., bacteria, fungi, nematodes, etc., harmful for insects, with the purpose of increasing their effectiveness. The results obtained show that the combined use of two entomopathogenic bacteria increases both the lethality and rapidity of action. From an application viewpoint, studies like this are essential to identify new methods and bioinsecticides and, once transferred to the field, can be crucial to eliminate or, at least, reduce the use of chemicals. Abstract Drosophila suzukii, Spotted Wing Drosophila (SWD), is a serious economic issue for thin-skinned fruit farmers. The invasion of this dipteran is mainly counteracted by chemical control methods; however, it would be desirable to replace them with biological control. All assays were performed with Bacillus thuringiensis (Bt), Xenorhabdus nematophila (Xn), and Xn secretions, administered orally in single or combination, then larval lethality was assessed at different times. Gut damage caused by Bt and the influence on Xn into the hemocoelic cavity was also evaluated. In addition, the hemolymph cell population was analyzed after treatments. The data obtained show that the combined use of Bt plus Xn secretions on larvae, compared to single administration of bacteria, significantly improved the efficacy and reduced the time of treatments. The results confirm the destructive action of Bt on the gut of SWD larvae, and that Bt-induced alteration promotes the passage of Xn to the hemocoel cavity. Furthermore, hemocytes decrease after bioinsecticides treatments. Our study demonstrates that combining bioinsecticides can improve the efficacy of biocontrol and such combinations should be tested in greenhouse and in field in the near future.
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Affiliation(s)
- Maristella Mastore
- Laboratory of Comparative Immunology and Parasitology, Department of Theoretical and Applied Sciences, University of Insubria, 21100 Varese, Italy; (M.M.); (S.C.)
| | - Sara Caramella
- Laboratory of Comparative Immunology and Parasitology, Department of Theoretical and Applied Sciences, University of Insubria, 21100 Varese, Italy; (M.M.); (S.C.)
| | - Silvia Quadroni
- Laboratory of Ecology, Department of Theoretical and Applied Sciences, University of Insubria, 21100 Varese, Italy;
| | - Maurizio Francesco Brivio
- Laboratory of Comparative Immunology and Parasitology, Department of Theoretical and Applied Sciences, University of Insubria, 21100 Varese, Italy; (M.M.); (S.C.)
- Correspondence: ; Tel.: +39-0332-421404
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12
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Jovanovic J, Ornelis VFM, Madder A, Rajkovic A. Bacillus cereus food intoxication and toxicoinfection. Compr Rev Food Sci Food Saf 2021; 20:3719-3761. [PMID: 34160120 DOI: 10.1111/1541-4337.12785] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 05/13/2021] [Accepted: 05/15/2021] [Indexed: 12/12/2022]
Abstract
Bacillus cereus is one of the leading etiological agents of toxin-induced foodborne diseases. Its omnipresence in different environments, spore formation, and its ability to adapt to varying conditions and produce harmful toxins make this pathogen a health hazard that should not be underestimated. Food poisoning by B. cereus can manifest itself as an emetic or diarrheal syndrome. The former is caused by the release of the potent peptide toxin cereulide, whereas the latter is the result of proteinaceous enterotoxins (e.g., hemolysin BL, nonhemolytic enterotoxin, and cytotoxin K). The final harmful effect is not only toxin and strain dependent, but is also affected by the stress responses, accessory virulence factors, and phenotypic properties under extrinsic, intrinsic, and explicit food conditions and host-related environment. Infamous portrait of B. cereus as a foodborne pathogen, as well as a causative agent of nongastrointestinal infections and even nosocomial complications, has inspired vast volumes of multidisciplinary research in food and clinical domains. As a result, extensive original data became available asking for a new, both broad and deep, multifaceted look into the current state-of-the art regarding the role of B. cereus in food safety. In this review, we first provide an overview of the latest knowledge on B. cereus toxins and accessory virulence factors. Second, we describe the novel taxonomy and some of the most pertinent phenotypic characteristics of B. cereus related to food safety. We link these aspects to toxin production, overall pathogenesis, and interactions with its human host. Then we reflect on the prevalence of different toxinotypes in foods opening the scene for epidemiological aspects of B. cereus foodborne diseases and methods available to prevent food poisoning including overview of the different available methods to detect B. cereus and its toxins.
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Affiliation(s)
- Jelena Jovanovic
- Department of Food Technology, Safety and Health, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Vincent F M Ornelis
- Department of Organic and Macromolecular Chemistry, Faculty of Sciences, Ghent University, Ghent, Belgium
| | - Annemieke Madder
- Department of Organic and Macromolecular Chemistry, Faculty of Sciences, Ghent University, Ghent, Belgium
| | - Andreja Rajkovic
- Department of Food Technology, Safety and Health, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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13
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Liu L, Li Z, Luo X, Zhang X, Chou SH, Wang J, He J. Which Is Stronger? A Continuing Battle Between Cry Toxins and Insects. Front Microbiol 2021; 12:665101. [PMID: 34140940 PMCID: PMC8203666 DOI: 10.3389/fmicb.2021.665101] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 04/20/2021] [Indexed: 12/20/2022] Open
Abstract
In this article, we review the latest works on the insecticidal mechanisms of Bacillus thuringiensis Cry toxins and the resistance mechanisms of insects against Cry toxins. Currently, there are two models of insecticidal mechanisms for Cry toxins, namely, the sequential binding model and the signaling pathway model. In the sequential binding model, Cry toxins are activated to bind to their cognate receptors in the mid-intestinal epithelial cell membrane, such as the glycophosphatidylinositol (GPI)-anchored aminopeptidases-N (APNs), alkaline phosphatases (ALPs), cadherins, and ABC transporters, to form pores that elicit cell lysis, while in the signaling pathway model, the activated Cry toxins first bind to the cadherin receptor, triggering an extensive cell signaling cascade to induce cell apoptosis. However, these two models cannot seem to fully describe the complexity of the insecticidal process of Cry toxins, and new models are required. Regarding the resistance mechanism against Cry toxins, the main method insects employed is to reduce the effective binding of Cry toxins to their cognate cell membrane receptors by gene mutations, or to reduce the expression levels of the corresponding receptors by trans-regulation. Moreover, the epigenetic mechanisms, host intestinal microbiota, and detoxification enzymes also play significant roles in the insects' resistance against Cry toxins. Today, high-throughput sequencing technologies like transcriptomics, proteomics, and metagenomics are powerful weapons for studying the insecticidal mechanisms of Cry toxins and the resistance mechanisms of insects. We believe that this review shall shed some light on the interactions between Cry toxins and insects, which can further facilitate the development and utilization of Cry toxins.
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Affiliation(s)
- Lu Liu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Zhou Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Xing Luo
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Xia Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China.,Department of Molecular Biology, Qingdao Vland Biotech Inc., Qingdao, China
| | - Shan-Ho Chou
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Jieping Wang
- Agricultural Bioresources Institute, Fujian Academy of Agricultural Sciences, Fuzhou, China
| | - Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
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The Food Poisoning Toxins of Bacillus cereus. Toxins (Basel) 2021; 13:toxins13020098. [PMID: 33525722 PMCID: PMC7911051 DOI: 10.3390/toxins13020098] [Citation(s) in RCA: 137] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/14/2021] [Accepted: 01/25/2021] [Indexed: 12/13/2022] Open
Abstract
Bacillus cereus is a ubiquitous soil bacterium responsible for two types of food-associated gastrointestinal diseases. While the emetic type, a food intoxication, manifests in nausea and vomiting, food infections with enteropathogenic strains cause diarrhea and abdominal pain. Causative toxins are the cyclic dodecadepsipeptide cereulide, and the proteinaceous enterotoxins hemolysin BL (Hbl), nonhemolytic enterotoxin (Nhe) and cytotoxin K (CytK), respectively. This review covers the current knowledge on distribution and genetic organization of the toxin genes, as well as mechanisms of enterotoxin gene regulation and toxin secretion. In this context, the exceptionally high variability of toxin production between single strains is highlighted. In addition, the mode of action of the pore-forming enterotoxins and their effect on target cells is described in detail. The main focus of this review are the two tripartite enterotoxin complexes Hbl and Nhe, but the latest findings on cereulide and CytK are also presented, as well as methods for toxin detection, and the contribution of further putative virulence factors to the diarrheal disease.
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15
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Natural bacterial isolates as an inexhaustible source of new bacteriocins. Appl Microbiol Biotechnol 2021; 105:477-492. [PMID: 33394148 DOI: 10.1007/s00253-020-11063-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/10/2020] [Accepted: 12/15/2020] [Indexed: 12/12/2022]
Abstract
Microorganisms isolated from various traditionally fermented food products prepared in households without commercial starter cultures are designated as natural isolates. In addition, this term is also used for microorganisms collected from various natural habitats or products (silage, soil, manure, plant and animal material, etc.) that do not contain any commercial starters or bacterial formulations. They are characterized by unique traits that are the result of the selective pressure of environmental conditions, as well as interactions with other organisms. The synthesis of antimicrobial molecules, including bacteriocins, is an evolutionary advantage and an adaptive feature that sets them apart from other microorganisms from a common environment. This review aims to underline the knowledge of bacteriocins produced by natural isolates, with a particular emphasis on the most common location of their genes and operons, plasmids, and the importance of the relationship between the plasmidome and the adaptive potential of the isolate. Applications of bacteriocins, ranging from natural food preservatives to supplements and drugs in pharmacology and medicine, will also be addressed. The latest challenges faced by researchers in isolating new natural isolates with desired characteristics will be discussed, as well as the production of new antimicrobials, nearly one century since the first discovery of colicins in 1925. KEY POINTS: • Natural bacterial isolates harbor unique properties shaped by diverse interactions. • Horizontal gene transfer enables constant engineering of new antimicrobials. • Fermented food products are important source of bacteriocin-producing natural isolates.
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Grahl MVC, Lopes FC, Martinelli AHS, Carlini CR, Fruttero LL. Structure-Function Insights of Jaburetox and Soyuretox: Novel Intrinsically Disordered Polypeptides Derived from Plant Ureases. Molecules 2020; 25:molecules25225338. [PMID: 33207637 PMCID: PMC7696265 DOI: 10.3390/molecules25225338] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/05/2020] [Accepted: 11/06/2020] [Indexed: 12/24/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) and intrinsically disordered regions (IDRs) do not have a stable 3D structure but still have important biological activities. Jaburetox is a recombinant peptide derived from the jack bean (Canavalia ensiformis) urease and presents entomotoxic and antimicrobial actions. The structure of Jaburetox was elucidated using nuclear magnetic resonance which reveals it is an IDP with small amounts of secondary structure. Different approaches have demonstrated that Jaburetox acquires certain folding upon interaction with lipid membranes, a characteristic commonly found in other IDPs and usually important for their biological functions. Soyuretox, a recombinant peptide derived from the soybean (Glycine max) ubiquitous urease and homologous to Jaburetox, was also characterized for its biological activities and structural properties. Soyuretox is also an IDP, presenting more secondary structure in comparison with Jaburetox and similar entomotoxic and fungitoxic effects. Moreover, Soyuretox was found to be nontoxic to zebra fish, while Jaburetox was innocuous to mice and rats. This profile of toxicity affecting detrimental species without damaging mammals or the environment qualified them to be used in biotechnological applications. Both peptides were employed to develop transgenic crops and these plants were active against insects and nematodes, unveiling their immense potentiality for field applications.
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Affiliation(s)
- Matheus V. Coste Grahl
- Graduate Program in Medicine and Health Sciences, Brain Institute of Rio Grande do Sul (InsCer), Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre CEP 90610-000, Brazil;
| | - Fernanda Cortez Lopes
- Graduate Program in Cellular and Molecular Biology, Center of Biotechnology, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, Building 43431, Porto Alegre CEP 91501-970, RS, Brazil;
| | - Anne H. Souza Martinelli
- Department of Biophysics & Deparment of Molecular Biology and Biotechnology-Biosciences Institute (IB), Universidade Federal do Rio Grande do Sul, UFRGS, Porto Alegre 91501-970, RS, Brazil;
| | - Celia R. Carlini
- Graduate Program in Medicine and Health Sciences, Brain Institute of Rio Grande do Sul (InsCer), Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre CEP 90610-000, Brazil;
- Brain Institute and School of Medicine, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre 90610-000, RS, Brazil
- Correspondence: (C.R.C.); (L.L.F.); Tel.: +55-51-3320-3485 (C.R.C.); +54-351-535-3850 (L.L.F.)
| | - Leonardo L. Fruttero
- Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba CP 5000, Argentina
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Córdoba CP 5000, Argentina
- Correspondence: (C.R.C.); (L.L.F.); Tel.: +55-51-3320-3485 (C.R.C.); +54-351-535-3850 (L.L.F.)
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Schwenk V, Riegg J, Lacroix M, Märtlbauer E, Jessberger N. Enteropathogenic Potential of Bacillus thuringiensis Isolates from Soil, Animals, Food and Biopesticides. Foods 2020; 9:foods9101484. [PMID: 33080854 PMCID: PMC7603059 DOI: 10.3390/foods9101484] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 12/14/2022] Open
Abstract
Despite its benefits as biological insecticide, Bacillus thuringiensis bears enterotoxins, which can be responsible for a diarrhoeal type of food poisoning. Thus, all 24 isolates from foodstuffs, animals, soil and commercially used biopesticides tested in this study showed the genetic prerequisites necessary to provoke the disease. Moreover, though highly strain-specific, various isolates were able to germinate and also to actively move, which are further requirements for the onset of the disease. Most importantly, all isolates could grow under simulated intestinal conditions and produce significant amounts of enterotoxins. Cytotoxicity assays classified 14 isolates as highly, eight as medium and only two as low toxic. Additionally, growth inhibition by essential oils (EOs) was investigated as preventive measure against putatively enteropathogenic B. thuringiensis. Cinnamon Chinese cassia showed the highest antimicrobial activity, followed by citral, oregano and winter savory. In all tests, high strain-specific variations appeared and must be taken into account when evaluating the hazardous potential of B. thuringiensis and using EOs as antimicrobials. Altogether, the present study shows a non-negligible pathogenic potential of B. thuringiensis, independently from the origin of isolation. Generally, biopesticide strains were indistinguishable from other isolates. Thus, the use of these pesticides might indeed increase the risk for consumers’ health. Until complete information about the safety of the applied strains and formulations is available, consumers or manufacturers might benefit from the antimicrobial activity of EOs to reduce the level of contamination.
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Affiliation(s)
- Valerie Schwenk
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (V.S.); (J.R.); (E.M.)
| | - Janina Riegg
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (V.S.); (J.R.); (E.M.)
| | - Monique Lacroix
- Centre Armand-Frappier Santé Biotechnologie, 531, boul. des Prairies, Laval, QC H7V 1B7, Canada;
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (V.S.); (J.R.); (E.M.)
| | - Nadja Jessberger
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (V.S.); (J.R.); (E.M.)
- Correspondence:
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Liu W, Liu X, Liu C, Zhang Z, Jin W. Development of a sensitive monoclonal antibody-based sandwich ELISA to detect Vip3Aa in genetically modified crops. Biotechnol Lett 2020; 42:1467-1478. [PMID: 32140882 PMCID: PMC7354279 DOI: 10.1007/s10529-020-02854-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 02/27/2020] [Indexed: 12/18/2022]
Abstract
Objectives To develop a sensitive monoclonal antibody-based sandwich enzyme-linked immunosorbent assay (ELISA) to detect Vip3Aa in genetically modified (GM) crops and their products. Results Vegetative insecticidal proteins (Vips) are secreted by Bacillus thuringiensis (Bt) and are known to be toxic to Lepidoptera species. Vip3Aa family proteins, Vip3Aa19 and Vip3Aa20, were successfully applied in GM crops to confer an effective and persistent insecticidal resistance. A sensitive monoclonal antibody-based sandwich ELISA was developed to detect Vip3Aa in GM crops and their products. Two monoclonal antibodies were raised against the overexpressed and purified His-Vip3Aa20, were purified from mouse ascites and characterized. A sandwich ELISA method was developed using the 2G3-1D7 monoclonal antibody for capture and the biotin-labeled 1F9-1F5 monoclonal antibody for detection of Vip3Aa20. The linear detection range of the method was found to be approximately 31.25–500 pg/ml, with a sensitivity of 10.24 pg/ml. Conclusions The established ELISA was effective for detecting Vip3Aa family proteins other than Vip3Aa8, and was successfully applied in the detection of Vip3Aa20 and Vip3Aa19 expressed in transgenic maize and cotton.
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Affiliation(s)
- Weixiao Liu
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Xuri Liu
- Department of Food and Biological Engineering, Handan Polytechnic College, Handan, 056001, China
| | - Chao Liu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Science, Beijing, 100101, China
| | - Zhe Zhang
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Wujun Jin
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
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Castella C, Pauron D, Hilliou F, Trang VT, Zucchini-Pascal N, Gallet A, Barbero P. Transcriptomic analysis of Spodoptera frugiperda Sf9 cells resistant to Bacillus thuringiensis Cry1Ca toxin reveals that extracellular Ca 2+, Mg 2+ and production of cAMP are involved in toxicity. Biol Open 2019; 8:bio.037085. [PMID: 30926594 PMCID: PMC6503997 DOI: 10.1242/bio.037085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Bacillus thuringiensis (Bt) produces pore forming toxins that have been used for pest control in agriculture for many years. However, their molecular and cellular mode of action is still unclear. While a first model - referred to as the pore forming model - is the most widely accepted scenario, a second model proposed that toxins could trigger an Mg2+-dependent intracellular signalling pathway leading to cell death. Although Cry1Ca has been shown to form ionic pores in the plasma membrane leading to cell swelling and death, we investigated the existence of other cellular or molecular events involved in Cry1Ca toxicity. The Sf9 insect cell line, derived from Spodoptera frugiperda, is highly and specifically sensitive to Cry1Ca. Through a selection program we developed various levels of laboratory-evolved Cry1Ca-resistant Sf9 cell lines. Using a specific S. frugiperda microarray we performed a comparative transcriptomic analysis between sensitive and resistant cells and revealed genes differentially expressed in resistant cells and related to cation-dependent signalling pathways. Ion chelators protected sensitive cells from Cry1Ca toxicity suggesting the necessity of both Ca2+ and/or Mg2+ for toxin action. Selected cells were highly resistant to Cry1Ca while toxin binding onto their plasma membrane was not affected. This suggested a resistance mechanism different from the classical 'loss of toxin binding'. We observed a correlation between Cry1Ca cytotoxicity and the increase of intracellular cAMP levels. Indeed, Sf9 sensitive cells produced high levels of cAMP upon toxin stimulation, while Sf9 resistant cells were unable to increase their intracellular cAMP. Together, these results provide new information about the mechanism of Cry1Ca toxicity and clues to potential resistance factors yet to discover.
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