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Zhang Y, Chen C, Du X, Yu Z, Min Q, Chen C, Wu H, Tan W, Guan X, Zhang L. Urea Cycle of Bacillus thuringiensis Affects Its Survival under UV Stress. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:7291-7298. [PMID: 38507714 DOI: 10.1021/acs.jafc.4c00167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
Bacillus thuringiensis (Bt) is widely used to produce biological pesticides. However, its persistence is limited because of ultraviolet (UV) rays. In our previous study, we found that exogenous intermediates of the urea cycle were beneficial to Bt for survival under UV stress. To further explore the effect of the urea cycle on the resistance mechanism of Bt, the rocF/argG gene, encoding arginase and argininosuccinate synthase, respectively, were knocked out and recovered in this study. After the target genes were removed, respectively, the urea cycle in the tested Bt was inhibited to varying degrees. The UV stress test showed that the urea cycle disorder could reduce the resistance of Bt under UV stress. Meanwhile, the antioxidant enzyme activities of Bt were also decreased to varying degrees due to the knockout of the target genes. All of these results revealed that the urea cycle can metabolically regulate the stress resistance of Bt.
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Affiliation(s)
- Yile Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection and College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian China
| | - Caixia Chen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection and College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian China
| | - Xi Du
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection and College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian China
| | - Zhen Yu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection and College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian China
| | - Qingqing Min
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection and College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian China
| | - Chunmei Chen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection and College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian China
| | - Haonan Wu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection and College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian China
| | - Weilong Tan
- Center for Disease Control and Prevention of Eastern Command, Nanjing 210000, China
| | - Xiong Guan
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection and College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian China
| | - Lingling Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education & Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection and College of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian China
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Huang L, Han G, Crickmore N, Li C, Xia Y, Song F, Xu J. Characterization of a novel cell wall hydrolase CwlE involved in Bacillus thuringiensis subsp . israelensis mother cell lysis. Front Microbiol 2023; 14:1250542. [PMID: 37829449 PMCID: PMC10565116 DOI: 10.3389/fmicb.2023.1250542] [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: 06/30/2023] [Accepted: 09/15/2023] [Indexed: 10/14/2023] Open
Abstract
Cell wall hydrolases are ubiquitous among spore-form bacteria and essential for mother cell lysis. In this study, a novel cell wall hydrolase gene cwlE involved in mother cell lysis was characterized from Bacillus thuringiensis subsp. israelensis (Bti) strain Bt-59. cwlE was specifically expressed in Bti and located in the large plasmid carrying the insecticidal genes. The encoded CwlE protein consists of a MurNAc-LAA domain and two highly conserved catalytic residues (E26 and E151). The recombinant CwlE-His protein was able to digest the cell wall of Bti, indicating that CwlE is an N-acetylmuramoyl-L-alanine amidase. Transcriptional analysis indicated that cwlE began to express at the early stage of stationary phase and was controlled by SigE. Single mutation of cwlE gene delayed Bti mother cell lysis, while double mutation of cwlE and sigK completely blocked Bti mother cell lysis. After exposure to UV light to deactivate the crystal proteins, the level of decrease of insecticidal activity against mosquito larvae of Bt-59 (ΔcwlE-sigK) was less than that observed for Bt-59. This study elucidates the mechanism of Bti mother cell lysis and provides an effective strategy for mosquito control using Bt products with increased persistence.
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Affiliation(s)
- Lixin Huang
- Department of Applied Microbiology, Lixiahe District Institute of Agricultural Sciences in Jiangsu/National Agricultural Experimental Station for Agricultural Microbiology in Yangzhou, Yangzhou, China
| | - Guangjie Han
- Department of Applied Microbiology, Lixiahe District Institute of Agricultural Sciences in Jiangsu/National Agricultural Experimental Station for Agricultural Microbiology in Yangzhou, Yangzhou, China
| | - Neil Crickmore
- Department of Biochemistry, School of Biological Sciences, University of Sussex, Brighton, United Kingdom
| | - Chuanming Li
- Department of Applied Microbiology, Lixiahe District Institute of Agricultural Sciences in Jiangsu/National Agricultural Experimental Station for Agricultural Microbiology in Yangzhou, Yangzhou, China
| | - Yang Xia
- Department of Applied Microbiology, Lixiahe District Institute of Agricultural Sciences in Jiangsu/National Agricultural Experimental Station for Agricultural Microbiology in Yangzhou, Yangzhou, China
| | - Fuping Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jian Xu
- Department of Applied Microbiology, Lixiahe District Institute of Agricultural Sciences in Jiangsu/National Agricultural Experimental Station for Agricultural Microbiology in Yangzhou, Yangzhou, China
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Wang J, Yu Q, Peng Q, Slamti L, Zhang R, Hou S, Lereclus D, Song F. Deletion of the novel gene mother cell lysis X results in Cry1Ac encapsulation in the Bacillus thuringiensis HD73. Front Microbiol 2022; 13:951830. [PMID: 36016772 PMCID: PMC9397120 DOI: 10.3389/fmicb.2022.951830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 07/14/2022] [Indexed: 11/13/2022] Open
Abstract
The novel protein MclX (mother cell lysis X) in Bacillus thuringiensis subsp. kurstaki strain HD73 (B. thuringiensis HD73) was characterized in this work. MclX has no known domain and its gene deletion in HD73 resulted in Cry1Ac encapsulation in the mother cell and did not influence Cry1Ac protein production or insecticidal activity. In vitro cell wall hydrolysis experiments showed that MclX cannot hydrolyze the cell wall. In mclX deletion mutants, the expression of cwlC (which encodes a key cell wall hydrolase) was significantly decreased, as shown by the β-galactosidase activity assay. MclX cannot directly bind to the cwlC promoter, based on the electrophoretic mobility shift assay (EMSA). The cwlC was reported to be regulated by σK and GerE. However, the transcriptional activities of sigK and gerE showed no difference between HD73 and the mclX deletion mutant. It is indicated that MclX influenced cwlC expression independently of σK or GerE, through a new pathway to regulate cwlC expression. mclX deletion could be a new approach for insecticidal protein encapsulation in Bacillus thuringiensis.
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Affiliation(s)
- Jiaojiao Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Qingyue Yu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Qi Peng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Leyla Slamti
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Ruibin Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Shuo Hou
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Didier Lereclus
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Fuping Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
- *Correspondence: Fuping Song,
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Zhu L, Chu Y, Zhang B, Yuan X, Wang K, Liu Z, Sun M. Creation of an Industrial Bacillus thuringiensis Strain With High Melanin Production and UV Tolerance by Gene Editing. Front Microbiol 2022; 13:913715. [PMID: 35935220 PMCID: PMC9355638 DOI: 10.3389/fmicb.2022.913715] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 05/02/2022] [Indexed: 11/16/2022] Open
Abstract
Bacillus thuringiensis produces insecticidal crystal proteins (ICPs) which exhibit strong insecticidal toxicity. But when used in the field, ICPs would be destroyed by ultraviolet (UV) radiation in sunlight, thus decreasing the insecticidal activity and shortening the persistence. To improve the duration of B. thuringiensis preparations, we endowed a highly toxic industrial B. thuringiensis HD-1 with UV tolerance by making it produce melanin, a pigment that absorbs UV radiation. In B. thuringiensis, melanin is derived from homogentisate (HGA), an intermediate in the tyrosine pathway. And the absence of homogentisate-1,2-dioxygenase (HmgA) will lead to the formation of melanin. In this study, we used the CRISPR/Cas9 system to knock out the hmgA gene and obtained a melanin-producing mutant HD-1-ΔhmgA from strain HD-1. The melanin yield by mutant HD-1-ΔhmgA reached 3.60 mg/mL. And the anti-UV test showed that melanin serves as a protection to both the organism and the ICPs. After UV irradiation for 3 h, mutant HD-1-ΔhmgA still had an 80% insecticidal activity against the cotton bollworm, Helicoverpa armigera, while the control line only had about 20%. This study creates a light-stable biopesticide prototype based on a classic industrial strain that can be applied directly and takes the melanin-producing strain as a concept to improve the preparation validity.
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Affiliation(s)
- Lingyi Zhu
- State Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Yawen Chu
- State Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
- Hubei Shuiguohu Senior High School, Wuhan, China
| | - Bowen Zhang
- State Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Ximu Yuan
- State Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Kai Wang
- State Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Zhiyu Liu
- State Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Ming Sun
- State Key Laboratory of Agricultural Microbiology, Hubei Hongshan Laboratory, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
- *Correspondence: Ming Sun
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Huang L, Xu L, Han G, Crickmore N, Song F, Xu J. Characterization of CwlC, an autolysin, and its role in mother cell lysis of Bacillus thuringiensis subsp. israelensis. Lett Appl Microbiol 2021; 74:92-102. [PMID: 34695235 DOI: 10.1111/lam.13590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 10/13/2021] [Accepted: 10/15/2021] [Indexed: 11/27/2022]
Abstract
Bacillus thuringiensis subsp. israelensis (Bti) has been proven to efficiently control mosquitoes, of which many species are important vectors of human disease. The larvicidal action is attributed to the parasporal crystals formed in the sporulating cells and released upon cell autolysis. In this study, a sporulation-specific cwlC gene that encodes an N-acetylmuramoyl-L -alanine amidase was characterized in Bti strain Bt-59. CwlC was the only cell wall hydrolase in Bti found to contain both MurNAc-LAA and Amidase02_C domains. A recombinant CwlC-His protein was able to digest the Bacillus cell wall. Deletion of the cwlC gene delayed Bti mother cell lysis without impacting vegetative growth or insecticidal efficacy. Transcriptional analyses indicated that cwlC was expressed at the late sporulation stage and was controlled by SigK. Two other cell wall hydrolase genes, cwlB and cwlE, with high expression levels at T14 in Bt-59, were also identified. Like cwlC, cwlB expression was controlled by SigK; in contrast, cwlE was found not to be under the control of this sigma factor and unlike the other two, its gene was found to be plasmid encoded.
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Affiliation(s)
- L Huang
- Department of Applied Microbiology, Jiangsu Lixiahe District Institute of Agricultural Sciences/National Agricultural Experimental Station for Agricultural Microbiology, Yangzhou, China
| | - L Xu
- Department of Applied Microbiology, Jiangsu Lixiahe District Institute of Agricultural Sciences/National Agricultural Experimental Station for Agricultural Microbiology, Yangzhou, China.,State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - G Han
- Department of Applied Microbiology, Jiangsu Lixiahe District Institute of Agricultural Sciences/National Agricultural Experimental Station for Agricultural Microbiology, Yangzhou, China
| | - N Crickmore
- Department of Biochemistry, School of Biological Sciences, University of Sussex, Brighton, UK
| | - F Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - J Xu
- Department of Applied Microbiology, Jiangsu Lixiahe District Institute of Agricultural Sciences/National Agricultural Experimental Station for Agricultural Microbiology, Yangzhou, China
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Barajas-Vargas AY, Ignacio-De la Cruz JL, Márquez-Benavides L, Hernández-Mendoza JL, Sánchez-Yáñez JM. Crecimiento de Triticum aestivum con Azotobacter vinelandii y Bacillus subtilis endófitas de Zea mays var mexicana (teocintle) a dosis restringida de fertilizante nitrogenado. JOURNAL OF THE SELVA ANDINA RESEARCH SOCIETY 2021. [DOI: 10.36610/j.jsars.2021.120200087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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7
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Vílchez S. Making 3D-Cry Toxin Mutants: Much More Than a Tool of Understanding Toxins Mechanism of Action. Toxins (Basel) 2020; 12:toxins12090600. [PMID: 32948025 PMCID: PMC7551160 DOI: 10.3390/toxins12090600] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/15/2020] [Accepted: 08/20/2020] [Indexed: 12/21/2022] Open
Abstract
3D-Cry toxins, produced by the entomopathogenic bacterium Bacillus thuringiensis, have been extensively mutated in order to elucidate their elegant and complex mechanism of action necessary to kill susceptible insects. Together with the study of the resistant insects, 3D-Cry toxin mutants represent one of the pillars to understanding how these toxins exert their activity on their host. The principle is simple, if an amino acid is involved and essential in the mechanism of action, when substituted, the activity of the toxin will be diminished. However, some of the constructed 3D-Cry toxin mutants have shown an enhanced activity against their target insects compared to the parental toxins, suggesting that it is possible to produce novel versions of the natural toxins with an improved performance in the laboratory. In this report, all mutants with an enhanced activity obtained by accident in mutagenesis studies, together with all the variants obtained by rational design or by directed mutagenesis, were compiled. A description of the improved mutants was made considering their historical context and the parallel development of the protein engineering techniques that have been used to obtain them. This report demonstrates that artificial 3D-Cry toxins made in laboratories are a real alternative to natural toxins.
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Affiliation(s)
- Susana Vílchez
- Institute of Biotechnology, Department of Biochemistry and Molecular Biology I, Faculty of Science, University of Granada, 18071 Granada, Spain
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Quan M, Peng J, Zhu Z, Zhou P, Luo S, Xie J, Xia L, Sun Y, Ding X. Construction of a Conditionally Asporogenous Bacillus thuringiensis Recombinant Strain Overproducing Cry Protein by Deletion of the leuB Gene. Front Microbiol 2020; 11:1769. [PMID: 32849393 PMCID: PMC7396631 DOI: 10.3389/fmicb.2020.01769] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 07/06/2020] [Indexed: 11/13/2022] Open
Abstract
One of the common shortcomings with Bacillus thuringiensis (Bt) biopesticides in field application is their instability under UV irradiation. In Bt, the leuB gene encodes the 3-isopropylmalate dehydrogenase. In addition to its role in leucine biosynthesis, LeuB would be likely recruited to catalyze the dehydrogenation of malate in the final step of tricarboxylic acid cycle during sporulation. In this study, we constructed a Bt recombinant strain in which the gene leuB was deleted by using the markerless gene deletion system. The ΔleuB mutant strain showed a conditionally asporogenous phenotype while overproducing insecticidal crystal proteins and retaining its insecticidal activity well in both fermentation and LB media. Furthermore, the metabolic regulation mechanisms of LeuB was elucidated by iTRAQ-based quantitative proteomics approach. Evidences from proteomics data suggested that the inhibited supply of pyruvate (carbon source) was an important factor related to the conditionally asporogenous feature of the mutant. Consistently, the mutant regained its ability to sporulate in LB medium by adding 1% glucose or 1% sodium pyruvate. Taken together, our study demonstrated that deletion of the leuB gene resulted in delayed or completely blocked mother cell lysis, allowing the crystals encapsulated within cells, which makes this recombinant strain a good candidate for developing Bt preparations with better UV-stability.
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Affiliation(s)
- Meifang Quan
- Hunan Provincial Key Laboratory of Microbial Molecular Biology, State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, China.,Key Laboratory of Molecular Epidemiology of Hunan Province, School of Medicine, Hunan Normal University, Changsha, China
| | - Jinli Peng
- Hunan Provincial Key Laboratory of Microbial Molecular Biology, State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, China
| | - Zirong Zhu
- Hunan Provincial Key Laboratory of Microbial Molecular Biology, State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, China
| | - Pengji Zhou
- Hunan Provincial Key Laboratory of Microbial Molecular Biology, State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, China
| | - Sisi Luo
- Hunan Provincial Key Laboratory of Microbial Molecular Biology, State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, China
| | - Junyan Xie
- Hunan Provincial Key Laboratory of Microbial Molecular Biology, State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, China
| | - Liqiu Xia
- Hunan Provincial Key Laboratory of Microbial Molecular Biology, State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, China
| | - Yunjun Sun
- Hunan Provincial Key Laboratory of Microbial Molecular Biology, State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, China
| | - Xuezhi Ding
- Hunan Provincial Key Laboratory of Microbial Molecular Biology, State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, China
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9
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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: 0.4] [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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10
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Lv J, Zhang X, Gao T, Cui T, Peng Q, Zhang J, Song F. Effect of the spoIIID mutation on mother cell lysis in Bacillus thuringiensis. Appl Microbiol Biotechnol 2019; 103:4103-4112. [PMID: 30953122 DOI: 10.1007/s00253-019-09722-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 02/19/2019] [Accepted: 02/23/2019] [Indexed: 11/28/2022]
Abstract
SpoIIID is a small, sequence-specific DNA-binding protein which can direct many genes' transcription and has an effect on spore formation in Bacillus subtilis. We investigated the role of SpoIIID in mother cell lysis in Bacillus thuringiensis. A β-galactosidase assay based on the promoter fusions with lacZ indicated that the sigK gene was positively regulated by SpoIIID and σK negatively regulated the expression of sigE. The spoIIID mutant strain exhibited no mother cell lysis in Schaeffer's sporulation medium (SSM) but did in ½ Luria-Bertani (LB) medium. cwlC is an essential hydrolase gene for mother cell lysis. Moreover, the expression of a PcwlC-lacZ fusion in spoIIID mutant was proved to be higher in ½ LB medium than in SSM. HD (ΔspoIIID)(ΔcwlC) mutant was obtained by knocking out the cwlC gene in HD(ΔspoIIID) and displayed no mother cell lysis in both SSM and ½ LB mediums. The deletion of spoIIID decreased the crystal protein production in HD73. The expression of Porf1cry8E and P5014 promoter fusions with lacZ gene in the acrystalliferous HD-(ΔspoIIID) mutant showed similar activity to that in the acrystalliferous HD73- strain before T7 and slightly higher than that in the acrystalliferous HD73- after T7. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that Cry1Ac production in HD-(ΔspoIIID) directed by the Porf1cry8E and P5014 promoters was at a similar level as that in HD73 wild strain. Altogether, these results suggested that the spoIIID mutant with Porf1cry8E or P5014 promoters could be an alternative delivery system for cry gene expression with no mature spore formation and medium-dependent mother cell lysis.
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Affiliation(s)
- Jing Lv
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Xin Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Tantan Gao
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Tingting Cui
- 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
| | - Jie Zhang
- 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.
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11
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Yang W, Ruan L, Tao J, Peng D, Zheng J, Sun M. Single Amino Acid Substitution in Homogentisate Dioxygenase Affects Melanin Production in Bacillus thuringiensis. Front Microbiol 2018; 9:2242. [PMID: 30364256 PMCID: PMC6193087 DOI: 10.3389/fmicb.2018.02242] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 09/03/2018] [Indexed: 12/20/2022] Open
Abstract
Bacillus thuringiensis formulation losing its activity under field conditions due to UV radiation and photoprotection of B. thuringiensis based on melanin has attracted the attention of researchers for many years. Here, a single amino acid substitution (G272E) in homogentisate 1,2-dioxygenase was found to be responsible for pigment overproduction in B. thuringiensis BMB181, a derivative of BMB171. Disrupting the gene encoding homogentisate dioxygenase in BMB171 induced the accumulation of the homogentisic acid and provoked an increased pigment formation. To gain insights into homogentisate 1,2-dioxygenase in B. thuringiensis, we constructed a total of 14 mutations with a single amino acid substitution, and six of the mutant proteins were found to affect the melanin production when substituted by alanine. This study provides a new way to construct pigment-overproducing strains by impairing the homogentisate dioxygenase with a single mutation in B. thuringiensis, and the findings will facilitate a better understanding of this enzyme.
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Affiliation(s)
- Wenjun Yang
- 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
| | - Jiangming Tao
- 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
| | - Jinshui Zheng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China.,College of Informatics, Huazhong Agricultural University, Wuhan, China
| | - Ming Sun
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
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12
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Novel Cell Wall Hydrolase CwlC from Bacillus thuringiensis Is Essential for Mother Cell Lysis. Appl Environ Microbiol 2018; 84:AEM.02640-17. [PMID: 29374039 DOI: 10.1128/aem.02640-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 01/10/2018] [Indexed: 11/20/2022] Open
Abstract
In this study, a sporulation-specific gene (tentatively named cwlC) involved in mother cell lysis in Bacillus thuringiensis was characterized. The encoded CwlC protein consists of an N-terminal N-acetylmuramoyl-l-alanine amidase (MurNAc-LAA) domain and a C-terminal amidase02 domain. The recombinant histidine-tagged CwlC proteins purified from Escherichia coli were able to directly bind to and digest the B. thuringiensis cell wall. The CwlC point mutations at the two conserved glutamic acid residues (Glu-24 and Glu-140) shown to be critical for the catalytic activity in homologous amidases resulted in a complete loss of cell wall lytic activity, suggesting that CwlC is an N-acetylmuramoyl-l-alanine amidase. Results of transcriptional analyses indicated that cwlC is transcribed as a monocistronic unit and that its expression is dependent on sporulation sigma factor K (σK). Deletion of cwlC completely blocked mother cell lysis during sporulation without impacting the sporulation frequency, Cry1Ac protein production, and insecticidal activity. Taken together, our data suggest that CwlC is an essential cell wall hydrolase for B. thuringiensis mother cell lysis during sporulation. Engineered B. thuringiensis strains targeting cwlC, which allows the crystal inclusion to remain encapsulated in the mother cell at the end of sporulation, may have the potential to become more effective biological control agents in agricultural applications since the crystal inclusion remains encapsulated in the mother cell at the end of sporulation.IMPORTANCE Mother cell lysis has been well studied in Bacillus subtilis, which involves three distinct yet functionally complementary cell wall hydrolases. In this study, a novel cell wall hydrolase, CwlC, was investigated and found to be essential for mother cell lysis in Bacillus thuringiensis CwlC of B. thuringiensis only shows 9 and 21% sequence identity with known B. subtilis mother cell hydrolases CwlB and CwlC, respectively, suggesting that mechanisms of mother cell lysis may differ between B. subtilis and B. thuringiensis The cwlC gene deletion completely blocked the release of spores and crystals from the mother cell without affecting insecticidal activity. This may provide a new effective strategy for crystal encapsulation against UV light inactivation.
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13
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A strong promoter of a non-cry gene directs expression of the cry1Ac gene in Bacillus thuringiensis. Appl Microbiol Biotechnol 2018. [DOI: 10.1007/s00253-018-8836-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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14
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Recombinant entomopathogenic agents: a review of biotechnological approaches to pest insect control. World J Microbiol Biotechnol 2017; 34:14. [DOI: 10.1007/s11274-017-2397-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 12/13/2017] [Indexed: 12/20/2022]
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15
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He X, Sun Z, He K, Guo S. Biopolymer microencapsulations of Bacillus thuringiensis crystal preparations for increased stability and resistance to environmental stress. Appl Microbiol Biotechnol 2017; 101:2779-2789. [PMID: 28050633 DOI: 10.1007/s00253-016-8070-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 12/12/2016] [Accepted: 12/17/2016] [Indexed: 10/20/2022]
Abstract
Parasporal crystals synthesized by Bacillus thuringiensis (Bt) have been widely used as microbial pesticides because of their toxicity to the larval stages of specific insects. However, parasporal crystals can be damaged by environmental stresses, such as high temperature, ultraviolet radiation, and desiccation. To reduce environmental susceptibility of parasporal crystals and extend the duration of their activity, we developed a new type of protection by making microcapsules of crystals (MCs). The microcapsules were self-assembled by alternate deposition (layer by layer) of low-cost chitosan and sodium alginate (or sodium carboxymethyl cellulose) on the crystal surface. Crystal toxins (Cry1Ac) were released from microcapsules at pH values above 9.0. Bioassay results demonstrated that microencapsulated preparations had larvicidal toxicity equivalent to the non-encapsulated form. Microencapsuled crystals were protected from environmental stresses such as high temperature and desiccation. The results indicate that microcapsule protection can enhance the efficacy of Bt in pest control, especially to Lepidoptera larvae that have a alkaline midgut.
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Affiliation(s)
- Xiaolin He
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Zhongqin Sun
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Kanglai He
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
| | - Shuyuan Guo
- School of Life Science, Beijing Institute of Technology, Beijing, China.
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16
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Construction of an environmental safe Bacillus thuringiensis engineered strain against Coleoptera. Appl Microbiol Biotechnol 2016; 100:4027-34. [DOI: 10.1007/s00253-015-7250-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 11/24/2015] [Accepted: 12/14/2015] [Indexed: 10/22/2022]
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17
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de Souza Freire I, Miranda-Vilela AL, Barbosa LCP, Martins ES, Monnerat RG, Grisolia CK. Evaluation of cytotoxicity, genotoxicity and hematotoxicity of the recombinant spore-crystal complexes Cry1Ia, Cry10Aa and Cry1Ba6 from Bacillus thuringiensis in Swiss mice. Toxins (Basel) 2014; 6:2872-85. [PMID: 25268978 PMCID: PMC4210873 DOI: 10.3390/toxins6102872] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 07/29/2014] [Accepted: 08/12/2014] [Indexed: 01/29/2023] Open
Abstract
The insecticidal properties of Cry-endotoxins from Bacillus thuringiensis (Bt) have long been used as spore-crystals in commercial spray formulations for insect control. Recently, some Bt-endotoxin genes have been cloned in many different plants. Toxicological evaluations of three spore-crystal endotoxins, BtCry1Ia, BtCry10Aa and BtCry1Ba6 from B. thuringiensis, were carried out on mice to understand their adverse effects on hematological systems and on genetic material. These three spore-crystals have shown toxic activity to the boll weevil, which is one of the most aggressive pests of the cotton crop. Cry1Ia, Cry10Aa and Cry1Ba6 did not increase the micronucleus frequency in the peripheral erythrocytes of mice and did not cause changes in the frequency of polychromatic erythrocytes. However, some hematologic disburbances were observed, specifically related to Cry1Ia and Cry1Ba6, respectively, for the erythroid and lymphoid lineage. Thus, although the profile of such adverse side effects can be related to their high level of exposure, which is not commonly found in the environment, results showed that these Bt spore-crystals were not harmless to mice, indicating that each spore-crystal endotoxin presents a characteristic profile of toxicity and might be investigated individually.
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Affiliation(s)
- Ingrid de Souza Freire
- Department of Genetics and Morphology, Institute of Biological Sciences, University of Brasilia, Brasília 70910-900, Brazil.
| | - Ana Luisa Miranda-Vilela
- Department of Genetics and Morphology, Institute of Biological Sciences, University of Brasilia, Brasília 70910-900, Brazil.
| | - Lilian Carla Pereira Barbosa
- Department of Genetics and Morphology, Institute of Biological Sciences, University of Brasilia, Brasília 70910-900, Brazil.
| | - Erica Soares Martins
- Instituto Mato-Grossense do Algodão-IMAmt/Faculdades Integradas ICESP/Promove de Brasília, Brasília 78008-000, Brazil.
| | - Rose Gomes Monnerat
- Laboratory of Bacteriology, Centro Nacional de Recursos Genéticos (CENARGEN), Brasília 70770-917, Brazil.
| | - Cesar Koppe Grisolia
- Department of Genetics and Morphology, Institute of Biological Sciences, University of Brasilia, Brasília 70910-900, Brazil.
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18
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Division of labour and terminal differentiation in a novel Bacillus thuringiensis strain. ISME JOURNAL 2014; 9:286-96. [PMID: 25083932 DOI: 10.1038/ismej.2014.122] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2014] [Revised: 05/12/2014] [Accepted: 06/11/2014] [Indexed: 11/08/2022]
Abstract
A major challenge in bacterial developmental biology has been to understand the mechanisms underlying cell fate decisions. Some differentiated cell types display cooperative behaviour. Cooperation is one of the greatest mysteries of evolutionary biology and microbes have been considered as an excellent system for experimentally testing evolution theories. Bacillus thuringiensis (Bt) is a spore-forming bacterium, which is genetically closely related to B. anthracis, the agent of anthrax, and to B. cereus, an opportunistic human pathogen. The defining feature that distinguishes Bt from its relatives is its ability to produce crystal inclusions in the sporulating cells. These toxins are solubilized after ingestion and are cooperative public goods in insect hosts. In this study, we describe a Bt strain LM1212 that presents the unique ability to terminally differentiate into crystal producers and spore formers. Transcriptional analysis based on lacZ and gfp reporter genes suggested that this phenotype is the consequence of a new type of cell differentiation associated with a novel regulation mode of cry gene expression. The differentiating crystal-producer phenotype has higher spore productivity than a typical Bt strain and is better able to compete with Cry toxin null 'cheaters'. Potentially, this division of labour provides additional fitness benefits in terms of spore viability or durability of Cry toxin.
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19
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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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20
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Screening of cry-type promoters with strong activity and application in Cry protein encapsulation in a sigK mutant. Appl Microbiol Biotechnol 2014; 98:7901-9. [PMID: 24928660 DOI: 10.1007/s00253-014-5874-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 05/15/2014] [Accepted: 05/24/2014] [Indexed: 10/25/2022]
Abstract
To optimize the expression of cry genes in a Bacillus thuringiensis sigK mutant failing in crystal releasing, the transcriptional activity of the cry promoters cry1A, cry3A, cry4A, and cry8E was compared using lacZ gene fusions. A beta-galactosidase assay indicated that the cry8E promoter showed the highest transcriptional activity. A novel Escherichia coli-B. thuringiensis shuttle vector pHT315-8E21b was constructed for cry gene expression using the cry8E promoter and the multiple cloning sites from vector pET21b, based on vector pHT315. SDS-PAGE analysis showed that the expression of the cry1Ac gene directed by the cry8E promoter was increased by approximately 2.4-fold over the expression directed by the cry3A promoter. The cry1Ba gene was expressed in the sigK mutant with the constructed vector pHT315-8E21b. Normal bipyramidal crystals encapsulated in mother cell were observed by transmission electron microscopy (TEM). The encapsulated Cry1Ba protein expressed in the sigK mutant showed activity against Ostrinia furnacalis and Plutella xylostella similar to that of the released Cry1Ba protein expressed in the acrystalliferous strain HD73 and can be protected from inactivation by UV light. All these results suggest that the cry8E promoter can be an efficient transcriptional element for cry gene expression in sigK mutants and can be utilized for the construction of a genetically engineered strain.
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21
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Crane J, Frodyma M, Bergstrom G. Nutrient-induced spore germination of a Bacillus amyloliquefaciens
biocontrol agent on wheat spikes. J Appl Microbiol 2014; 116:1572-83. [DOI: 10.1111/jam.12480] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 02/04/2014] [Accepted: 02/13/2014] [Indexed: 11/29/2022]
Affiliation(s)
- J.M. Crane
- Department of Plant Pathology and Plant-Microbe Biology; Cornell University; Ithaca NY USA
| | | | - G.C. Bergstrom
- Department of Plant Pathology and Plant-Microbe Biology; Cornell University; Ithaca NY USA
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22
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Freire IS, Miranda-Vilela AL, Fascineli ML, Oliveira-Filho EC, Martins ES, Monnerat RG, Grisolia CK. Genotoxic evaluation in Oreochromis niloticus (Fish: Characidae) of recombinant spore-crystal complexes Cry1Ia, Cry10Aa and Cry1Ba6 from Bacillus thuringiensis. ECOTOXICOLOGY (LONDON, ENGLAND) 2014; 23:267-272. [PMID: 24374720 DOI: 10.1007/s10646-013-1170-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/18/2013] [Indexed: 06/03/2023]
Abstract
Bioinsecticides from Bacillus thuringiensis (Bt) are widely used around the world in biological control against larval stages of many insect species. Bt has been considered a biopesticide that is highly specific to different orders of insects, non-polluting and harmless to humans and other vertebrates, thus becoming a viable alternative for combating agricultural pests and insect vectors of diseases. The family of Bt δ-endotoxins are crystal-protein inclusions showing toxicity to insects' midgut, causing cell lysis leading to starvation, septicemia and death. The aim of this study is to evaluate the genotoxic potential of recombinant Bt spore-crystals expressing Cry1Ia, Cry10Aa and Cry1Ba6 on peripheral erythrocyte cells of Oreochromis niloticus, through comet assay, micronucleus (MN) test and nuclear abnormalities (NA) analysis. Fish (n = 10/group) were exposed for 96 h at 10(7) spores 30 l(-1), 10(8) spores 30 l(-1) or 10(9) spores 30 l(-1) of Bt spore-crystals. Cry1Ia showed a significant increase in comet cells at levels 1 and 2, but not at levels 3 and 4, so it was not mutagenic nor did it induce MN or NA. These three spore-crystals showed some fish toxicity at only the highest exposure level, which normally does not occur in the field.
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Affiliation(s)
- I S Freire
- Department of Genetics and Morphology, Institute of Biological Sciences, University of Brasilia, Brasília, DF, Brazil
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23
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Transcriptional regulation and characteristics of a novel N-acetylmuramoyl-L-alanine amidase gene involved in Bacillus thuringiensis mother cell lysis. J Bacteriol 2013; 195:2887-97. [PMID: 23603740 DOI: 10.1128/jb.00112-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Bacillus thuringiensis, a novel N-acetylmuramoyl-L-alanine amidase gene (named cwlB) was detected, and the CwlB protein was purified and characterized. Reverse transcription-PCR (RT-PCR) results indicated that cwlB and an upstream gene (named cwlA) formed one transcriptional unit. 5' rapid amplification of cDNA ends (5'-RACE)-PCR and transcriptional fusions with the lacZ gene indicated that transcription of the operon was directed by a promoter, P(cwlA), which is located upstream from the cwlA gene and that the transcription start site is a single 5'-end nucleotide residue T located 25 nucleotides (bp) upstream from the cwlA translational start codon. Moreover, the activity of P(cwlA) was controlled by σ(K). Morphological analysis suggested that the mutation of cwlB could delay spore release compared to the timing of spore release in the wild-type strain. Western blot assay demonstrated that purified CwlB bound to the B. thuringiensis cell wall. Observations with laser confocal microscopy and a green fluorescent protein-based reporter system demonstrated that the CwlB protein localizes to the cell envelope. All results suggest that the CwlB protein is involved in mother cell lysis in B. thuringiensis.
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24
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Ben Khedher S, Zouari N, Messaddeq N, Schultz P, Jaoua S. Overproduction of Delta-Endotoxins by Sporeless Bacillus thuringiensis Mutants Obtained by Nitrous Acid Mutagenesis. Curr Microbiol 2010; 62:38-43. [DOI: 10.1007/s00284-010-9670-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Accepted: 05/04/2010] [Indexed: 10/19/2022]
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25
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Yan G, Song F, Shu C, Liu J, Liu C, Huang D, Feng S, Zhang J. An engineered Bacillus thuringiensis strain with insecticidal activity against Scarabaeidae (Anomala corpulenta) and Chrysomelidae (Leptinotarsa decemlineata and Colaphellus bowringi). Biotechnol Lett 2009; 31:697-703. [DOI: 10.1007/s10529-009-9913-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 12/17/2008] [Accepted: 12/18/2008] [Indexed: 10/21/2022]
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26
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Ghelardi E, Celandroni F, Salvetti S, Fiscarelli E, Senesi S. Bacillus thuringiensis pulmonary infection: critical role for bacterial membrane-damaging toxins and host neutrophils. Microbes Infect 2007; 9:591-8. [PMID: 17387030 DOI: 10.1016/j.micinf.2007.02.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Revised: 01/23/2007] [Accepted: 02/02/2007] [Indexed: 12/01/2022]
Abstract
The occurrence of Bacillus thuringiensis bacteremia in a neutropenic patient suffering from severe pulmonary disease addressed the question of whether the aggressive behavior of B. thuringiensis depended on the host status and/or on the membrane-damaging toxins the isolate produced. After intratracheal injection, BALB/c mice developed pneumonia followed by fatal dissemination into deep organs, with mice rendered neutropenic by cyclophosphamide injection being extremely more susceptible to infection than normal animals. In animals infected with isogenic strains of B. thuringiensis progressively more defective in membrane-damaging toxins (407 Cry->IP2>MP02), an increase in the 50% lethal dose was registered (3.9x10(5), 1.1x10(6), 1.2x10(7)CFU). Consistently, after non-lethal dose application, only 407 Cry- replicated intrapulmonary, reaching a bacterial burden 4.7-fold and 40.9-fold higher than IP2 (P=0.018) and MP02 (P=0.008) at 48h post-inoculation. Notably, the time-course of infection was similar in animals infected with viable bacilli or spores, with neutropenic mice always being more susceptible to infection. The overall results indicate that B. thuringiensis may be responsible for opportunistic infections and strongly suggest that membrane-damaging toxins contribute to intrapulmonary bacterial persistence favoring dissemination.
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Affiliation(s)
- Emilia Ghelardi
- Dipartimento di Patologia Sperimentale, Biotecnologie Mediche, Infettivologia ed Epidemiologia, Università di Pisa, Via San Zeno 37, 56127 Pisa, Italy
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27
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Crickmore N. Beyond the spore – past and future developments of Bacillus thuringiensis as a biopesticide. J Appl Microbiol 2006; 101:616-9. [PMID: 16907811 DOI: 10.1111/j.1365-2672.2006.02936.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Formulated and sporulated cultures of Bacillus thuringiensis (Bt) are widely used as foliar sprays as part of integrated pest management strategies against insect pests of agricultural crops. Although in several cases the presence of the spore has been shown to improve the activity of the product, other Bt-based insecticides have been developed in which the spore is absent. The most notable of these are transgenic plants expressing just the insect toxin gene from the bacterium. This paper will discuss these developments, and the advantages and disadvantages of having the spore present.
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Affiliation(s)
- N Crickmore
- School of Life Sciences, University of Sussex, Falmer, Brighton, UK.
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28
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Molecular approaches for identification and construction of novel insecticidal genes for crop protection. World J Microbiol Biotechnol 2005. [DOI: 10.1007/s11274-005-9027-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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29
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Seo JH, Yeo JS, Cha HJ. Baculoviral polyhedrin-Bacillus thuringiensis toxin fusion protein: a protein-based bio-insecticide expressed in Escherichia coli. Biotechnol Bioeng 2005; 92:166-72. [PMID: 15981278 DOI: 10.1002/bit.20592] [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: 11/06/2022]
Abstract
Previously, we found that baculoviral polyhedrin (Polh) used as a fusion partner for recombinant expression in Escherichia coli showed almost the same characteristics (rapid solubilization under alkaline conditions and specific degradation by specific alkaline proteases in insect midgut) as the native baculoviral Polh, and formed easily isolatable inclusion bodies. Here, Polh derived from the Autographa californica nuclear polyhedrosis virus (AcNPV) was fused with a Bacillus thuringiensis (Bt) toxin protein (truncated Cry1Ac having toxin region as a model Bt toxin) for the novel generation of a new bio-insecticide. The Polh-Cry1Ac fusion protein (approximately 99 kDa) was highly expressed (3.6-fold induction as compared to E. coli-derived single Cry1Ac (approximately 68 kDa)) as an insoluble inclusion body fraction in E. coli. Trypsin and alpha-chymotrypsin, which have similar properties to the insect midgut alkaline proteases, rapidly degraded the Polh portion in vitro, leaving only the toxic Cry1Ac protein behind. In vivo, the Polh-Cry1Ac fusion protein showed high insecticidal activity against the pest, Plutella xylostella. Because this novel bio-insecticide employs E. coli as the host, mass production at a low cost should be possible. Also, since this is a protein-based insecticide, living modified organism (LMO) issues such as environmental and ecological safety can be avoided.
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Affiliation(s)
- Jeong Hyun Seo
- Department of Chemical Engineering & Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, Korea
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30
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Schallmey M, Singh A, Ward OP. Developments in the use of Bacillus species for industrial production. Can J Microbiol 2004; 50:1-17. [PMID: 15052317 DOI: 10.1139/w03-076] [Citation(s) in RCA: 652] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Bacillus species continue to be dominant bacterial workhorses in microbial fermentations. Bacillus subtilis (natto) is the key microbial participant in the ongoing production of the soya-based traditional natto fermentation, and some Bacillus species are on the Food and Drug Administration's GRAS (generally regarded as safe) list. The capacity of selected Bacillus strains to produce and secrete large quantities (20-25 g/L) of extracellular enzymes has placed them among the most important industrial enzyme producers. The ability of different species to ferment in the acid, neutral, and alkaline pH ranges, combined with the presence of thermophiles in the genus, has lead to the development of a variety of new commercial enzyme products with the desired temperature, pH activity, and stability properties to address a variety of specific applications. Classical mutation and (or) selection techniques, together with advanced cloning and protein engineering strategies, have been exploited to develop these products. Efforts to produce and secrete high yields of foreign recombinant proteins in Bacillus hosts initially appeared to be hampered by the degradation of the products by the host proteases. Recent studies have revealed that the slow folding of heterologous proteins at the membrane-cell wall interface of Gram-positive bacteria renders them vulnerable to attack by wall-associated proteases. In addition, the presence of thiol-disulphide oxidoreductases in B. subtilis may be beneficial in the secretion of disulphide-bond-containing proteins. Such developments from our understanding of the complex protein translocation machinery of Gram-positive bacteria should allow the resolution of current secretion challenges and make Bacillus species preeminent hosts for heterologous protein production. Bacillus strains have also been developed and engineered as industrial producers of nucleotides, the vitamin riboflavin, the flavor agent ribose, and the supplement poly-gamma-glutamic acid. With the recent characterization of the genome of B. subtilis 168 and of some related strains, Bacillus species are poised to become the preferred hosts for the production of many new and improved products as we move through the genomic and proteomic era.
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