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Membrane-Binding Biomolecules Influence the Rate of Vesicle Exchange between Bacteria. Appl Environ Microbiol 2022; 88:e0134622. [PMID: 36342184 PMCID: PMC9746307 DOI: 10.1128/aem.01346-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The exchange of bacterial extracellular vesicles facilitates molecular exchange between cells, including the horizontal transfer of genetic material. Given the implications of such transfer events on cell physiology and adaptation, some bacterial cells have likely evolved mechanisms to regulate vesicle exchange. Past work has identified mechanisms that influence the formation of extracellular vesicles, including the production of small molecules that modulate membrane structure; however, whether these mechanisms also modulate vesicle uptake and have an overall impact on the rate of vesicle exchange is unknown. Here, we show that membrane-binding molecules produced by microbes influence both the formation and uptake of extracellular vesicles and have the overall impact of increasing the vesicle exchange rate within a bacterial coculture. In effect, production of compounds that increase vesicle exchange rates encourage gene exchange between neighboring cells. The ability of several membrane-binding compounds to increase vesicle exchange was demonstrated. Three of these compounds, nisin, colistin, and polymyxin B, are antimicrobial peptides added at sub-inhibitory concentrations. These results suggest that a potential function of exogenous compounds that bind to membranes may be the regulation of vesicle exchange between cells. IMPORTANCE The exchange of bacterial extracellular vesicles is one route of gene transfer between bacteria, although it was unclear if bacteria developed strategies to modulate the rate of gene transfer within vesicles. In eukaryotes, there are many examples of specialized molecules that have evolved to facilitate the production, loading, and uptake of vesicles. Recent work with bacteria has shown that some small molecules influence membrane curvature and induce vesicle formation. Here, we show that similar compounds facilitate vesicle uptake, thereby increasing the overall rate of vesicle exchange within bacterial populations. The addition of membrane-binding compounds, several of them antibiotics at subinhibitory concentrations, to a bacterial coculture increased the rate of horizontal gene transfer via vesicle exchange.
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Osterloh A. Vaccination against Bacterial Infections: Challenges, Progress, and New Approaches with a Focus on Intracellular Bacteria. Vaccines (Basel) 2022; 10:vaccines10050751. [PMID: 35632507 PMCID: PMC9144739 DOI: 10.3390/vaccines10050751] [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: 03/30/2022] [Revised: 05/08/2022] [Accepted: 05/09/2022] [Indexed: 12/13/2022] Open
Abstract
Many bacterial infections are major health problems worldwide, and treatment of many of these infectious diseases is becoming increasingly difficult due to the development of antibiotic resistance, which is a major threat. Prophylactic vaccines against these bacterial pathogens are urgently needed. This is also true for bacterial infections that are still neglected, even though they affect a large part of the world’s population, especially under poor hygienic conditions. One example is typhus, a life-threatening disease also known as “war plague” caused by Rickettsia prowazekii, which could potentially come back in a war situation such as the one in Ukraine. However, vaccination against bacterial infections is a challenge. In general, bacteria are much more complex organisms than viruses and as such are more difficult targets. Unlike comparatively simple viruses, bacteria possess a variety of antigens whose immunogenic potential is often unknown, and it is unclear which antigen can elicit a protective and long-lasting immune response. Several vaccines against extracellular bacteria have been developed in the past and are still used successfully today, e.g., vaccines against tetanus, pertussis, and diphtheria. However, while induction of antibody production is usually sufficient for protection against extracellular bacteria, vaccination against intracellular bacteria is much more difficult because effective defense against these pathogens requires T cell-mediated responses, particularly the activation of cytotoxic CD8+ T cells. These responses are usually not efficiently elicited by immunization with non-living whole cell antigens or subunit vaccines, so that other antigen delivery strategies are required. This review provides an overview of existing antibacterial vaccines and novel approaches to vaccination with a focus on immunization against intracellular bacteria.
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Affiliation(s)
- Anke Osterloh
- Department of Infection Immunology, Research Center Borstel, Parkallee 22, 23845 Borstel, Germany
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3
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Chen Y, Li J, Zhang S, Hu J, Chen X, Lin T, Dang D, Fan J. Controlling expression and inhibiting function of the toxin reporter for simple detection of the promoters’ activities in Escherichia coli. Enzyme Microb Technol 2022; 158:110051. [DOI: 10.1016/j.enzmictec.2022.110051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 04/10/2022] [Accepted: 04/11/2022] [Indexed: 01/09/2023]
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Chen H, Ji H, Kong X, Lei P, Yang Q, Wu W, Jin L, Sun D. Bacterial Ghosts-Based Vaccine and Drug Delivery Systems. Pharmaceutics 2021; 13:1892. [PMID: 34834306 PMCID: PMC8622331 DOI: 10.3390/pharmaceutics13111892] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/26/2021] [Accepted: 11/02/2021] [Indexed: 12/13/2022] Open
Abstract
Bacterial ghosts (BGs) are empty bacterial envelopes of Gram-negative bacteria produced by controlled expressions of cloned gene E, forming a lysis tunnel structure within the envelope of the living bacteria. Globally, BGs have been used as vaccine delivery systems and vaccine adjuvants. There is an increasing interest in the development of novel delivery systems that are based on BGs for biomedical applications. Due to intact reservation of bacterial cell membranes, BGs have an inherent immunogenicity, which enables targeted drug delivery and controlled release. As carrier vehicles, BGs protect drugs from interference by external factors. In recent years, there has been an increasing interest in BG-based delivery systems against tumors, inflammation, and infection, among others. Herein, we reviewed the preparation methods for BGs, interactions between BGs and the host, and further highlighted research progress in BG development.
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Affiliation(s)
- Haojie Chen
- Institute of Life Sciences & Engineering Laboratory of Zhejiang Province for Pharmaceutical Development of Growth Factors, Wenzhou University, Wenzhou 325035, China; (H.C.); (H.J.); (X.K.); (P.L.); (W.W.)
| | - Hao Ji
- Institute of Life Sciences & Engineering Laboratory of Zhejiang Province for Pharmaceutical Development of Growth Factors, Wenzhou University, Wenzhou 325035, China; (H.C.); (H.J.); (X.K.); (P.L.); (W.W.)
| | - Xiangjun Kong
- Institute of Life Sciences & Engineering Laboratory of Zhejiang Province for Pharmaceutical Development of Growth Factors, Wenzhou University, Wenzhou 325035, China; (H.C.); (H.J.); (X.K.); (P.L.); (W.W.)
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao 999078, China
| | - Pengyu Lei
- Institute of Life Sciences & Engineering Laboratory of Zhejiang Province for Pharmaceutical Development of Growth Factors, Wenzhou University, Wenzhou 325035, China; (H.C.); (H.J.); (X.K.); (P.L.); (W.W.)
| | - Qinsi Yang
- Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou 325000, China;
| | - Wei Wu
- Institute of Life Sciences & Engineering Laboratory of Zhejiang Province for Pharmaceutical Development of Growth Factors, Wenzhou University, Wenzhou 325035, China; (H.C.); (H.J.); (X.K.); (P.L.); (W.W.)
- Key Laboratory for Biorheological Science and Technology of Ministry of Education & State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing 400030, China
| | - Libo Jin
- Institute of Life Sciences & Engineering Laboratory of Zhejiang Province for Pharmaceutical Development of Growth Factors, Wenzhou University, Wenzhou 325035, China; (H.C.); (H.J.); (X.K.); (P.L.); (W.W.)
| | - Da Sun
- Institute of Life Sciences & Engineering Laboratory of Zhejiang Province for Pharmaceutical Development of Growth Factors, Wenzhou University, Wenzhou 325035, China; (H.C.); (H.J.); (X.K.); (P.L.); (W.W.)
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5
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Pawlowski J, Apothéloz‐Perret‐Gentil L, Altermatt F. Environmental DNA: What's behind the term? Clarifying the terminology and recommendations for its future use in biomonitoring. Mol Ecol 2020; 29:4258-4264. [DOI: 10.1111/mec.15643] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 08/20/2020] [Accepted: 09/07/2020] [Indexed: 02/06/2023]
Affiliation(s)
- Jan Pawlowski
- Department of Genetics and Evolution University of Geneva Geneva Switzerland
- ID‐Gene ecodiagnostics, Campus Biotech Innovation Park Geneva Switzerland
- Institute of Oceanology Polish Academy of Sciences Sopot Poland
| | - Laure Apothéloz‐Perret‐Gentil
- Department of Genetics and Evolution University of Geneva Geneva Switzerland
- ID‐Gene ecodiagnostics, Campus Biotech Innovation Park Geneva Switzerland
| | - Florian Altermatt
- Department of Aquatic Ecology Eawag: Swiss Federal Institute of Aquatic Science and Technology Dübendorf Switzerland
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zürich Switzerland
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Menacho‐Melgar R, Moreb EA, Efromson JP, Yang T, Hennigan JN, Wang R, Lynch MD. Improved two‐stage protein expression and purification via autoinduction of both autolysis and auto DNA/RNA hydrolysis conferred by phage lysozyme and DNA/RNA endonuclease. Biotechnol Bioeng 2020; 117:2852-2860. [DOI: 10.1002/bit.27444] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 05/06/2020] [Accepted: 05/26/2020] [Indexed: 01/11/2023]
Affiliation(s)
| | - Eirik A. Moreb
- Department of Biomedical Engineering Duke University Durham North Carolina
| | - John P. Efromson
- Department of Biomedical Engineering Duke University Durham North Carolina
| | - Tian Yang
- Department of Biomedical Engineering Duke University Durham North Carolina
| | | | - Ruixin Wang
- Department of Biomedical Engineering Duke University Durham North Carolina
| | - Michael D. Lynch
- Department of Biomedical Engineering Duke University Durham North Carolina
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Abstract
INTRODUCTION Bacterial ghosts are intact bacterial cell envelopes that are emptied of their content by gentle biological or chemical poring methods. Ghost techniques increase the safety of the killed vaccines, while maintaining their antigenicity due to mild preparation procedures. Moreover, ghost-platforms may express and/or carry several antigens or plasmid-DNA encoding for protein epitopes. AREAS COVERED In this review, the development in ghost-vaccine production over the last 30 years is classified and discussed. The different applications of ghost-vaccines, how they trigger the immune system, their advantages and limitations are displayed. The phage-mediated lysis, molecular manipulation of the lysis-genes, and the biotechnological production of ghosts are described. The trials are classified according to the pattern of lysis and to the type of bacteria. Further subdivision includes chronological ordered application of the ghost as alternative-killed vaccine, recombinant antigen platform, plasmid DNA carrier, adjuvants, and dendritic cell inducer. Particular trials for specific pathogens or from distinct research schools are gathered. EXPERT OPINION Ghosts are highly qualified to act as immune-presenting platforms that express and/or carry several recombinant and DNA vaccines, as well as, being efficient alternative-killed vaccines. The coming years will show more molecular advances to develop ghost-production and to express more antigens.
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Affiliation(s)
- Ali M Batah
- Tropical Disease Research Center, University of Science and Technology , Sana'a, Yemen
| | - Tarek A Ahmad
- Morehouse School of Medicine , Atlanta, GA, USA.,Library Sector, Bibliotheca Alexandrina , Alexandria, Egypt
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Calderón-Franco D, Lin Q, van Loosdrecht MCM, Abbas B, Weissbrodt DG. Anticipating Xenogenic Pollution at the Source: Impact of Sterilizations on DNA Release From Microbial Cultures. Front Bioeng Biotechnol 2020; 8:171. [PMID: 32232035 PMCID: PMC7082761 DOI: 10.3389/fbioe.2020.00171] [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] [Received: 12/18/2019] [Accepted: 02/19/2020] [Indexed: 11/23/2022] Open
Abstract
The dissemination of DNA and xenogenic elements across waterways is under scientific and public spotlight due to new gene-editing tools, such as do-it-yourself (DIY) CRISPR-Cas kits deployable at kitchen table. Over decades, prevention of spread of genetically modified organisms (GMOs), antimicrobial resistances (AMR), and pathogens from transgenic systems has focused on microbial inactivation. However, sterilization methods have not been assessed for DNA release and integrity. Here, we investigated the fate of intracellular DNA from cultures of model prokaryotic (Escherichia coli) and eukaryotic (Saccharomyces cerevisiae) cells that are traditionally used as microbial chassis for genetic modifications. DNA release was tracked during exposure of these cultures to conventional sterilization methods. Autoclaving, disinfection with glutaraldehyde, and microwaving are used to inactivate broths, healthcare equipment, and GMOs produced at kitchen table. DNA fragmentation and PCR-ability were measured on top of cell viability and morphology. Impact of these methods on DNA integrity was verified on a template of free λ DNA. Intense regular autoclaving (121°C, 20 min) resulted in the most severe DNA degradation and lowest household gene amplification capacity: 1.28 ± 0.11, 2.08 ± 0.03, and 4.96 ± 0.28 logs differences to the non-treated controls were measured from E. coli, S. cerevisiae, and λ DNA, respectively. Microwaving exerted strong DNA fragmentation after 100 s of exposure when free λ DNA was in solution (3.23 ± 0.06 logs difference) but a minor effect was observed when DNA was released from E. coli and S. cerevisiae (0.24 ± 0.14 and 1.32 ± 0.02 logs differences with the control, respectively). Glutaraldehyde prevented DNA leakage by preserving cell structures, while DNA integrity was not altered. The results show that current sterilization methods are effective on microorganism inactivation but do not safeguard an aqueous residue exempt of biologically reusable xenogenic material, being regular autoclaving the most severe DNA-affecting method. Reappraisal of sterilization methods is required along with risk assessment on the emission of DNA fragments in urban systems and nature.
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Affiliation(s)
| | | | | | | | - David G. Weissbrodt
- Department of Biotechnology, Delft University of Technology, Delft, Netherlands
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9
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Abstract
Bacterial ghosts (BG) are empty cell envelopes derived from Gram-negative bacteria. They contain many innate immunostimulatory agonists, and are potent activators of a broad range of cell types involved in innate and adaptive immunity. Several considerable studies have demonstrated the effectiveness of BG as adjuvants as well as their ability to induce proinflammatory cytokine production by a range of immune and non-immune cell types. These proinflammatory cytokines trigger a generalized recruitment of T and B lymphocytes to lymph nodes that maximize the chances of encounter with their cognate antigen, and subsequent elicitation of potent immune responses. The plasticity of BG has allowed for the generation of envelope-bound foreign antigens in immunologically active forms that have proven to be effective vaccines in animal models. Besides their adjuvant property, BG also effectively deliver DNA-encoded antigens to dendritic cells, thereby leading to high transfection efficiencies, which subsequently result in higher gene expressions and improved immunogenicity of DNA-based vaccines. In this review, we summarize our understanding of BG interactions with the host immune system, their exploitation as an adjuvant and a delivery system, and address important areas of future research interest.
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Affiliation(s)
- Irshad A Hajam
- College of Veterinary Medicine, Chonbuk National University, Iksan, 54596, Republic of Korea
| | - Pervaiz A Dar
- Department of Medicine, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, 43614, USA
| | - Gayeon Won
- College of Veterinary Medicine, Chonbuk National University, Iksan, 54596, Republic of Korea
| | - John Hwa Lee
- College of Veterinary Medicine, Chonbuk National University, Iksan, 54596, Republic of Korea.
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10
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Gawin A, Valla S, Brautaset T. The XylS/Pm regulator/promoter system and its use in fundamental studies of bacterial gene expression, recombinant protein production and metabolic engineering. Microb Biotechnol 2017; 10:702-718. [PMID: 28276630 PMCID: PMC5481539 DOI: 10.1111/1751-7915.12701] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/04/2017] [Accepted: 02/07/2017] [Indexed: 12/21/2022] Open
Abstract
The XylS/Pm regulator/promoter system originating from the Pseudomonas putida TOL plasmid pWW0 is widely used for regulated low‐ and high‐level recombinant expression of genes and gene clusters in Escherichia coli and other bacteria. Induction of this system can be graded by using different cheap benzoic acid derivatives, which enter cells by passive diffusion, operate in a dose‐dependent manner and are typically not metabolized by the host cells. Combinatorial mutagenesis and selection using the bla gene encoding β‐lactamase as a reporter have demonstrated that the Pm promoter, the DNA sequence corresponding to the 5′ untranslated end of its cognate mRNA and the xylS coding region can be modified and improved relative to various types of applications. By combining such mutant genetic elements, altered and extended expression profiles were achieved. Due to their unique properties, obtained systems serve as a genetic toolbox valuable for heterologous protein production and metabolic engineering, as well as for basic studies aiming at understanding fundamental parameters affecting bacterial gene expression. The approaches used to modify XylS/Pm should be adaptable for similar improvements also of other microbial expression systems. In this review, we summarize constructions, characteristics, refinements and applications of expression tools using the XylS/Pm system.
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Affiliation(s)
- Agnieszka Gawin
- Department of Biotechnology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Svein Valla
- Department of Biotechnology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Trygve Brautaset
- Department of Biotechnology, Norwegian University of Science and Technology, Trondheim, Norway
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11
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Hu YOO, Karlson B, Charvet S, Andersson AF. Diversity of Pico- to Mesoplankton along the 2000 km Salinity Gradient of the Baltic Sea. Front Microbiol 2016; 7:679. [PMID: 27242706 PMCID: PMC4864665 DOI: 10.3389/fmicb.2016.00679] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 04/26/2016] [Indexed: 01/12/2023] Open
Abstract
Microbial plankton form the productive base of both marine and freshwater ecosystems and are key drivers of global biogeochemical cycles of carbon and nutrients. Plankton diversity is immense with representations from all major phyla within the three domains of life. So far, plankton monitoring has mainly been based on microscopic identification, which has limited sensitivity and reproducibility, not least because of the numerical majority of plankton being unidentifiable under the light microscope. High-throughput sequencing of taxonomic marker genes offers a means to identify taxa inaccessible by traditional methods; thus, recent studies have unveiled an extensive previously unknown diversity of plankton. Here, we conducted ultra-deep Illumina sequencing (average 105 sequences/sample) of rRNA gene amplicons of surface water eukaryotic and bacterial plankton communities sampled in summer along a 2000 km transect following the salinity gradient of the Baltic Sea. Community composition was strongly correlated with salinity for both bacterial and eukaryotic plankton assemblages, highlighting the importance of salinity for structuring the biodiversity within this ecosystem. In contrast, no clear trends in alpha-diversity for bacterial or eukaryotic communities could be detected along the transect. The distribution of major planktonic taxa followed expected patterns as observed in monitoring programs, but groups novel to the Baltic Sea were also identified, such as relatives to the coccolithophore Emiliana huxleyi detected in the northern Baltic Sea. This study provides the first ultra-deep sequencing-based survey on eukaryotic and bacterial plankton biogeography in the Baltic Sea.
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Affiliation(s)
- Yue O O Hu
- Science for Life Laboratory, Division of Gene Technology, School of Biotechnology, KTH Royal Institute of Technology Stockholm, Sweden
| | - Bengt Karlson
- Oceanography, Research & Development, Swedish Meteorological and Hydrological Institute Gothenburg, Sweden
| | - Sophie Charvet
- Leibniz Institute for Baltic Sea Research Warnemünde Rostock, Germany
| | - Anders F Andersson
- Science for Life Laboratory, Division of Gene Technology, School of Biotechnology, KTH Royal Institute of Technology Stockholm, Sweden
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12
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Abstract
Active containment systems are a major tool for reducing the uncertainty associated with the introduction of monocultures, genetically engineered or not, into target habitats for a large number of biotechnological applications (e.g., bioremediation, bioleaching, biopesticides, biofuels, biotransformations, live vaccines, etc.). While biological containment reduces the survival of the introduced organism outside the target habitat and/or upon completion of the projected task, gene containment strategies reduce the lateral spread of the key genetic determinants to indigenous microorganisms. In fundamental research, suicide circuits become relevant tools to address the role of gene transfer, mainly plasmid transfer, in evolution and how this transfer contributes to genome plasticity and to the rapid adaptation of microbial communities to environmental changes. Many lethal functions and regulatory circuits have been used and combined to design efficient containment systems. As many new genomes are being sequenced, novel lethal genes and regulatory elements are available, e.g., new toxin-antitoxin modules, and they could be used to increase further the current containment efficiencies and to expand containment to other organisms. Although the current containment systems can increase the predictability of genetically modified organisms in the environment, containment will never be absolute, due to the existence of mutations that lead to the appearance of surviving subpopulations. In this sense, orthogonal systems (xenobiology) appear to be the solution for setting a functional genetic firewall that will allow absolute containment of recombinant organisms.
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13
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Hu YOO, Karlson B, Charvet S, Andersson AF. Diversity of Pico- to Mesoplankton along the 2000 km Salinity Gradient of the Baltic Sea. Front Microbiol 2016; 7:679. [PMID: 27242706 DOI: 10.3389/fmicb.2016.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 04/26/2016] [Indexed: 05/22/2023] Open
Abstract
Microbial plankton form the productive base of both marine and freshwater ecosystems and are key drivers of global biogeochemical cycles of carbon and nutrients. Plankton diversity is immense with representations from all major phyla within the three domains of life. So far, plankton monitoring has mainly been based on microscopic identification, which has limited sensitivity and reproducibility, not least because of the numerical majority of plankton being unidentifiable under the light microscope. High-throughput sequencing of taxonomic marker genes offers a means to identify taxa inaccessible by traditional methods; thus, recent studies have unveiled an extensive previously unknown diversity of plankton. Here, we conducted ultra-deep Illumina sequencing (average 10(5) sequences/sample) of rRNA gene amplicons of surface water eukaryotic and bacterial plankton communities sampled in summer along a 2000 km transect following the salinity gradient of the Baltic Sea. Community composition was strongly correlated with salinity for both bacterial and eukaryotic plankton assemblages, highlighting the importance of salinity for structuring the biodiversity within this ecosystem. In contrast, no clear trends in alpha-diversity for bacterial or eukaryotic communities could be detected along the transect. The distribution of major planktonic taxa followed expected patterns as observed in monitoring programs, but groups novel to the Baltic Sea were also identified, such as relatives to the coccolithophore Emiliana huxleyi detected in the northern Baltic Sea. This study provides the first ultra-deep sequencing-based survey on eukaryotic and bacterial plankton biogeography in the Baltic Sea.
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Affiliation(s)
- Yue O O Hu
- Science for Life Laboratory, Division of Gene Technology, School of Biotechnology, KTH Royal Institute of Technology Stockholm, Sweden
| | - Bengt Karlson
- Oceanography, Research & Development, Swedish Meteorological and Hydrological Institute Gothenburg, Sweden
| | - Sophie Charvet
- Leibniz Institute for Baltic Sea Research Warnemünde Rostock, Germany
| | - Anders F Andersson
- Science for Life Laboratory, Division of Gene Technology, School of Biotechnology, KTH Royal Institute of Technology Stockholm, Sweden
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Lan WS, Lu TK, Qin ZF, Shi XJ, Wang JJ, Hu YF, Chen B, Zhu YH, Liu Z. Genetically modified microorganism Spingomonas paucimobilis UT26 for simultaneously degradation of methyl-parathion and γ-hexachlorocyclohexane. ECOTOXICOLOGY (LONDON, ENGLAND) 2014; 23:840-850. [PMID: 24648032 DOI: 10.1007/s10646-014-1224-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/06/2014] [Indexed: 06/03/2023]
Abstract
Bioremediation of pesticide residues by bacteria is an efficient and environmentally friendly method to deal with environmental pollution. In this study, a genetically modified microorganism (GMM) named UT26XEGM was constructed by introducing a parathion hydrolase gene into an initially γ-hexachlorocyclohexane (γ-HCH) degrading bacterium Spingomonas paucimobilis UT26. In order to reduce its potential risk of gene escaping into the environment for the public concern on biosafety, a suicide system was also designed that did not interfere with the performance of the GMM until its physiological function was activated by specific signal. The system was designed with circuiting suicide cassettes consisting of killing genes gef and ecoRIR from Escherichia coli controlled by Pm promoter and the xylS gene. The cell viability and original degradation characteristics were not affected by the insertion of exogenous genes. The novel GMM was capable of degrading methyl-parathion and γ-HCH simultaneously. In laboratory scale testing, the recombinant bacteria were successfully applied to the bioremediation of mixed pesticide residues with the activity of self-destruction after 3-methylbenzoate induction.
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Affiliation(s)
- Wen S Lan
- Shenzhen R&D Key Laboratory of Alien Pest Detection Technology, Animal & Plant Inspection and Quarantine Technical Center, Shenzhen Entry-Exit Inspection and Quarantine Bureau, 1011 Fuqiang Road, Shenzhen, 518045, People's Republic of China,
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15
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Muhammad A, Champeimont J, Mayr UB, Lubitz W, Kudela P. Bacterial ghosts as carriers of protein subunit and DNA-encoded antigens for vaccine applications. Expert Rev Vaccines 2014; 11:97-116. [DOI: 10.1586/erv.11.149] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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16
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Kamioka T, Sohya S, Wu N, Maki T, Matsuda T, Ikegami T, Nakamura H, Kuroda Y. Extraction of recombinant protein from Escherichia coli by using a novel cell autolysis activity of VanX. Anal Biochem 2013; 439:212-7. [PMID: 23624113 DOI: 10.1016/j.ab.2013.04.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 03/29/2013] [Accepted: 04/04/2013] [Indexed: 11/29/2022]
Abstract
Escherichia coli is a versatile, low-cost, and popular host for expressing recombinant proteins. However, extracting recombinant proteins from E. coli requires cell wall breakage, which is both time- and effort-consuming. Here we report a novel cell breakage method based on our recent finding that VanX, which is a d-Ala-d-Ala dipeptidase encoded in a vancomycin-resistant VanA gene cluster, exhibits a strong cell lysis activity when expressed in isolation in E. coli. In our strategy, we coexpress VanX with the target protein, causing cell autolysis and release of the cellular content into the culture medium. We demonstrated this strategy for two model proteins, a green fluorescent protein variant (GFPuv) and Gaussia luciferase, and optimized the autolysis conditions and coexpression vectors. The fluorescence activity of GFPuv collected from the medium was identical to that of GFPuv purified by conventional methods. Cell breakage by VanX-mediated autolysis is very simple to implement and will efficiently complement traditional methods.
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Affiliation(s)
- Tetsuya Kamioka
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan
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Rezzonico F, Stockwell VO, Duffy B. Plant agricultural streptomycin formulations do not carry antibiotic resistance genes. Antimicrob Agents Chemother 2009; 53:3173-7. [PMID: 19414583 PMCID: PMC2704632 DOI: 10.1128/aac.00036-09] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 03/10/2009] [Accepted: 04/23/2009] [Indexed: 11/20/2022] Open
Abstract
Streptomycin is used in plant agriculture for bacterial disease control, particularly against fire blight in pome fruit orchards. Concerns that this may increase environmental antibiotic resistance have led to bans or restrictions on use. Experience with antibiotic use in animal feeds raises the possible influence of formulation-delivered resistance genes. We demonstrate that agricultural streptomycin formulations do not carry producer organism resistance genes. By using an optimized extraction procedure, Streptomyces 16S rRNA genes and the streptomycin resistance gene strA were not detected in agricultural streptomycin formulations. This diminishes the likelihood for one potential factor in resistance development due to streptomycin use.
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Affiliation(s)
- Fabio Rezzonico
- Agroscope Changins-Wädenswil, ACW, Swiss National Competence Center for Fire Blight, Wädenswil, Switzerland
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Lin Z, Cai Z. Cell lysis methods for high-throughput screening or miniaturized assays. Biotechnol J 2009; 4:210-5. [DOI: 10.1002/biot.200800222] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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19
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Ekong EE, Okenu DN, Mania-Pramanik J, He Q, Igietseme JU, Ananaba GA, Lyn D, Black C, Eko FO. A Vibrio cholerae ghost-based subunit vaccine induces cross-protective chlamydial immunity that is enhanced by CTA2B, the nontoxic derivative of cholera toxin. ACTA ACUST UNITED AC 2008; 55:280-91. [PMID: 19040663 DOI: 10.1111/j.1574-695x.2008.00493.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The Vibrio cholerae ghost (rVCG) platform is an effective carrier and delivery system for designing efficacious Chlamydia vaccines. We investigated whether CTA2B, the nontoxic derivative of cholera toxin, can augment protective immunity conferred by an rVCG-based chlamydial vaccine and enhance cross-protection against heterologous chlamydial strains. An rVCG vaccine coexpressing chlamydial major outer membrane protein and CTA2B was genetically constructed and antigens were targeted to the inner membrane of V. cholerae before ghost production by gene E-mediated lysis. Effective immunomodulation by CTA2B was demonstrated by the ability of the vaccine construct to enhance the activation and maturation of dendritic cells in vitro. Also, C57BL/6 mice immunized via mucosal and systemic routes showed increased specific mucosal and systemic antibody and T-helper type-1 (Th1) responses, irrespective of the route. The enhanced production of IFN-gamma, but not IL-4 by genital mucosal and splenic T cells, indicated a predominantly Th1 response. Clearance of the Chlamydia muridarum vaginal infection was significantly enhanced by codelivery of the vaccine with CTA2B, with the intravaginal route showing a moderate advantage. These results indicate that the rVCG-based vaccine is capable of inducing cross-protection against heterologous chlamydial serovars and that incorporation of mucosal adjuvants, such as CTA2B in the rVCG delivery platform, may enhance protective immunity.
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Affiliation(s)
- Eno E Ekong
- Morehouse School of Medicine, Atlanta, GA 30310, USA
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20
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Cai Z, Xu W, Xue R, Lin Z. Facile, reagentless and in situ release of Escherichia coli intracellular enzymes by heat-inducible autolytic vector for high-throughput screening. Protein Eng Des Sel 2008; 21:681-7. [DOI: 10.1093/protein/gzn049] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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21
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Li S, Xu L, Hua H, Ren C, Lin Z. A set of UV-inducible autolytic vectors for high throughput screening. J Biotechnol 2007; 127:647-52. [PMID: 16950533 DOI: 10.1016/j.jbiotec.2006.07.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Revised: 07/18/2006] [Accepted: 07/27/2006] [Indexed: 11/22/2022]
Abstract
A high throughput screening scheme is often a prerequisite for directed evolution of enzymes or metagenomic analysis of DNA samples. For assaying intracellular enzymes of interest (e.g. when Escherichia coli is used), it requires cell lysis in many cases, chemical or enzymatic, which can be tedious and cost-consuming. In this study, a set of UV-inducible autolytic vectors was constructed to offer a simpler means of cell lysis that is free of additional liquid handling. The SRRz lysis gene cassette from bacteriophage Lambda was cloned downstream of a UV-inducible promoter, the recA promoter or the umuDC promoter, and further inserted into the backbone of pUC18, and transformed into E. coli BL21 cells. The SRRz expression and cell lysis was induced by UV irradiation. For both the recA and umuDC promoters, at 30 degrees C the lysis efficiency was found to be consistent and above 60% as measured using beta-galactosidase as the reporter. However, at 37 degrees C the lysis profiles were found to be erratic. UV lysis in 96-well plates also produced consistent lysis results that were comparable to those obtained by lysozyme treatment, demonstrating the utility of these autolytic vectors in high throughput screening. This set of artificial SRRz autolysis units should be transferable to other vectors. Surprisingly, it was found that the E. coli BL21(DE3) was also partially disrupted under UV irradiation, with a lysis efficiency of 44.5% at 30 degrees C, and 22.5% at 37 degrees C.
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Affiliation(s)
- Shuang Li
- Department of Chemical Engineering, Tsinghua University, 1 Tsinghua Garden Road, Beijing 100084, PR China
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22
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Macmillan L, Ifere GO, He Q, Igietseme JU, Kellar KL, Okenu DM, Eko FO. A recombinant multivalent combination vaccine protects against Chlamydia and genital herpes. ACTA ACUST UNITED AC 2006; 49:46-55. [PMID: 17094789 DOI: 10.1111/j.1574-695x.2006.00165.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chlamydia trachomatis and Herpes simplex virus type 2 (HSV-2) genital infections pose a considerable public health challenge worldwide. Considering the high incidence of coinfections by the two pathogens, a combination vaccine that can be administered as a single regimen would be highly desirable. Recombinant Vibrio cholerae ghosts (rVCG) offer an attractive approach for the induction of humoral and cellular immune responses against human and animal pathogens. In this study, we evaluated a bivalent combination vaccine formulation comprising rVCG expressing chlamydial MOMP and HSV-2 glycoprotein D in mice for immunogenicity and protective efficacy against genital challenge with either pathogen. Mice immunized with the combination vaccine elicited secretory IgA and IgG2a antibodies to both chlamydial and HSV-2 antigens in serum and vaginal secretions. Robust antigen-specific mucosal and systemic T helper type 1 responses were induced in mice as measured by increased interferon-gamma levels produced by immune T cells in response to restimulation with target antigen in vitro. In addition, mice immunized with the combination vaccine were prophylactically protected from genital challenge with high doses of live Chlamydia and HSV-2. Thus, the combination vaccine regimen delivered by rVCG elicited adequate immune effectors that simultaneously protected against the individual pathogens.
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Affiliation(s)
- Lucinda Macmillan
- Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, Atlanta, Georgia 30310, USA
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23
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Xu L, Li S, Ren C, Cai Z, Lin Z. Heat-inducible autolytic vector for high-throughput screening. Biotechniques 2006; 41:319-23. [PMID: 16989092 DOI: 10.2144/000112219] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In directed evolution, a high-throughput screening system is often a prerequisite for sampling the enzyme variants. When the target enzyme is expressed intracellularly, for example when Escherichia coli is used as the host, chemical or enzymatic disruption of cell membrane is often required in many cases, which can be tedious, time-consuming, and costly. In this study, a set of heat-inducible autolytic vectors were constructed to solve this problem, in which the SRRz lysis gene cassette from bacteriophage λ was placed downstream of heat-inducible promoters, λ cI857/pRpromoter and its mutant, cI857/pR(M). The artificial autolytic units were inserted into the backbone of pUC18 (away from the multiple cloning sites). For the wild promoter, cI857/pR, the SRRz lysis cassette was expressed by temperature up-shift from 28° to 38°C, and the lysis efficiency of transformed bacterial cells was found to be consistent and could reach 96.3% as measured by the reporter β-galactosidase assay. In order to obtain a higher cell growth rate, the mutant promoter cI857/pR(M) was utilized to allow bacteria growth at 35°C and lysis at 42°C. However, this heat-inducible system showed significant inconsistency in terms of lysis efficiency. Bacillus subtilis 168 lipase A gene was further in-serted into the multiple cloning sites of the autolytic vector containing cI857/pR, and 93.7% of the expressed lipase activity was found in the culture medium upon heat induction, demon-strating the utility of the vector for expression and rapid extracellular assay of heterologous enzymes.
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Affiliation(s)
- Lihua Xu
- Tsinghua University, Beijing, China
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24
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Iwaki M, Arakawa Y. Transformation of Acinetobacter sp. BD413 with DNA from commercially available genetically modified potato and papaya. Lett Appl Microbiol 2006; 43:215-21. [PMID: 16869908 DOI: 10.1111/j.1472-765x.2006.01924.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM To estimate the likelihood of transfer of kanamycin-resistance gene (nptII) from commercially available genetically modified (GM) plants. METHODS AND RESULTS Acinetobacter sp. BD413 carrying a plasmid containing an inactivated nptII gene was treated with DNA derived from GM potato and GM papaya. Kanamycin-resistant transformants were obtained at a frequency of 10-30 microg(-1) DNA. Calculation of the results suggested that 6-9 x 10(4) molecules of genomic DNA from GM plants were needed to obtain one transformant. However, such transformation events were not detectable in the absence of the plasmid in the host strain. CONCLUSIONS Acinetobacter sp. BD413 was transformed with DNA derived from GM potato and GM papaya, in the presence of an inactivated nptII gene on a plasmid. However, the frequency of such events in the natural environment on wild-type strains, while evidently low, remains unknown. SIGNIFICANCE AND IMPACT OF THE STUDY Our results may help to evaluate potential risks associated with the use of antibiotic-resistance determinants as genetic markers in GM plants. Complete risk assessment must consider factors other than transformation frequency alone, including the natural background of antibiotic resistance present in bacterial populations, and the spectrum and clinical use of the antimicrobial agents in question.
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Affiliation(s)
- M Iwaki
- Department of Bacterial Pathogenesis and Infection Control, National Institute of Infectious Diseases, Tokyo, Japan.
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25
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Mayr UB, Walcher P, Azimpour C, Riedmann E, Haller C, Lubitz W. Bacterial ghosts as antigen delivery vehicles. Adv Drug Deliv Rev 2005; 57:1381-91. [PMID: 15878634 DOI: 10.1016/j.addr.2005.01.027] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2004] [Accepted: 01/25/2005] [Indexed: 10/25/2022]
Abstract
The bacterial ghost system is a novel vaccine delivery system unusual in that it combines excellent natural intrinsic adjuvant properties with versatile carrier functions for foreign antigens. The efficient tropism of bacterial ghosts (BG) for antigen presenting cells promotes the generation of both cellular and humoral responses to heterologous antigens and carrier envelope structures. The simplicity of both BG production and packaging of (multiple) target antigens makes them particularly suitable for use as combination vaccines. Further advantages of BG vaccines include a long shelf-life without the need of cold-chain storage due to their freeze-dried status, they are safe as they do not involve host DNA or live organisms, they exhibit improved potency with regard to target antigens compared to conventional approaches, they are versatile with regards to DNA or protein antigen choice and size, and as a delivery system they offer high bioavailability.
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Affiliation(s)
- Ulrike Beate Mayr
- Department of Medical/Pharmaceutical Chemistry, University of Vienna, A-1090 Vienna, Austria
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26
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Wolffs P, Norling B, Rådström P. Risk assessment of false-positive quantitative real-time PCR results in food, due to detection of DNA originating from dead cells. J Microbiol Methods 2005; 60:315-23. [PMID: 15649533 DOI: 10.1016/j.mimet.2004.10.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 10/01/2004] [Accepted: 10/07/2004] [Indexed: 11/29/2022]
Abstract
Real-time PCR technology is increasingly used for detection and quantification of pathogens in food samples. A main disadvantage of nucleic acid detection is the inability to distinguish between signals originating from viable cells and DNA released from dead cells. In order to gain knowledge concerning risks of false-positive results due to detection of DNA originating from dead cells, quantitative PCR (qPCR) was used to investigate the degradation kinetics of free DNA in four types of meat samples. Results showed that the fastest degradation rate was observed (1 log unit per 0.5 h) in chicken homogenate, whereas the slowest rate was observed in pork rinse (1 log unit per 120.5 h). Overall results indicated that degradation occurred faster in chicken samples than in pork samples and faster at higher temperatures. Based on these results, it was concluded that, especially in pork samples, there is a risk of false-positive PCR results. This was confirmed in a quantitative study on cell death and signal persistence over a period of 28 days, employing three different methods, i.e. viable counts, direct qPCR, and finally floatation, a recently developed discontinuous density centrifugation method, followed by qPCR. Results showed that direct qPCR resulted in an overestimation of up to 10 times of the amount of cells in the samples compared to viable counts, due to detection of DNA from dead cells. However, after using floatation prior to qPCR, results resembled the viable count data. This indicates that by using of floatation as a sample treatment step prior to qPCR, the risk of false-positive PCR results due to detection of dead cells, can be minimized.
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Affiliation(s)
- Petra Wolffs
- Applied Microbiology, Lund Institute of Technology, Lund University, SE-221 00 Lund, Sweden.
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27
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Hatfaludi T, Liska M, Zellinger D, Ousman JP, Szostak M, Ambrus A, Jalava K, Lubitz W. Bacterial ghost technology for pesticide delivery. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2004; 52:5627-5634. [PMID: 15373403 DOI: 10.1021/jf049489w] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Bacterial ghosts are nondenaturated empty cell envelopes of Gram-negative bacteria produced by E-mediated lysis. Such envelopes from the plant-adhering bacterium Pectobacterium cypripedii were tested for their ability to adhere to plant material and to be used as carriers for pesticide delivery. We show, using fluorescence-labeled P. cypripedii ghosts, that depending on the target plants 55 or 10% (rice or soya, respectively) of the applied bacterial ghosts was retained on the leaves after heavy simulated rain (84 mm). Furthermore, the bacterial ghosts could be loaded with the lipophilic triazole fungicide tebuconazole. In subsequent plant experiments in the glass house, the efficacy of the loaded bacterial ghost for resistance to rainfall and the protective and curative effects against the pathogens Erysiphe graminis, Leptosphaeria nodorum, and Pyrenophora teres on barley and wheat and against Sphaerotheca fuliginea on cucumber were tested. The bacterial ghosts were compared primarily with a commercial tebuconazole formulation, a wettable powder, as it has similar physical characteristics. The comparison revealed similar effects and showed consistently higher or comparable efficacy against the pathogens. The standard operational comparison with the most protective, cereal specific emulsion of oil in water displayed that the bacterial ghosts had equal to or lower efficacy than the emulsion. This study confirmed the potential of bacterial ghost platform technology as a new alternative carrier system for pesticides.
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Affiliation(s)
- Tamás Hatfaludi
- Institute for Microbiology and Genetics, Section Microbiology and Biotechnology, University of Vienna, UZAII 2B522 Althanstrasse 14, A-1090 Vienna, Austria.
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28
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Riedmann EM, Kyd JM, Smith AM, Gomez-Gallego S, Jalava K, Cripps AW, Lubitz W. Construction of recombinant S-layer proteins (rSbsA) and their expression in bacterial ghosts--a delivery system for the nontypeable Haemophilus influenzae antigen Omp26. FEMS IMMUNOLOGY AND MEDICAL MICROBIOLOGY 2003; 37:185-92. [PMID: 12832124 DOI: 10.1016/s0928-8244(03)00070-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
This study has investigated the feasibility of a combination of recombinant surface layer (S-layer) proteins and empty bacterial cell envelopes (ghosts) to deliver candidate antigens for a vaccine against nontypeable Haemophilus influenzae (NTHi) infections. The S-layer gene sbsA from Bacillus stearothermophilus PV72 was used for the construction of fusion proteins. Fusion of maltose binding protein (MBP) to the N-terminus of SbsA allowed expression of the S-layer in the periplasm of Escherichia coli. The outer membrane protein (Omp) 26 of NTHi was inserted into the N-terminal and C-terminal regions of SbsA. The presence of the fused antigen Omp26 was demonstrated by Western blot experiments using anti-Omp26 antisera. Electron microscopy showed that the recombinant SbsA maintained the ability to self-assemble into sheet-like and cylindrical structures. Recombinant E. coli cell envelopes (ghosts) were produced by the expression of SbsA/Omp26 fusion proteins prior to gene E-mediated lysis. Intraperitoneal immunization with these recombinant bacterial ghosts induced an Omp26-specific antibody response in BALB/c mice. These results demonstrate that the NTHi antigen, Omp26, was expressed in the S-layer self-assembly product and this construct was immunogenic for Omp26 when administered to mice in bacterial cell envelopes.
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Affiliation(s)
- Eva M Riedmann
- Institute of Microbiology and Genetics, Vienna Biocentre, University of Vienna, 1090 Vienna, Austria
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29
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Lee H, Vázquez-Laslop N, Klyachko KA, Neyfakh AA. Isolation of antibiotic hypersusceptibility mutants of Acinetobacter spp. by selection for DNA release. Antimicrob Agents Chemother 2003; 47:1267-74. [PMID: 12654657 PMCID: PMC152507 DOI: 10.1128/aac.47.4.1267-1274.2003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Isolation of bacterial mutants hypersusceptible to antibiotics can reveal novel targets for antibiotic potentiators. However, identification of such mutants is a difficult task which normally requires laborious replica plating of thousands of colonies. The technique proposed here allows for the positive selection of genetic knockout mutants leading to hypersusceptibility. This technique, designated SDR (selection for DNA release), involves introduction of random insertions of a marker gene into the chromosome of a highly transformable bacterial species, followed by treatment of the obtained library with an antibiotic at subinhibitory concentrations. DNA released by lysing bacteria is collected and used to transform fresh bacteria, selecting for insertion of the marker gene. These selection cycles are repeated until variants with a hypersusceptibility phenotype caused by insertion of the marker begin to dominate in the library. This approach allowed for isolation of a number of mutants of the gram-negative opportunistic pathogen Acinetobacter sp. susceptible to 4- to 16-times-lower concentrations of ampicillin than wild-type bacteria. The mutations affected proteins involved in peptidoglycan turnover and, surprisingly, proteins involved in exopolysaccharide production. A further modification of the SDR technique is described which allows for selecting mutants hypersensitive to agents that affect bacterial physiology but do not cause cell lysis, e.g., inhibitors of translation. This application of SDR is illustrated here by identification of several mutants of Acinetobacter sp. with increased susceptibility (two- to fivefold decrease in the MIC) to erythromycin. The same technique can be used to identify prospective targets for potentiators of many other antibacterial agents.
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Affiliation(s)
- Hyunwoo Lee
- Center for Pharmaceutical Biotechnology and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois, Chicago, Illinois 60607, USA
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30
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Bernhardt TG, Roof WD, Young R. The Escherichia coli FKBP-type PPIase SlyD is required for the stabilization of the E lysis protein of bacteriophage phi X174. Mol Microbiol 2002; 45:99-108. [PMID: 12100551 DOI: 10.1046/j.1365-2958.2002.02984.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Most bacteriophages abruptly terminate their vegetative cycle by causing lysis of the host cell. The ssDNA phage phi X174 uses a single lysis gene, E, encoding a 91-amino-acid membrane protein that causes lysis of Escherichia coli by inhibiting MraY, a conserved enzyme of murein biosynthesis. Recessive mutations in the host gene slyD (sensitivity to lysis) absolutely block E-mediated lysis and phi X174 plaque formation. The slyD gene encodes a FKBP-type peptidyl-prolyl cis-trans isomerase (PPIase). To investigate the molecular basis of this unique FKBP-dependence, spontaneous plaque-forming mutants of phi X174 were isolated on a slyD lawn. All of these Epos ('plates on slyD') suppressors encode proteins with either a R3H or L19F change. The double mutant was also isolated and generated the largest plaques on the slyD lawn. A c-myc epitope tag sequence was incorporated into the parental E and Epos genes without effect on lytic function. Western blots and pulse-chase labelling experiments showed that both Epos and E are highly unstable in a slyD background; however, Epos is synthesized at a higher rate, allowing a lysis-sufficient level of Epos to accumulate. Our results indicate that SlyD is required for stabilizing the E protein and allowing it to accumulate to the levels required to exert its lytic effect. These data are discussed in terms of a model for the specific role of the SlyD PPIase in E folding, and of the use of the very strict SlyD- dependence phenotype for identifying elements of PPIase selectivity.
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Affiliation(s)
- Thomas G Bernhardt
- Department of Biochemistry and Biophysics, Texas A and M University, 77843-2128, USA
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31
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Friedrich A, Hartsch T, Averhoff B. Natural transformation in mesophilic and thermophilic bacteria: identification and characterization of novel, closely related competence genes in Acinetobacter sp. strain BD413 and Thermus thermophilus HB27. Appl Environ Microbiol 2001; 67:3140-8. [PMID: 11425734 PMCID: PMC92993 DOI: 10.1128/aem.67.7.3140-3148.2001] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mesophile Acinetobacter sp. strain BD413 and the extreme thermophile Thermus thermophilus HB27 display high frequencies of natural transformation. In this study we identified and characterized a novel competence gene in Acinetobacter sp. strain BD413, comA, whose product displays significant similarities to the competence proteins ComA and ComEC in Neisseria and Bacillus species. Transcription of comA correlated with growth phase-dependent transcriptional regulation of the recently identified pilin-like factors of the transformation machinery. This finding strongly suggests that comA is part of a competence regulon. Examination of the genome sequence of T. thermophilus HB27 led to detection of a comA/comEC-like open reading frame (ORF) which is flanked by an ORF whose product shows significant similarities to the Bacillus subtilis competence protein ComEA. To examine whether these two ORFs, designated comEC and comEA, are implicated in natural transformation of T. thermophilus HB27, both were disrupted by using a thermostable kanamycin resistance marker. Natural transformation in comEC mutants was reduced 1,000-fold, whereas in comEA mutants the natural transformation phenotype was completely eliminated. These results strongly suggest that both genes, comEC and comEA, are required for natural transformation in T. thermophilus HB27. Several transmembrane alpha-helices are predicted based on the amino acid sequences of ComA in Acinetobacter sp. strain BD413 and ComEC in T. thermophilus HB27, which suggests that ComA and ComEC are located in the inner membrane and function in DNA transport through the cytoplasmic membrane.
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Affiliation(s)
- A Friedrich
- Department of Genetics and Microbiology, Ludwig Maximilians University, 80638 Munich, Germany
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32
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Haslberger AG, Kohl G, Felnerova D, Mayr UB, Fürst-Ladani S, Lubitz W. Activation, stimulation and uptake of bacterial ghosts in antigen presenting cells. J Biotechnol 2000; 83:57-66. [PMID: 11000461 DOI: 10.1016/s0168-1656(00)00298-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Bacterial ghosts have been shown to be an innovative system to prepare vaccines of various bacteria with all features of the intact bacterial cell envelopes, especially all antigenic epitopes, but also to target recombinant proteins inserted in the cell envelopes of the ghost preparations to specific antigen presenting cells. To investigate the activation of the antigen presenting cell by bacterial ghosts in more detail we studied the uptake of bacterial ghosts in dendritic porcine cells and RAW macrophages and the induction of inflammatory mediators or mediators directing the immune response in THP-1 human macrophage cell line. The synthesis of inflammatory macrophage mediators such as TNFalpha in the THP1 cell line was stimulated by a hundred-fold higher dose of ghosts from Vibrio cholerae than the corresponding LPS using ELISA-analysis. These results confirm in vivo experiments indicating no toxic effects of ghosts in rabbits even after intravenous administration in doses stimulating significant humoral responses. We were also able to see a significant activation of IL-12 indicated by the analysis of IL-12(p70) synthesis and IL-12(p40) mRNA accumulation. This interleukine is of special importance in the activation of cellular TH1 immune responses. A rapid uptake of bacterial ghosts in macrophages within 10-30 min could be confirmed by electron microscopy. As antigen presentation is especially effective in porcine dendritic cells (DC) and even a low capacity of antigen uptake is sufficient for an induction of immune responses we investigated uptake and activation of bacterial ghosts by DC. DC are known to be phagocytic in specific immature stages. We found a significant uptake of bacterial ghosts from Actinobacillus pleuropneumoniae (App) and V. cholerae conjugated with FITC (fluorescinisothiocyanate) within 2 h. These data suggest that bacterial ghosts effectively stimulate monocytes and macrophages for the induction of TH1 directed immune responses and dendritic cells treated with bacterial ghosts may serve as a promising vehicle for active immunization and immunotherapy in situ.
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Affiliation(s)
- A G Haslberger
- Institute of Microbiology and Genetics, University of Vienna, Biocenter, Dr Bohrgasse 9, A-1030, Vienna, Austria
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33
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Nielsen KM, Smalla K, van Elsas JD. Natural transformation of Acinetobacter sp. strain BD413 with cell lysates of Acinetobacter sp., Pseudomonas fluorescens, and Burkholderia cepacia in soil microcosms. Appl Environ Microbiol 2000; 66:206-12. [PMID: 10618225 PMCID: PMC91807 DOI: 10.1128/aem.66.1.206-212.2000] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/1999] [Accepted: 10/20/1999] [Indexed: 11/20/2022] Open
Abstract
To elucidate the biological significance of dead bacterial cells in soil to the intra- and interspecies transfer of gene fragments by natural transformation, we have exposed the kanamycin-sensitive recipient Acinetobacter sp. strain BD413(pFG4) to lysates of the kanamycin-resistant donor bacteria Acinetobacter spp., Pseudomonas fluorescens, and Burkholderia cepacia. Detection of gene transfer was facilitated by the recombinational repair of a partially (317 bp) deleted kanamycin resistance gene in the recipient bacterium. The investigation revealed a significant potential of these DNA sources to transform Acinetobacter spp. residing both in sterile and in nonsterile silt loam soil. Heat-treated (80 degrees C, 15 min) cell lysates were capable of transforming strain BD413 after 4 days of incubation in sterile soil and for up to 8 h in nonsterile soil. Transformation efficiencies obtained in vitro and in situ with the various lysates were similar to or exceeded those obtained with conventionally purified DNA. The presence of cell debris did not inhibit transformation in soil, and the debris may protect DNA from rapid biological inactivation. Natural transformation thus provides Acinetobacter spp. with an efficient mechanism to access genetic information from different bacterial species in soil. The relatively short-term biological activity (e.g., transforming activity) of chromosomal DNA in soil contrasts the earlier reported long-term physical stability of DNA, where fractions have been found to persist for several weeks in soil. Thus, there seems to be a clear difference between the physical and the functional significance of chromosomal DNA in soil.
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Affiliation(s)
- K M Nielsen
- Unigen and Department of Botany, Norwegian University of Science and Technology, 7491 Trondheim, Norway.
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34
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Kaplan DL, Mello C, Sano T, Cantor C, Smith C. Streptavidin-based containment systems for genetically engineered microorganisms. BIOMOLECULAR ENGINEERING 1999; 16:135-40. [PMID: 10796996 DOI: 10.1016/s1050-3862(99)00040-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The use of genetically modified microorganisms for environmental remediation continues to be debated. Conditional lethal systems with tightly regulated gene expression can be used to contain released microorganisms and ameliorate some of the concerns about horizontal gene transfer. We have described streptavidin-based suicide systems to address these concerns and evaluated their function in Pseudomonas putida containing the TOL plasmid for aromatic hydrocarbon metabolism. Tight regulation of expression of a truncated streptavidin gene was required to avoid premature production of the toxic protein. Streptavidin expression was induced by the absence of 3-methyl benzoate (hydrocarbon substrate) which resulted in the elimination of 99.9% of the bacterial culture within eight hours. Low mutant escape rates at 10(-7) per cell per generation were also realized.
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Affiliation(s)
- D L Kaplan
- Department of Chemical Engineering and Biotechnology Center, Tufts University, Medford, MA 02155, USA.
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Djordjevic GM, O'Sullivan DJ, Walker SA, Conkling MA, Klaenhammer TR. A triggered-suicide system designed as a defense against bacteriophages. J Bacteriol 1997; 179:6741-8. [PMID: 9352925 PMCID: PMC179604 DOI: 10.1128/jb.179.21.6741-6748.1997] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A novel bacteriophage protection system for Lactococcus lactis based on a genetic trap, in which a strictly phage-inducible promoter isolated from the lytic phage phi31 is used to activate a bacterial suicide system after infection, was developed. The lethal gene of the suicide system consists of the three-gene restriction cassette LlaIR+, which is lethal across a wide range of gram-positive bacteria. The phage-inducible trigger promoter (phi31P) and the LlaIR+ restriction cassette were cloned in Escherichia coli on a high-copy-number replicon to generate pTRK414H. Restriction activity was not apparent in E. coli or L. lactis prior to phage infection. In phage challenges of L. lactis(pTRK414H) with phi31, the efficiency of plaquing was lowered to 10(-4) and accompanied by a fourfold reduction in burst size. Center-of-infection assays revealed that only 15% of infected cells released progeny phage. In addition to phage phi31, the phi31P/LlaIR+ suicide cassette also inhibited four phi31-derived recombinant phages at levels at least 10-fold greater than that of phi31. The phi31P/LlaIR+-based suicide system is a genetically engineered form of abortive infection that traps and eliminates phages potentially evolving in fermentation environments by destroying the phage genome and killing the propagation host. This type of phage-triggered suicide system could be designed for any bacterium-phage combination, given a universal lethal gene and an inducible promoter which is triggered by the infecting bacteriophage.
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Affiliation(s)
- G M Djordjevic
- Department of Microbiology, North Carolina State University, Raleigh 27695-7624, USA
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Nielsen KM, van Weerelt MD, Berg TN, Bones AM, Hagler AN, van Elsas JD. Natural transformation and availability of transforming DNA to Acinetobacter calcoaceticus in soil microcosms. Appl Environ Microbiol 1997; 63:1945-52. [PMID: 9143126 PMCID: PMC168486 DOI: 10.1128/aem.63.5.1945-1952.1997] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
A small microcosm, based on optimized in vitro transformation conditions, was used to study the ecological factors affecting the transformation of Acinetobacter calcoaceticus BD413 in soil. The transforming DNA used was A. calcoaceticus homologous chromosomal DNA with an inserted gene cassette containing a kanamycin resistance gene, nptII. The effects of soil type (silt loam or loamy sand), bacterial cell density, time of residence of A. calcoaceticus or of DNA in soil before transformation, transformation period, and nutrient input were investigated. There were clear inhibitory effects of the soil matrix on transformation and DNA availability. A. calcoaceticus cells reached stationary phase and lost the ability to be transformed shortly after introduction into sterile soil. The use of an initially small number of A. calcoaceticus cells and nutrients, resulting in bacterial growth, enhanced transformation frequencies within a limited period. The availability of introduced DNA for transformation of A. calcoaceticus cells disappeared within a few hours in soil. Differences in transformation frequencies between soils were found; A. calcoaceticus cells were transformed at a higher rate and for a longer period in a silt loam than in a loamy sand. Physical separation of DNA and A. calcoaceticus cells had a negative effect on transformation. Transformation was also detected in nonsterile soil microcosms, albeit only in the presence of added nutrients and at a reduced frequency. These results suggest that chromosomal DNA released into soil rapidly becomes unavailable for transformation of A. calcoaceticus. In addition, strain BD413 quickly loses the ability to receive, stabilize, and/or express exogenous DNA after introduction into soil.
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Affiliation(s)
- K M Nielsen
- Unigen-Center for Molecular Biology, Norwegian University of Science and Technology, Trondheim, Norway
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Szafranski P, Mello CM, Sano T, Smith CL, Kaplan DL, Cantor CR. A new approach for containment of microorganisms: dual control of streptavidin expression by antisense RNA and the T7 transcription system. Proc Natl Acad Sci U S A 1997; 94:1059-63. [PMID: 9037005 PMCID: PMC19743 DOI: 10.1073/pnas.94.4.1059] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The use of microorganisms in the open environment would be of less concern if they were endowed with programmed self-destruction mechanisms. Here, we propose a new genetic design to increase the effectiveness of cell suicide systems. It ensures very tight control of the derepression of cell death by the combination of the bacteriophage T7 RNA polymerase-lysozyme system and an inducible synthesis of antisense RNA and the Escherichia coli LacI repressor. Functionality of this regulatory concept was tested by applying it to containment of Gram-negative bacteria, based on the conditional expression of the lethal Streptomyces avidinii streptavidin gene. Toxicity of streptavidin is derived from its exceptionally high binding affinity for an essential prosthetic group, D-biotin. The entire construct was designed to allow the soil bacterium Pseudomonas putida to survive only in the presence of aromatic hydrocarbons and their derivatives which it can degrade. Under favorable growth conditions, clones escaping killing appeared at frequencies of only 10(-7)-10(-8) per cell per generation. The general requirement for biotin through the living world should make streptavidin-based conditional lethal designs applicable to a broad range of containment strategies.
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Affiliation(s)
- P Szafranski
- Department of Biomedical Engineering, Boston University, MA 02215, USA
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Paget E, Simonet P. Development of engineered genomic DNA to monitor the natural transformation ofPseudomonas stutzeriin soil-like microcosms. Can J Microbiol 1997. [DOI: 10.1139/m97-011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The goal of this paper was to demonstrate whether natural transformation could occur in the environment to promote horizontal gene transfer between bacteria. Microcosms consisting of clay, clay and humic acids, or sterile soil were compared with respect to the natural transformation of Pseudomonas stutzeri by mineral-adsorbed DNA. Genes conferring resistance to tetracycline and ampicillin were first inserted in P. stutzeri pp100 chromosome via the pSUP202 suicide plasmid. Then, DNA extracted from the engineered P. stutzeri strain was used for transformation experiments, allowing the new transformed cells to be detected by hybridization with a tet probe. It turned out that DNA adsorbed on clay or soil particles and in presence of humic acids still transformed competent cells with frequencies up to 10−8transformants/viable cell. Finally, natural transformation assays involving two different DNAs were carried out in sterile soil microcosms. The use of nonisogenic DNA extracted from a rifampicin-resistant Pseudomonas fluorescens strain resulted in production of transformants, while isogenic DNA from our engineered strain failed to produce any. These observations confirmed that extracellular DNA adsorbed on a soil matrix composed of minerals and organic matter could still transform competent bacteria under environmental conditions.Key words: transformation, Pseudomonas stutzeri, soil microcosm, DNA, suicide plasmid.
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Rosselló-Mora RA, Lalucat J, Moore ER. Strain M300 Represents a new Genomovar within Pseudomonas stutzeri. Syst Appl Microbiol 1996. [DOI: 10.1016/s0723-2020(96)80031-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Ronchel MC, Ramos C, Jensen LB, Molin S, Ramos JL. Construction and behavior of biologically contained bacteria for environmental applications in bioremediation. Appl Environ Microbiol 1995; 61:2990-4. [PMID: 7487030 PMCID: PMC167574 DOI: 10.1128/aem.61.8.2990-2994.1995] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The survival of microorganisms can be predicted through the use of active biological containment systems. We have constructed contained Pseudomonas putida strains that degrade alkylbenzoates. The modified strain carries a fusion of the Plac promoter to the gef gene, which encodes a killing protein. Expression from Plac is controlled through a regulatory cascade, so that Plac is switched on or off by the absence or presence of alkylbenzoates, respectively. Similar uncontained strains were also constructed and tested as a control. Contained and uncontained strains were genetically stable, and their survival and functionality in soil microcosms were as expected. Both contained and uncontained strains survived well in soils supplemented with alkylaromatics, whereas survival of the contained strain in soil microcosms without methylbenzoates was markedly reduced, in contrast to the control strain, which survived in these soils in the absence of alkylbenzoates. The TOL plasmid was transferred in soils between Pseudomonas strains but was not able to mobilize the elements of the containment system.
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Affiliation(s)
- M C Ronchel
- Department of Biochemistry and Molecular and Cellular Biology of Plants, Consejo Superior de Investigaciones Científicas, Granada, Spain
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