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Guo Y, Xia Y, Liang Z, Yang S, Guo S, Sun L, Huo YX. Plasmid-Stabilizing Strains for Antibiotic-Free Chemical Fermentation. ACS Synth Biol 2024; 13:2820-2832. [PMID: 39120497 DOI: 10.1021/acssynbio.4c00241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
Plasmid-mediated antibiotic-free fermentation holds significant industrial potential. However, the requirements for host elements and energy during plasmid inheritance often cause cell burden, leading to plasmid loss and reduced production. The stable maintenance of plasmids is primarily achieved through a complex mechanism, making it challenging to rationally design plasmid-stabilizing strains and characterize the associated genetic factors. In this study, we introduced a fluorescence-based high-throughput method and successfully screened plasmid-stabilizing strains from the genomic fragment-deletion strains of Escherichia coli MG1655 and Bacillus subtilis 168. The application of EcΔ50 in antibiotic-free fermentation increased the alanine titer 2.9 times. The enhanced plasmid stability in EcΔ50 was attributed to the coordinated deletion of genes involved in plasmid segregation and replication control, leading to improved plasmid maintenance and increased plasmid copy number. The increased plasmid stability of BsΔ44 was due to the deletion of the phage SPP1 surface receptor gene yueB, resulting in minimized sporulation, improved plasmid segregational stability and host adaptation. Antibiotic-free fermentation results showed that strain BsΔyueB exhibited a 61.99% higher acetoin titer compared to strain Bs168, reaching 3.96 g/L. When used for the fermentation of the downstream product, 2,3-butanediol, strain BsΔyueB achieved an 80.63% higher titer than Bs168, reaching 14.94 g/L using rich carbon and nitrogen feedstocks. Overall, our work provided a plasmid-stabilizing chassis for E. coli and B. subtilis, highlighting their potential for antibiotic-free fermentation of valuable products and metabolic engineering applications.
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Affiliation(s)
- Yingjie Guo
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, 100081 Beijing, China
| | - Yan Xia
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, 100081 Beijing, China
| | - Zeyu Liang
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, 100081 Beijing, China
| | - Shenyan Yang
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, 100081 Beijing, China
| | - Shuyuan Guo
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, 100081 Beijing, China
| | - Lichao Sun
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, 100081 Beijing, China
- Tangshan Research Institute, Beijing Institute of Technology, 063611 Hebei, China
| | - Yi-Xin Huo
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, 100081 Beijing, China
- Tangshan Research Institute, Beijing Institute of Technology, 063611 Hebei, China
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2
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Bolten S, Lott TT, Ralyea RD, Gianforte A, Trmcic A, Orsi RH, Martin NH, Wiedmann M. Intensive Environmental Sampling and Whole Genome Sequence-based Characterization of Listeria in Small- and Medium-sized Dairy Facilities Reveal Opportunities for Simplified and Size-appropriate Environmental Monitoring Strategies. J Food Prot 2024; 87:100254. [PMID: 38417482 DOI: 10.1016/j.jfp.2024.100254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 02/17/2024] [Accepted: 02/21/2024] [Indexed: 03/01/2024]
Abstract
Small- and medium-sized dairy processing facilities (SMDFs) may face unique challenges with respect to controlling Listeria in their processing environments, e.g., due to limited resources. The aim of this study was to implement and evaluate environmental monitoring programs (EMPs) for Listeria control in eight SMDFs in a ∼1-year longitudinal study; this included a comparison of pre-operation (i.e., after cleaning and sanitation and prior to production) and mid-operation (i.e., at least 4 h into production) sampling strategies. Among 2,072 environmental sponge samples collected across all facilities, 272 (13%) were positive for Listeria. Listeria prevalence among pre- and mid-operation samples (15% and 17%, respectively), was not significantly different. Whole genome sequencing (WGS) performed on select isolates to characterize Listeria persistence patterns revealed repeated isolation of closely related Listeria isolates (i.e., ≤20 high-quality single nucleotide polymorphism [hqSNP] differences) in 5/8 facilities over >6 months, suggesting Listeria persistence and/or reintroduction was relatively common among the SMDFs evaluated here. WGS furthermore showed that for 41 sites where samples collected pre- and mid-operation were positive for Listeria, Listeria isolates obtained were highly related (i.e., ≤10 hqSNP differences), suggesting that pre-operation sampling alone may be sufficient and more effective for detecting sites of Listeria persistence. Importantly, our data also showed that only 1/8 of facilities showed a significant decrease in Listeria prevalence over 1 year, indicating continued challenges with Listeria control in at least some SMDFs. We conclude that options for simplified Listeria EMPs (e.g., with a focus on pre-operation sampling, which allows for more rapid identification of likely persistence sites) may be valuable for improved Listeria control in SMDFs.
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Affiliation(s)
- Samantha Bolten
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853, USA; Food Safety Laboratory, Department of Food Science, Cornell University, Ithaca, NY 14853, USA
| | - Timothy T Lott
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853, USA
| | - Robert D Ralyea
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853, USA
| | - Anika Gianforte
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853, USA
| | - Aljosa Trmcic
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853, USA
| | - Renato H Orsi
- Food Safety Laboratory, Department of Food Science, Cornell University, Ithaca, NY 14853, USA
| | - Nicole H Martin
- Milk Quality Improvement Program, Department of Food Science, Cornell University, Ithaca, NY 14853, USA
| | - Martin Wiedmann
- Food Safety Laboratory, Department of Food Science, Cornell University, Ithaca, NY 14853, USA.
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Lammens EM, Volke DC, Schroven K, Voet M, Kerremans A, Lavigne R, Hendrix H. A SEVA-based, CRISPR-Cas3-assisted genome engineering approach for Pseudomonas with efficient vector curing. Microbiol Spectr 2023; 11:e0270723. [PMID: 37975669 PMCID: PMC10715078 DOI: 10.1128/spectrum.02707-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 10/18/2023] [Indexed: 11/19/2023] Open
Abstract
IMPORTANCE The CRISPR-Cas3 editing system as presented here facilitates the creation of genomic alterations in Pseudomonas putida and Pseudomonas aeruginosa in a straightforward manner. By providing the Cas3 system as a vector set with Golden Gate compatibility and different antibiotic markers, as well as by employing the established Standard European Vector Architecture (SEVA) vector set to provide the homology repair template, this system is flexible and can readily be ported to a multitude of Gram-negative hosts. Besides genome editing, the Cas3 system can also be used as an effective and universal tool for vector curing. This is achieved by introducing a spacer that targets the origin-of-transfer, present on the majority of established (SEVA) vectors. Based on this, the Cas3 system efficiently removes up to three vectors in only a few days. As such, this curing approach may also benefit other genomic engineering methods or remove naturally occurring plasmids from bacteria.
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Affiliation(s)
| | - Daniel Christophe Volke
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Kaat Schroven
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Leuven, Belgium
| | - Marleen Voet
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Leuven, Belgium
| | - Alison Kerremans
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Leuven, Belgium
| | - Rob Lavigne
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Leuven, Belgium
| | - Hanne Hendrix
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Leuven, Belgium
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Tran TT, Cole M, Tomas E, Scott A, Topp E. Potential selection and maintenance of manure-originated multi-drug resistant plasmids at sub-clinical concentrations for tetracycline family antibiotics. Can J Microbiol 2023; 69:339-350. [PMID: 37267627 DOI: 10.1139/cjm-2022-0240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The goal of this study was to (a) determine the minimum selection concentrations of tetracycline family antibiotics necessary to maintain plasmids carrying tetracycline-resistant genes and (b) correlate these results to environmental hotspot concentrations reported in previous studies. This study used two plasmids (pT295A and pT413A) originating from dairy manure in a surrogate Escherichia coli host CV601. The minimum selection concentrations of antibiotics tested in nutrient-rich medium were determined as follows: 0.1 mg/L for oxytetracycline, 0.45 mg/L for chlortetracycline, and 0.13-0.25 mg/L for tetracycline. Mixing oxytetracycline and chlortetracycline had minimum selection concentration values increased 2-fold compared to those in single antibiotic tests. Minimum selection concentrations found in this study were lower than reported environmental hotspot concentrations, suggesting that tetracycline family antibiotics were likely to be the driver for the selection and maintenance of these plasmids. Relatively high plasmid loss rates (>90%) were observed when culturing a strain carrying a tetracycline-resistant plasmid in antibiotic-free nutrient-rich and nutrient-defined media. Overall, results suggested that these plasmids can be maintained at concentrations environmentally relevant in wastewater treatment plants, sewage, manure, and manured soil; however, they are unstable and easily lost in the absence of antibiotics.
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Affiliation(s)
- Tam T Tran
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St, London, ON N5V 4T3, Canada
- Department of Biology, University of Western Ontario, 1151 Richmond St, London, ON N6A 3K7, Canada
| | - Marlena Cole
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St, London, ON N5V 4T3, Canada
| | - Emily Tomas
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St, London, ON N5V 4T3, Canada
| | - Andrew Scott
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St, London, ON N5V 4T3, Canada
| | - Edward Topp
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St, London, ON N5V 4T3, Canada
- Department of Biology, University of Western Ontario, 1151 Richmond St, London, ON N6A 3K7, Canada
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Forero-Hurtado D, Corredor-Rozo ZL, Ruiz-Castellanos JS, Márquez-Ortiz RA, Abril D, Vanegas N, Lafaurie GI, Chambrone L, Escobar-Pérez J. Worldwide Dissemination of blaKPC Gene by Novel Mobilization Platforms in Pseudomonas aeruginosa: A Systematic Review. Antibiotics (Basel) 2023; 12:antibiotics12040658. [PMID: 37107020 PMCID: PMC10134989 DOI: 10.3390/antibiotics12040658] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 03/11/2023] [Accepted: 03/12/2023] [Indexed: 03/30/2023] Open
Abstract
The dissemination of blaKPC-harboring Pseudomonas aeruginosa (KPC-Pa) is considered a serious public health problem. This study provides an overview of the epidemiology of these isolates to try to elucidate novel mobilization platforms that could contribute to their worldwide spread. A systematic review in PubMed and EMBASE was performed to find articles published up to June 2022. In addition, a search algorithm using NCBI databases was developed to identify sequences that contain possible mobilization platforms. After that, the sequences were filtered and pair-aligned to describe the blaKPC genetic environment. We found 691 KPC-Pa isolates belonging to 41 different sequence types and recovered from 14 countries. Although the blaKPC gene is still mobilized by the transposon Tn4401, the non-Tn4401 elements (NTEKPC) were the most frequent. Our analysis allowed us to identify 25 different NTEKPC, mainly belonging to the NTEKPC-I, and a new type (proposed as IVa) was also observed. This is the first systematic review that consolidates information about the behavior of the blaKPC acquisition in P. aeruginosa and the genetic platforms implied in its successful worldwide spread. Our results show high NTEKPC prevalence in P. aeruginosa and an accelerated dynamic of unrelated clones. All information collected in this review was used to build an interactive online map.
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Ping L, Zhuoya L, Pei J, Jingchao C, Yi L, Guosheng L, Hailei W. Editing of a Specific Strain of Escherichia coli in the Mouse Gut Using Native Phages. Microbiol Spectr 2022; 10:e0180422. [PMID: 36301104 PMCID: PMC9770003 DOI: 10.1128/spectrum.01804-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 09/20/2022] [Indexed: 01/05/2023] Open
Abstract
There is a lack of methodological investigation of the in situ functions of bacterial species in microecosystems. Here, we used native phages as a microbial editing tool for eliminating Escherichia coli strain MG1655 labeled with green fluorescent protein (GFP) in the mouse gut. The virulent phages (W1 and W3) possessed host specificity at both the genus and species levels, resulting in an 8.8-log10 difference in the titer of viable bacteria after 12 h of phage treatment compared with that in the phage-free control in an in vitro test. In vivo, they reduced strain MG1655 colonizing the mouse gut at concentrations of 106 to 108 CFU g-1 to a 102 CFU g-1 level, which is almost undetectable by the plate colony-counting method. Moreover, the impact of phage treatment on the microbial community structure of the mouse gut was not significant (P > 0.05), indicating that native phages can effectively edit a target bacterium, with limited perturbation of microbial diversity and relative abundance. Therefore, we developed an engineering technique for investigation of the functions of a specific bacterium by depleting its abundance in microecosystems. IMPORTANCE This report describes a gut engineering technique for investigation of the functions of a specific bacterium. Native phages with host specificity can knock down the corresponding E. coli strain in the mouse gut with limited perturbation of microbial diversity and relative abundance, indicating that they, as a microbial editing tool, can effectively edit the abundance of a target bacterium. Such an approach is undoubtedly of interest in the context of lack of knowledge of how to methodologically study the in situ function of a specific species in a complex microecosystem.
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Affiliation(s)
- Li Ping
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Li Zhuoya
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Jia Pei
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Chen Jingchao
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Li Yi
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Liu Guosheng
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Wang Hailei
- College of Life Sciences, Henan Normal University, Xinxiang, China
- Advanced Environmental Biotechnology Center, Nanyang Technological University, Singapore, Singapore
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The Specificity of ParR Binding Determines the Incompatibility of Conjugative Plasmids in Clostridium perfringens. mBio 2022; 13:e0135622. [PMID: 35726914 PMCID: PMC9426499 DOI: 10.1128/mbio.01356-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Plasmids that encode the same replication machinery are generally unable to coexist in the same bacterial cell. However, Clostridium perfringens strains often carry multiple conjugative toxin or antibiotic resistance plasmids that are closely related and encode similar Rep proteins. In many bacteria, plasmid partitioning upon cell division involves a ParMRC system; in C. perfringens plasmids, there are approximately 10 different ParMRC families, with significant differences in amino acid sequences between each ParM family (15% to 54% identity). Since plasmids carrying genes belonging to the same ParMRC family are not observed in the same strain, these families appear to represent the basis for plasmid compatibility in C. perfringens. To understand this process, we examined the key recognition steps between ParR DNA-binding proteins and their parC binding sites. The ParR proteins bound to sequences within a parC site from the same ParMRC family but could not interact with a parC site from a different ParMRC family. These data provide evidence that compatibility of the conjugative toxin plasmids of C. perfringens is mediated by their parMRC-like partitioning systems. This process provides a selective advantage by enabling the host bacterium to maintain separate plasmids that encode toxins that are specific for different host targets.
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8
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Danielewicz N, Dai W, Rosato F, Webb ME, Striedner G, Römer W, Turnbull WB, Mairhofer J. In-Depth Characterization of a Re-Engineered Cholera Toxin Manufacturing Process Using Growth-Decoupled Production in Escherichia coli. Toxins (Basel) 2022; 14:396. [PMID: 35737057 PMCID: PMC9228256 DOI: 10.3390/toxins14060396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 05/24/2022] [Accepted: 05/31/2022] [Indexed: 12/10/2022] Open
Abstract
Non-toxic derivatives of the cholera toxin are extensively used in neuroscience, as neuronal tracers to reveal the location of cells in the central nervous system. They are, also, being developed as vaccine components and drug-delivery vehicles. Production of cholera-toxin derivatives is often non-reproducible; the quality and quantity require extensive fine-tuning to produce them in lab-scale settings. In our studies, we seek a resolution to this problem, by expanding the molecular toolbox of the Escherichia coli expression system with suitable production, purification, and offline analytics, to critically assess the quality of a probe or drug delivery, based on a non-toxic derivative of the cholera toxin. We present a re-engineered Cholera Toxin Complex (rCTC), wherein its toxic A1 domain was replaced with Maltose Binding Protein (MBP), as a model for an rCTC-based targeted-delivery vehicle. Here, we were able to improve the rCTC production by 11-fold (168 mg/L vs. 15 mg/L), in comparison to a host/vector combination that has been previously used (BL21(DE3) pTRBAB5-G1S). This 11-fold increase in the rCTC production capability was achieved by (1) substantial vector backbone modifications, (2) using Escherichia coli strains capable of growth-decoupling (V strains), (3) implementing a well-tuned fed-batch production protocol at a 1 L scale, and (4) testing the stability of the purified product. By an in-depth characterization of the production process, we revealed that secretion of rCTC across the E. coli Outer Membrane (OM) is processed by the Type II secretion-system general secretory pathway (gsp-operon) and that cholera toxin B-pentamerization is, likely, the rate-limiting step in complex formation. Upon successful manufacturing, we have validated the biological activity of rCTC, by measuring its binding affinity to its carbohydrate receptor GM1 oligosaccharide (Kd = 40 nM), or binding to Jurkat cells (93 pM) and delivering the cargo (MBP) in a retrograde fashion to the cell.
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Affiliation(s)
- Natalia Danielewicz
- enGenes Biotech GmbH, Mooslackengasse 17, 1190 Vienna, Austria;
- Department of Biotechnology, University of Natural Resources and Life Sciences, Muthgasse 11, 1190 Vienna, Austria;
| | - Wenyue Dai
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; (W.D.); (M.E.W.); (W.B.T.)
| | - Francesca Rosato
- Faculty of Biology, University of Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany; (F.R.); (W.R.)
- Signaling Research Centers BIOSS and CIBSS, University of Freiburg, Schänzlestraße 18, 79104 Freiburg, Germany
| | - Michael E. Webb
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; (W.D.); (M.E.W.); (W.B.T.)
| | - Gerald Striedner
- Department of Biotechnology, University of Natural Resources and Life Sciences, Muthgasse 11, 1190 Vienna, Austria;
| | - Winfried Römer
- Faculty of Biology, University of Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany; (F.R.); (W.R.)
- Signaling Research Centers BIOSS and CIBSS, University of Freiburg, Schänzlestraße 18, 79104 Freiburg, Germany
- Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, 79104 Freiburg, Germany
| | - W. Bruce Turnbull
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; (W.D.); (M.E.W.); (W.B.T.)
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Mishra D, Srinivasan R. Catching a Walker in the Act-DNA Partitioning by ParA Family of Proteins. Front Microbiol 2022; 13:856547. [PMID: 35694299 PMCID: PMC9178275 DOI: 10.3389/fmicb.2022.856547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 04/28/2022] [Indexed: 12/01/2022] Open
Abstract
Partitioning the replicated genetic material is a crucial process in the cell cycle program of any life form. In bacteria, many plasmids utilize cytoskeletal proteins that include ParM and TubZ, the ancestors of the eukaryotic actin and tubulin, respectively, to segregate the plasmids into the daughter cells. Another distinct class of cytoskeletal proteins, known as the Walker A type Cytoskeletal ATPases (WACA), is unique to Bacteria and Archaea. ParA, a WACA family protein, is involved in DNA partitioning and is more widespread. A centromere-like sequence parS, in the DNA is bound by ParB, an adaptor protein with CTPase activity to form the segregation complex. The ParA ATPase, interacts with the segregation complex and partitions the DNA into the daughter cells. Furthermore, the Walker A motif-containing ParA superfamily of proteins is associated with a diverse set of functions ranging from DNA segregation to cell division, cell polarity, chemotaxis cluster assembly, cellulose biosynthesis and carboxysome maintenance. Unifying principles underlying the varied range of cellular roles in which the ParA superfamily of proteins function are outlined. Here, we provide an overview of the recent findings on the structure and function of the ParB adaptor protein and review the current models and mechanisms by which the ParA family of proteins function in the partitioning of the replicated DNA into the newly born daughter cells.
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Affiliation(s)
- Dipika Mishra
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, India
- Homi Bhabha National Institutes, Mumbai, India
| | - Ramanujam Srinivasan
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, India
- Homi Bhabha National Institutes, Mumbai, India
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Gekenidis MT, Rigotti S, Hummerjohann J, Walsh F, Drissner D. Long-Term Persistence of blaCTX-M-15 in Soil and Lettuce after Introducing Extended-Spectrum β-Lactamase (ESBL)-Producing Escherichia coli via Manure or Water. Microorganisms 2020; 8:E1646. [PMID: 33114244 PMCID: PMC7690902 DOI: 10.3390/microorganisms8111646] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 01/03/2023] Open
Abstract
The number of environmental antibiotic-resistant bacteria (ARB) has increased dramatically since the start of antibiotic mass production for broad bacterial infection treatment in 1944. Nowadays, ARB and their resistance-determining genes (ARGs) are readily detected in all environments, including the human food chain. A highly relevant food group in this context is fresh produce, frequent raw consumption of which facilitates direct transfer of ARB and ARGs to the consumer. Here, we investigate the persistence of an extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli) pEK499 and its clinically most important ARG (blaCTX-M-15), after introduction via irrigation water or manure into a lettuce-growing system. Culturable ESBL-producing E. coli persisted longest in soil and when introduced via manure (until 9 weeks after introduction), while being undetectable on lettuce beyond day 7. In contrast, qPCR detection of blaCTX-M-15 was much more frequent: introduction via water significantly increased blaCTX-M-15 on lettuce until week 4, as opposed to manure, which affected the soil in the long-term (9 weeks) while leading to blaCTX-M-15 detection on lettuce until day 7 only. Our findings demonstrate long-term persistence of undesired ARB and ARG after their introduction via both irrigation and amendment. Such an understanding of the persistence kinetics of an ESBL-producing E. coli and plasmid-encoded blaCTX-M-15 aids the determination of critical actions in order to mitigate their transfer to the consumer.
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Affiliation(s)
| | - Serena Rigotti
- Microbiological Food Safety, Agroscope, 8820 Wädenswil, Switzerland;
| | - Jörg Hummerjohann
- Microbiological Food Safety, Agroscope, 3003 Liebefeld, Switzerland;
| | - Fiona Walsh
- Department of Biology, Maynooth University, W23 F2H6 Maynooth, Co. Kildare, Ireland;
| | - David Drissner
- Department of Life Sciences, Albstadt-Sigmaringen University, 72488 Sigmaringen, Germany;
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11
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Gulli J, Kroll E, Rosenzweig F. Encapsulation enhances protoplast fusant stability. Biotechnol Bioeng 2020; 117:1696-1709. [PMID: 32100874 PMCID: PMC7318116 DOI: 10.1002/bit.27318] [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: 10/27/2019] [Revised: 02/18/2020] [Accepted: 02/24/2020] [Indexed: 01/13/2023]
Abstract
A barrier to cost‐efficient biomanufacturing is the instability of engineered genetic elements, such as plasmids. Instability can also manifest at the whole‐genome level, when fungal dikaryons revert to parental species due to nuclear segregation during cell division. Here, we show that by encapsulating Saccharomyces cerevisiae‐Pichia stipitis dikaryons in an alginate matrix, we can limit cell division and preserve their expanded metabolic capabilities. As a proxy to cellulosic ethanol production, we tested the capacity of such cells to carry out ethanologenic fermentation of glucose and xylose, examining substrate use, ploidy, and cell viability in relation to planktonic fusants, as well as in relation to planktonic and encapsulated cell cultures consisting of mixtures of these species. Glucose and xylose consumption and ethanol production by encapsulated dikaryons were greater than planktonic controls. Simultaneous co‐fermentation did not occur; rather the order and kinetics of glucose and xylose catabolism by encapsulated dikaryons were similar to cultures where the two species were encapsulated together. Over repeated cycles of fed‐batch culture, encapsulated S. cerevisiae‐P. stipitis fusants exhibited a dramatic increase in genomic stability, relative to planktonic fusants. Encapsulation also increased the stability of antibiotic‐resistance plasmids used to mark each species and preserved a fixed ratio of S. cerevisiae to P. stipitis cells in mixed cultures. Our data demonstrate how encapsulating cells in an extracellular matrix restricts cell division and, thereby, preserves the stability and biological activity of entities ranging from genomes to plasmids to mixed populations, each of which can be essential to cost‐efficient biomanufacturing.
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Affiliation(s)
- Jordan Gulli
- School of Biological Sciences, College of Science, Georgia Institute of Technology, Atlanta, Georgia
| | - Eugene Kroll
- School of Biological Sciences, College of Science, Georgia Institute of Technology, Atlanta, Georgia
| | - Frank Rosenzweig
- School of Biological Sciences, College of Science, Georgia Institute of Technology, Atlanta, Georgia.,Parker Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia
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12
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Volke DC, Friis L, Wirth NT, Turlin J, Nikel PI. Synthetic control of plasmid replication enables target- and self-curing of vectors and expedites genome engineering of Pseudomonas putida. Metab Eng Commun 2020; 10:e00126. [PMID: 32215253 PMCID: PMC7090339 DOI: 10.1016/j.mec.2020.e00126] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/23/2020] [Accepted: 02/29/2020] [Indexed: 02/07/2023] Open
Abstract
Genome engineering of non-conventional microorganisms calls for the development of dedicated synthetic biology tools. Pseudomonas putida is a Gram-negative, non-pathogenic soil bacterium widely used for metabolic engineering owing to its versatile metabolism and high levels of tolerance to different types of stress. Genome editing of P. putida largely relies on homologous recombination events, assisted by helper plasmid-based expression of genes encoding DNA modifying enzymes. Plasmid curing from selected isolates is the most tedious and time-consuming step of this procedure, and implementing commonly used methods to this end in P. putida (e.g. temperature-sensitive replicons) is often impractical. To tackle this issue, we have developed a toolbox for both target- and self-curing of plasmid DNA in Pseudomonas species. Our method enables plasmid-curing in a simple cultivation step by combining in vivo digestion of vectors by the I-SceI homing nuclease with synthetic control of plasmid replication, triggered by the addition of a cheap chemical inducer (3-methylbenzoate) to the medium. The system displays an efficiency of vector curing >90% and the screening of plasmid-free clones is greatly facilitated by the use of fluorescent markers that can be selected according to the application intended. Furthermore, quick genome engineering of P. putida using self-curing plasmids is demonstrated through genome reduction of the platform strain EM42 by eliminating all genes encoding β-lactamases, the catabolic ben gene cluster, and the pyoverdine synthesis machinery. Physiological characterization of the resulting streamlined strain, P. putida SEM10, revealed advantageous features that could be exploited for metabolic engineering. Plasmid-curing is the most time-consuming step in genome engineering approaches. We have developed a system for easy target- and self-curing of plasmid DNA. Synthetic control of replication and highly-specific in vivo DNA digestion were used. Plasmid curing with this system displays an efficiency >90% in a 24-h cultivation. Quick genome engineering facilitated genome reduction of P. putida.
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Affiliation(s)
- Daniel C Volke
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kgs Lyngby, Denmark
| | - Laura Friis
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kgs Lyngby, Denmark
| | - Nicolas T Wirth
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kgs Lyngby, Denmark
| | - Justine Turlin
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kgs Lyngby, Denmark
| | - Pablo I Nikel
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kgs Lyngby, Denmark
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13
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Willms IM, Yuan J, Penone C, Goldmann K, Vogt J, Wubet T, Schöning I, Schrumpf M, Buscot F, Nacke H. Distribution of Medically Relevant Antibiotic Resistance Genes and Mobile Genetic Elements in Soils of Temperate Forests and Grasslands Varying in Land Use. Genes (Basel) 2020; 11:E150. [PMID: 32019196 PMCID: PMC7073645 DOI: 10.3390/genes11020150] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/22/2020] [Accepted: 01/24/2020] [Indexed: 12/28/2022] Open
Abstract
Antibiotic-resistant pathogens claim the lives of thousands of people each year and are currently considered as one of the most serious threats to public health. Apart from clinical environments, soil ecosystems also represent a major source of antibiotic resistance determinants, which can potentially disseminate across distinct microbial habitats and be acquired by human pathogens via horizontal gene transfer. Therefore, it is of global importance to retrieve comprehensive information on environmental factors, contributing to an accumulation of antibiotic resistance genes and mobile genetic elements in these ecosystems. Here, medically relevant antibiotic resistance genes, class 1 integrons and IncP-1 plasmids were quantified via real time quantitative PCR in soils derived from temperate grasslands and forests, varying in land use over a large spatial scale. The generated dataset allowed an analysis, decoupled from regional influences, and enabled the identification of land use practices and soil characteristics elevating the abundance of antibiotic resistance genes and mobile genetic elements. In grassland soils, the abundance of the macrolide resistance gene mefA as well as the sulfonamide resistance gene sul2 was positively correlated with organic fertilization and the abundance of aac(6')-lb, conferring resistance to different aminoglycosides, increased with mowing frequency. With respect to forest soils, the beta-lactam resistance gene blaIMP-12 was significantly correlated with fungal diversity which might be due to the fact that different fungal species can produce beta-lactams. Furthermore, except blaIMP-5 and blaIMP-12, the analyzed antibiotic resistance genes as well as IncP-1 plasmids and class-1 integrons were detected less frequently in forest soils than in soils derived from grassland that are commonly in closer proximity to human activities.
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Affiliation(s)
- Inka M. Willms
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University of Göttingen, D-37077 Göttingen, Germany; (I.M.W.); (J.Y.)
| | - Jingyue Yuan
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University of Göttingen, D-37077 Göttingen, Germany; (I.M.W.); (J.Y.)
| | - Caterina Penone
- Institute of Plant Sciences, University of Bern, CH-3013 Bern, Switzerland;
| | - Kezia Goldmann
- Department of Soil Ecology, UFZ—Helmholtz Centre for Environmental Research, D-06120 Halle-Saale, Germany; (K.G.); (F.B.)
| | - Juliane Vogt
- Terrestrial Ecology Research Group, Department of Ecology and Ecosystem Management, Technical University of Munich, D-85354 Freising, Germany;
| | - Tesfaye Wubet
- Department of Community Ecology, UFZ—Helmholtz Centre for Environmental Research, D-06120 Halle-Saale, Germany;
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, D-04103 Leipzig, Germany
| | - Ingo Schöning
- Max Planck Institute for Biogeochemistry, D-07745 Jena, Germany; (I.S.); (M.S.)
| | - Marion Schrumpf
- Max Planck Institute for Biogeochemistry, D-07745 Jena, Germany; (I.S.); (M.S.)
| | - François Buscot
- Department of Soil Ecology, UFZ—Helmholtz Centre for Environmental Research, D-06120 Halle-Saale, Germany; (K.G.); (F.B.)
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, D-04103 Leipzig, Germany
| | - Heiko Nacke
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University of Göttingen, D-37077 Göttingen, Germany; (I.M.W.); (J.Y.)
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14
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Fleece ME, Nshama R, Walongo T, Kimathi C, Gratz J, Rogawski McQuade ET, Liu J, Pholwat S, Mduma E, Houpt ER, Platts-Mills JA. Longitudinal Assessment of Antibiotic Resistance in Fecal Escherichia coli in Tanzanian Children. Am J Trop Med Hyg 2020; 100:1110-1114. [PMID: 30834886 DOI: 10.4269/ajtmh.18-0789] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Antibiotic-resistant bacterial infections are a major public health problem, and children in low-resource settings represent a particularly high-risk group. Few data are available on the dynamics of and risk factors for gastrointestinal carriage of antibiotic-resistant bacteria in these vulnerable populations. In this study, we described the antibiotic susceptibility profiles of Escherichia coli isolated from stool specimens collected from children aged 6 to 60 months enrolled in a birth cohort study in Haydom, Tanzania. We estimated the association between sociodemographic risk factors, child illnesses, and antibiotic exposure and E. coli drug resistance. Carriage of antibiotic-resistant E. coli was common starting early in life and did not clearly increase with age. The majority of isolates were resistant to ampicillin (749/837; 89.5%), cefazolin (742/837; 88.6%), and cotrimoxazole (721/837; 86.1%). Resistance to amoxicillin/clavulanate (361/836; 43.2%), ampicillin/sulbactam (178/819; 21.7%), nalidixic acid (131/831; 15.8%), and azithromycin (115/837; 13.7%) was also seen. Only 1.8% (15/837) of the pooled E. coli isolates met the criteria for extended-spectrum beta-lactamase production. High antibiotic use (0.26 additional resistant antibiotic classes; 95% CI: 0.05, 0.47) and high income (0.28 additional resistant antibiotic classes; 95% CI: 0.06, 0.50) were associated with the carriage of antibiotic-resistant E. coli, whereas hospital birth, crowding in the home, improved drinking water and sanitation, and common childhood illnesses were not. In this setting, the carriage of antibiotic-resistant E. coli was common. Other than recent antibiotic exposure and high income, individual risk factors for the acquisition and carriage of resistance could not be identified, suggesting that population-level interventions are needed.
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Affiliation(s)
- Molly E Fleece
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia
| | | | | | | | - Jean Gratz
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia
| | | | - Jie Liu
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia
| | - Suporn Pholwat
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia
| | - Esto Mduma
- Haydom Global Health Institute, Haydom, Tanzania
| | - Eric R Houpt
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia
| | - James A Platts-Mills
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia
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15
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Olalekan A, Onwugamba F, Iwalokun B, Mellmann A, Becker K, Schaumburg F. High proportion of carbapenemase-producing Escherichia coli and Klebsiella pneumoniae among extended-spectrum β-lactamase-producers in Nigerian hospitals. J Glob Antimicrob Resist 2019; 21:8-12. [PMID: 31525542 DOI: 10.1016/j.jgar.2019.09.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/29/2019] [Accepted: 09/07/2019] [Indexed: 10/26/2022] Open
Abstract
OBJECTIVES Carbapenem-resistant Enterobacterales are a global problem, however little is known about the burden and origin of carbapenem resistance in Africa. The objectives of this study were to determine the proportion of carbapenem-resistant isolates among extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E), to identify the underlying mechanisms of resistance and to assess the population structure of carbapenem-resistant isolates from Nigeria. METHODS ESBL-E isolates (n = 175) from infections were collected at four hospitals in Lagos, Nigeria, from July 2016 to January 2018 and were screened for carbapenem resistance using a VITEK®2 automated system. All carbapenem-resistant ESBL-E (CRE) were screened for blaKPC, blaCTX-M, blaCMY-2, blaNDM, blaVIM, blaIMP, blaOXA-181 and blaOXA-48 genes. Genotyping of randomly selected isolates was performed by whole-genome sequencing. RESULTS The isolates included Escherichia coli (n = 113; 64.6%) and Klebsiella pneumoniae (n = 62; 35.4%). Of the 175 ESBL-E isolates, 48 (27.4%) were resistant to carbapenems (15 E. coli and 33 K. pneumoniae). CRE isolates carried blaNDM (n = 30; 62.5%), blaNDM + blaOXA-181 (n = 10; 20.8%), blaOXA-181 (n = 2; 4.2%) and blaNDM + blaOXA-48 (n = 1; 2.1%); no carbapenemase gene was detected in 5 isolates (10.4%). The isolates showed low diversity and were mainly associated with multilocus sequence typing (MLST) sequence types ST410 for E. coli and ST395 and ST147 for K. pneumoniae. CONCLUSION Carbapenem resistance is frequent among ESBL-E in Nigeria and is mainly associated with blaNDM. Genotyping suggested that the observed clones possibly originated from Southeast Asia.
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Affiliation(s)
- Adesola Olalekan
- Department of Medical Laboratory Science, College of Medicine, University of Lagos, Lagos, Nigeria
| | - Francis Onwugamba
- Institute of Medical Microbiology, University Hospital Münster, Domagkstraße 10, 48149 Münster, Germany
| | - Bamidele Iwalokun
- Molecular Biology and Biotechnology Department, Nigerian Institute of Medical Research, Lagos, Nigeria
| | - Alexander Mellmann
- Institute of Medical Microbiology, University Hospital Münster, Domagkstraße 10, 48149 Münster, Germany; Institute of Hygiene, University Hospital Münster, Münster, Germany
| | - Karsten Becker
- Institute of Medical Microbiology, University Hospital Münster, Domagkstraße 10, 48149 Münster, Germany
| | - Frieder Schaumburg
- Institute of Medical Microbiology, University Hospital Münster, Domagkstraße 10, 48149 Münster, Germany.
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16
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Barazesh M, Mostafavipour Z, Kavousipour S, Mohammadi S, Mokarram P. Two Simple Methods for Optimizing the Production of "Difficult-to-Express" GnRH-DFF40 Chimeric Protein. Adv Pharm Bull 2019; 9:423-431. [PMID: 31592077 PMCID: PMC6773931 DOI: 10.15171/apb.2019.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 06/23/2019] [Accepted: 06/24/2019] [Indexed: 12/20/2022] Open
Abstract
Purpose: GnRH-DFF40 (gonadotropin releasing hormone - DNA fragmentation factor 40) is
a humanized recombinant immunotoxin and serves as a prospective candidate for targeted
therapy of gonadotropin releasing hormone receptor (GnRHR) overexpressing malignancies.
However, its production in Escherichia coli in a soluble and functional form still remains a
challenge. Here we introduce two successful and reproducible conditions for production and
purification of “difficult-to-express” GnRH-DFF40 protein.
Methods: A synthetic codon optimized GnRH-DFF40 fusion gene was cloned in pET28a
plasmid. Two methods including high cell density IPTG induction (HCDI) and autoinduction
method (AIM) with a focus on obtaining high cell density have been investigated to enhance the
protein production in (E. coli). Moreover, to obtain higher protein production several factors in
the AIM method including carbon sources, incubation time and temperature, plasmid stability
and double colony selection, were optimized.
Results: Remarkable amounts of soluble GnRH-DFF40 protein were achieved by both methods.
Cell density and protein yields in AIM was about 1.5 fold higher than that what obtained using
HCDI. Initial screening showed that 25ºC is better to achieve higher protein production in both
methods. pH alterations in AIM were maintained in a more constant level at 25ºC and 37ºC
temperatures without any detrimental effects on cell growth during protein production phase
up to 21 hours after incubation. Plasmid stability during growth and expression induction phase
was maintained at a high level of 98% and 96% for AIM and HCDI methods, respectively. After
parameter optimization and double colony selection in AIM, a very high yield of recombinant
protein was achieved (528.3 mg/L).
Conclusion: With the optimization of these high cell density expression methods, reproducible
manifold enhancement of soluble protein yields can be achieved for “difficult-to-express”
GnRH-DFF40 compared to conventional expression methods.
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Affiliation(s)
- Mahdi Barazesh
- Department of Biotechnology, School of Advanced Medical Science and Technologies, Shiraz University of Medical Sciences, Shiraz, IR Iran
| | - Zohreh Mostafavipour
- Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran.,Recombinant Proteins Lab, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran
| | - Soudabeh Kavousipour
- Department of Biotechnology, School of Advanced Medical Science and Technologies, Shiraz University of Medical Sciences, Shiraz, IR Iran
| | - Shiva Mohammadi
- Department of Biotechnology, School of Advanced Medical Science and Technologies, Shiraz University of Medical Sciences, Shiraz, IR Iran
| | - Pooneh Mokarram
- Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, IR Iran
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17
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Revitt-Mills SA, Vidor CJ, Watts TD, Lyras D, Rood JI, Adams V. Virulence Plasmids of the Pathogenic Clostridia. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0034-2018. [PMID: 31111816 PMCID: PMC11257192 DOI: 10.1128/microbiolspec.gpp3-0034-2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Indexed: 12/12/2022] Open
Abstract
The clostridia cause a spectrum of diseases in humans and animals ranging from life-threatening tetanus and botulism, uterine infections, histotoxic infections and enteric diseases, including antibiotic-associated diarrhea, and food poisoning. The symptoms of all these diseases are the result of potent protein toxins produced by these organisms. These toxins are diverse, ranging from a multitude of pore-forming toxins to phospholipases, metalloproteases, ADP-ribosyltransferases and large glycosyltransferases. The location of the toxin genes is the unifying theme of this review because with one or two exceptions they are all located on plasmids or on bacteriophage that replicate using a plasmid-like intermediate. Some of these plasmids are distantly related whilst others share little or no similarity. Many of these toxin plasmids have been shown to be conjugative. The mobile nature of these toxin genes gives a ready explanation of how clostridial toxin genes have been so widely disseminated both within the clostridial genera as well as in the wider bacterial community.
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Affiliation(s)
- Sarah A Revitt-Mills
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Callum J Vidor
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Thomas D Watts
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Dena Lyras
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Julian I Rood
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Vicki Adams
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
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