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Toda N, Inoue-Kashino N, Fujita H, Yoshida R, Nimura-Matsune K, Watanabe S, Kuroda A, Kashino Y, Hirota R. Cell morphology engineering enhances grazing resistance of Synechococcus elongatus PCC 7942 for non-sterile large-scale cultivation. J Biosci Bioeng 2024; 137:245-253. [PMID: 38336581 DOI: 10.1016/j.jbiosc.2024.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 01/04/2024] [Accepted: 01/04/2024] [Indexed: 02/12/2024]
Abstract
In the practical scale of cyanobacterial cultivation, the golden algae Poterioochromonas malhamensis is a well-known predator that causes devastating damage to the culture, referred to as pond crash. The establishment and maintenance of monoculture conditions are ideal for large-scale cultures. However, this is a difficult challenge because microbial contamination is unavoidable in practical-scale culture facilities. In the present study, we unexpectedly observed the pond crash phenomenon during the pilot-scale cultivation of Synechococcus elongatus PCC 7942 using a 100-L photobioreactor. This was due to the contamination with P. malhamensis, which probably originated from residual fouling. Interestingly, we found that S.elongatus PCC 7942 can alter its morphological structure when subjected to continuous grazing pressure from predators, resulting in cells that were more than 100 times longer than those of the wild-type strain. These hyper-elongated S.elongatus PCC 7942 cells had mutations in the genes encoding FtsZ or Ftn2 which are involved in bacterial cell division. Importantly, the elongated phenotype remained stable during cultivation, enabling S.elongatus PCC 7942 to thrive and resist grazing. The cultivation of the elongated S.elongatus PCC 7942 mutant strain in a 100-L pilot-scale photobioreactor under non-sterile conditions resulted in increased cyanobacterial biomass without encountering pond crash. This study demonstrates an efficient strategy for cyanobacterial cell culture in practical-scale bioreactors without the need for extensive decontamination or sterilization of the growth medium and culture facility, which can contribute to economically viable cultivation and bioprocessing of microalgae.
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Affiliation(s)
- Narumi Toda
- Unit of Biotechnology, Division of Biological and Life Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Natsuko Inoue-Kashino
- Graduate School of Science, University of Hyogo, 3-2-1 Koto, Kamigori, Ako-gun, Hyogo, 678-1297, Japan
| | - Hazaya Fujita
- Graduate School of Science, University of Hyogo, 3-2-1 Koto, Kamigori, Ako-gun, Hyogo, 678-1297, Japan
| | - Ryosuke Yoshida
- Unit of Biotechnology, Division of Biological and Life Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Kaori Nimura-Matsune
- Department of Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan
| | - Satoru Watanabe
- Department of Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan
| | - Akio Kuroda
- Unit of Biotechnology, Division of Biological and Life Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan; Seto Inland Sea Carbon-neutral Research Center, Hiroshima University, 2445 Mukaishima-cho, Onomichi, Hiroshima 722-0073, Japan
| | - Yasuhiro Kashino
- Graduate School of Science, University of Hyogo, 3-2-1 Koto, Kamigori, Ako-gun, Hyogo, 678-1297, Japan
| | - Ryuichi Hirota
- Unit of Biotechnology, Division of Biological and Life Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan; Seto Inland Sea Carbon-neutral Research Center, Hiroshima University, 2445 Mukaishima-cho, Onomichi, Hiroshima 722-0073, Japan.
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2
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Kobayashi I, Imamura S, Hirota R, Kuroda A, Tanaka K. Expression of bacterial phosphite dehydrogenase confers phosphite availability in a unicellular red alga Cyanidioschyzon merolae. J GEN APPL MICROBIOL 2024; 69:287-291. [PMID: 37587047 DOI: 10.2323/jgam.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/18/2023]
Abstract
Microalgae are promising cell factories for producing value-added products. Large-scale microalgal cultivation suffers from invasion by contaminating microorganisms. Since most contaminating organisms cannot utilize phosphite as a unique phosphorus source, phosphite-utilizing ability may provide a growth advantage against contaminating organisms and solve this problem. Studies showed that microorganisms, typically unable to metabolize phosphite, can utilize phosphite by expressing exogenous phosphite dehydrogenase. Here, we constructed Cyanidioschyzon merolae strains introduced with the phosphite dehydrogenase gene, ptxD, from Ralstonia sp. 4506. The ptxD-introduced strains grew in a phosphite-dependent manner, with the phosphite-related growth rate almost matching that with phosphate as sole phosphorus source.
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Affiliation(s)
- Ikki Kobayashi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology
| | - Sousuke Imamura
- Space Environment and Energy Laboratories, Nippon Telegraph and Telephone Corporation
| | - Ryuichi Hirota
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University
| | - Akio Kuroda
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University
| | - Kan Tanaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology
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3
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Wang Y, Li YQ, Wang MJ, Luo CB. Non-sterilized conversion of whole lignocellulosic components into polyhydroxybutyrate by Halomonas sp. Y3 with a dual anti-microbial contamination system. Int J Biol Macromol 2023; 241:124606. [PMID: 37116849 DOI: 10.1016/j.ijbiomac.2023.124606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/12/2023] [Accepted: 04/21/2023] [Indexed: 04/30/2023]
Abstract
Polyhydroxybutyrate (PHB) production from lignocellulosic biomass is challenging due to the need for whole components and energy-effective conversion. Herein, Halomonas sp. Y3, a ligninolytic bacterium with the capacity to produce PHB from lignin and cellulose- and hemicellulose-derived sugars, is employed to explore its feasibility. This strain shows high sugar tolerance up to 200 g/L of glucose and 120 g/L of xylose. A dual anti-microbial contamination system (DACS) containing alkali-halophilic system (AHS) and phosphite-urea system (PUS) is presented, successfully achieving a completely aseptic effect and resulting in a total of 8.2 g of PHB production from 100 g bamboo biomass. We further develop a stage-fed-batch fermentation to promote the complete utilization of xylose. Approximately 69.99 g of dry cell weight (DCW) and 46.45 g of PHB with 66.35 % are obtained from a total of 296.58 g of sugars and 5.70 g of lignin, showing a significant advancement for LCB bioconversion. We then delete the native phosphate transporters, rendering the strain unable to grow on phosphate-loaded media, effectively improving the strain biosafety without compromising its ability to produce PHB. Overall, our findings demonstrate the potential of Y3 as a classic bacterium strain for PHB production with potential uses in industry.
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Affiliation(s)
- Yan Wang
- College of Life Science, Leshan Normal University, Leshan 614000, China
| | - Yuan-Qiu Li
- College of Life Science, Leshan Normal University, Leshan 614000, China; College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Ming-Jun Wang
- College of Life Science, Leshan Normal University, Leshan 614000, China
| | - Chao-Bing Luo
- College of Life Science, Leshan Normal University, Leshan 614000, China.
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4
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Pavão G, Sfalcin I, Bonatto D. Biocontainment Techniques and Applications for Yeast Biotechnology. Fermentation 2023. [DOI: 10.3390/fermentation9040341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Biocontainment techniques for genetically modified yeasts (GMYs) are pivotal due to the importance of these organisms for biotechnological processes and also due to the design of new yeast strains by using synthetic biology tools and technologies. Due to the large genetic modifications that many yeast strains display, it is highly desirable to avoid the leakage of GMY cells into natural environments and, consequently, the spread of synthetic genes and circuits by horizontal or vertical gene transfer mechanisms within the microorganisms. Moreover, it is also desirable to avoid patented yeast gene technologies spreading outside the production facility. In this review, the different biocontainment technologies currently available for GMYs were evaluated. Interestingly, uniplex-type biocontainment approaches (UTBAs), which rely on nutrient auxotrophies induced by gene mutation or deletion or the expression of the simple kill switches apparatus, are still the major biocontainment approaches in use with GMY. While bacteria such as Escherichia coli account for advanced biocontainment technologies based on synthetic biology and multiplex-type biocontainment approaches (MTBAs), GMYs are distant from this scenario due to many reasons. Thus, a comparison of different UTBAs and MTBAs applied for GMY and genetically engineered microorganisms (GEMs) was made, indicating the major advances of biocontainment techniques for GMYs.
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Hoffmann SA, Diggans J, Densmore D, Dai J, Knight T, Leproust E, Boeke JD, Wheeler N, Cai Y. Safety by design: Biosafety and biosecurity in the age of synthetic genomics. iScience 2023; 26:106165. [PMID: 36895643 PMCID: PMC9988571 DOI: 10.1016/j.isci.2023.106165] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Abstract
Technologies to profoundly engineer biology are becoming increasingly affordable, powerful, and accessible to a widening group of actors. While offering tremendous potential to fuel biological research and the bioeconomy, this development also increases the risk of inadvertent or deliberate creation and dissemination of pathogens. Effective regulatory and technological frameworks need to be developed and deployed to manage these emerging biosafety and biosecurity risks. Here, we review digital and biological approaches of a range of technology readiness levels suited to address these challenges. Digital sequence screening technologies already are used to control access to synthetic DNA of concern. We examine the current state of the art of sequence screening, challenges and future directions, and environmental surveillance for the presence of engineered organisms. As biosafety layer on the organism level, we discuss genetic biocontainment systems that can be used to created host organisms with an intrinsic barrier against unchecked environmental proliferation.
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Affiliation(s)
- Stefan A Hoffmann
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
| | - James Diggans
- Twist Bioscience, 681 Gateway Boulevard, South San Francisco, CA 9408, USA
| | - Douglas Densmore
- Department of Electrical and Computer Engineering, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA
| | - Junbiao Dai
- CAS Key Laboratory of Quantitative Engineering Biology, Guangdong Provincial Key Laboratory of Synthetic Genomics and Shenzhen Key Laboratory of Synthetic Genomics, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Tom Knight
- Ginkgo Bioworks, 27 Drydock Avenue, Boston, MA 02210, USA
| | - Emily Leproust
- Twist Bioscience, 681 Gateway Boulevard, South San Francisco, CA 9408, USA
| | - Jef D Boeke
- Institute for Systems Genetics, and Department of Biochemistry & Molecular Pharmacology, NYU Langone Health, 435 East 30th Street, New York, NY 10016, USA.,Department of Biomedical Engineering, NYU Tandon School of Engineering, Brooklyn, NY 11201, USA
| | - Nicole Wheeler
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Yizhi Cai
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
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6
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Murakami H, Sano K, Motomura K, Kuroda A, Hirota R. Assessment of horizontal gene transfer-mediated destabilization of Synechococcus elongatus PCC 7942 biocontainment system. J Biosci Bioeng 2023; 135:190-195. [PMID: 36653270 DOI: 10.1016/j.jbiosc.2022.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/08/2022] [Accepted: 12/08/2022] [Indexed: 01/18/2023]
Abstract
Biological containment is a biosafety strategy that prevents the dispersal of genetically modified organisms in natural ecosystems. We previously established a biocontainment system that makes bacterial growth dependent on the availability of phosphite (Pt), an ecologically rare form of phosphorus (P), by introducing Pt metabolic pathway genes and disrupting endogenous phosphate and organic phosphate transporter genes. Although this system proved highly effective, horizontal gene transfer (HGT) mediated recovery of a P transporter gene is considered as a potential pathway to abolish the Pt-dependent growth, resulting in escape from the containment. Here, we assessed the risk of HGT driven escape using the Pt-dependent cyanobacterium Synechococcus elongatus PCC 7942. Transformation experiments revealed that the Pt-dependent strain could regain phosphate transporter genes from the S. elongatus PCC 7942 wild-type genome and from the genome of the closely related strain, S. elongatus UTEX 2973. Transformed S. elongatus PCC 7942 became viable in a phosphate-containing medium. Meanwhile, transformation of the Synechocystis sp. PCC 6803 genome or environmental DNA did not yield escape strains, suggesting that only genetic material derived from phylogenetically-close species confer high risk to generate escape. Eliminating a single gene necessary for natural competence from the Pt-dependent strain reduced the escape occurrence rate. These results demonstrate that natural competence could be a potential risk to destabilize Pt-dependence, and therefore inhibiting exogenous DNA uptake would be effective for enhancing the robustness of the gene disruption-dependent biocontainment.
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Affiliation(s)
- Hiroki Murakami
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Kosuke Sano
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Kei Motomura
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Akio Kuroda
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Ryuichi Hirota
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan.
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7
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Govindasamy R, Gayathiri E, Sankar S, Venkidasamy B, Prakash P, Rekha K, Savaner V, Pari A, Thirumalaivasan N, Thiruvengadam M. Emerging Trends of Nanotechnology and Genetic Engineering in Cyanobacteria to Optimize Production for Future Applications. Life (Basel) 2022; 12. [PMID: 36556378 DOI: 10.3390/life12122013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 11/20/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022]
Abstract
Nanotechnology has the potential to revolutionize various fields of research and development. Multiple nanoparticles employed in a nanotechnology process are the magic elixir that provides unique features that are not present in the component's natural form. In the framework of contemporary research, it is inappropriate to synthesize microparticles employing procedures that include noxious elements. For this reason, scientists are investigating safer ways to produce genetically improved Cyanobacteria, which has many novel features and acts as a potential candidate for nanoparticle synthesis. In recent decades, cyanobacteria have garnered significant interest due to their prospective nanotechnological uses. This review will outline the applications of genetically engineered cyanobacteria in the field of nanotechnology and discuss its challenges and future potential. The evolution of cyanobacterial strains by genetic engineering is subsequently outlined. Furthermore, the recombination approaches that may be used to increase the industrial potential of cyanobacteria are discussed. This review provides an overview of the research undertaken to increase the commercial avenues of cyanobacteria and attempts to explain prospective topics for future research.
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Hirota R, Katsuura ZI, Momokawa N, Murakami H, Watanabe S, Ishida T, Ikeda T, Funabashi H, Kuroda A. Gatekeeper Residue Replacement in a Phosphite Transporter Enhances Mutational Robustness of the Biocontainment Strategy. ACS Synth Biol 2022; 11:3397-3404. [PMID: 36202772 DOI: 10.1021/acssynbio.2c00296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Biocontainment is a key methodology to reduce environmental risk through the deliberate release of genetically modified microorganisms. Previously, we developed a phosphite (HPO32-)-dependent biocontainment strategy, by expressing a phosphite-specific transporter HtxBCDE and phosphite dehydrogenase in bacteria devoid of their indigenous phosphate (HPO42-) transporters. This strategy did not allow Escherichia coli to generate escape mutants (EMs) in growth media containing phosphate as a phosphorus source using an assay with a detection limit of 1.9 × 10-13. In this study, we found that the coexistence of a high dose of phosphate (>0.5 mM) with phosphite in the growth medium allows the phosphite-dependent E. coli strain to generate EMs at a frequency of approximately 5.4 × 10-10. In all EMs, the mutation was a single amino acid substitution of phenylalanine to cysteine or serine at position 210 of HtxC, the transmembrane domain protein of the phosphorus compound transporter HtxBCDE. Replacement of the HtxC F210 residue with the other 17 amino acids revealed that HtxC F210 is crucial in determining substrate specificity of HtxBCDE. Based on the finding of the role of HtxC F210 as a "gatekeeper" residue for this transporter, we demonstrate that the replacement of HtxC F210 with amino acids resulting from codons that require two simultaneous point mutations to generate phosphate permissive HtxC mutants can reduce the rate of EM generation to an undetectable level. These findings also provide novel insights into the functional classification of HtxBCDE as a noncanonical ATP-binding cassette transporter in which the transmembrane domain protein participates in substrate recognition.
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Affiliation(s)
- Ryuichi Hirota
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Zen-Ichiro Katsuura
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Naoki Momokawa
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Hiroki Murakami
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Satoru Watanabe
- Department of Bioscience, Tokyo University of Agriculture, Tokyo 156-8502, Japan
| | - Takenori Ishida
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Takeshi Ikeda
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Hisakage Funabashi
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Akio Kuroda
- Unit of Biotechnology, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
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Asin-Garcia E, Batianis C, Li Y, Fawcett JD, de Jong I, Dos Santos VAPM. Phosphite synthetic auxotrophy as an effective biocontainment strategy for the industrial chassis Pseudomonas putida. Microb Cell Fact 2022; 21:156. [PMID: 35934698 PMCID: PMC9358898 DOI: 10.1186/s12934-022-01883-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 07/26/2022] [Indexed: 11/12/2022] Open
Abstract
The inclusion of biosafety strategies into strain engineering pipelines is crucial for safe-by-design biobased processes. This in turn might enable a more rapid regulatory acceptance of bioengineered organisms in both industrial and environmental applications. For this reason, we equipped the industrially relevant microbial chassis Pseudomonas putida KT2440 with an effective biocontainment strategy based on a synthetic dependency on phosphite, which is generally not readily available in the environment. The produced PSAG-9 strain was first engineered to assimilate phosphite through the genome-integration of a phosphite dehydrogenase and a phosphite-specific transport complex. Subsequently, to deter the strain from growing on naturally assimilated phosphate, all native genes related to its transport were identified and deleted generating a strain unable to grow on media containing any phosphorous source other than phosphite. PSAG-9 exhibited fitness levels with phosphite similar to those of the wild type with phosphate, and low levels of escape frequency. Beyond biosafety, this strategy endowed P. putida with the capacity to be cultured under non-sterile conditions using phosphite as the sole phosphorous source with a reduced risk of contamination by other microbes, while displaying enhanced NADH regenerative capacity. These industrially beneficial features complement the metabolic advantages for which this species is known for, thereby strengthening it as a synthetic biology chassis with potential uses in industry, with suitability towards environmental release.
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Affiliation(s)
- Enrique Asin-Garcia
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Wageningen, 6708 WE, The Netherlands
| | - Christos Batianis
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Wageningen, 6708 WE, The Netherlands
| | - Yunsong Li
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Wageningen, 6708 WE, The Netherlands
| | - James D Fawcett
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Wageningen, 6708 WE, The Netherlands.,Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington, London, SW72BX, UK
| | - Ivar de Jong
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Wageningen, 6708 WE, The Netherlands.,The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark
| | - Vitor A P Martins Dos Santos
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Wageningen, 6708 WE, The Netherlands. .,LifeGlimmer GmbH, 12163, Berlin, Germany. .,Bioprocess Engineering Group, Wageningen University & Research, Wageningen, 6700 AA, The Netherlands.
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Inoue H, Tajima K, Mitsumori C, Inoue-Kashino N, Miura T, Ifuku K, Hirota R, Kashino Y, Fujita K, Kinoshita H. Biodiversity risk assessment of genetically modified Chaetoceros gracilis for outdoor cultivation. J GEN APPL MICROBIOL 2022; 68:151-162. [PMID: 35650023 DOI: 10.2323/jgam.2021.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
A genetically modified (GM) strain of the diatom Chaetoceros gracilis expressing the phosphite dehydrogenase gene (ptxD), which is a useful gene both for the biological containment and the avoidance of microbial contamination, was characterized to estimate the risk against the biodiversity by laboratory experiments. GM strain could grow in the medium containing phosphite as a sole source of phosphorus, while its general characteristics such as growth, salt tolerance, heat and dehydration resistance in the normal phosphate-containing medium were equivalent to those of wild type (WT) strain. The increase in potential toxicity of GM strain against plant, crustacean, fish and mammal was also disproved. The dispersal ability of WT strain cultured in an outdoor raceway pond was investigated for 28 days by detecting the psb31 gene in vessels, settled at variable distances (between 5 and 60 m) from the pond. The diatom was detected only in one vessel placed 5 m apart. To estimate the influence on the environment, WT and GM strains were inoculated into freshwater, seawater and soil. The influence on the microbiome in those samples was assessed by 16S rRNA gene amplicon sequencing, in addition to the analysis of the survivability of those strains in the freshwater and the seawater. The results indicated that the effect to the microbiome and the survivability were comparable between WT and GM strains. All results showed that the introduction of the ptxD gene into the diatom had a low risk on biodiversity.
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Affiliation(s)
- Hidetoshi Inoue
- Biological Resource Center, National Institute of Technology and Evaluation (NITE)
| | - Kumiko Tajima
- Biological Resource Center, National Institute of Technology and Evaluation (NITE)
| | - Cristina Mitsumori
- Biological Resource Center, National Institute of Technology and Evaluation (NITE)
| | | | - Takamasa Miura
- Biological Resource Center, National Institute of Technology and Evaluation (NITE)
| | | | - Ryuichi Hirota
- Graduate School of Integrated Sciences for Life, Hiroshima University
| | | | - Katsutoshi Fujita
- Biological Resource Center, National Institute of Technology and Evaluation (NITE)
| | - Hiroshi Kinoshita
- Biological Resource Center, National Institute of Technology and Evaluation (NITE)
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11
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Sebesta J, Xiong W, Guarnieri MT, Yu J. Biocontainment of Genetically Engineered Algae. Front Plant Sci 2022; 13:839446. [PMID: 35310623 PMCID: PMC8924478 DOI: 10.3389/fpls.2022.839446] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 02/07/2022] [Indexed: 06/14/2023]
Abstract
Algae (including eukaryotic microalgae and cyanobacteria) have been genetically engineered to convert light and carbon dioxide to many industrially and commercially relevant chemicals including biofuels, materials, and nutritional products. At industrial scale, genetically engineered algae may be cultivated outdoors in open ponds or in closed photobioreactors. In either case, industry would need to address a potential risk of the release of the engineered algae into the natural environment, resulting in potential negative impacts to the environment. Genetic biocontainment strategies are therefore under development to reduce the probability that these engineered bacteria can survive outside of the laboratory or industrial setting. These include active strategies that aim to kill the escaped cells by expression of toxic proteins, and passive strategies that use knockouts of native genes to reduce fitness outside of the controlled environment of labs and industrial cultivation systems. Several biocontainment strategies have demonstrated escape frequencies below detection limits. However, they have typically done so in carefully controlled experiments which may fail to capture mechanisms of escape that may arise in the more complex natural environment. The selection of biocontainment strategies that can effectively kill cells outside the lab, while maintaining maximum productivity inside the lab and without the need for relatively expensive chemicals will benefit from further attention.
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12
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Dahlin LR, Guarnieri MT. Heterologous expression of phosphite dehydrogenase in the chloroplast or nucleus enables phosphite utilization and genetic selection in Picochlorum spp. ALGAL RES 2022; 62:102604. [DOI: 10.1016/j.algal.2021.102604] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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13
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Yuan H, Wang Y, Liu Y, Zhang M, Zou Z. A novel dominant selection system for plant transgenics based on phosphite metabolism catalyzed by bacterial alkaline phosphatase. PLoS One 2021; 16:e0259600. [PMID: 34735551 PMCID: PMC8568168 DOI: 10.1371/journal.pone.0259600] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 10/21/2021] [Indexed: 11/19/2022] Open
Abstract
Selective markers are generally indispensable in plant genetic transformation, of which the frequently used are of antibiotic or herbicide resistance. However, the increasing concerns on transgenic biosafety have encouraged many new and safe selective markers emerging, with an eminent representative as phosphite (Phi) in combination to its dehydrogenase (PTDH, e.g. PtxD). As bacterial alkaline phosphatase (BAP) can resemble PtxD to oxidatively convert toxic Phi into metabolizable phosphate (Pi), herein we harnessed it as the substitute of PtxD to develop an alternative Phi-based selection system. We first validated the Escherichia coli BAP (EcBAP) did own an extra enzymatic activity of oxidizing Phi to Pi. We further revealed EcBAP could be used as a dominant selective marker for Agrobacterium-mediated tobacco transformation. Although the involved Phi selection for transformed tobacco cells surprisingly required the presence of Pi, it showed a considerable transformation efficiency and dramatically accelerated transformation procedure, as compared to the routine kanamycin selection and the well-known PtxD/Phi system. Moreover, the EcBAP transgenic tobaccos could metabolize toxic Phi as a phosphorus (P) fertilizer thus underlying Phi-resistance, and competitively possess a dominant growth over wild-type tobacco and weeds under Phi stress. Therefore, this novel BAP/Phi-coupled system, integrating multiple advantages covering biosafe dominant selective marker, plant P utilization and weed management, can provide a PTDH-bypass technological choice to engineer transgenic plant species, especially those of great importance for sustainable agriculture.
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Affiliation(s)
- Hang Yuan
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, School of Life Sciences, Yunnan Normal University, Kunming, Yunnan, China
| | - Yuxian Wang
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, School of Life Sciences, Yunnan Normal University, Kunming, Yunnan, China
| | - Yanjuan Liu
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, School of Life Sciences, Yunnan Normal University, Kunming, Yunnan, China
| | - Mengru Zhang
- NHC Key Laboratory of Drug Addiction Medicine, The First Affiliated Hospital, Kunming Medical University, Kunming, Yunnan, China
| | - Zhurong Zou
- Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, School of Life Sciences, Yunnan Normal University, Kunming, Yunnan, China
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14
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Abstract
Biocontainment is a safeguard strategy for preventing uncontrolled proliferation of genetically engineered microorganisms (GEMs) in the environment. Biocontained GEMs are designed to survive only in the presence of a specific molecule. The design of a pollutant-degrading and pollutant-dependent GEM prevents its proliferation after cleaning the environment. In this study, we present a biocontained toluene-degrading bacterium based on Acinetobacter sp. Tol 5. The bamA gene, which encodes an essential outer membrane protein, was deleted from the chromosome of Tol 5 but complemented with a plasmid carrying a bamA gene regulated by the Pu promoter and the regulatory protein XylR. The resultant strain (PuBamA) degraded toluene, similarly to the wild-type Tol 5. Although the cell growth of the PuBamA strain was remarkably inhibited after toluene depletion, escape mutants emerged at a frequency of 1 per 5.3 × 10−7 cells. Analyses of escape mutants revealed that insertion sequences (ISs) carrying promoters were inserted between the Pu promoter and the bamA gene on the complemented plasmid. MinION deep sequencing of the plasmids extracted from the escape mutants enabled the identification of three types of ISs involved in the emergence of escape mutants, suggesting a strategy for reducing it. IMPORTANCE GEMs are beneficial for various applications, including environmental protection. However, the risks of GEM release into the environment have been debated for a long time. If a pollutant is employed as a specific molecule for a biocontainment system, GEMs capable of degrading pollutants are available for environmental protection. Nevertheless, to our knowledge, biocontained degraders for real pollutants have not been reported in academic journals so far. This is possibly due to the difficulty in the expression of enzymes for degrading pollutants in a tractable bacterium such as Escherichia coli. On the other hand, bacteria with enzymes for degrading pollutants are often intractable as a host of GEMs due to the shortage of tools for genetic manipulation. This study reports the feasibility of a biocontainment strategy for a toluene degrader. Our results provide useful insights into the construction of a GEM biocontainment system for environmental protection.
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15
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Toda N, Murakami H, Kanbara A, Kuroda A, Hirota R. Phosphite Reduces the Predation Impact of Poterioochromonasmalhamensis on Cyanobacterial Culture. Plants (Basel) 2021; 10:plants10071361. [PMID: 34371564 PMCID: PMC8309446 DOI: 10.3390/plants10071361] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 06/28/2021] [Accepted: 06/28/2021] [Indexed: 11/16/2022]
Abstract
Contamination by the predatory zooplankton Poterioochromonas malhamensis is one of the major threats that causes catastrophic damage to commercial-scale microalgal cultivation. However, knowledge of how to manage predator contamination is limited. Previously, we established a phosphite (Pt)-based culture system by engineering Synechococcus elongatus, which exerted a competitive growth advantage against microbial contaminants that compete with phosphate source. Here, we examined whether Pt is effective in suppressing predator-type contamination. Co-culture experiment of Synechococcus with isolated P. malhamensis revealed that, although an addition of Pt at low concentrations up to 2.0 mM was not effective, increased dosage of Pt (~20 mM) resulted in the reduced grazing impact of P. malhamensis. By using unsterilized raw environmental water collected from rivers or ponds, we found that the suppression effect of Pt was dependent on the type of environmental water used. Eukaryotic microbial community analysis of the cultures using environmental water samples revealed that Paraphysomonas, a colorless Chrysophyceae, emerged and dominated under high-Pt conditions, suggesting that Paraphysomonas is insensitive to Pt compared to P. malhamensis. These findings may provide a clue for developing a strategy to reduce the impact of grazer contamination in commercial-scale microalgal cultivation.
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Lei M, Peng X, Sun W, Zhang D, Wang Z, Yang Z, Zhang C, Yu B, Niu H, Ying H, Ouyang P, Liu D, Chen Y. Nonsterile l-Lysine Fermentation Using Engineered Phosphite-Grown Corynebacterium glutamicum. ACS Omega 2021; 6:10160-10167. [PMID: 34056170 PMCID: PMC8153679 DOI: 10.1021/acsomega.1c00226] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 03/29/2021] [Indexed: 06/12/2023]
Abstract
Fermentation using Corynebacterium glutamicum is an important method for the industrial production of amino acids. However, conventional fermentation processes using C. glutamicum are susceptible to microbial contamination and therefore require equipment sterilization or antibiotic dosing. To establish a more robust fermentation process, l-lysine-producing C. glutamicum was engineered to efficiently utilize xenobiotic phosphite (Pt) by optimizing the expression of Pt dehydrogenase in the exeR genome locus. This ability provided C. glutamicum with a competitive advantage over common contaminating microbes when grown on media containing Pt as a phosphorus source instead of phosphate. As a result, the engineered strain could produce 41.00 g/L l-lysine under nonsterile conditions during batch fermentation for 60 h, whereas the original strain required 72 h to produce 40.78 g/L l-lysine under sterile conditions. Therefore, the recombinant strain can efficiently produce l-lysine under nonsterilized conditions with unaffected production efficiency. Although this anticontamination strategy has been previously reported for other species, this is the first time it has been demonstrated in C. glutamicum; these findings should aid in the further development of cost-efficient amino acid fermentation processes.
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Affiliation(s)
- Ming Lei
- National
Engineering Research Center for Biotechnology, College of Biotechnology
and Pharmaceutical Engineering, Nanjing
Tech University, Nanjing 211816, China
- State
Key Laboratory of Materials-Oriented Chemical Engineering, College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Xiwei Peng
- National
Engineering Research Center for Biotechnology, College of Biotechnology
and Pharmaceutical Engineering, Nanjing
Tech University, Nanjing 211816, China
- State
Key Laboratory of Materials-Oriented Chemical Engineering, College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Wenjun Sun
- National
Engineering Research Center for Biotechnology, College of Biotechnology
and Pharmaceutical Engineering, Nanjing
Tech University, Nanjing 211816, China
- State
Key Laboratory of Materials-Oriented Chemical Engineering, College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Di Zhang
- National
Engineering Research Center for Biotechnology, College of Biotechnology
and Pharmaceutical Engineering, Nanjing
Tech University, Nanjing 211816, China
- State
Key Laboratory of Materials-Oriented Chemical Engineering, College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Zhenyu Wang
- National
Engineering Research Center for Biotechnology, College of Biotechnology
and Pharmaceutical Engineering, Nanjing
Tech University, Nanjing 211816, China
- State
Key Laboratory of Materials-Oriented Chemical Engineering, College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Zhengjiao Yang
- National
Engineering Research Center for Biotechnology, College of Biotechnology
and Pharmaceutical Engineering, Nanjing
Tech University, Nanjing 211816, China
- State
Key Laboratory of Materials-Oriented Chemical Engineering, College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Chong Zhang
- National
Engineering Research Center for Biotechnology, College of Biotechnology
and Pharmaceutical Engineering, Nanjing
Tech University, Nanjing 211816, China
- State
Key Laboratory of Materials-Oriented Chemical Engineering, College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Bin Yu
- National
Engineering Research Center for Biotechnology, College of Biotechnology
and Pharmaceutical Engineering, Nanjing
Tech University, Nanjing 211816, China
- State
Key Laboratory of Materials-Oriented Chemical Engineering, College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Huanqing Niu
- National
Engineering Research Center for Biotechnology, College of Biotechnology
and Pharmaceutical Engineering, Nanjing
Tech University, Nanjing 211816, China
- State
Key Laboratory of Materials-Oriented Chemical Engineering, College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Hanjie Ying
- National
Engineering Research Center for Biotechnology, College of Biotechnology
and Pharmaceutical Engineering, Nanjing
Tech University, Nanjing 211816, China
- State
Key Laboratory of Materials-Oriented Chemical Engineering, College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
- School
of Chemical Engineering and Energy, Zhengzhou
University, Zhengzhou 450001, China
| | - Pingkai Ouyang
- National
Engineering Research Center for Biotechnology, College of Biotechnology
and Pharmaceutical Engineering, Nanjing
Tech University, Nanjing 211816, China
- State
Key Laboratory of Materials-Oriented Chemical Engineering, College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
| | - Dong Liu
- National
Engineering Research Center for Biotechnology, College of Biotechnology
and Pharmaceutical Engineering, Nanjing
Tech University, Nanjing 211816, China
- State
Key Laboratory of Materials-Oriented Chemical Engineering, College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
- School
of Chemical Engineering and Energy, Zhengzhou
University, Zhengzhou 450001, China
| | - Yong Chen
- National
Engineering Research Center for Biotechnology, College of Biotechnology
and Pharmaceutical Engineering, Nanjing
Tech University, Nanjing 211816, China
- State
Key Laboratory of Materials-Oriented Chemical Engineering, College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
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17
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Abdel-Hady GN, Ikeda T, Ishida T, Funabashi H, Kuroda A, Hirota R. Engineering Cofactor Specificity of a Thermostable Phosphite Dehydrogenase for a Highly Efficient and Robust NADPH Regeneration System. Front Bioeng Biotechnol 2021; 9:647176. [PMID: 33869158 PMCID: PMC8047080 DOI: 10.3389/fbioe.2021.647176] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 03/15/2021] [Indexed: 11/13/2022] Open
Abstract
Nicotinamide adenine dinucleotide phosphate (NADP)-dependent dehydrogenases catalyze a range of chemical reactions useful for practical applications. However, their dependence on the costly cofactor, NAD(P)H remains a challenge which must be addressed. Here, we engineered a thermotolerant phosphite dehydrogenase from Ralstonia sp. 4506 (RsPtxD) by relaxing the cofactor specificity for a highly efficient and robust NADPH regeneration system. The five amino acid residues, Cys174-Pro178, located at the C-terminus of β7-strand region in the Rossmann-fold domain of RsPtxD, were changed by site-directed mutagenesis, resulting in four mutants with a significantly increased preference for NADP. The catalytic efficiency of mutant RsPtxDHARRA for NADP (K cat/K M)NADP was 44.1 μM-1 min-1, which was the highest among the previously reported phosphite dehydrogenases. Moreover, the RsPtxDHARRA mutant exhibited high thermostability at 45°C for up to 6 h and high tolerance to organic solvents, when bound with NADP. We also demonstrated the applicability of RsPtxDHARRA as an NADPH regeneration system in the coupled reaction of chiral conversion of 3-dehydroshikimate to shikimic acid by the thermophilic shikimate dehydrogenase of Thermus thermophilus HB8 at 45°C, which could not be supported by the parent RsPtxD enzyme. Therefore, the RsPtxDHARRA mutant might be a promising alternative NADPH regeneration system for practical applications.
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Affiliation(s)
- Gamal Nasser Abdel-Hady
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Hiroshima, Japan.,Department of Genetics, Faculty of Agriculture, Minia University, Minia, Egypt
| | - Takeshi Ikeda
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Hiroshima, Japan.,Unit of Biotechnology, Division of Biological and Life Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Takenori Ishida
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Hiroshima, Japan.,Unit of Biotechnology, Division of Biological and Life Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Hisakage Funabashi
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Hiroshima, Japan.,Unit of Biotechnology, Division of Biological and Life Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Akio Kuroda
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Hiroshima, Japan.,Unit of Biotechnology, Division of Biological and Life Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Ryuichi Hirota
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Hiroshima, Japan.,Unit of Biotechnology, Division of Biological and Life Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
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18
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Cui J, Xie Y, Sun T, Chen L, Zhang W. Deciphering and engineering photosynthetic cyanobacteria for heavy metal bioremediation. Sci Total Environ 2021; 761:144111. [PMID: 33352345 DOI: 10.1016/j.scitotenv.2020.144111] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 11/22/2020] [Accepted: 11/22/2020] [Indexed: 06/12/2023]
Abstract
Environmental pollution caused by heavy metals has received worldwide attentions due to their ubiquity, poor degradability and easy bioaccumulation in host cells. As one potential solution, photosynthetic cyanobacteria have been considered as promising remediation chassis and widely applied in various bioremediation processes of heavy-metals. Meanwhile, deciphering resistant mechanisms and constructing tolerant chassis towards heavy metals could greatly contribute to the successful application of the cyanobacteria-based bioremediation in the future. In this review, first we summarized recent application of cyanobacteria in heavy metals bioremediation using either live or dead cells. Second, resistant mechanisms and strategies for enhancing cyanobacterial bioremediation of heavy metals were discussed. Finally, potential challenges and perspectives for improving bioremediation of heavy metals by cyanobacteria were presented.
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Affiliation(s)
- Jinyu Cui
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, PR China; Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin 300072, PR China; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, PR China
| | - Yaru Xie
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, PR China; Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin 300072, PR China; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, PR China
| | - Tao Sun
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, PR China; Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin 300072, PR China; Center for Biosafety Research and Strategy, Tianjin University, Tianjin 300072, PR China; Law School of Tianjin University, Tianjin 300072, PR China.
| | - Lei Chen
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, PR China; Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin 300072, PR China; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, PR China.
| | - Weiwen Zhang
- Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300072, PR China; Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin 300072, PR China; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, PR China; Center for Biosafety Research and Strategy, Tianjin University, Tianjin 300072, PR China; Law School of Tianjin University, Tianjin 300072, PR China
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19
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Lee HJ, Choi JI, Woo HM. Biocontainment of Engineered Synechococcus elongatus PCC 7942 for Photosynthetic Production of α-Farnesene from CO 2. J Agric Food Chem 2021; 69:698-703. [PMID: 33411536 DOI: 10.1021/acs.jafc.0c07020] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Biocontainment systems have been developed to mitigate the concerns regarding biosafety and environmental risk because of the possible escape of genetically modified organisms into the environment following large-scale outdoor cultivation. Here, we present a biocontainment system entailing genetically modified Synechococcus elongatus PCC 7942, also engineered for α-farnesene production using a de-evolutionary strategy. In this approach, the gene cluster encoding the β-carboxysome and the associated carbon concentrating mechanism (CCM) were deleted in the α-farnesene-producing cyanobacteria, resulting in no cell growth and no α-farnesene production at ambient CO2 concentrations (100% air bubbling). However, cell growth and α-farnesene production were detected in the CCM-deficient strains at high CO2 concentrations (5% CO2 [v/v], 10% CO2 [v/v]), albeit at levels lower than those of the parental control. To overcome this limitation, the overexpression of carbonic anhydrase and bicarbonate transporter genes in the CCM-deficient strains restored cell growth and the production level of α-farnesene (5.0 ± 0.6 mg/L) to that of the parental control. The production of α-farnesene in the later strains strictly depended on CO2 concentration in the photobioreactor and did not rely on a chemical induction process. Thus, next generation bio-solar cell factories could be promoted with the suggested biocontainment system.
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Affiliation(s)
- Hyun Jeong Lee
- Department of Food Science and Biotechnology, Sungkyunkwan University (SKKU), 2066 Seobu-ro, Jangan-gu, Suwon 16419, Republic of Korea
- BioFoundry Research Center, Institute of Biotechnology and Bioengineering, Sungkyunkwan University (SKKU), 2066 Seobu-ro, Jangan-gu, Suwon 16419, Republic of Korea
| | - Jong-Il Choi
- Department of Biotechnology and Bioengineering, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 61186, Republic of Korea
| | - Han Min Woo
- Department of Food Science and Biotechnology, Sungkyunkwan University (SKKU), 2066 Seobu-ro, Jangan-gu, Suwon 16419, Republic of Korea
- BioFoundry Research Center, Institute of Biotechnology and Bioengineering, Sungkyunkwan University (SKKU), 2066 Seobu-ro, Jangan-gu, Suwon 16419, Republic of Korea
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20
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Kallergi A, Asin‐Garcia E, Martins dos Santos VAP, Landeweerd L. Context matters: On the road to responsible biosafety technologies in synthetic biology. EMBO Rep 2021; 22:e51227. [PMID: 33369847 PMCID: PMC7788449 DOI: 10.15252/embr.202051227] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 07/07/2020] [Indexed: 11/09/2022] Open
Abstract
Biosafety is a major challenge for developing for synthetic organisms. An early focus on application and their context could assist with the design of appropriate genetic safeguards.
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Affiliation(s)
- Amalia Kallergi
- Institute for Science in SocietyRadboud UniversityNijmegenThe Netherlands
| | - Enrique Asin‐Garcia
- Laboratory of Systems and Synthetic BiologyWageningen University & ResearchWageningenThe Netherlands
| | - Vitor AP Martins dos Santos
- Laboratory of Systems and Synthetic BiologyWageningen University & ResearchWageningenThe Netherlands
- LifeGlimmer GmbHBerlinGermany
| | - Laurens Landeweerd
- Institute for Science in SocietyRadboud UniversityNijmegenThe Netherlands
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21
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Xu Y, Wu Y, Esquivel-elizondo S, Dolfing J, Rittmann BE. Using Microbial Aggregates to Entrap Aqueous Phosphorus. Trends Biotechnol 2020; 38:1292-303. [DOI: 10.1016/j.tibtech.2020.03.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/23/2020] [Accepted: 03/24/2020] [Indexed: 02/06/2023]
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22
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Guo ZW, Ou XY, Liang S, Gao HF, Zhang LY, Zong MH, Lou WY. Recruiting a Phosphite Dehydrogenase/Formamidase-Driven Antimicrobial Contamination System in Bacillus subtilis for Nonsterilized Fermentation of Acetoin. ACS Synth Biol 2020; 9:2537-2545. [PMID: 32786356 DOI: 10.1021/acssynbio.0c00312] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Microbial contamination, especially in large-scale processes, is partly a life-or-death issue for industrial fermentation. Therefore, the aim of this research was to create an antimicrobial contamination system in Bacillus subtilis 168 (an ideal acetoin producer for its safety and acetoin synthesis potential). First, introduction of the formamidase (FmdA) from Helicobacter pylori and the phosphite dehydrogenase (PtxD) from Pseudomonas stutzeri enabled the engineered Bacillus subtilis to simultaneously assimilate formamide and phosphite as nitrogen (N) and phosphorus (P) sources. Thus, the engineered B. subtilis became the dominant population in a potentially contaminated system, while contaminated microbes were starved of key nutrients. Second, stepwise metabolic engineering via chromosome-based overexpression of the relevant glycolysis and acetoin biosynthesis genes led to a 1.12-fold increment in acetoin titer compared with the starting host. Finally, with our best acetoin producer, 25.56 g/L acetoin was synthesized in the fed-batch fermentation, with a productivity of 0.33 g/L/h and a yield of 0.37 g/g under a nonsterilized and antibiotic-free system. More importantly, our work fulfills many key criteria of sustainable chemistry since sterilization is abolished, contributing to the simplified fermentation operation with lower energy consumption and cost.
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Affiliation(s)
- Ze-Wang Guo
- School of Food Science and Engineering, South China University of Technology, No. 381 Wushan Road, Guangzhou 510640, Guangdong, China
| | - Xiao-Yang Ou
- School of Food Science and Engineering, South China University of Technology, No. 381 Wushan Road, Guangzhou 510640, Guangdong, China
| | - Shan Liang
- School of Food Science and Engineering, South China University of Technology, No. 381 Wushan Road, Guangzhou 510640, Guangdong, China
| | - Hui-Fang Gao
- College of Life Sciences, Fujian Agriculture and Forestry University, No. 15 Shangxiadian Road, Fuzhou 350002, Fujian, China
| | - Liao-Yuan Zhang
- College of Life Sciences, Fujian Agriculture and Forestry University, No. 15 Shangxiadian Road, Fuzhou 350002, Fujian, China
| | - Min-Hua Zong
- School of Food Science and Engineering, South China University of Technology, No. 381 Wushan Road, Guangzhou 510640, Guangdong, China
| | - Wen-Yong Lou
- School of Food Science and Engineering, South China University of Technology, No. 381 Wushan Road, Guangzhou 510640, Guangdong, China
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23
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Stevens DR, Hammes-Schiffer S. Examining the Mechanism of Phosphite Dehydrogenase with Quantum Mechanical/Molecular Mechanical Free Energy Simulations. Biochemistry 2020; 59:943-954. [PMID: 32031785 DOI: 10.1021/acs.biochem.9b01089] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The projected decline of available phosphorus necessitates alternative methods to derive usable phosphate for fertilizer and other applications. Phosphite dehydrogenase oxidizes phosphite to phosphate with the cofactor NAD+ serving as the hydride acceptor. In addition to producing phosphate, this enzyme plays an important role in NADH cofactor regeneration processes. Mixed quantum mechanical/molecular mechanical free energy simulations were performed to elucidate the mechanism of this enzyme and to identify the protonation states of the substrate and product. Specifically, the finite temperature string method with umbrella sampling was used to generate the free energy surfaces and determine the minimum free energy paths for six different initial conditions that varied in the protonation state of the substrate and the position of the nucleophilic water molecule. In contrast to previous studies, the mechanism predicted by all six independent strings is a concerted but asynchronous dissociative mechanism in which hydride transfer from the phosphite substrate to NAD+ occurs prior to attack by the nucleophilic water molecule. His292 is identified as the most likely general base that deprotonates the attacking water molecule. However, Arg237 could also serve as this base if it were deprotonated and His292 were protonated prior to the main chemical transformation, although this scenario is less probable. The simulations indicate that the phosphite substrate is monoanionic in its active form and that the most likely product is dihydrogen phosphate. These mechanistic insights may be helpful for designing mutant enzymes or artificial constructs that convert phosphite to phosphate and NAD+ to NADH more effectively.
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Affiliation(s)
- David R Stevens
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
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González-Morales SI, Pacheco-Gutiérrez NB, Ramírez-Rodríguez CA, Brito-Bello AA, Estrella-Hernández P, Herrera-Estrella L, López-Arredondo DL. Metabolic engineering of phosphite metabolism in Synechococcus elongatus PCC 7942 as an effective measure to control biological contaminants in outdoor raceway ponds. Biotechnol Biofuels 2020; 13:119. [PMID: 32670406 PMCID: PMC7346359 DOI: 10.1186/s13068-020-01759-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 07/02/2020] [Indexed: 05/03/2023]
Abstract
BACKGROUND The use of cyanobacteria and microalgae as cell factories to produce biofuels and added-value bioproducts has received great attention during the last two decades. Important investments have been made by public and private sectors to develop this field. However, it has been a challenge to develop a viable and cost-effective platform for cultivation of cyanobacteria and microalgae under outdoor conditions. Dealing with contamination caused by bacteria, weedy algae/cyanobacteria and other organisms is a major constraint to establish effective cultivation processes. RESULTS Here, we describe the implementation in the cyanobacterium Synechococcus elongatus PCC 7942 of a phosphorus selective nutrition system to control biological contamination during cultivation. The system is based on metabolic engineering of S. elongatus to metabolize phosphite, a phosphorus source not normally metabolized by most organisms, by expressing a bacterial phosphite oxidoreductase (PtxD). Engineered S. elongatus strains expressing PtxD grow at a similar rate on media supplemented with phosphite as the non-transformed control supplemented with phosphate. We show that when grown in media containing phosphite as the sole phosphorus source in glass flasks, the engineered strain was able to grow and outcompete biological contaminants even when the system was intentionally inoculated with natural competitors isolated from an irrigation canal. The PtxD/phosphite system was successfully used for outdoor cultivation of engineered S. elongatus in 100-L cylindrical reactors and 1000-L raceway ponds, under non-axenic conditions and without the need of sterilizing containers and media. Finally, we also show that the PtxD/phosphite system can be used as selectable marker for S. elongatus PCC 7942 transgenic strains selection, eliminating the need of antibiotic resistance genes. CONCLUSIONS Our results suggest that the PtxD/phosphite system is a stable and sufficiently robust strategy to control biological contaminants without the need of sterilization or other complex aseptic procedures. Our data show that the PtxD/phosphite system can be used as selectable marker and allows production of the cyanobacterium S. elongatus PCC 7942 in non-axenic outdoor reactors at lower cost, which in principle should be applicable to other cyanobacteria and microalgae engineered to metabolize phosphite.
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Affiliation(s)
| | | | | | - Alethia A. Brito-Bello
- StelaGenomics México, S de RL de CV, Av. Camino Real de Guanajuato s/n, Irapuato, 36821 Guanajuato, Mexico
| | | | - Luis Herrera-Estrella
- Laboratorio Nacional de Genómica para la Biodiversidad, Unidad de Genómica Avanzada del Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Km 9.6 carretera Irapuato León, Irapuato, 36500 Guanajuato, Mexico
- Institute of Genomics for Crop Abiotic Stress Tolerance, Texas Tech University, Lubbock, TX 79409 USA
| | - Damar L. López-Arredondo
- StelaGenomics México, S de RL de CV, Av. Camino Real de Guanajuato s/n, Irapuato, 36821 Guanajuato, Mexico
- Institute of Genomics for Crop Abiotic Stress Tolerance, Texas Tech University, Lubbock, TX 79409 USA
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25
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Changko S, Rajakumar PD, Young REB, Purton S. The phosphite oxidoreductase gene, ptxD as a bio-contained chloroplast marker and crop-protection tool for algal biotechnology using Chlamydomonas. Appl Microbiol Biotechnol 2020; 104:675-686. [PMID: 31788712 PMCID: PMC6943410 DOI: 10.1007/s00253-019-10258-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 09/10/2019] [Accepted: 11/12/2019] [Indexed: 12/17/2022]
Abstract
Edible microalgae have potential as low-cost cell factories for the production and oral delivery of recombinant proteins such as vaccines, anti-bacterials and gut-active enzymes that are beneficial to farmed animals including livestock, poultry and fish. However, a major economic and technical problem associated with large-scale cultivation of microalgae, even in closed photobioreactors, is invasion by contaminating microorganisms. Avoiding this requires costly media sterilisation, aseptic techniques during set-up and implementation of 'crop-protection' strategies during cultivation. Here, we report a strain improvement approach in which the chloroplast of Chlamydomonas reinhardtii is engineered to allow oxidation of phosphite to its bio-available form: phosphate. We have designed a synthetic version of the bacterial gene (ptxD)-encoding phosphite oxidoreductase such that it is highly expressed in the chloroplast but has a Trp→Opal codon reassignment for bio-containment of the transgene. Under mixotrophic conditions, the growth rate of the engineered alga is unaffected when phosphate is replaced with phosphite in the medium. Furthermore, under non-sterile conditions, growth of contaminating microorganisms is severely impeded in phosphite medium. This, therefore, offers the possibility of producing algal biomass under non-sterile conditions. The ptxD gene can also serve as a dominant marker for genetic engineering of any C. reinhardtii strain, thereby avoiding the use of antibiotic resistance genes as markers and allowing the 'retro-fitting' of existing engineered strains. As a proof of concept, we demonstrate the application of our ptxD technology to a strain expressing a subunit vaccine targeting a major viral pathogen of farmed fish.
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Affiliation(s)
- Saowalak Changko
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Priscilla D Rajakumar
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Rosanna E B Young
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Saul Purton
- Algal Research Group, Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK.
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26
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Abstract
Recent synthetic biology efforts have raised biosafety concerns for possible release of engineered cyanobacteria into natural environments. To address the issues, we developed a controllable metal ion induced biocontainment system for two model cyanobacteria. First, six ion-inducible promoters were respectively evaluated in both Synechococcus elongatus PCC 7942 and the fast-growing cyanobacterium Synechococcus elongatus UTEX 2973, leading to the identification of an iron ion-repressed promoter PisiAB with low leakage and a reduction-fold of 5.4 and 7.9, respectively. Second, holin-endolysin and nuclease NucA systems were introduced, the inhibition rate of which against two Synechococcus strains varied from 61% to 86.4%. Third, two toxin/antitoxin modules were identified capable of inducing programmed suicide in both Synechococcus strains after induction. Furthermore, an escape experiment was conducted and the results showed that the system was able to achieve an escape frequency below the detection limit of 10-9 after 3 days' duration, demonstrating the strategy integrating iron ion-inducible promoter PisiAB and that toxin/antitoxin modules could be a useful tool for cyanobacterium biocontainment.
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Affiliation(s)
- Yuqing Zhou
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin, 300072, P. R. China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, P. R. China
| | | | - Zixi Chen
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin, 300072, P. R. China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, P. R. China
| | | | - Lei Chen
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin, 300072, P. R. China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, P. R. China
| | - Weiwen Zhang
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin, 300072, P. R. China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, P. R. China
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27
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Howe GW, van der Donk WA. Temperature-Independent Kinetic Isotope Effects as Evidence for a Marcus-like Model of Hydride Tunneling in Phosphite Dehydrogenase. Biochemistry 2019; 58:4260-4268. [PMID: 31535852 PMCID: PMC6852621 DOI: 10.1021/acs.biochem.9b00732] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Phosphite dehydrogenase catalyzes the transfer of a hydride from phosphite to NAD+, producing phosphate and NADH. We have evaluated the role of hydride tunneling in a thermostable variant of this enzyme (17X-PTDH) by measuring the temperature dependence of the primary 2H kinetic isotope effects (KIEs) between 5 and 45 °C. Pre-steady-state kinetic measurements were used to demonstrate that the hydride transfer is rate-determining across this temperature range and that the observed KIEs are equal to the intrinsic isotope effect on the chemical step. The KIEs on the pre-exponential factor (AH/AD) and the activation energy (ΔEa) were 1.6 ± 0.1 and 0.21 ± 0.05 kcal/mol, respectively, suggesting that 17X-PTDH facilitates extensive tunneling of both isotopes via a Marcus-like model. Site-directed mutagenesis was used to evaluate the role of an active site threonine (Thr104) found on the back face of the nicotinamide in promoting the close packing of the substrates. In mutants with reduced steric bulk at this position, values of AH/AD and ΔEa fall within the range describing semiclassical "over the barrier" reactivity, suggesting that Thr104 acts as a steric backstop to promote tunneling in 17X-PTDH. Whereas hydrogen tunneling is now a widely appreciated feature of C-H activating enzymes, these observations with a P-H activating system are consistent with the proposal that tunneling is likely to be a common feature on all enzymes that catalyze hydrogen transfers.
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Affiliation(s)
- Graeme W Howe
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States.,Carl R. Woese Institute for Genomic Biology , University of Illinois at Urbana-Champaign , 1206 West Gregory Drive , Urbana , Illinois 61801 , United States
| | - Wilfred A van der Donk
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States.,Carl R. Woese Institute for Genomic Biology , University of Illinois at Urbana-Champaign , 1206 West Gregory Drive , Urbana , Illinois 61801 , United States.,Howard Hughes Medical Institute , University of Illinois at Urbana-Champaign , 1206 West Gregory Drive , Urbana , Illinois 61801 , United States
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28
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Sandoval-Vargas JM, Jiménez-Clemente LA, Macedo-Osorio KS, Oliver-Salvador MC, Fernández-Linares LC, Durán-Figueroa NV, Badillo-Corona JA. Use of the ptxD gene as a portable selectable marker for chloroplast transformation in Chlamydomonas reinhardtii. Mol Biotechnol 2019; 61:461-468. [PMID: 30997667 DOI: 10.1007/s12033-019-00177-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Synthetic biology and genetic engineering in algae offer an unprecedented opportunity to develop species with traits that can help solve the problems associated with food and energy supply in the 21st century. In the green alga Chlamydomonas reinhardtii, foreign genes can be expressed from the chloroplast genome for molecular farming and metabolic engineering to obtain commodities and high-value molecules. To introduce these genes, selectable markers, which rely mostly on the use of antibiotics, are needed. This has risen social concern associated with the potential risk of horizontal gene transfer across life kingdoms, which has led to a quest for antibiotic-free selectable markers. Phosphorus (P) is a scarce nutrient element that most organisms can only assimilate in its most oxidized form as phosphate (Pi); however, some organisms are able to oxidize phosphite (Phi) to Pi prior to incorporation into the central metabolism of P. As an alternative to the use of the two positive selectable makers already available for chloroplast transformation in C. reinhardtii, the aadA and the aphA-6 genes, that require the use of antibiotics, we investigated if a phosphite-based selection method could be used for the direct recovery of chloroplast transformed lines in this alga. Here we show that following bombardment with a vector carrying the ptxD gene from Pseudomonas stutzeri WM88, only cells that integrate and express the gene proliferate and form colonies using Phi as the sole P source. Our results demonstrate that a selectable marker based on the assimilation of Phi can be used for chloroplasts transformation in a biotechnologically relevant organism. The portable selectable marker we have developed is, in more than 18 years, the latest addition to the markers available for selection of chloroplast transformed cells in C. reinhardtii. The ptxD gene will contribute to the repertoire of tools available for synthetic biology and genetic engineering in the chloroplast of C. reinhardtii.
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Affiliation(s)
- José M Sandoval-Vargas
- Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología, Av. Acueducto SN, Col. Barrio la Laguna Ticomán, 07340, Mexico City, Mexico
| | - Luis A Jiménez-Clemente
- Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología, Av. Acueducto SN, Col. Barrio la Laguna Ticomán, 07340, Mexico City, Mexico
| | - Karla S Macedo-Osorio
- Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología, Av. Acueducto SN, Col. Barrio la Laguna Ticomán, 07340, Mexico City, Mexico
| | - María C Oliver-Salvador
- Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología, Av. Acueducto SN, Col. Barrio la Laguna Ticomán, 07340, Mexico City, Mexico
| | - Luis C Fernández-Linares
- Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología, Av. Acueducto SN, Col. Barrio la Laguna Ticomán, 07340, Mexico City, Mexico
| | - Noé V Durán-Figueroa
- Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología, Av. Acueducto SN, Col. Barrio la Laguna Ticomán, 07340, Mexico City, Mexico
| | - Jesús A Badillo-Corona
- Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología, Av. Acueducto SN, Col. Barrio la Laguna Ticomán, 07340, Mexico City, Mexico.
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29
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Adams NBP, Robertson AJ, Hunter CN, Hitchcock A, Bisson C. Phosphite binding by the HtxB periplasmic binding protein depends on the protonation state of the ligand. Sci Rep 2019; 9:10231. [PMID: 31308436 DOI: 10.1038/s41598-019-46557-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/01/2019] [Indexed: 02/08/2023] Open
Abstract
Phosphorus acquisition is critical for life. In low phosphate conditions, some species of bacteria have evolved mechanisms to import reduced phosphorus compounds, such as phosphite and hypophosphite, as alternative phosphorus sources. Uptake is facilitated by high-affinity periplasmic binding proteins (PBPs) that bind cargo in the periplasm and shuttle it to an ATP-binding cassette (ABC)-transporter in the bacterial inner membrane. PtxB and HtxB are the PBPs responsible for binding phosphite and hypophosphite, respectively. They recognize the P-H bond of phosphite/hypophosphite via a conserved P-H...π interaction, which confers nanomolar dissociation constants for their respective ligands. PtxB also has a low-level binding affinity for phosphate and hypophosphite, whilst HtxB can facilitate phosphite uptake in vivo. However, HtxB does not bind phosphate, thus the HtxBCDE transporter has recently been successfully exploited for biocontainment of genetically modified organisms by phosphite-dependent growth. Here we use a combination of X-ray crystallography, NMR and Microscale Thermophoresis to show that phosphite binding to HtxB depends on the protonation state of the ligand, suggesting that pH may effect the efficiency of phosphite uptake by HtxB in biotechnology applications.
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30
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Selão TT, Włodarczyk A, Nixon PJ, Norling B. Growth and selection of the cyanobacterium Synechococcus sp. PCC 7002 using alternative nitrogen and phosphorus sources. Metab Eng 2019; 54:255-263. [PMID: 31063791 DOI: 10.1016/j.ymben.2019.04.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 04/08/2019] [Accepted: 04/29/2019] [Indexed: 12/14/2022]
Abstract
Cyanobacteria, such as Synechococcus sp. PCC 7002 (Syn7002), are promising chassis strains for "green" biotechnological applications as they can be grown in seawater using oxygenic photosynthesis to fix carbon dioxide into biomass. Their other major nutritional requirements for efficient growth are sources of nitrogen (N) and phosphorus (P). As these organisms are more economically cultivated in outdoor open systems, there is a need to develop cost-effective approaches to prevent the growth of contaminating organisms, especially as the use of antibiotic selection markers is neither economically feasible nor ecologically desirable due to the risk of horizontal gene transfer. Here we have introduced a synthetic melamine degradation pathway into Syn7002 and evolved the resulting strain to efficiently use the nitrogen-rich xenobiotic compound melamine as the sole N source. We also show that expression of phosphite dehydrogenase in the absence of its cognate phosphite transporter permits growth of Syn7002 on phosphite and can be used as a selectable marker in Syn7002. We combined these two strategies to generate a strain that can grow on melamine and phosphite as sole N and P sources, respectively. This strain is able to resist deliberate contamination in large excess and should be a useful chassis for metabolic engineering and biotechnological applications using cyanobacteria.
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Affiliation(s)
| | - Artur Włodarczyk
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Peter J Nixon
- School of Biological Sciences, Nanyang Technological University, Singapore; Sir Ernst Chain Building- Wolfson Laboratories, Department of Life Sciences, Imperial College London, S. Kensington Campus, London, SW7 2AZ, UK
| | - Birgitta Norling
- School of Biological Sciences, Nanyang Technological University, Singapore.
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31
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Howe GW, van der Donk WA. 18O Kinetic Isotope Effects Reveal an Associative Transition State for Phosphite Dehydrogenase Catalyzed Phosphoryl Transfer. J Am Chem Soc 2018; 140:17820-17824. [PMID: 30525552 DOI: 10.1021/jacs.8b06301] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Phosphite dehydrogenase (PTDH) catalyzes an unusual phosphoryl transfer reaction in which water displaces a hydride leaving group. Despite extensive effort, it remains unclear whether PTDH catalysis proceeds via an associative or dissociative mechanism. Here, primary 2H and secondary 18O kinetic isotope effects (KIEs) were determined and used together with computation to characterize the transition state (TS) catalyzed by a thermostable PTDH (17X-PTDH). The large, normal 18O KIEs suggest an associative mechanism. Various transition state structures were computed within a model of the enzyme active site and 2H and 18O KIEs were predicted to evaluate the accuracy of each TS. This analysis suggests that 17X-PTDH catalyzes an associative process with little leaving group displacement and extensive nucleophilic participation. This tight TS is likely a consequence of the extremely poor leaving group requiring significant P-O bond formation to expel the hydride. This finding contrasts with the dissociative TSs in most phosphoryl transfer reactions from phosphate mono- and diesters.
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Affiliation(s)
- Graeme W Howe
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States.,Carl R. Woese Institute for Genomic Biology , University of Illinois at Urbana-Champaign , 1206 West Gregory Drive , Urbana , Illinois 61801 , United States
| | - Wilfred A van der Donk
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States.,Carl R. Woese Institute for Genomic Biology , University of Illinois at Urbana-Champaign , 1206 West Gregory Drive , Urbana , Illinois 61801 , United States.,Howard Hughes Medical Institute , University of Illinois at Urbana-Champaign , 1206 West Gregory Drive , Urbana , Illinois 61801 , United States
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