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Kaur M, Mingeot-Leclercq MP. Maintenance of bacterial outer membrane lipid asymmetry: insight into MlaA. BMC Microbiol 2024; 24:186. [PMID: 38802775 PMCID: PMC11131202 DOI: 10.1186/s12866-023-03138-8] [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: 03/28/2023] [Accepted: 11/29/2023] [Indexed: 05/29/2024] Open
Abstract
The outer membrane (OM) of Gram-negative bacteria acts as an effective barrier to protect against toxic compounds. By nature, the OM is asymmetric with the highly packed lipopolysaccharide (LPS) at the outer leaflet and glycerophospholipids at the inner leaflet. OM asymmetry is maintained by the Mla system, in which is responsible for the retrograde transport of glycerophospholipids from the OM to the inner membrane. This system is comprised of six Mla proteins, including MlaA, an OM lipoprotein involved in the removal of glycerophospholipids that are mis-localized at the outer leaflet of the OM. Interestingly, MlaA was initially identified - and called VacJ - based on its role in the intracellular spreading of Shigella flexneri.Many open questions remain with respect to the Mla system and the mechanism involved in the translocation of mislocated glycerophospholipids at the outer leaflet of the OM, by MlaA. After summarizing the current knowledge on MlaA, we focus on the impact of mlaA deletion on OM lipid composition and biophysical properties of the OM. How changes in OM lipid composition and biophysical properties can impact the generation of membrane vesicles and membrane permeability is discussed. Finally, we explore whether and how MlaA might be a candidate for improving the activity of antibiotics and as a vaccine candidate.Efforts dedicated to understanding the relationship between the OM lipid composition and the mechanical strength of the bacterial envelope and, in turn, how such properties act against external stress, are needed for the design of new targets or drugs for Gram-negative infections.
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Affiliation(s)
- M Kaur
- Louvain Drug Research Institute, Université catholique de Louvain, Unité de Pharmacologie cellulaire et moléculaire, B1.73.05; 73 Av E. Mounier, Brussels, 1200, Belgium
| | - M-P Mingeot-Leclercq
- Louvain Drug Research Institute, Université catholique de Louvain, Unité de Pharmacologie cellulaire et moléculaire, B1.73.05; 73 Av E. Mounier, Brussels, 1200, Belgium.
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2
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Borchert AJ, Bleem AC, Lim HG, Rychel K, Dooley KD, Kellermyer ZA, Hodges TL, Palsson BO, Beckham GT. Machine learning analysis of RB-TnSeq fitness data predicts functional gene modules in Pseudomonas putida KT2440. mSystems 2024; 9:e0094223. [PMID: 38323821 PMCID: PMC10949508 DOI: 10.1128/msystems.00942-23] [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: 09/14/2023] [Accepted: 01/07/2024] [Indexed: 02/08/2024] Open
Abstract
There is growing interest in engineering Pseudomonas putida KT2440 as a microbial chassis for the conversion of renewable and waste-based feedstocks, and metabolic engineering of P. putida relies on the understanding of the functional relationships between genes. In this work, independent component analysis (ICA) was applied to a compendium of existing fitness data from randomly barcoded transposon insertion sequencing (RB-TnSeq) of P. putida KT2440 grown in 179 unique experimental conditions. ICA identified 84 independent groups of genes, which we call fModules ("functional modules"), where gene members displayed shared functional influence in a specific cellular process. This machine learning-based approach both successfully recapitulated previously characterized functional relationships and established hitherto unknown associations between genes. Selected gene members from fModules for hydroxycinnamate metabolism and stress resistance, acetyl coenzyme A assimilation, and nitrogen metabolism were validated with engineered mutants of P. putida. Additionally, functional gene clusters from ICA of RB-TnSeq data sets were compared with regulatory gene clusters from prior ICA of RNAseq data sets to draw connections between gene regulation and function. Because ICA profiles the functional role of several distinct gene networks simultaneously, it can reduce the time required to annotate gene function relative to manual curation of RB-TnSeq data sets. IMPORTANCE This study demonstrates a rapid, automated approach for elucidating functional modules within complex genetic networks. While Pseudomonas putida randomly barcoded transposon insertion sequencing data were used as a proof of concept, this approach is applicable to any organism with existing functional genomics data sets and may serve as a useful tool for many valuable applications, such as guiding metabolic engineering efforts in other microbes or understanding functional relationships between virulence-associated genes in pathogenic microbes. Furthermore, this work demonstrates that comparison of data obtained from independent component analysis of transcriptomics and gene fitness datasets can elucidate regulatory-functional relationships between genes, which may have utility in a variety of applications, such as metabolic modeling, strain engineering, or identification of antimicrobial drug targets.
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Affiliation(s)
- Andrew J. Borchert
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Alissa C. Bleem
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Agile BioFoundry, Emeryville, California, USA
| | - Hyun Gyu Lim
- Department of Bioengineering, University of California San Diego, La Jolla, California, USA
- Joint BioEnergy Institute, Emeryville, California, USA
- Department of Biological Engineering, Inha University, Incheon, Korea
| | - Kevin Rychel
- Department of Bioengineering, University of California San Diego, La Jolla, California, USA
| | - Keven D. Dooley
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
- Agile BioFoundry, Emeryville, California, USA
| | - Zoe A. Kellermyer
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Tracy L. Hodges
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
- Agile BioFoundry, Emeryville, California, USA
| | - Bernhard O. Palsson
- Department of Bioengineering, University of California San Diego, La Jolla, California, USA
- Joint BioEnergy Institute, Emeryville, California, USA
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
- Department of Pediatrics, University of California, San Diego, California, USA
| | - Gregg T. Beckham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
- Agile BioFoundry, Emeryville, California, USA
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3
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Li J, Lu X, Zou X, Ye BC. Recent Advances in Microbial Metabolic Engineering for Production of Natural Phenolic Acids. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:4538-4551. [PMID: 38377566 DOI: 10.1021/acs.jafc.3c07658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Phenolic acids are important natural bioactive compounds with varied physiological functions. They are extensively used in food, pharmaceutical, cosmetic, and other chemical industries and have attractive market prospects. Compared to plant extraction and chemical synthesis, microbial fermentation for phenolic acid production from renewable carbon sources has significant advantages. This review focuses on the structural information, physiological functions, current applications, and biosynthesis pathways of phenolic acids, especially advances in the development of metabolically engineered microbes for the production of phenolic acids. This review provides useful insights concerning phenolic acid production through metabolic engineering of microbial cell factories.
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Affiliation(s)
- Jin Li
- College of Pharmacy and Bioengineering, Chongqing University of Technology, Chongqing 400054, China
| | - Xiumin Lu
- College of Pharmacy and Bioengineering, Chongqing University of Technology, Chongqing 400054, China
| | - Xiang Zou
- College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Bang-Ce Ye
- Laboratory of Biosystems and Microanalysis, Institute of Engineering Biology and Health, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China
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4
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Bitzenhofer NL, Höfel C, Thies S, Weiler AJ, Eberlein C, Heipieper HJ, Batra‐Safferling R, Sundermeyer P, Heidler T, Sachse C, Busche T, Kalinowski J, Belthle T, Drepper T, Jaeger K, Loeschcke A. Exploring engineered vesiculation by Pseudomonas putida KT2440 for natural product biosynthesis. Microb Biotechnol 2024; 17:e14312. [PMID: 37435812 PMCID: PMC10832525 DOI: 10.1111/1751-7915.14312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 06/25/2023] [Indexed: 07/13/2023] Open
Abstract
Pseudomonas species have become promising cell factories for the production of natural products due to their inherent robustness. Although these bacteria have naturally evolved strategies to cope with different kinds of stress, many biotechnological applications benefit from engineering of optimised chassis strains with specially adapted tolerance traits. Here, we explored the formation of outer membrane vesicles (OMV) of Pseudomonas putida KT2440. We found OMV production to correlate with the recombinant production of a natural compound with versatile beneficial properties, the tripyrrole prodigiosin. Further, several P. putida genes were identified, whose up- or down-regulated expression allowed controlling OMV formation. Finally, genetically triggering vesiculation in production strains of the different alkaloids prodigiosin, violacein, and phenazine-1-carboxylic acid, as well as the carotenoid zeaxanthin, resulted in up to three-fold increased product yields. Consequently, our findings suggest that the construction of robust strains by genetic manipulation of OMV formation might be developed into a useful tool which may contribute to improving limited biotechnological applications.
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Affiliation(s)
- Nora Lisa Bitzenhofer
- Institute of Molecular Enzyme Technology (IMET)Heinrich Heine University DüsseldorfDüsseldorfGermany
| | - Carolin Höfel
- Institute of Molecular Enzyme Technology (IMET)Heinrich Heine University DüsseldorfDüsseldorfGermany
| | - Stephan Thies
- Institute of Molecular Enzyme Technology (IMET)Heinrich Heine University DüsseldorfDüsseldorfGermany
| | - Andrea Jeanette Weiler
- Institute of Molecular Enzyme Technology (IMET)Heinrich Heine University DüsseldorfDüsseldorfGermany
| | - Christian Eberlein
- Department of Environmental BiotechnologyHelmholtz Centre for Environmental Research (UFZ)LeipzigGermany
| | - Hermann J. Heipieper
- Department of Environmental BiotechnologyHelmholtz Centre for Environmental Research (UFZ)LeipzigGermany
| | - Renu Batra‐Safferling
- Institute of Biological Information Processing – Structural Biochemistry (IBI‐7: Structural Biochemistry)Forschungszentrum JülichJülichGermany
| | - Pia Sundermeyer
- Ernst‐Ruska Centre for Microscopy and Spectroscopy with Electrons (ER‐C‐3/Structural Biology)Forschungszentrum JülichJülichGermany
- Institute for Biological Information Processing 6 (IBI‐6/ Structural Cellular Biology)Forschungszentrum JülichJülichGermany
| | - Thomas Heidler
- Ernst‐Ruska Centre for Microscopy and Spectroscopy with Electrons (ER‐C‐3/Structural Biology)Forschungszentrum JülichJülichGermany
- Institute for Biological Information Processing 6 (IBI‐6/ Structural Cellular Biology)Forschungszentrum JülichJülichGermany
| | - Carsten Sachse
- Ernst‐Ruska Centre for Microscopy and Spectroscopy with Electrons (ER‐C‐3/Structural Biology)Forschungszentrum JülichJülichGermany
- Institute for Biological Information Processing 6 (IBI‐6/ Structural Cellular Biology)Forschungszentrum JülichJülichGermany
- Department of BiologyHeinrich Heine University DüsseldorfDüsseldorfGermany
| | - Tobias Busche
- Center for Biotechnology (CeBiTec)Bielefeld UniversityBielefeldGermany
- Bielefeld University, Medical School East Westphalia‐LippeBielefeld UniversityBielefeldGermany
| | - Jörn Kalinowski
- Center for Biotechnology (CeBiTec)Bielefeld UniversityBielefeldGermany
| | - Thomke Belthle
- DWI─Leibniz‐Institute for Interactive MaterialsAachenGermany
- Functional and Interactive Polymers, Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityAachenGermany
| | - Thomas Drepper
- Institute of Molecular Enzyme Technology (IMET)Heinrich Heine University DüsseldorfDüsseldorfGermany
| | - Karl‐Erich Jaeger
- Institute of Molecular Enzyme Technology (IMET)Heinrich Heine University DüsseldorfDüsseldorfGermany
- Institute of Bio‐ and Geosciences IBG‐1: BiotechnologyForschungszentrum JülichJülichGermany
| | - Anita Loeschcke
- Institute of Molecular Enzyme Technology (IMET)Heinrich Heine University DüsseldorfDüsseldorfGermany
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5
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Wynands B, Kofler F, Sieberichs A, da Silva N, Wierckx N. Engineering a Pseudomonas taiwanensis 4-coumarate platform for production of para-hydroxy aromatics with high yield and specificity. Metab Eng 2023; 78:115-127. [PMID: 37209862 PMCID: PMC10360455 DOI: 10.1016/j.ymben.2023.05.004] [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: 01/18/2023] [Revised: 04/26/2023] [Accepted: 05/16/2023] [Indexed: 05/22/2023]
Abstract
Aromatics are valuable bulk or fine chemicals with a myriad of important applications. Currently, their vast majority is produced from petroleum associated with many negative aspects. The bio-based synthesis of aromatics contributes to the much-required shift towards a sustainable economy. To this end, microbial whole-cell catalysis is a promising strategy allowing the valorization of abundant feedstocks derived from biomass to yield de novo-synthesized aromatics. Here, we engineered tyrosine-overproducing derivatives of the streamlined chassis strain Pseudomonas taiwanensis GRC3 for efficient and specific production of 4-coumarate and derived aromatics. This required pathway optimization to avoid the accumulation of tyrosine or trans-cinnamate as byproducts. Although application of tyrosine-specific ammonia-lyases prevented the formation of trans-cinnamate, they did not completely convert tyrosine to 4-coumarate, thereby displaying a significant bottleneck. The use of a fast but unspecific phenylalanine/tyrosine ammonia-lyase from Rhodosporidium toruloides (RtPAL) alleviated this bottleneck, but caused phenylalanine conversion to trans-cinnamate. This byproduct formation was greatly reduced through the reverse engineering of a point mutation in prephenate dehydratase domain-encoding pheA. This upstream pathway engineering enabled efficient 4-coumarate production with a specificity of >95% despite using an unspecific ammonia-lyase, without creating an auxotrophy. In shake flask batch cultivations, 4-coumarate yields of up to 21.5% (Cmol/Cmol) from glucose and 32.4% (Cmol/Cmol) from glycerol were achieved. Additionally, the product spectrum was diversified by extending the 4-coumarate biosynthetic pathway to enable the production of 4-vinylphenol, 4-hydroxyphenylacetate, and 4-hydroxybenzoate with yields of 32.0, 23.0, and 34.8% (Cmol/Cmol) from glycerol, respectively.
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Affiliation(s)
- Benedikt Wynands
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Franziska Kofler
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Anka Sieberichs
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Nadine da Silva
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Nick Wierckx
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.
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6
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Borchert AJ, Bleem A, Beckham GT. RB-TnSeq identifies genetic targets for improved tolerance of Pseudomonas putida towards compounds relevant to lignin conversion. Metab Eng 2023; 77:208-218. [PMID: 37059293 DOI: 10.1016/j.ymben.2023.04.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Revised: 03/21/2023] [Accepted: 04/12/2023] [Indexed: 04/16/2023]
Abstract
Lignin-derived mixtures intended for bioconversion commonly contain high concentrations of aromatic acids, aliphatic acids, and salts. The inherent toxicity of these chemicals places a significant bottleneck upon the effective use of microbial systems for the valorization of these mixtures. Pseudomonas putida KT2440 can tolerate stressful quantities of several lignin-related compounds, making this bacterium a promising host for converting these chemicals to valuable bioproducts. Nonetheless, further increasing P. putida tolerance to chemicals in lignin-rich substrates has the potential to improve bioprocess performance. Accordingly, we employed random barcoded transposon insertion sequencing (RB-TnSeq) to reveal genetic determinants in P. putida KT2440 that influence stress outcomes during exposure to representative constituents found in lignin-rich process streams. The fitness information obtained from the RB-TnSeq experiments informed engineering of strains via deletion or constitutive expression of several genes. Namely, ΔgacAS, ΔfleQ, ΔlapAB, ΔttgR::Ptac:ttgABC, Ptac:PP_1150:PP_1152, ΔrelA, and ΔPP_1430 mutants showed growth improvement in the presence of single compounds, and some also exhibited greater tolerance when grown using a complex chemical mixture representative of a lignin-rich chemical stream. Overall, this work demonstrates the successful implementation of a genome-scale screening tool for the identification of genes influencing stress tolerance against notable compounds within lignin-enriched chemical streams, and the genetic targets identified herein offer promising engineering targets for improving feedstock tolerance in lignin valorization strains of P. putida KT2440.
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Affiliation(s)
- Andrew J Borchert
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA; Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Alissa Bleem
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA; Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Gregg T Beckham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA; Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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7
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Recent progress in the synthesis of advanced biofuel and bioproducts. Curr Opin Biotechnol 2023; 80:102913. [PMID: 36854202 DOI: 10.1016/j.copbio.2023.102913] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 01/20/2023] [Accepted: 01/30/2023] [Indexed: 02/27/2023]
Abstract
Energy is one of the most complex fields of study and an issue that influences nearly every aspect of modern life. Over the past century, combustion of fossil fuels, particularly in the transportation sector, has been the dominant form of energy release. Refining of petroleum and natural gas into liquid transportation fuels is also the centerpiece of the modern chemical industry used to produce materials, solvents, and other consumer goods. In the face of global climate change, the world is searching for alternative, sustainable means of producing energy carriers and chemical building blocks. The use of biofuels in engines predates modern refinery optimization and today represents a small but significant fraction of liquid transportation fuels burnt each year. Similarly, white biotechnology has been used to produce many natural products through fermentation. The evolution of recombinant DNA technology into modern synthetic biology has expanded the scope of biofuels and bioproducts that can be made by biocatalysts. This opinion examines the current trends in this research space, highlighting the substantial growth in computational tools and the growing influence of renewable electricity in the design of metabolic engineering strategies. In short, advanced biofuel and bioproduct synthesis remains a vibrant and critically important field of study whose focus is shifting away from the conversion of lignocellulosic biomass toward a broader consideration of how to reduce carbon dioxide to fuels and chemical products.
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8
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Virklund A, Jensen SI, Nielsen AT, Woodley JM. Combining genetic engineering and bioprocess concepts for improved phenylpropanoid production. Biotechnol Bioeng 2023; 120:613-628. [PMID: 36418654 DOI: 10.1002/bit.28292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 11/02/2022] [Accepted: 11/22/2022] [Indexed: 11/26/2022]
Abstract
The group of natural aromatic compounds known as phenylpropanoids has diverse applications, but current methods of production which are largely based on synthesis from petrochemicals or extraction from agricultural biomass are unsustainable. Bioprocessing is a promising alternative, but improvements in production titers and rates are required to make this method profitable. Here the recent advances in genetic engineering and bioprocess concepts for the production of phenylpropanoids are presented for the purpose of identifying successful strategies, including adaptive laboratory evolution, enzyme engineering, in-situ product removal, and biocatalysis. The pros and cons of bacterial and yeast hosts for phenylpropanoid production are discussed, also in the context of different phenylpropanoid targets and bioprocess concepts. Finally, some broad recommendations are made regarding targets for continued improvement and areas requiring specific attention from researchers to further improve production titers and rates.
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Affiliation(s)
- Alexander Virklund
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Lyngby, Denmark
| | - Sheila I Jensen
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Alex T Nielsen
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - John M Woodley
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Lyngby, Denmark
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9
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Calero P, Gurdo N, Nikel PI. Role of the CrcB transporter of Pseudomonas putida in the multi-level stress response elicited by mineral fluoride. Environ Microbiol 2022; 24:5082-5104. [PMID: 35726888 PMCID: PMC9796867 DOI: 10.1111/1462-2920.16110] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 06/16/2022] [Accepted: 06/19/2022] [Indexed: 01/07/2023]
Abstract
The presence of mineral fluoride (F- ) in the environment has both a geogenic and anthropogenic origin, and the halide has been described to be toxic in virtually all living organisms. While the evidence gathered in different microbial species supports this notion, a systematic exploration of the effects of F- salts on the metabolism and physiology of environmental bacteria remained underexplored thus far. In this work, we studied and characterized tolerance mechanisms deployed by the model soil bacterium Pseudomonas putida KT2440 against NaF. By adopting systems-level omic approaches, including functional genomics and metabolomics, we gauged the impact of this anion at different regulatory levels under conditions that impair bacterial growth. Several genes involved in halide tolerance were isolated in a genome-wide Tn-Seq screening-among which crcB, encoding an F- -specific exporter, was shown to play the predominant role in detoxification. High-resolution metabolomics, combined with the assessment of intracellular and extracellular pH values and quantitative physiology experiments, underscored the key nodes in central carbon metabolism affected by the presence of F- . Taken together, our results indicate that P. putida undergoes a general, multi-level stress response when challenged with NaF that significantly differs from that caused by other saline stressors. While microbial stress responses to saline and oxidative challenges have been extensively studied and described in the literature, very little is known about the impact of fluoride (F- ) on bacterial physiology and metabolism. This state of affairs contrasts with the fact that F- is more abundant than other halides in the Earth crust (e.g. in some soils, the F- concentration can reach up to 1 mg gsoil -1 ). Understanding the global effects of NaF treatment on bacterial physiology is not only relevant to unveil distinct mechanisms of detoxification but it could also guide microbial engineering approaches for the target incorporation of fluorine into value-added organofluorine molecules. In this regard, the soil bacterium P. putida constitutes an ideal model to explore such scenarios, since this species is particularly known for its high level of stress resistance against a variety of physicochemical perturbations.
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Affiliation(s)
- Patricia Calero
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of DenmarkKongens LyngbyDenmark
| | - Nicolás Gurdo
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of DenmarkKongens LyngbyDenmark
| | - Pablo I. Nikel
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of DenmarkKongens LyngbyDenmark
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10
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Zou L, Jin X, Tao Y, Zheng Z, Ouyang J. Unraveling the mechanism of furfural tolerance in engineered Pseudomonas putida by genomics. Front Microbiol 2022; 13:1035263. [PMID: 36338095 PMCID: PMC9630843 DOI: 10.3389/fmicb.2022.1035263] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 09/30/2022] [Indexed: 07/24/2023] Open
Abstract
As a dehydration product of pentoses in hemicellulose sugar streams derived from lignocellulosic biomass, furfural is a prevalent inhibitor in the efficient microbial conversion process. To solve this obstacle, exploiting a biorefinery strain with remarkable furfural tolerance capability is essential. Pseudomonas putida KT2440 (P. putida) has served as a valuable bacterial chassis for biomass biorefinery. Here, a high-concentration furfural-tolerant P. putida strain was developed via adaptive laboratory evolution (ALE). The ALE resulted in a previously engineered P. putida strain with substantially increased furfural tolerance as compared to wild-type. Whole-genome sequencing of the adapted strains and reverse engineering validation of key targets revealed for the first time that several genes and their mutations, especially for PP_RS19785 and PP_RS18130 [encoding ATP-binding cassette (ABC) transporters] as well as PP_RS20740 (encoding a hypothetical protein), play pivotal roles in the furfural tolerance and conversion of this bacterium. Finally, strains overexpressing these three striking mutations grew well in highly toxic lignocellulosic hydrolysate, with cell biomass around 9-, 3.6-, and two-fold improvement over the control strain, respectively. To our knowledge, this study first unravels the furan aldehydes tolerance mechanism of industrial workhorse P. putida, which provides a new foundation for engineering strains to enhance furfural tolerance and further facilitate the valorization of lignocellulosic biomass.
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11
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Rodríguez-Ochoa JI, Fragoso-Jiménez JC, Flores N, Martínez LM, Bolivar F, Martinez A, Gosset G. Global transcriptomic response of Escherichia coli to p-coumaric acid. Microb Cell Fact 2022; 21:148. [PMID: 35858942 PMCID: PMC9301823 DOI: 10.1186/s12934-022-01874-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 07/07/2022] [Indexed: 11/10/2022] Open
Abstract
The aromatic compound p-coumaric acid (p-CA) is a secondary metabolite produced by plants. This aromatic acid and derived compounds have positive effects on human health, so there is interest in producing them in biotechnological processes with recombinant Escherichia coli strains. To determine the physiologic response of E. coli W3110 to p-CA, dynamic expression analysis of selected genes fused to a fluorescent protein reporter as well as RNA-seq and RT-qPCR were performed. The observed transcriptional profile revealed the induction of genes involved in functions related to p-CA active export, synthesis of cell wall and membrane components, synthesis of amino acids, detoxification of formaldehyde, phosphate limitation, acid stress, protein folding and degradation. Downregulation of genes encoding proteins involved in energy production, carbohydrate import and metabolism, as well as several outer and plasma membrane proteins was detected. This response is indicative of cell envelope damage causing the leakage of intracellular components including amino acids and phosphate-containing compounds. The cellular functions responding to p-CA that were identified in this study will help in defining targets for production strains improvement.
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Affiliation(s)
- José Ignacio Rodríguez-Ochoa
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Juan Carlos Fragoso-Jiménez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Noemí Flores
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Luz María Martínez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Francisco Bolivar
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Alfredo Martinez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Guillermo Gosset
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.
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12
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In-stream product recovery of p-coumaric acid heterologously produced: Implementation of a continuous liquid-liquid extraction assisted by hollow fiber membrane contactor. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.121083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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13
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Bacterial Community Assembly, Succession, and Metabolic Function during Outdoor Cultivation of Microchloropsis salina. mSphere 2022; 7:e0023122. [PMID: 35730934 PMCID: PMC9429889 DOI: 10.1128/msphere.00231-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Outdoor cultivation of microalgae has promising potential for renewable bioenergy, but there is a knowledge gap on the structure and function of the algal microbiome that coinhabits these ecosystems. Here, we describe the assembly mechanisms, taxonomic structure, and metabolic potential of bacteria associated with Microchloropsis salina cultivated outdoors. Open mesocosms were inoculated with algal cultures that were either free of bacteria or coincubated with one of two different strains of alga-associated bacteria and were sampled across five time points taken over multiple harvesting rounds of a 40-day experiment. Using quantitative analyses of metagenome-assembled genomes (MAGs), we tracked bacterial community compositional abundance and taxon-specific functional capacity involved in algal-bacterial interactions. One of the inoculated bacteria (Alteromonas sp.) persisted and dispersed across mesocosms, whereas the other inoculated strain (Phaeobacter gallaeciensis) disappeared by day 17 while a taxonomically similar but functionally distinct Phaeobacter strain became established. The inoculated strains were less abundant than 6 numerically dominant newly recruited taxa with functional capacities for mutualistic or saprophytic lifestyles, suggesting a generalist approach to persistence. This includes a highly abundant unclassified Rhodobacteraceae species that fluctuated between 25% and 77% of the total community. Overall, we did not find evidence for priority effects exerted by the distinct inoculum conditions; all mesocosms converged with similar microbial community compositions by the end of the experiment. Instead, we infer that the 15 total populations were retained due to host selection, as they showed high metabolic potential for algal-bacterial interactions such as recycling alga-produced carbon and nitrogen and production of vitamins and secondary metabolites associated with algal growth and senescence, including B vitamins, tropodithietic acid, and roseobacticides. IMPORTANCE Bacteria proliferate in nutrient-rich aquatic environments, including engineered algal biofuel systems, where they remineralize photosynthates, exchange secondary metabolites with algae, and can influence system output of biomass or oil. Despite this, knowledge on the microbial ecology of algal cultivation systems is lacking, and the subject is worthy of investigation. Here, we used metagenomics to characterize the metabolic capacities of the predominant bacteria associated with the biofuel-relevant microalga Microchloropsis salina and to predict testable metabolic interactions between algae and manipulated communities of bacteria. We identified a previously undescribed and uncultivated organism that dominated the community. Collectively, the microbial community may interact with the alga in cultivation via exchange of secondary metabolites which could affect algal success, which we demonstrate as a possible outcome from controlled experiments with metabolically analogous isolates. These findings address the scalability of lab-based algal-bacterial interactions through to cultivation systems and more broadly provide a framework for empirical testing of genome-based metabolic predictions.
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14
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Borchert AJ, Bleem A, Beckham GT. Experimental and Analytical Approaches for Improving the Resolution of Randomly Barcoded Transposon Insertion Sequencing (RB-TnSeq) Studies. ACS Synth Biol 2022; 11:2015-2021. [PMID: 35657709 PMCID: PMC9208016 DOI: 10.1021/acssynbio.2c00119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Randomly barcoded transposon insertion sequencing (RB-TnSeq) is an efficient, multiplexed method to determine microbial gene function during growth under a selection condition of interest. This technique applies to growth, tolerance, and persistence studies in a variety of hosts, but the wealth of data generated can complicate the identification of the most critical gene targets. Experimental and analytical methods for improving the resolution of RB-TnSeq are proposed, using Pseudomonas putida KT2440 as an example organism. Several key parameters, such as baseline media selection, substantially influence the determination of gene fitness. We also present options to increase statistical confidence in gene fitness, including increasing the number of biological replicates and passaging the baseline culture in parallel with selection conditions. These considerations provide practitioners with several options to identify genes of importance in TnSeq data sets, thereby streamlining metabolic characterization.
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Affiliation(s)
- Andrew J. Borchert
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Alissa Bleem
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Gregg T. Beckham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
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15
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Xue Y, Qiu T, Sun Z, Liu F, Yu B. Mercury bioremediation by engineered Pseudomonas putida KT2440 with adaptationally optimized biosecurity circuit. Environ Microbiol 2022; 24:3022-3036. [PMID: 35555952 DOI: 10.1111/1462-2920.16038] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/25/2022] [Accepted: 05/04/2022] [Indexed: 01/15/2023]
Abstract
Hazardous materials, such as heavy metals, are the major sources of health risk. Using genetically modified organisms (GMOs) to dispose heavy metals has the advantages of strong environmental compatibility and high efficiency. However, the biosecurity of GMOs used in the environment is a major concern. In this study, a self-controlled genetic circuit was designed and carefully fine-tuned for programmable expression in Pseudomonas putida KT2440, which is a widely used strain for environmental bioremediation. The cell behaviours were controlled by automatically sensing the variation of Hg2+ concentration without any inducer requirement or manual interventions. More than 98% Hg2+ was adsorbed by the engineered strain with a high cell recovery rate of 96% from waterbody. The remaining cells were killed by the suicide module after the mission was accomplished. The escape frequency of the engineered P. putida strain was lower than 10-9 , which meets the recommendation of US NIH guideline for GMOs release (<10-8 ). The same performance was achieved in a model experiment by using natural lake water with addition of Hg2+ . The microbial diversity analysis further confirmed that the remediation process made little impact on the indigenous ecosystem. Thus, this study provides a practical method for environmental remediation by using GMOs.
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Affiliation(s)
- Yubin Xue
- CAS Key Laboratory of Microbial Physiological & Metabolic Engineering, State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Tianlei Qiu
- Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology, Beijing Agro-Biotechnology Research Center, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China
| | - Zhi Sun
- CAS Key Laboratory of Microbial Physiological & Metabolic Engineering, State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Feixia Liu
- CAS Key Laboratory of Microbial Physiological & Metabolic Engineering, State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Bo Yu
- CAS Key Laboratory of Microbial Physiological & Metabolic Engineering, State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
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16
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Jayakody LN, Chinmoy B, Turner TL. Trends in valorization of highly-toxic lignocellulosic biomass derived-compounds via engineered microbes. BIORESOURCE TECHNOLOGY 2022; 346:126614. [PMID: 34954359 DOI: 10.1016/j.biortech.2021.126614] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 12/18/2021] [Accepted: 12/19/2021] [Indexed: 05/26/2023]
Abstract
Lignocellulosic biomass-derived fuels, chemicals, and materials are promising sustainable solutions to replace the current petroleum-based production. The direct microbial conversion of thermos-chemically pretreated lignocellulosic biomass is hampered by the presence of highly toxic chemical compounds. Also, thermo-catalytic upgrading of lignocellulosic biomass generates wastewater that contains heterogeneous toxic chemicals, a mixture of unutilized carbon. Metabolic engineering efforts have primarily focused on the conversion of carbohydrates in lignocellulose biomass; substantial opportunities exist to harness value from toxic lignocellulose-derived toxic compounds. This article presents the comprehensive metabolic routes and tolerance mechanisms to develop robust synthetic microbial cell factories to valorize the highly toxic compounds to advanced-platform chemicals. The obtained platform chemicals can be used to manufacture high-value biopolymers and biomaterials via a hybrid biochemical approach for replacing petroleum-based incumbents. The proposed strategy enables a sustainable bio-based materials economy by microbial biofunneling of lignocellulosic biomass-derived toxic molecules, an untapped biogenic carbon.
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Affiliation(s)
- Lahiru N Jayakody
- School of Biological Science, Southern Illinois University Carbondale, Carbondale, IL, USA; Fermentation Science Institute, Southern Illinois University Carbondale, Carbondale, IL, USA.
| | - Baroi Chinmoy
- Illinois Sustainable Technology Center, University of Illinois Urbana Champaign, IL, USA
| | - Timothy L Turner
- Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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17
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Lu C, Batianis C, Akwafo EO, Wijffels RH, Martins Dos Santos VAP, Weusthuis RA. When metabolic prowess is too much of a good thing: how carbon catabolite repression and metabolic versatility impede production of esterified α,ω-diols in Pseudomonas putida KT2440. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:218. [PMID: 34801079 PMCID: PMC8606055 DOI: 10.1186/s13068-021-02066-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 11/06/2021] [Indexed: 05/16/2023]
Abstract
BACKGROUND Medium-chain-length α,ω-diols (mcl-diols) are important building blocks in polymer production. Recently, microbial mcl-diol production from alkanes was achieved in E. coli (albeit at low rates) using the alkane monooxygenase system AlkBGTL and esterification module Atf1. Owing to its remarkable versatility and conversion capabilities and hence potential for enabling an economically viable process, we assessed whether the industrially robust P. putida can be a suitable production organism of mcl-diols. RESULTS AlkBGTL and Atf1 were successfully expressed as was shown by oxidation of alkanes to alkanols, and esterification to alkyl acetates. However, the conversion rate was lower than that by E. coli, and not fully to diols. The conversion was improved by using citrate instead of glucose as energy source, indicating that carbon catabolite repression plays a role. By overexpressing the activator of AlkBGTL-Atf1, AlkS and deleting Crc or CyoB, key genes in carbon catabolite repression of P. putida increased diacetoxyhexane production by 76% and 65%, respectively. Removing Crc/Hfq attachment sites of mRNAs resulted in the highest diacetoxyhexane production. When the intermediate hexyl acetate was used as substrate, hexanol was detected. This indicated that P. putida expressed esterases, hampering accumulation of the corresponding esters and diesters. Sixteen putative esterase genes present in P. putida were screened and tested. Among them, Est12/K was proven to be the dominant one. Deletion of Est12/K halted hydrolysis of hexyl acetate and diacetoxyhexane. As a result of relieving catabolite repression and preventing the hydrolysis of ester, the optimal strain produced 3.7 mM hexyl acetate from hexane and 6.9 mM 6-hydroxy hexyl acetate and diacetoxyhexane from hexyl acetate, increased by 12.7- and 4.2-fold, respectively, as compared to the starting strain. CONCLUSIONS This study shows that the metabolic versatility of P. putida, and the associated carbon catabolite repression, can hinder production of diols and related esters. Growth on mcl-alcohol and diol esters could be prevented by deleting the dominant esterase. Carbon catabolite repression could be relieved by removing the Crc/Hfq attachment sites. This strategy can be used for efficient expression of other genes regulated by Crc/Hfq in Pseudomonas and related species to steer bioconversion processes.
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Affiliation(s)
- Chunzhe Lu
- Bioprocess Engineering, Wageningen University and Research, Wageningen, The Netherlands
| | - Christos Batianis
- Laboratory of Systems and Synthetic Biology, Wageningen University and Research, Wageningen, The Netherlands
| | - Edward Ofori Akwafo
- Bioprocess Engineering, Wageningen University and Research, Wageningen, The Netherlands
| | - Rene H Wijffels
- Bioprocess Engineering, Wageningen University and Research, Wageningen, The Netherlands
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | - Vitor A P Martins Dos Santos
- Bioprocess Engineering, Wageningen University and Research, Wageningen, The Netherlands
- Laboratory of Systems and Synthetic Biology, Wageningen University and Research, Wageningen, The Netherlands
- Lifeglimmer GmbH, Berlin, Germany
| | - Ruud A Weusthuis
- Bioprocess Engineering, Wageningen University and Research, Wageningen, The Netherlands.
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18
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Characterization of highly ferulate-tolerant Acinetobacter baylyi ADP1 isolates by a rapid reverse-engineering method. Appl Environ Microbiol 2021; 88:e0178021. [PMID: 34788063 DOI: 10.1128/aem.01780-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Adaptive laboratory evolution (ALE) is a powerful approach for improving phenotypes of microbial hosts. Evolved strains typically contain numerous mutations that can be revealed by whole-genome sequencing. However, determining the contribution of specific mutations to new phenotypes is typically challenging and laborious. This task is complicated by factors such as the mutation type, the genomic context, and the interplay between different mutations. Here, a novel approach was developed to identify the significance of mutations in strains evolved from Acinetobacter baylyi ADP1. This method, termed Rapid Advantageous Mutation ScrEening and Selection (RAMSES), was used to analyze mutants that emerged from stepwise adaptation to, and consumption of, high levels of ferulate, a common lignin-derived aromatic compound. After whole-genome sequence analysis, RAMSES allowed rapid determination of effective mutations and seamless introduction of the beneficial mutations into the chromosomes of new strains with different genetic backgrounds. This simple approach to reverse-engineering exploits the natural competence and high recombination efficiency of ADP1. Mutated DNA, added directly to growing cells, replaces homologous chromosomal regions to generate transformants that will become enriched if there is selective benefit. Thus, advantageous mutations can be rapidly identified. Here, the growth advantage of transformants under selective pressure revealed key mutations in genes related to aromatic transport, including hcaE, hcaK, and vanK, and a gene, ACIAD0482, which is associated with lipopolysaccharide synthesis. This study provides insights into enhanced utilization of industrially relevant aromatic substrates and demonstrates the use of A. baylyi ADP1 as a convenient platform for strain development and evolution studies. Importance Microbial conversion of lignin-enriched streams is a promising approach for lignin valorization. However, the lignin-derived aromatic compounds are toxic to cells at relevant concentrations. Although adaptive laboratory evolution (ALE) is a powerful approach to develop more tolerant strains, it is typically laborious to identify the mechanisms underlying phenotypic improvement. We employed Acinetobacter baylyi ADP1, an aromatic compound degrading strain that may be useful for biotechnology. The natural competence and high recombination efficiency of this strain can be exploited for critical applications such as the breakdown of lignin and plastics, abundant polymers composed of aromatic subunits. The natural transformability of this bacterium enabled us to develop a novel approach for rapid screening of advantageous mutations from ALE-derived aromatic-tolerant ADP1-derived strains. We clarified the mechanisms and genetic targets for improved tolerance towards common lignin-derived aromatic compounds. This study facilitates metabolic engineering for lignin valorization.
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19
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20
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Towards robust Pseudomonas cell factories to harbour novel biosynthetic pathways. Essays Biochem 2021; 65:319-336. [PMID: 34223620 PMCID: PMC8314020 DOI: 10.1042/ebc20200173] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 05/01/2021] [Accepted: 05/24/2021] [Indexed: 02/07/2023]
Abstract
Biotechnological production in bacteria enables access to numerous valuable chemical compounds. Nowadays, advanced molecular genetic toolsets, enzyme engineering as well as the combinatorial use of biocatalysts, pathways, and circuits even bring new-to-nature compounds within reach. However, the associated substrates and biosynthetic products often cause severe chemical stress to the bacterial hosts. Species of the Pseudomonas clade thus represent especially valuable chassis as they are endowed with multiple stress response mechanisms, which allow them to cope with a variety of harmful chemicals. A built-in cell envelope stress response enables fast adaptations that sustain membrane integrity under adverse conditions. Further, effective export machineries can prevent intracellular accumulation of diverse harmful compounds. Finally, toxic chemicals such as reactive aldehydes can be eliminated by oxidation and stress-induced damage can be recovered. Exploiting and engineering these features will be essential to support an effective production of natural compounds and new chemicals. In this article, we therefore discuss major resistance strategies of Pseudomonads along with approaches pursued for their targeted exploitation and engineering in a biotechnological context. We further highlight strategies for the identification of yet unknown tolerance-associated genes and their utilisation for engineering next-generation chassis and finally discuss effective measures for pathway fine-tuning to establish stable cell factories for the effective production of natural compounds and novel biochemicals.
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21
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The Pseudomonas aeruginosa substrate-binding protein Ttg2D functions as a general glycerophospholipid transporter across the periplasm. Commun Biol 2021; 4:448. [PMID: 33837253 PMCID: PMC8035174 DOI: 10.1038/s42003-021-01968-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 03/04/2021] [Indexed: 11/19/2022] Open
Abstract
In Pseudomonas aeruginosa, Ttg2D is the soluble periplasmic phospholipid-binding component of an ABC transport system thought to be involved in maintaining the asymmetry of the outer membrane. Here we use the crystallographic structure of Ttg2D at 2.5 Å resolution to reveal that this protein can accommodate four acyl chains. Analysis of the available structures of Ttg2D orthologs shows that they conform a new substrate-binding-protein structural cluster. Native and denaturing mass spectrometry experiments confirm that Ttg2D, produced both heterologously and homologously and isolated from the periplasm, can carry two diacyl glycerophospholipids as well as one cardiolipin. Binding is notably promiscuous, allowing the transport of various molecular species. In vitro binding assays coupled to native mass spectrometry show that binding of cardiolipin is spontaneous. Gene knockout experiments in P. aeruginosa multidrug-resistant strains reveal that the Ttg2 system is involved in low-level intrinsic resistance against certain antibiotics that use a lipid-mediated pathway to permeate through membranes. Yero et al. elucidate the function of Ttg2D, a Pseudomonas aeruginosa periplasmic protein, in maintaining phospholipid asymmetry between the outer and inner membrane. Gram negative bacteria have inner and outer membranes that differ in phospholipd composition. Using X-ray crystallography and mass spectrometry, the authors show that Ttg2D can carry two diacyl glycerophospholipids or a cardiolipin. The authors also identify a role for Ttg2D in resistance against antibiotics that use a lipid-mediated pathway into the cell.
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22
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Riley LA, Guss AM. Approaches to genetic tool development for rapid domestication of non-model microorganisms. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:30. [PMID: 33494801 PMCID: PMC7830746 DOI: 10.1186/s13068-020-01872-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 12/30/2020] [Indexed: 05/04/2023]
Abstract
Non-model microorganisms often possess complex phenotypes that could be important for the future of biofuel and chemical production. They have received significant interest the last several years, but advancement is still slow due to the lack of a robust genetic toolbox in most organisms. Typically, "domestication" of a new non-model microorganism has been done on an ad hoc basis, and historically, it can take years to develop transformation and basic genetic tools. Here, we review the barriers and solutions to rapid development of genetic transformation tools in new hosts, with a major focus on Restriction-Modification systems, which are a well-known and significant barrier to efficient transformation. We further explore the tools and approaches used for efficient gene deletion, DNA insertion, and heterologous gene expression. Finally, more advanced and high-throughput tools are now being developed in diverse non-model microbes, paving the way for rapid and multiplexed genome engineering for biotechnology.
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Affiliation(s)
- Lauren A Riley
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Bredesen Center, University of Tennessee, Knoxville, TN, 37996, USA
| | - Adam M Guss
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
- Bredesen Center, University of Tennessee, Knoxville, TN, 37996, USA.
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23
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Kuepper J, Otto M, Dickler J, Behnken S, Magnus J, Jäger G, Blank LM, Wierckx N. Adaptive laboratory evolution of Pseudomonas putida and Corynebacterium glutamicum to enhance anthranilate tolerance. Microbiology (Reading) 2020; 166:1025-1037. [DOI: 10.1099/mic.0.000982] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Microbial bioproduction of the aromatic acid anthranilate (ortho-aminobenzoate) has the potential to replace its current, environmentally demanding production process. The host organism employed for such a process needs to fulfil certain demands to achieve industrially relevant product levels. As anthranilate is toxic for microorganisms, the use of particularly robust production hosts can overcome issues from product inhibition. The microorganisms
Corynebacterium glutamicum
and
Pseudomonas putida
are known for high tolerance towards a variety of chemicals and could serve as promising platform strains. In this study, the resistance of both wild-type strains towards anthranilate was assessed. To further enhance their native tolerance, adaptive laboratory evolution (ALE) was applied. Sequential batch fermentation processes were developed, adapted to the cultivation demands for
C. glutamicum
and P. putida, to enable long-term cultivation in the presence of anthranilate. Isolation and analysis of single mutants revealed phenotypes with improved growth behaviour in the presence of anthranilate for both strains. The characterization and improvement of both potential hosts provide an important basis for further process optimization and will aid the establishment of an industrially competitive method for microbial synthesis of anthranilate.
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Affiliation(s)
- Jannis Kuepper
- Institute of Applied Microbiology, RWTH Aachen University, 52074 Aachen, Germany
| | - Maike Otto
- Institute of Bio- and Geosciences (IBG-1: Biotechnology), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Institute of Applied Microbiology, RWTH Aachen University, 52074 Aachen, Germany
| | - Jasmin Dickler
- Institute of Applied Microbiology, RWTH Aachen University, 52074 Aachen, Germany
| | | | | | - Gernot Jäger
- Covestro Deutschland AG, 51365 Leverkusen, Germany
| | - Lars M. Blank
- Institute of Applied Microbiology, RWTH Aachen University, 52074 Aachen, Germany
| | - Nick Wierckx
- Institute of Bio- and Geosciences (IBG-1: Biotechnology), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
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Banerjee D, Eng T, Lau AK, Sasaki Y, Wang B, Chen Y, Prahl JP, Singan VR, Herbert RA, Liu Y, Tanjore D, Petzold CJ, Keasling JD, Mukhopadhyay A. Genome-scale metabolic rewiring improves titers rates and yields of the non-native product indigoidine at scale. Nat Commun 2020; 11:5385. [PMID: 33097726 PMCID: PMC7584609 DOI: 10.1038/s41467-020-19171-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 09/30/2020] [Indexed: 01/06/2023] Open
Abstract
High titer, rate, yield (TRY), and scalability are challenging metrics to achieve due to trade-offs between carbon use for growth and production. To achieve these metrics, we take the minimal cut set (MCS) approach that predicts metabolic reactions for elimination to couple metabolite production strongly with growth. We compute MCS solution-sets for a non-native product indigoidine, a sustainable pigment, in Pseudomonas putida KT2440, an emerging industrial microbe. From the 63 solution-sets, our omics guided process identifies one experimentally feasible solution requiring 14 simultaneous reaction interventions. We implement a total of 14 genes knockdowns using multiplex-CRISPRi. MCS-based solution shifts production from stationary to exponential phase. We achieve 25.6 g/L, 0.22 g/l/h, and ~50% maximum theoretical yield (0.33 g indigoidine/g glucose). These phenotypes are maintained from batch to fed-batch mode, and across scales (100-ml shake flasks, 250-ml ambr®, and 2-L bioreactors).
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Affiliation(s)
- Deepanwita Banerjee
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Thomas Eng
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Andrew K Lau
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yusuke Sasaki
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Brenda Wang
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yan Chen
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Jan-Philip Prahl
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Advanced Biofuel and Bioproduct Process Development Unit, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
| | - Vasanth R Singan
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Robin A Herbert
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yuzhong Liu
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Deepti Tanjore
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Advanced Biofuel and Bioproduct Process Development Unit, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
| | - Christopher J Petzold
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Jay D Keasling
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- QB3 Institute, University of California-Berkeley, 5885 Hollis Street, 4th Floor, Emeryville, CA, 94608, USA
- Department of Chemical & Biomolecular Engineering, University of California, Berkeley, CA, 94720, USA
- Department of Bioengineering, University of California, Berkeley, CA, 94720, USA
- Novo Nordisk Foundation Center for Biosustainability, Technical University Denmark, 2970, Horsholm, Denmark
- Synthetic Biochemistry Center, Institute for Synthetic Biology, Shenzhen Institutes for Advanced Technologies, Shenzhen, China
| | - Aindrila Mukhopadhyay
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA.
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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25
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Current state of aromatics production using yeast: achievements and challenges. Curr Opin Biotechnol 2020; 65:65-74. [DOI: 10.1016/j.copbio.2020.01.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 01/21/2020] [Accepted: 01/24/2020] [Indexed: 12/14/2022]
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26
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Mohamed ET, Werner AZ, Salvachúa D, Singer CA, Szostkiewicz K, Rafael Jiménez-Díaz M, Eng T, Radi MS, Simmons BA, Mukhopadhyay A, Herrgård MJ, Singer SW, Beckham GT, Feist AM. Adaptive laboratory evolution of Pseudomonas putida KT2440 improves p-coumaric and ferulic acid catabolism and tolerance. Metab Eng Commun 2020; 11:e00143. [PMID: 32963959 PMCID: PMC7490845 DOI: 10.1016/j.mec.2020.e00143] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 08/05/2020] [Accepted: 08/20/2020] [Indexed: 01/27/2023] Open
Abstract
Pseudomonas putida KT2440 is a promising bacterial chassis for the conversion of lignin-derived aromatic compound mixtures to biofuels and bioproducts. Despite the inherent robustness of this strain, further improvements to aromatic catabolism and toxicity tolerance of P. putida will be required to achieve industrial relevance. Here, tolerance adaptive laboratory evolution (TALE) was employed with increasing concentrations of the hydroxycinnamic acids p-coumaric acid (pCA) and ferulic acid (FA) individually and in combination (pCA + FA). The TALE experiments led to evolved P. putida strains with increased tolerance to the targeted acids as compared to wild type. Specifically, a 37 h decrease in lag phase in 20 g/L pCA and a 2.4-fold increase in growth rate in 30 g/L FA was observed. Whole genome sequencing of intermediate and endpoint evolved P. putida populations revealed several expected and non-intuitive genetic targets underlying these aromatic catabolic and toxicity tolerance enhancements. PP_3350 and ttgB were among the most frequently mutated genes, and the beneficial contributions of these mutations were verified via gene knockouts. Deletion of PP_3350, encoding a hypothetical protein, recapitulated improved toxicity tolerance to high concentrations of pCA, but not an improved growth rate in high concentrations of FA. Deletion of ttgB, part of the TtgABC efflux pump, severely inhibited growth in pCA + FA TALE-derived strains but did not affect growth in pCA + FA in a wild type background, suggesting epistatic interactions. Genes involved in flagellar movement and transcriptional regulation were often mutated in the TALE experiments on multiple substrates, reinforcing ideas of a minimal and deregulated cell as optimal for domesticated growth. Overall, this work demonstrates increased tolerance towards and growth rate at the expense of hydroxycinnamic acids and presents new targets for improving P. putida for microbial lignin valorization. Pseudomonas putida was evolved in increasing hydroxycinnamic acid concentrations. The lag phase in high p-coumaric acid concentration was reduced. The growth rate and tolerance to high ferulic acid concentration was increased. PP_3350 and ttgB contribute to the observed phenotypes.
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Affiliation(s)
- Elsayed T Mohamed
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Allison Z Werner
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA.,Center for Bioenergy Innovation, Oak Ridge, TN, USA
| | - Davinia Salvachúa
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA
| | - Christine A Singer
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA
| | - Kiki Szostkiewicz
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA
| | - Manuel Rafael Jiménez-Díaz
- Joint BioEnergy Institute, Emeryville, CA, USA.,Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Thomas Eng
- Joint BioEnergy Institute, Emeryville, CA, USA.,Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Mohammad S Radi
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Blake A Simmons
- Joint BioEnergy Institute, Emeryville, CA, USA.,Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Aindrila Mukhopadhyay
- Joint BioEnergy Institute, Emeryville, CA, USA.,Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Markus J Herrgård
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Steven W Singer
- Joint BioEnergy Institute, Emeryville, CA, USA.,Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Gregg T Beckham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA.,Center for Bioenergy Innovation, Oak Ridge, TN, USA
| | - Adam M Feist
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark.,Joint BioEnergy Institute, Emeryville, CA, USA.,Department of Bioengineering, University of California, San Diego, CA, USA
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27
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Common problems associated with the microbial productions of aromatic compounds and corresponding metabolic engineering strategies. Biotechnol Adv 2020; 41:107548. [DOI: 10.1016/j.biotechadv.2020.107548] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 04/06/2020] [Accepted: 04/08/2020] [Indexed: 01/06/2023]
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Ma C, Mu Q, Xue Y, Xue Y, Yu B, Ma Y. One major facilitator superfamily transporter is responsible for propionic acid tolerance in Pseudomonas putida KT2440. Microb Biotechnol 2020; 14:386-391. [PMID: 32476222 PMCID: PMC7936288 DOI: 10.1111/1751-7915.13597] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 04/29/2020] [Accepted: 04/30/2020] [Indexed: 11/27/2022] Open
Abstract
Propionic acid (PA) has been widely used as a food preservative and chemical intermediate in the agricultural and pharmaceutical industries. Environmental and friendly biotechnological production of PA from biomass has been considered as an alternative to the traditional petrochemical route. However, because PA is a strong inhibitor of cell growth, the biotechnological host should be not only able to produce the compound but the host should be robust. In this study, we identified key PA tolerance factors in Pseudomonas putida KT2440 strain by comparative transcriptional analysis in the presence or absence of PA stress. The identified major facilitator superfamily (MFS) transporter gene cluster of PP_1271, PP_1272 and PP_1273 was experimentally verified to be involved in PA tolerance in P. putida strains. Overexpression of this cluster improved tolerance to PA in a PA producing strain, what is useful to further engineer this robust platform not only for PA synthesis but for the production of other weak acids.
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Affiliation(s)
- Chao Ma
- CAS Key Laboratory of Microbial Physiological & Metabolic Engineering, State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.,State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qingxuan Mu
- CAS Key Laboratory of Microbial Physiological & Metabolic Engineering, State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yubin Xue
- CAS Key Laboratory of Microbial Physiological & Metabolic Engineering, State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yanfen Xue
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Bo Yu
- CAS Key Laboratory of Microbial Physiological & Metabolic Engineering, State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yanhe Ma
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
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29
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Ma C, Mu Q, Wang L, Shi Y, Zhu L, Zhang S, Xue Y, Tao Y, Ma Y, Yu B. Bio-production of high-purity propionate by engineering l-threonine degradation pathway in Pseudomonas putida. Appl Microbiol Biotechnol 2020; 104:5303-5313. [DOI: 10.1007/s00253-020-10619-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/30/2020] [Accepted: 04/09/2020] [Indexed: 01/08/2023]
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30
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Outer membrane vesicles catabolize lignin-derived aromatic compounds in Pseudomonas putida KT2440. Proc Natl Acad Sci U S A 2020; 117:9302-9310. [PMID: 32245809 DOI: 10.1073/pnas.1921073117] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Lignin is an abundant and recalcitrant component of plant cell walls. While lignin degradation in nature is typically attributed to fungi, growing evidence suggests that bacteria also catabolize this complex biopolymer. However, the spatiotemporal mechanisms for lignin catabolism remain unclear. Improved understanding of this biological process would aid in our collective knowledge of both carbon cycling and microbial strategies to valorize lignin to value-added compounds. Here, we examine lignin modifications and the exoproteome of three aromatic-catabolic bacteria: Pseudomonas putida KT2440, Rhodoccocus jostii RHA1, and Amycolatopsis sp. ATCC 39116. P. putida cultivation in lignin-rich media is characterized by an abundant exoproteome that is dynamically and selectively packaged into outer membrane vesicles (OMVs). Interestingly, many enzymes known to exhibit activity toward lignin-derived aromatic compounds are enriched in OMVs from early to late stationary phase, corresponding to the shift from bioavailable carbon to oligomeric lignin as a carbon source. In vivo and in vitro experiments demonstrate that enzymes contained in the OMVs are active and catabolize aromatic compounds. Taken together, this work supports OMV-mediated catabolism of lignin-derived aromatic compounds as an extracellular strategy for nutrient acquisition by soil bacteria and suggests that OMVs could potentially be useful tools for synthetic biology and biotechnological applications.
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31
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Fabian BK, Tetu SG, Paulsen IT. Application of Transposon Insertion Sequencing to Agricultural Science. FRONTIERS IN PLANT SCIENCE 2020; 11:291. [PMID: 32256512 PMCID: PMC7093568 DOI: 10.3389/fpls.2020.00291] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 02/26/2020] [Indexed: 06/11/2023]
Abstract
Many plant-associated bacteria have the ability to positively affect plant growth and there is growing interest in utilizing such bacteria in agricultural settings to reduce reliance on pesticides and fertilizers. However, our capacity to utilize microbes in this way is currently limited due to patchy understanding of bacterial-plant interactions at a molecular level. Traditional methods of studying molecular interactions have sought to characterize the function of one gene at a time, but the slow pace of this work means the functions of the vast majority of bacterial genes remain unknown or poorly understood. New approaches to improve and speed up investigations into the functions of bacterial genes in agricultural systems will facilitate efforts to optimize microbial communities and develop microbe-based products. Techniques enabling high-throughput gene functional analysis, such as transposon insertion sequencing analyses, have great potential to be widely applied to determine key aspects of plant-bacterial interactions. Transposon insertion sequencing combines saturation transposon mutagenesis and high-throughput sequencing to simultaneously investigate the function of all the non-essential genes in a bacterial genome. This technique can be used for both in vitro and in vivo studies to identify genes involved in microbe-plant interactions, stress tolerance and pathogen virulence. The information provided by such investigations will rapidly accelerate the rate of bacterial gene functional determination and provide insights into the genes and pathways that underlie biotic interactions, metabolism, and survival of agriculturally relevant bacteria. This knowledge could be used to select the most appropriate plant growth promoting bacteria for a specific set of conditions, formulating crop inoculants, or developing crop protection products. This review provides an overview of transposon insertion sequencing, outlines how this approach has been applied to study plant-associated bacteria, and proposes new applications of these techniques for the benefit of agriculture.
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Affiliation(s)
- Belinda K. Fabian
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - Sasha G. Tetu
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - Ian T. Paulsen
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW, Australia
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
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32
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Li WJ, Narancic T, Kenny ST, Niehoff PJ, O’Connor K, Blank LM, Wierckx N. Unraveling 1,4-Butanediol Metabolism in Pseudomonas putida KT2440. Front Microbiol 2020; 11:382. [PMID: 32256468 PMCID: PMC7090098 DOI: 10.3389/fmicb.2020.00382] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 02/20/2020] [Indexed: 12/30/2022] Open
Abstract
Plastics, in all forms, are a ubiquitous cornerstone of modern civilization. Although humanity undoubtedly benefits from the versatility and durability of plastics, they also cause a tremendous burden for the environment. Bio-upcycling is a promising approach to reduce this burden, especially for polymers that are currently not amenable to mechanical recycling. Wildtype P. putida KT2440 is able to grow on 1,4-butanediol as sole carbon source, but only very slowly. Adaptive laboratory evolution (ALE) led to the isolation of several strains with significantly enhanced growth rate and yield. Genome re-sequencing and proteomic analysis were applied to characterize the genomic and metabolic basis of efficient 1,4-butanediol metabolism. Initially, 1,4-butanediol is oxidized to 4-hydroxybutyrate, in which the highly expressed dehydrogenase enzymes encoded within the PP_2674-2680 ped gene cluster play an essential role. The resulting 4-hydroxybutyrate can be metabolized through three possible pathways: (i) oxidation to succinate, (ii) CoA activation and subsequent oxidation to succinyl-CoA, and (iii) beta oxidation to glycolyl-CoA and acetyl-CoA. The evolved strains were both mutated in a transcriptional regulator (PP_2046) of an operon encoding both beta-oxidation related genes and an alcohol dehydrogenase. When either the regulator or the alcohol dehydrogenase is deleted, no 1,4-butanediol uptake or growth could be detected. Using a reverse engineering approach, PP_2046 was replaced by a synthetic promotor (14g) to overexpress the downstream operon (PP_2047-2051), thereby enhancing growth on 1,4-butanediol. This work provides a deeper understanding of microbial 1,4-butanediol metabolism in P. putida, which is also expandable to other aliphatic alpha-omega diols. It enables the more efficient metabolism of these diols, thereby enabling biotechnological valorization of plastic monomers in a bio-upcycling approach.
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Affiliation(s)
- Wing-Jin Li
- Institute of Applied Microbiology-iAMB, Aachen Biology and Biotechnology-ABBt, RWTH Aachen University, Aachen, Germany
| | - Tanja Narancic
- UCD Earth Institute and School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- BEACON – SFI Bioeconomy Research Centre, University College Dublin, Dublin, Ireland
| | - Shane T. Kenny
- Bioplastech Ltd., NovaUCD, Belfield Innovation Park, University College Dublin, Dublin, Ireland
| | - Paul-Joachim Niehoff
- Institute of Applied Microbiology-iAMB, Aachen Biology and Biotechnology-ABBt, RWTH Aachen University, Aachen, Germany
| | - Kevin O’Connor
- UCD Earth Institute and School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- BEACON – SFI Bioeconomy Research Centre, University College Dublin, Dublin, Ireland
| | - Lars M. Blank
- Institute of Applied Microbiology-iAMB, Aachen Biology and Biotechnology-ABBt, RWTH Aachen University, Aachen, Germany
| | - Nick Wierckx
- Institute of Applied Microbiology-iAMB, Aachen Biology and Biotechnology-ABBt, RWTH Aachen University, Aachen, Germany
- Institute of Bio- and Geosciences IBG-1: Biotechnology, Forschungszentrum Jülich, Jülich, Germany
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Otto M, Wynands B, Lenzen C, Filbig M, Blank LM, Wierckx N. Rational Engineering of Phenylalanine Accumulation in Pseudomonas taiwanensis to Enable High-Yield Production of Trans-Cinnamate. Front Bioeng Biotechnol 2019; 7:312. [PMID: 31824929 PMCID: PMC6882275 DOI: 10.3389/fbioe.2019.00312] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 10/23/2019] [Indexed: 12/31/2022] Open
Abstract
Microbial biocatalysis represents a promising alternative for the production of a variety of aromatic chemicals, where microorganisms are engineered to convert a renewable feedstock under mild production conditions into a valuable chemical building block. This study describes the rational engineering of the solvent-tolerant bacterium Pseudomonas taiwanensis VLB120 toward accumulation of L-phenylalanine and its conversion into the chemical building block t-cinnamate. We recently reported rational engineering of Pseudomonas toward L-tyrosine accumulation by the insertion of genetic modifications that allow both enhanced flux and prevent aromatics degradation. Building on this knowledge, three genes encoding for enzymes involved in the degradation of L-phenylalanine were deleted to allow accumulation of 2.6 mM of L-phenylalanine from 20 mM glucose. The amino acid was subsequently converted into the aromatic model compound t-cinnamate by the expression of a phenylalanine ammonia-lyase (PAL) from Arabidopsis thaliana. The engineered strains produced t-cinnamate with yields of 23 and 39% Cmol Cmol−1 from glucose and glycerol, respectively. Yields were improved up to 48% Cmol Cmol−1 from glycerol when two enzymes involved in the shikimate pathway were additionally overexpressed, however with negative impact on strain performance and reproducibility. Production titers were increased in fed-batch fermentations, in which 33.5 mM t-cinnamate were produced solely from glycerol, in a mineral medium without additional complex supplements. The aspect of product toxicity was targeted by the utilization of a streamlined, genome-reduced strain, which improves upon the already high tolerance of P. taiwanensis VLB120 toward t-cinnamate.
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Affiliation(s)
- Maike Otto
- Institute of Bio- and Geosciences (IBG-1: Biotechnology), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Benedikt Wynands
- Institute of Bio- and Geosciences (IBG-1: Biotechnology), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Christoph Lenzen
- Institute of Applied Microbiology, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
| | - Melanie Filbig
- Institute of Applied Microbiology, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
| | - Lars M Blank
- Institute of Applied Microbiology, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University, Aachen, Germany
| | - Nick Wierckx
- Institute of Bio- and Geosciences (IBG-1: Biotechnology), Forschungszentrum Jülich GmbH, Jülich, Germany
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34
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Promoting microbial utilization of phenolic substrates from bio-oil. ACTA ACUST UNITED AC 2019; 46:1531-1545. [DOI: 10.1007/s10295-019-02208-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 06/21/2019] [Indexed: 10/26/2022]
Abstract
Abstract
The economic viability of the biorefinery concept is limited by the valorization of lignin. One possible method of lignin valorization is biological upgrading with aromatic-catabolic microbes. In conjunction, lignin monomers can be produced by fast pyrolysis and fractionation. However, biological upgrading of these lignin monomers is limited by low water solubility. Here, we address the problem of low water solubility with an emulsifier blend containing approximately 70 wt% Tween® 20 and 30 wt% Span® 80. Pseudomonas putida KT2440 grew to an optical density (OD600) of 1.0 ± 0.2 when supplied with 1.6 wt% emulsified phenolic monomer-rich product produced by fast pyrolysis of red oak using an emulsifier dose of 0.076 ± 0.002 g emulsifier blend per g of phenolic monomer-rich product. This approach partially mitigated the toxicity of the model phenolic monomer p-coumarate to the microbe, but not benzoate or vanillin. This study provides a proof of concept that processing of biomass-derived phenolics to increase aqueous availability can enhance microbial utilization.
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Shin SK, Ko YJ, Hyeon JE, Han SO. Studies of advanced lignin valorization based on various types of lignolytic enzymes and microbes. BIORESOURCE TECHNOLOGY 2019; 289:121728. [PMID: 31277889 DOI: 10.1016/j.biortech.2019.121728] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 06/26/2019] [Accepted: 06/28/2019] [Indexed: 06/09/2023]
Abstract
Lignin is a robust material that is considered useless because it has an inhibitory effect on microbes and acts as a physical barrier for cellulose degradation. Therefore, it has been removed from cellulosic biomass to produce high-value materials. However, lignin monomers can be converted to value-added chemicals such as biodegradable plastics and food additives by appropriately engineered microbes. Lignin degradation through peroxidase, laccase and other proteins with auxiliary activity is the first step in lignin valorization. Metabolic engineering of microorganisms for increased tolerance and production yield is the second step for lignin valorization. Here, this review offers a summary of current biotechnologies using various enzymatic activities, synergistic enzyme mixtures and metabolic engineering for lignin valorization in biorefinery.
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Affiliation(s)
- Sang Kyu Shin
- Department of Biotechnology, Korea University, Seoul 02841, Republic of Korea
| | - Young Jin Ko
- Department of Biotechnology, Korea University, Seoul 02841, Republic of Korea
| | - Jeong Eun Hyeon
- Department of Biotechnology, Korea University, Seoul 02841, Republic of Korea; Department of Food Science and Biotechnology, College of Knowledge-Based Services Engineering, Sungshin Women's University, Seoul 01133, Republic of Korea; Department of Food and Nutrition, College of Health & Wellness, Sungshin Women's University, Seoul 01133, Republic of Korea
| | - Sung Ok Han
- Department of Biotechnology, Korea University, Seoul 02841, Republic of Korea.
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Fernández‐Cabezón L, Cros A, Nikel PI. Evolutionary Approaches for Engineering Industrially Relevant Phenotypes in Bacterial Cell Factories. Biotechnol J 2019; 14:e1800439. [DOI: 10.1002/biot.201800439] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 04/08/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Lorena Fernández‐Cabezón
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of Denmark 2800 Kongens Lyngby Denmark
| | - Antonin Cros
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of Denmark 2800 Kongens Lyngby Denmark
| | - Pablo I. Nikel
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of Denmark 2800 Kongens Lyngby Denmark
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37
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Salmela M, Lehtinen T, Efimova E, Santala S, Santala V. Alkane and wax ester production from lignin‐related aromatic compounds. Biotechnol Bioeng 2019; 116:1934-1945. [DOI: 10.1002/bit.27005] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/29/2019] [Accepted: 04/18/2019] [Indexed: 12/24/2022]
Affiliation(s)
- Milla Salmela
- Faculty of Engineering and Natural Sciences, Hervanta CampusTampere UniversityTampere Finland
| | - Tapio Lehtinen
- Faculty of Engineering and Natural Sciences, Hervanta CampusTampere UniversityTampere Finland
| | - Elena Efimova
- Faculty of Engineering and Natural Sciences, Hervanta CampusTampere UniversityTampere Finland
| | - Suvi Santala
- Faculty of Engineering and Natural Sciences, Hervanta CampusTampere UniversityTampere Finland
| | - Ville Santala
- Faculty of Engineering and Natural Sciences, Hervanta CampusTampere UniversityTampere Finland
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38
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Poblete-Castro I, Wittmann C, Nikel PI. Biochemistry, genetics and biotechnology of glycerol utilization in Pseudomonas species. Microb Biotechnol 2019; 13:32-53. [PMID: 30883020 PMCID: PMC6922529 DOI: 10.1111/1751-7915.13400] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 02/17/2019] [Accepted: 02/23/2019] [Indexed: 11/30/2022] Open
Abstract
The use of renewable waste feedstocks is an environment‐friendly choice contributing to the reduction of waste treatment costs and increasing the economic value of industrial by‐products. Glycerol (1,2,3‐propanetriol), a simple polyol compound widely distributed in biological systems, constitutes a prime example of a relatively cheap and readily available substrate to be used in bioprocesses. Extensively exploited as an ingredient in the food and pharmaceutical industries, glycerol is also the main by‐product of biodiesel production, which has resulted in a progressive drop in substrate price over the years. Consequently, glycerol has become an attractive substrate in biotechnology, and several chemical commodities currently produced from petroleum have been shown to be obtained from this polyol using whole‐cell biocatalysts with both wild‐type and engineered bacterial strains. Pseudomonas species, endowed with a versatile and rich metabolism, have been adopted for the conversion of glycerol into value‐added products (ranging from simple molecules to structurally complex biopolymers, e.g. polyhydroxyalkanoates), and a number of metabolic engineering strategies have been deployed to increase the number of applications of glycerol as a cost‐effective substrate. The unique genetic and metabolic features of glycerol‐grown Pseudomonas are presented in this review, along with relevant examples of bioprocesses based on this substrate – and the synthetic biology and metabolic engineering strategies implemented in bacteria of this genus aimed at glycerol valorization.
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Affiliation(s)
- Ignacio Poblete-Castro
- Biosystems Engineering Laboratory, Center for Bioinformatics and Integrative Biology, Faculty of Natural Sciences, Universidad Andrés Bello, Santiago de Chile, Chile
| | - Christoph Wittmann
- Institute of Systems Biotechnology, Universität des Saarlandes, Saarbrücken, Germany
| | - Pablo I Nikel
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kgs Lyngby, Denmark
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39
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Synthetic metabolic pathway for the production of 1-alkenes from lignin-derived molecules. Microb Cell Fact 2019; 18:48. [PMID: 30857542 PMCID: PMC6410514 DOI: 10.1186/s12934-019-1097-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 02/28/2019] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Integration of synthetic metabolic pathways to catabolically diverse chassis provides new opportunities for sustainable production. One attractive scenario is the use of abundant waste material to produce a readily collectable product, which can reduce the production costs. Towards that end, we established a cellular platform for the production of semivolatile medium-chain α-olefins from lignin-derived molecules: we constructed 1-undecene synthesis pathway in Acinetobacter baylyi ADP1 using ferulate, a lignin-derived model compound, as the sole carbon source for both cell growth and product synthesis. RESULTS In order to overcome the toxicity of ferulate, we first applied adaptive laboratory evolution to A. baylyi ADP1, resulting in a highly ferulate-tolerant strain. The adapted strain exhibited robust growth in 100 mM ferulate while the growth of the wild type strain was completely inhibited. Next, we expressed two heterologous enzymes in the wild type strain to confer 1-undecene production from glucose: a fatty acid decarboxylase UndA from Pseudomonas putida, and a thioesterase 'TesA from Escherichia coli. Finally, we constructed the 1-undecene synthesis pathway in the ferulate-tolerant strain. The engineered cells were able to produce biomass and 1-undecene solely from ferulate, and excreted the product directly to the culture headspace. CONCLUSIONS In this study, we employed a bacterium Acinetobacter baylyi ADP1 to integrate a natural aromatics degrading pathway to a synthetic production route, allowing the upgradation of lignin derived molecules to value-added products. We developed a highly ferulate-tolerant strain and established the biosynthesis of an industrially relevant chemical, 1-undecene, solely from the lignin-derived model compound. This study reports the production of alkenes from lignin derived molecules for the first time and demonstrates the potential of lignin as a sustainable resource in the bio-based synthesis of valuable products.
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Calero P, Nikel PI. Chasing bacterial chassis for metabolic engineering: a perspective review from classical to non-traditional microorganisms. Microb Biotechnol 2019; 12:98-124. [PMID: 29926529 PMCID: PMC6302729 DOI: 10.1111/1751-7915.13292] [Citation(s) in RCA: 143] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 05/28/2018] [Accepted: 05/29/2018] [Indexed: 12/27/2022] Open
Abstract
The last few years have witnessed an unprecedented increase in the number of novel bacterial species that hold potential to be used for metabolic engineering. Historically, however, only a handful of bacteria have attained the acceptance and widespread use that are needed to fulfil the needs of industrial bioproduction - and only for the synthesis of very few, structurally simple compounds. One of the reasons for this unfortunate circumstance has been the dearth of tools for targeted genome engineering of bacterial chassis, and, nowadays, synthetic biology is significantly helping to bridge such knowledge gap. Against this background, in this review, we discuss the state of the art in the rational design and construction of robust bacterial chassis for metabolic engineering, presenting key examples of bacterial species that have secured a place in industrial bioproduction. The emergence of novel bacterial chassis is also considered at the light of the unique properties of their physiology and metabolism, and the practical applications in which they are expected to outperform other microbial platforms. Emerging opportunities, essential strategies to enable successful development of industrial phenotypes, and major challenges in the field of bacterial chassis development are also discussed, outlining the solutions that contemporary synthetic biology-guided metabolic engineering offers to tackle these issues.
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Affiliation(s)
- Patricia Calero
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of Denmark2800Kongens LyngbyDenmark
| | - Pablo I. Nikel
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of Denmark2800Kongens LyngbyDenmark
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Nikel PI, de Lorenzo V. Pseudomonas putida as a functional chassis for industrial biocatalysis: From native biochemistry to trans-metabolism. Metab Eng 2018; 50:142-155. [DOI: 10.1016/j.ymben.2018.05.005] [Citation(s) in RCA: 245] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Revised: 05/07/2018] [Accepted: 05/10/2018] [Indexed: 12/12/2022]
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Calero P, Jensen SI, Bojanovič K, Lennen RM, Koza A, Nielsen AT. Genome-wide identification of tolerance mechanisms toward p-coumaric acid in Pseudomonas putida. Biotechnol Bioeng 2017; 115:762-774. [PMID: 29131301 PMCID: PMC5814926 DOI: 10.1002/bit.26495] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 10/16/2017] [Accepted: 11/08/2017] [Indexed: 01/12/2023]
Abstract
The soil bacterium Pseudomonas putida KT2440 has gained increasing biotechnological interest due to its ability to tolerate different types of stress. Here, the tolerance of P. putida KT2440 toward eleven toxic chemical compounds was investigated. P. putida was found to be significantly more tolerant toward three of the eleven compounds when compared to Escherichia coli. Increased tolerance was for example found toward p‐coumaric acid, an interesting precursor for polymerization with a significant industrial relevance. The tolerance mechanism was therefore investigated using the genome‐wide approach, Tn‐seq. Libraries containing a large number of miniTn5‐Km transposon insertion mutants were grown in the presence and absence of p‐coumaric acid, and the enrichment or depletion of mutants was quantified by high‐throughput sequencing. Several genes, including the ABC transporter Ttg2ABC and the cytochrome c maturation system (ccm), were identified to play an important role in the tolerance toward p‐coumaric acid of this bacterium. Most of the identified genes were involved in membrane stability, suggesting that tolerance toward p‐coumaric acid is related to transport and membrane integrity.
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Affiliation(s)
- Patricia Calero
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Lyngby, Denmark
| | - Sheila I Jensen
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Lyngby, Denmark
| | - Klara Bojanovič
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Lyngby, Denmark
| | - Rebecca M Lennen
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Lyngby, Denmark
| | - Anna Koza
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Lyngby, Denmark
| | - Alex T Nielsen
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Lyngby, Denmark
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