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Courtney DK, Su Y, Jacobson T, Khana D, Ailiani A, Amador-Noguez D, Pfleger BF. Relative Activities of the β-ketoacyl-CoA and Acyl-CoA Reductases Influence Product Profile and Flux in a Reversed β-Oxidation Pathway. ACS Catal 2023; 13:5914-5925. [PMID: 38094510 PMCID: PMC10718561 DOI: 10.1021/acscatal.3c00379] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
The β-Oxidation pathway, normally involved in the catabolism of fatty acids, can be functionally made to act as a fermentative, iterative, elongation pathway when driven by the activity of a trans-enoyl-CoA reductase. The terminal acyl-CoA reduction to alcohol can occur on substrates with varied chain lengths, leading to a broad distribution of fermentation products in vivo. Tight control of the average chain length and product profile is desirable as chain length greatly influences molecular properties and commercial value. Lacking a termination enzyme with a narrow chain length preference, we sought alternative factors that could influence the product profile and pathway flux in the iterative pathway. In this study, we reconstituted the reversed β-oxidation (R-βox) pathway in vitro with a purified tri-functional complex (FadBA) responsible for the thiolase, enoyl-CoA hydratase and hydroxyacyl-CoA dehydrogenase activities, a trans-enoyl-CoA reductase (TER), and an acyl-CoA reductase (ACR). Using this system, we determined the rate limiting step of the elongation cycle and demonstrated that by controlling the ratio of these three enzymes and the ratio of NADH and NADPH, we can influence the average chain length of the alcohol product profile.
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Affiliation(s)
- Dylan K. Courtney
- Department of Chemical and Biological Engineering, University of Wisconsin – Madison, Madison, WI, USA
| | - Yun Su
- Department of Chemical and Biological Engineering, University of Wisconsin – Madison, Madison, WI, USA
| | - Tyler Jacobson
- Department of Bacteriology, University of Wisconsin – Madison, Madison, WI, USA
| | - Daven Khana
- Department of Bacteriology, University of Wisconsin – Madison, Madison, WI, USA
| | - Aditya Ailiani
- Department of Biomedical Engineering, University of Wisconsin – Madison, Madison, WI, USA
| | | | - Brian F. Pfleger
- Department of Chemical and Biological Engineering, University of Wisconsin – Madison, Madison, WI, USA
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2
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de Vrije T, Nagtegaal RM, Veloo RM, Kappen FHJ, de Wolf FA. Medium chain length polyhydroxyalkanoate produced from ethanol by Pseudomonas putida grown in liquid obtained from acidogenic digestion of organic municipal solid waste. BIORESOURCE TECHNOLOGY 2023; 375:128825. [PMID: 36878376 DOI: 10.1016/j.biortech.2023.128825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 02/27/2023] [Accepted: 03/01/2023] [Indexed: 06/18/2023]
Abstract
Production of medium chain length polyhydroxyalkanoate (mcl-PHA) up to about 6 g.L-1 was obtained by feeding ethanol to Pseudomonas putida growing in liquid obtained from acidogenic digestion of organic municipal solid waste. Washing the wet, heat-inactivated Pseudomonas cells at the end of the fermentation with ethanol obviated the need of drying the biomass and enabled the removal of contaminating lipids before solvent-mediated extraction of PHA. Using 'green' solvents, 90 to near 100% of the mcl-PHA was extracted and purities of 71-78% mcl-PHA were reached already by centrifugation and decantation without further filtration for biomass removal. The mcl-PHA produced in this way consists of 10-18% C8, 72-78% C10 and 8-12% C12 chains (entirely medium chain length), has a crystallinity and melting temperature of ∼13% and ∼49 °C, respectively, and is a stiff rubberlike, colourless material at room temperature.
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Affiliation(s)
- Truus de Vrije
- Wageningen Food & Biobased Research, Bornse Weilanden 9, NL-6708 WG Wageningen, The Netherlands.
| | - Ricardo M Nagtegaal
- Wageningen Food & Biobased Research, Bornse Weilanden 9, NL-6708 WG Wageningen, The Netherlands
| | - Ruud M Veloo
- Wageningen Food & Biobased Research, Bornse Weilanden 9, NL-6708 WG Wageningen, The Netherlands
| | - Frans H J Kappen
- Wageningen Food & Biobased Research, Bornse Weilanden 9, NL-6708 WG Wageningen, The Netherlands
| | - Frits A de Wolf
- Wageningen Food & Biobased Research, Bornse Weilanden 9, NL-6708 WG Wageningen, The Netherlands
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3
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Bhattacharyya M, Dhar R, Basu S, Das A, Reynolds DM, Dutta TK. Molecular evaluation of the metabolism of estrogenic di(2-ethylhexyl) phthalate in Mycolicibacterium sp. Microb Cell Fact 2023; 22:82. [PMID: 37101185 PMCID: PMC10134610 DOI: 10.1186/s12934-023-02096-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 04/12/2023] [Indexed: 04/28/2023] Open
Abstract
BACKGROUND Di(2-ethylhexyl) phthalate (DEHP) is a widely detected plasticizer and a priority pollutant of utmost concern for its adverse impact on humans, wildlife and the environment. To eliminate such toxic burden, biological processes are the most promising ways to combat rampant environmental insults under eco-friendly conditions. The present study investigated the biochemical and molecular assessment of the catabolic potential of Mycolicibacterium sp. strain MBM in the assimilation of estrogenic DEHP. RESULTS A detailed biochemical study revealed an initial hydrolytic pathway of degradation for DEHP followed by the assimilation of hydrolyzed phthalic acid and 2-ethylhexanol to TCA cycle intermediates. Besides the inducible nature of DEHP-catabolic enzymes, strain MBM can efficiently utilize various low- and high-molecular-weight phthalate diesters and can grow under moderately halotolerant conditions. Whole genome sequence analysis exhibited a genome size of 6.2 Mb with a GC content of 66.51% containing 6,878 coding sequences, including multiple genes, annotated as relevant to the catabolism of phthalic acid esters (PAEs). Substantiating the annotated genes through transcriptome assessment followed by RT-qPCR analysis, the possible roles of upregulated genes/gene clusters in the metabolism of DEHP were revealed, reinforcing the biochemical pathway of degradation at the molecular level. CONCLUSIONS A detailed co-relation of biochemical, genomic, transcriptomic and RT-qPCR analyses highlights the PAE-degrading catabolic machineries in strain MBM. Further, due to functional attributes in the salinity range of both freshwater and seawater, strain MBM may find use as a suitable candidate in the bioremediation of PAEs.
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Affiliation(s)
- Mousumi Bhattacharyya
- Department of Microbiology, Bose Institute, EN-80, Sector V, Salt Lake, Kolkata, West Bengal, 700091, India
| | - Rinita Dhar
- Department of Microbiology, Bose Institute, EN-80, Sector V, Salt Lake, Kolkata, West Bengal, 700091, India
| | - Suman Basu
- Department of Microbiology, Bose Institute, EN-80, Sector V, Salt Lake, Kolkata, West Bengal, 700091, India
| | - Avijit Das
- Department of Microbiology, Bose Institute, EN-80, Sector V, Salt Lake, Kolkata, West Bengal, 700091, India
| | - Darren M Reynolds
- Centre for Research in Biosciences, Department of Applied Sciences, University of the West of England, Bristol, BS16 1QY, UK
| | - Tapan K Dutta
- Department of Microbiology, Bose Institute, EN-80, Sector V, Salt Lake, Kolkata, West Bengal, 700091, India.
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Zhu Y, Ai M, Jia X. Optimization of a Two-Species Microbial Consortium for Improved Mcl-PHA Production From Glucose-Xylose Mixtures. Front Bioeng Biotechnol 2022; 9:794331. [PMID: 35083203 PMCID: PMC8784772 DOI: 10.3389/fbioe.2021.794331] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 12/20/2021] [Indexed: 11/13/2022] Open
Abstract
Polyhydroxyalkanoates (PHAs) have attracted much attention as a good substitute for petroleum-based plastics, especially mcl-PHA due to their superior physical and mechanical properties with broader applications. Artificial microbial consortia can solve the problems of low metabolic capacity of single engineered strains and low conversion efficiency of natural consortia while expanding the scope of substrate utilization. Therefore, the use of artificial microbial consortia is considered a promising method for the production of mcl-PHA. In this work, we designed and constructed a microbial consortium composed of engineered Escherichia coli MG1655 and Pseudomonas putida KT2440 based on the "nutrition supply-detoxification" concept, which improved mcl-PHA production from glucose-xylose mixtures. An engineered E. coli that preferentially uses xylose was engineered with an enhanced ability to secrete acetic acid and free fatty acids (FFAs), producing 6.44 g/L acetic acid and 2.51 g/L FFAs with 20 g/L xylose as substrate. The mcl-PHA producing strain of P. putida in the microbial consortium has been engineered to enhance its ability to convert acetic acid and FFAs into mcl-PHA, producing 0.75 g/L mcl-PHA with mixed substrates consisting of glucose, acetic acid, and octanoate, while also reducing the growth inhibition of E. coli by acetic acid. The further developed artificial microbial consortium finally produced 1.32 g/L of mcl-PHA from 20 g/L of a glucose-xylose mixture (1:1) after substrate competition control and process optimization. The substrate utilization and product synthesis functions were successfully divided into the two strains in the constructed artificial microbial consortium, and a mutually beneficial symbiosis of "nutrition supply-detoxification" with a relatively high mcl-PHA titer was achieved, enabling the efficient accumulation of mcl-PHA. The consortium developed in this study is a potential platform for mcl-PHA production from lignocellulosic biomass.
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Affiliation(s)
- Yinzhuang Zhu
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Mingmei Ai
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Xiaoqiang Jia
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, China
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5
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de Oliveira RD, Novello V, da Silva LF, Gomez JGC, Le Roux GAC. Glucose metabolism in Pseudomonas aeruginosa is cyclic when producing Polyhydroxyalkanoates and Rhamnolipids. J Biotechnol 2021; 342:54-63. [PMID: 34687809 DOI: 10.1016/j.jbiotec.2021.10.007] [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: 02/10/2021] [Revised: 10/11/2021] [Accepted: 10/14/2021] [Indexed: 10/20/2022]
Abstract
Pseudomonas aeruginosa is an important chassis for production of polyhydroxyalkanoates (PHA) and rhamnolipids (RHL). Advances in the understanding of the biosynthesis metabolism of these biocompounds are crucial for increasing yield. 13C-Metabolic Flux Ratio Analysis (13C-MFA) is a technique to estimate in vivo metabolic fluxes ratios. PHA and RHL are essentially non-growth associated products of biotechnological interest and both contain hydroxyalkanoates (HAs), whose labeling patterns could be accessed by GC-MS. In this study, to reveal the relative contributions of the Entner-Doudoroff (ED) pathway and the non-oxidative Pentose Phosphate (PP) pathway to PHA and RHL production, 13C-MFA was performed in Pseudomonas aeruginosa LFM634 when supplied with labeled glucose. This bacterial strain lacks both functional EMP and the oxidative PP branch. Labeling patterns in HAs were measured. Experiments with [U-13C] glucose indicated a low flux though PP pathway. An optimal design of labeling experiment showed that [6-13C] glucose would be the best substrate to enable an estimation of the ED flux with high accuracy. Results of experiments performed with this isotope indicated that about two-thirds of glyceraldehyde 3-phosphate is recycled through a cyclic ED architecture, suggesting that P. aeruginosa utilizes that cycle to regulate the NADPH/Acetyl-CoA ratio for PHA and RHL biosynthesis.
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Affiliation(s)
| | - Vânia Novello
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Brazil
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6
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Dartiailh C, Blunt W, Sharma PK, Liu S, Cicek N, Levin DB. The Thermal and Mechanical Properties of Medium Chain-Length Polyhydroxyalkanoates Produced by Pseudomonas putida LS46 on Various Substrates. Front Bioeng Biotechnol 2021; 8:617489. [PMID: 33553122 PMCID: PMC7859343 DOI: 10.3389/fbioe.2020.617489] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 12/21/2020] [Indexed: 11/13/2022] Open
Abstract
Medium chain-length polyhydroxyalkanoates (mcl-PHA) were produced by Pseudomonas putida LS46 cultured with a variety of carbohydrate and fatty acid substrates. The monomer compositions and molecular weights of the polymers varied greatly and was dependent on whether the substrate was metabolized via the fatty acid degradation or the de novo fatty acid synthesis pathways. The highest molecular weights were obtained from medium chain-length fatty acids, whereas low molecular weights were obtained from longer chain-length and more unsaturated fatty acids or carbohydrates. The differences in monomer compositions and molecular weights due to the choice of substrate did not affect the polymer thermal degradation point. The glass transition temperatures varied from -39.4°C to -52.7°C. The melting points, when observed, ranged from 43.2°C to 51.2°C. However, a profound substrate effect was observed on the crystallinity of these polymers. Reduced crystallinity was observed when the monomer compositions deviated away from C8-C10 monomer lengths. The highest crystallinity was observed from medium chain-length fatty acids, which resulted in polymers with the highest tensile strength. The polymer produced from octanoic acid exhibited the highest tensile strength of 4.3 MPa with an elongation-at-break of 162%, whereas the polymers produced from unsaturated, long-chain fatty acids remained amorphous. A comparative analysis of the substrate effect on the physical-mechanical and thermal properties of mcl-PHAs better clarifies the relationship between the monomer composition and their potential applications, and also aids to direct future PHA synthesis research toward properties of interest.
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Affiliation(s)
| | | | | | | | | | - David B. Levin
- Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB, Canada
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Flores-Sánchez A, Rathinasabapathy A, López-Cuellar MDR, Vergara-Porras B, Pérez-Guevara F. Biosynthesis of polyhydroxyalkanoates from vegetable oil under the co-expression of fadE and phaJ genes in Cupriavidus necator. Int J Biol Macromol 2020; 164:1600-1607. [PMID: 32768477 DOI: 10.1016/j.ijbiomac.2020.07.275] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 07/15/2020] [Accepted: 07/19/2020] [Indexed: 11/17/2022]
Abstract
The acyl-CoA dehydrogenase (FadE) and (R)-specific enoyl-CoA hydratase (PhaJ) are functionally related to the degradation of fatty acids and the synthesis of polyhydroxyalkanoates (PHAs). To verify this, a recombinant Cupriavidus necator H16 harboring the plasmid -pMPJAS03- with fadE from Escherichia coli strain K12 and phaJ1 from Pseudomonas putida strain KT2440 under the arabinose promoter (araC-PBAD) was constructed. The impact of co-expressing fadE and phaJ genes on C. necator H16/pMPJAS03 maintaining the wild-type synthase on short-chain-length/medium-chain-length PHA formation from canola or avocado oil at different arabinose concentrations was investigated. The functional activity of fadEE.c led to obtaining higher biomass and PHA concentrations compared to the cultures without expressing the gene. While high transcriptional levels of phaJ1P.p, at 0.1% of arabinose, aid the wild-type synthase to polymerize larger-side chain monomers, such as 3-Hydroxyoctanoate (3HO) and 3-Hydroxydecanoate (3HD). The presence of even small amounts of 3HO and 3HD in the co-polymers significantly depresses the melting temperature of the polymers, compared to those composed of pure 3-hydroxybutyrate (3HB). Our data presents supporting evidence that the synthesis of larger-side chain monomers by the recombinant strain relies not only upon the affinity of the wild-type synthase but also on the functionality of the intermediate supplying enzymes.
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Affiliation(s)
- Araceli Flores-Sánchez
- Escuela de Ingeniería y Ciencias, Tecnológico de Monterrey, ITESM, Atizapán de Zaragoza, México 52926, Mexico
| | - Arthi Rathinasabapathy
- Departamento de Biotecnología y Bioingeniería, Centro de Investigación y Estudios Avanzados (CINVESTAV), Ciudad de México 07360, Mexico
| | - Ma Del Rocío López-Cuellar
- Cuerpo Académico de Biotecnología Agroalimentaria, Instituto de Ciencias Agropecuarias, Universidad Autónoma del Estado de Hidalgo, Hidalgo 43600, Mexico
| | - Berenice Vergara-Porras
- Escuela de Ingeniería y Ciencias, Tecnológico de Monterrey, ITESM, Atizapán de Zaragoza, México 52926, Mexico; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Fermín Pérez-Guevara
- Departamento de Biotecnología y Bioingeniería, Centro de Investigación y Estudios Avanzados (CINVESTAV), Ciudad de México 07360, Mexico.
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8
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Liu CH, Chen HY, Chen YLL, Sheu DS. The polyhydroxyalkanoate (PHA) synthase 1 of Pseudomonas sp. H9 synthesized a 3-hydroxybutyrate-dominant hybrid of short- and medium-chain-length PHA. Enzyme Microb Technol 2020; 143:109719. [PMID: 33375979 DOI: 10.1016/j.enzmictec.2020.109719] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 11/20/2020] [Accepted: 11/26/2020] [Indexed: 12/30/2022]
Abstract
Pseudomonas sp. H9 (H9), an environmental strain isolated from a riverbank soil sample collected in southern Taiwan, is Gram-negative and shares a 99 % sequence identity to Pseudomonas putida KT2440 based on 16S rRNA gene analysis. H9 produced novel polyhydroxyalkanoates (PHA) including a hybrid PHA, comprised of 3-hydroxyvalerate (37 mol%) and medium-chain-length (MCL) monomers from valerate, as well as a 3-hydroxyhexanoate-dominant (93 mol%) MCL-PHA from hexanoate. Next-generation sequencing analysis showed H9 had a typical class II PHA operon, consisted of phaC1H9-phaZH9-phaC2H9, in which phaC1H9 was the sole active PHA synthase in H9. Deletion of phaC1H9 gene led to a complete loss of its PHA accumulation capability. Knockout of phaC2H9 gene, in contrast, affected neither bacterial growth nor PHA accumulation. When co-expressed with the phaAB genes of Ralstonia eutropha H16 in the PHA mutant strain Pseudomonas sp. H9ΔC1, phaC1H9 synthesized a hybrid PHA consisted of 3-hydroxybutyrate (3HB) (75 mol%) and MCL-monomers, confirmed in analyses using hot-acetone fractionation and 13C-NMR spectroscopy. As a novel PHA synthase, PhaC1H9 possesses a broad substrate specificity to synthesize a hybrid of SCL- and MCL-PHA, known to have many mechanical properties for potential applications.
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Affiliation(s)
- Chung-Hsien Liu
- Department of Marine Biotechnology, National Kaohsiung University of Science and Technology, Kaohsiung, 81157, Taiwan
| | - Houng-Yung Chen
- Department of Oceanography, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
| | - Yuh-Ling Lee Chen
- Department of Oceanography, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
| | - Der-Shyan Sheu
- Department of Marine Biotechnology, National Kaohsiung University of Science and Technology, Kaohsiung, 81157, Taiwan; Department of Oceanography, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan.
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9
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Shahid S, Razzaq S, Farooq R, Nazli ZIH. Polyhydroxyalkanoates: Next generation natural biomolecules and a solution for the world's future economy. Int J Biol Macromol 2020; 166:297-321. [PMID: 33127548 DOI: 10.1016/j.ijbiomac.2020.10.187] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 10/21/2020] [Accepted: 10/23/2020] [Indexed: 02/08/2023]
Abstract
Petrochemical plastics have become a cause of pollution for decades and finding alternative plastics that are environmental friendly. Polyhydroxyalkanoate (PHA), a biopolyester produced by microbial cells, has characteristics (biocompatible, biodegradable, non-toxic) that make it appropriate as a biodegradable plastic substance. The different forms of PHA make it suitable to a wide choice of products, from packaging materials to biomedical applications. The major challenge in commercialization of PHA is the cost of manufacturing. There are a lot of factors that could affect the efficiency of a development method. The development of new strategic parameters for better synthesis, including consumption of low cost carbon substrates, genetic modification of PHA-producing strains, and fermentational strategies are discussed. Recently, many efforts have been made to develop a method for the cost-effective production of PHAs. The isolation, analysis as well as characterization of PHAs are significant factors for any developmental process. Due to the biodegradable and biocompatible properties of PHAs, they are majorly used in biomedical applications such as vascular grafting, heart tissue engineering, skin tissue repairing, liver tissue engineering, nerve tissue engineering, bone tissue engineering, cartilage tissue engineering and therapeutic carrier. The emerging and interesting area of research is the development of self-healing biopolymer that could significantly broaden the operational life and protection of the polymeric materials for a broad range of uses. Biodegradable and biocompatible polymers are considered as the green materials in place of petroleum-based plastics in the future.
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Affiliation(s)
- Salma Shahid
- Department of Biochemistry, Government College Women University Faisalabad, Pakistan.
| | - Sadia Razzaq
- Department of Chemistry, Government College Women University Faisalabad, Pakistan
| | - Robina Farooq
- Department of Chemistry, Government College Women University Faisalabad, Pakistan
| | - Zill-I-Huma Nazli
- Department of Chemistry, Government College Women University Faisalabad, Pakistan
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Adeleye AT, Odoh CK, Enudi OC, Banjoko OO, Osiboye OO, Toluwalope Odediran E, Louis H. Sustainable synthesis and applications of polyhydroxyalkanoates (PHAs) from biomass. Process Biochem 2020. [DOI: 10.1016/j.procbio.2020.05.032] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Zhang X, Lin Y, Wu Q, Wang Y, Chen GQ. Synthetic Biology and Genome-Editing Tools for Improving PHA Metabolic Engineering. Trends Biotechnol 2020; 38:689-700. [DOI: 10.1016/j.tibtech.2019.10.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 10/13/2019] [Accepted: 10/14/2019] [Indexed: 12/17/2022]
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12
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Efficacy of medium chain-length polyhydroxyalkanoate biosynthesis from different biochemical pathways under oxygen-limited conditions using Pseudomonas putida LS46. Process Biochem 2019. [DOI: 10.1016/j.procbio.2019.04.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Diverse metabolic pathways in the degradation of phenylalkanoic acids and their monohydroxylated derivatives in Cupriavidus sp. strain ST-14. Process Biochem 2018. [DOI: 10.1016/j.procbio.2018.08.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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14
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Cultivation temperature modulated the monomer composition and polymer properties of polyhydroxyalkanoate synthesized by Cupriavidus sp. L7L from levulinate as sole carbon source. Int J Biol Macromol 2018; 118:1558-1564. [DOI: 10.1016/j.ijbiomac.2018.06.193] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 06/24/2018] [Accepted: 06/30/2018] [Indexed: 01/22/2023]
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15
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Häuslein I, Sahr T, Escoll P, Klausner N, Eisenreich W, Buchrieser C. Legionella pneumophila CsrA regulates a metabolic switch from amino acid to glycerolipid metabolism. Open Biol 2018; 7:rsob.170149. [PMID: 29093212 PMCID: PMC5717341 DOI: 10.1098/rsob.170149] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Accepted: 10/02/2017] [Indexed: 02/01/2023] Open
Abstract
Legionella pneumophila CsrA plays a crucial role in the life-stage-specific expression of virulence phenotypes and metabolic activity. However, its exact role is only partly known. To elucidate how CsrA impacts L. pneumophila metabolism we analysed the CsrA depended regulation of metabolic functions by comparative 13C-isotopologue profiling and oxygen consumption experiments of a L. pneumophila wild-type (wt) strain and its isogenic csrA− mutant. We show that a csrA− mutant has significantly lower respiration rates when serine, alanine, pyruvate, α-ketoglutarate or palmitate is the sole carbon source. By contrast, when grown in glucose or glycerol, no differences in respiration were detected. Isotopologue profiling uncovered that the transfer of label from [U-13C3]serine via pyruvate into the citrate cycle and gluconeogenesis was lower in the mutant as judged from the labelling patterns of protein-derived amino acids, cell-wall-derived diaminopimelate, sugars and amino sugars and 3-hydroxybutyrate derived from polyhydroxybutyrate (PHB). Similarly, the incorporation of [U-13C6]glucose via the glycolysis/Entner–Doudoroff (ED) pathway but not via the pentose phosphate pathway was repressed in the csrA− mutant. On the other hand, fluxes due to [U-13C3]glycerol utilization were increased in the csrA− mutant. In addition, we showed that exogenous [1,2,3,4-13C4]palmitic acid is efficiently used for PHB synthesis via 13C2-acetyl-CoA. Taken together, CsrA induces serine catabolism via the tricarboxylic acid cycle and glucose degradation via the ED pathway, but represses glycerol metabolism, fatty acid degradation and PHB biosynthesis, in particular during exponential growth. Thus, CsrA has a determining role in substrate usage and carbon partitioning during the L. pneumophila life cycle and regulates a switch from amino acid usage in replicative phase to glycerolipid usage during transmissive growth.
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Affiliation(s)
- Ina Häuslein
- Department of Chemistry, Biochemistry, Technische Universität München, Garching, Germany
| | - Tobias Sahr
- Institut Pasteur, Biologie des Bactéries Intracellulaires, Paris, France.,CNRS UMR 3525, Paris, France
| | - Pedro Escoll
- Institut Pasteur, Biologie des Bactéries Intracellulaires, Paris, France.,CNRS UMR 3525, Paris, France
| | - Nadine Klausner
- Department of Chemistry, Biochemistry, Technische Universität München, Garching, Germany
| | - Wolfgang Eisenreich
- Department of Chemistry, Biochemistry, Technische Universität München, Garching, Germany
| | - Carmen Buchrieser
- Institut Pasteur, Biologie des Bactéries Intracellulaires, Paris, France .,CNRS UMR 3525, Paris, France
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Oliva-Arancibia B, Órdenes-Aenishanslins N, Bruna N, Ibarra PS, Zacconi FC, Pérez-Donoso JM, Poblete-Castro I. Co-synthesis of medium-chain-length polyhydroxyalkanoates and CdS quantum dots nanoparticles in Pseudomonas putida KT2440. J Biotechnol 2017; 264:29-37. [PMID: 29056529 DOI: 10.1016/j.jbiotec.2017.10.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 10/17/2017] [Accepted: 10/18/2017] [Indexed: 12/15/2022]
Abstract
Microbial polymers and nanomaterials production is a promising alternative for sustainable bioeconomics. To this end, we used Pseudomonas putida KT2440 as a cell factory in batch cultures to coproduce two important nanotechnology materials- medium-chain-length (MCL)-polyhydroxyalkanoates (PHAs) and CdS fluorescent nanoparticles (i.e. quantum dots [QDots]). Due to high cadmium resistance, biomass and PHA yields were almost unaffected by coproduction conditions. Fluorescent nanocrystal biosynthesis was possible only in presence of cysteine. Furthermore, this process took place exclusively in the cell, displaying the classical emission spectra of CdS QDots under UV-light exposure. Cell fluorescence, zeta potential values, and particles size of QDots depended on cadmium concentration and exposure time. Using standard PHA-extraction procedures, the biosynthesized QDots remained associated with the biomass, and the resulting PHAs presented no traces of CdS QDots. Transmission electron microscopy located the synthesized PHAs in the cell cytoplasm, whereas CdS nanocrystals were most likely located within the periplasmic space, exhibiting no apparent interaction. This is the first report presenting the microbial coproduction of MCL-PHAs and CdS QDots in P. putida KT2440, thus constituting a foundation for further bioprocess developments and strain engineering towards the efficient synthesis of these highly relevant bioproducts for nanotechnology.
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Affiliation(s)
- Barbara Oliva-Arancibia
- Biosystems Engineering Laboratory, Center for Bioinformatics and Integrative Biology (CBIB), Faculty of Biological Sciences, Universidad Andres Bello, República 239, 8370146 Santiago, Chile
| | - Nicolás Órdenes-Aenishanslins
- BioNanotechnology and Microbiology Laboratory, Center for Bioinformatics and Integrative Biology (CBIB), Faculty of Biological Sciences, Universidad Andres Bello, República 239, 8370146 Santiago, Chile
| | - Nicolas Bruna
- BioNanotechnology and Microbiology Laboratory, Center for Bioinformatics and Integrative Biology (CBIB), Faculty of Biological Sciences, Universidad Andres Bello, República 239, 8370146 Santiago, Chile
| | - Paula S Ibarra
- Biosystems Engineering Laboratory, Center for Bioinformatics and Integrative Biology (CBIB), Faculty of Biological Sciences, Universidad Andres Bello, República 239, 8370146 Santiago, Chile
| | - Flavia C Zacconi
- Departamento de Química Orgánica, Facultad de Química, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, Macul, 78204336 Santiago, Chile
| | - José M Pérez-Donoso
- BioNanotechnology and Microbiology Laboratory, Center for Bioinformatics and Integrative Biology (CBIB), Faculty of Biological Sciences, Universidad Andres Bello, República 239, 8370146 Santiago, Chile
| | - Ignacio Poblete-Castro
- Biosystems Engineering Laboratory, Center for Bioinformatics and Integrative Biology (CBIB), Faculty of Biological Sciences, Universidad Andres Bello, República 239, 8370146 Santiago, Chile.
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17
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Fontaine P, Mosrati R, Corroler D. Medium chain length polyhydroxyalkanoates biosynthesis in Pseudomonas putida mt-2 is enhanced by co-metabolism of glycerol/octanoate or fatty acids mixtures. Int J Biol Macromol 2017; 98:430-435. [PMID: 28174083 DOI: 10.1016/j.ijbiomac.2017.01.115] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 01/16/2017] [Accepted: 01/25/2017] [Indexed: 10/20/2022]
Abstract
The synthesis of medium chain length polyhydroxyalkanoates (mcl-PHAs) by Pseudomonas putida mt-2 was investigated under nitrogen-rich then deficient conditions with glycerol/octanoate or long-chain fatty acids (LCFAs) as carbon sources. When mixed, glycerol and octanoate were co-assimilated regardless of nitrogen availability but provided that glycerol uptake has been already triggered under non-limiting nutrient conditions. This concomitant consumption allowed to enhance mcl-PHAs accumulation (up to 57% of cell dry weight (CDW)) under both non-limiting and nitrogen deficient conditions. Octanoate then mostly drove anabolism of the polyester with 3-hydroxyoctanoate (3HO) synthesized as the main monomer (83%). If the preferred PHA precursor octanoate was supplied, glycerol was mainly involved in cell growth and/or maintenance but very little in PHA production even under nitrogen starvation. P. putida cells accumulated higher amounts of mcl-PHAs when grown on mixtures of LCFAs compared to LCFAs supplied as single substrate (25% and 9% of CDW, respectively). However, only a weak enrichment of the polyester was observed after transfer of cells in a fresh nitrogen-free medium containing the same combination of LCFAs. Some typical units within the polyester were related to the LCFAs ratio supplied in the medium indicating that tailor-made monomers could be synthesized.
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Affiliation(s)
- Paul Fontaine
- Normandie Univ., UNICAEN, UR ABTE, 14000 Caen, France
| | - Ridha Mosrati
- Normandie Univ., UNICAEN, UR ABTE, 14000 Caen, France
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18
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Effect of volatile fatty acids mixtures on the simultaneous photofermentative production of hydrogen and polyhydroxybutyrate. Bioprocess Biosyst Eng 2016; 40:231-239. [DOI: 10.1007/s00449-016-1691-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 10/05/2016] [Indexed: 10/20/2022]
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19
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Biological System as Reactor for the Production of Biodegradable Thermoplastics, Polyhydroxyalkanoates. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1201/b19347-12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] Open
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20
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Chen GQ, Hajnal I, Wu H, Lv L, Ye J. Engineering Biosynthesis Mechanisms for Diversifying Polyhydroxyalkanoates. Trends Biotechnol 2016; 33:565-574. [PMID: 26409776 DOI: 10.1016/j.tibtech.2015.07.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 07/24/2015] [Accepted: 07/30/2015] [Indexed: 11/15/2022]
Abstract
Polyhydroxyalkanoates (PHA) are a family of diverse biopolyesters synthesized by bacteria. PHA diversity, as reflected by its monomers, homopolymers, random and block copolymers, as well as functional polymers, can now be generated by engineering the three basic synthesis pathways including the acetoacetyl-CoA pathway, in situ fatty acid synthesis, and/or β-oxidation cycles, as well as PHA synthase specificity. It is now possible to tailor the PHA structures via genome editing or process engineering. The increasing PHA diversity and maturing PHA production technology should lead to more focused research into their low-cost and/or high-value applications.
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Affiliation(s)
- Guo-Qiang Chen
- Ministry of Education Key Lab of Bioinformatics, School of Life Sciences, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China; Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084, China; Beijing Key Laboratory of Protein Therapeutics, Tsinghua University, Beijing 100084, China.
| | - Ivan Hajnal
- Ministry of Education Key Lab of Bioinformatics, School of Life Sciences, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Hong Wu
- Ministry of Education Key Lab of Bioinformatics, School of Life Sciences, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Li Lv
- Ministry of Education Key Lab of Bioinformatics, School of Life Sciences, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jianwen Ye
- Ministry of Education Key Lab of Bioinformatics, School of Life Sciences, Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, 100084, China
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21
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Ge L, Tan GYA, Wang L, Chen CL, Li L, Tan SN, Wang JY. Determination of monomeric composition in polyhydroxyalkanoates by liquid chromatography coupled with on-line mass spectrometry and off-line nuclear magnetic resonance. Talanta 2015; 146:107-13. [PMID: 26695241 DOI: 10.1016/j.talanta.2015.08.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2015] [Revised: 08/14/2015] [Accepted: 08/14/2015] [Indexed: 10/23/2022]
Abstract
Polyhydroxyalkanoates (PHAs) are commercially-valuable biocompatible and biodegradable polymers with many potential medical, pharmaceutical and other industrial applications. The analysis of PHA monomeric composition is especially challenging due to the broad chemical diversity of PHA monomers and lack of analytical standards to represent the chemically-diverse PHA monomer constituents. In this study, a novel strategy based on on-line liquid chromatography-mass spectrometry (LC-MS) and off-line liquid chromatography-nuclear magnetic resonance (LC-NMR) was established to quantify seven PHA monomers with available standards and used to elucidate the structures of unknown PHA monomers. The strategy was successfully applied for the determination of monomeric composition in bacterial PHAs isolated from Pseudomonads cultivated on different carbon sources after hydrolysis. The results of this work demonstrated that the newly-developed strategy was efficient, repeatable, and could have good potential to be employed for detailed analysis of PHA monomeric composition.
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Affiliation(s)
- Liya Ge
- Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore.
| | - Giin-Yu Amy Tan
- Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore; Division of Environmental and Water Resources Engineering, School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Lin Wang
- Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore
| | - Chia-Lung Chen
- Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore
| | - Ling Li
- Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore
| | - Swee Ngin Tan
- Natural Sciences and Science Education Academic Group, Nanyang Technological University, 1 Nanyang Walk, 637616, Singapore.
| | - Jing-Yuan Wang
- Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore; Division of Environmental and Water Resources Engineering, School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
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Ultrasound-Assisted Rapid Extraction of Bacterial Intracellular Medium-Chain-Length Poly(3-Hydroxyalkanoates) (mcl-PHAs) in Medium Mixture of Solvent/Marginal Non-solvent. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2015. [DOI: 10.1007/s13369-015-1833-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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23
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Mohd Razaif-Mazinah MR, Mohamad Annuar MS, Sharifuddin Y. Effects of even and odd number fatty acids cofeeding on PHA production and composition inPseudomonas putidaBet001 isolated from palm oil mill effluent. Biotechnol Appl Biochem 2015; 63:92-100. [DOI: 10.1002/bab.1354] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 01/24/2015] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Yusrizam Sharifuddin
- Institute of Biological Sciences; Faculty of Science; University of Malaya; Kuala Lumpur Malaysia
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Tan GYA, Chen CL, Ge L, Li L, Tan SN, Wang JY. Bioconversion of styrene to poly(hydroxyalkanoate) (PHA) by the new bacterial strain Pseudomonas putida NBUS12. Microbes Environ 2015; 30:76-85. [PMID: 25740622 PMCID: PMC4356467 DOI: 10.1264/jsme2.me14138] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Styrene is a toxic pollutant commonly found in waste effluents from plastic processing industries. We herein identified and characterized microorganisms for bioconversion of the organic eco-pollutant styrene into a valuable biopolymer medium-chain-length poly(hydroxyalkanoate) (mcl-PHA). Twelve newly-isolated styrene-degrading Pseudomonads were obtained and partial phaC genes were detected by PCR in these isolates. These isolates assimilated styrene to produce mcl-PHA, forming PHA contents between 0.05±0.00 and 23.10±3.25% cell dry mass (% CDM). The best-performing isolate was identified as Pseudomonas putida NBUS12. A genetic analysis of 16S rDNA and phaZ genes revealed P. putida NBUS12 as a genetically-distinct strain from existing phenotypically-similar bacterial strains. This bacterium achieved a final biomass of 1.28±0.10 g L−1 and PHA content of 32.49±2.40% CDM. The extracted polymer was mainly comprised of 3-hydroxyhexanoate (C6 ), 3-hydroxyoctanoate (C8 ), 3-hydroxydecanoate (C10 ), 3-hydroxydodecanoate (C12 ), and 3-hydroxytetradecanoate (C14 ) monomers at a ratio of 2:42:1257:17:1. These results collectively suggested that P. putida NBUS12 is a promising candidate for the biotechnological conversion of styrene into mcl-PHA.
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Affiliation(s)
- Giin-Yu Amy Tan
- Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore 637141, Singapore; Division of Environmental and Water Resources Engineering, School of Civil and Environmental Engineering, Nanyang Technological University
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25
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Sano M, Chin T, Takahashi T, Ohara H, Aso Y. A simple TLC-densitometric method for the quantification of acrylic acid in aqueous solutions. JPC-J PLANAR CHROMAT 2015. [DOI: 10.1556/jpc.28.2015.1.2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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26
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Chen YJ, Huang YC, Lee CY. Production and characterization of medium-chain-length polyhydroxyalkanoates by Pseudomonas mosselii TO7. J Biosci Bioeng 2014; 118:145-52. [DOI: 10.1016/j.jbiosc.2014.01.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 01/24/2014] [Accepted: 01/27/2014] [Indexed: 11/25/2022]
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27
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Liu Y, Huang S, Zhang Y, Xu F. Isolation and characterization of a thermophilic Bacillus shackletonii K5 from a biotrickling filter for the production of polyhydroxybutyrate. J Environ Sci (China) 2014; 26:1453-1462. [PMID: 25079994 DOI: 10.1016/j.jes.2014.05.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/09/2013] [Accepted: 12/08/2013] [Indexed: 06/03/2023]
Abstract
Polyhydroxyalkanoates (PHAs) are aliphatic polyesters accumulated intracellularly by both Gram-negative and Gram-positive bacteria. However, compared to the PHAs of Gram-negative bacteria, few endotoxins (lipopolysaccharides, LPS), which would be co-purified with PHAs and cause immunogenic reactions, are found in the PHAs produced by Gram-positive bacteria. A thermophilic Gram-positive bacterium K5, which exhibited good growth and polyhydroxybutyrate (PHB)-accumulating ability, has been isolated and characterized from a biotrickling filter designed for the removal of NOx from flue gas in a coal-fired power plant in China. Based on the biochemical characterization and 16S rRNA gene sequence (Genbank accession no. JX437933), the strain K5 has been identified as Bacillus shackletonii, which has rarely been reported in the literature, and this report is the first time that B. shackletonii has been found to accumulate PHB. The strain K5 was able to utilize glucose as carbon source to synthesize PHB at a broad range of temperatures (from 35 to 50°C), and the ideal temperature was 45°C. The strain K5 could effectively yield PHB of up to 69.9% of its cell dry weight (CDW) (2.28 g/L) in flask experiments employing glucose as carbon source at 45°C, followed by 56.8% and 52.3% of its CDW when using sodium succinate and glycerol as carbon source, respectively. For batch cultivation, the strain K5 was able to produce PHB of up to 72.6% of its cell dry weight (9.76 g/L) employing glucose as carbon source at 45°C and pH7.0.
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Affiliation(s)
- Yong Liu
- Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, College of Environment and Energy, South China University of Technology, Guangzhou 510006, China; State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Shaobin Huang
- Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, College of Environment and Energy, South China University of Technology, Guangzhou 510006, China; State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education China, Guangzhou 510006, China; The Key Laboratory of Environmental Protection and Eco-Remediation of Guangdong Regular Higher Education Institutions, Guangzhou 510006, China.
| | - Yongqing Zhang
- Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, College of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education China, Guangzhou 510006, China
| | - Fuqian Xu
- Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, College of Environment and Energy, South China University of Technology, Guangzhou 510006, China; State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China
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28
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Catone MV, Ruiz JA, Castellanos M, Segura D, Espin G, López NI. High polyhydroxybutyrate production in Pseudomonas extremaustralis is associated with differential expression of horizontally acquired and core genome polyhydroxyalkanoate synthase genes. PLoS One 2014; 9:e98873. [PMID: 24887088 PMCID: PMC4041789 DOI: 10.1371/journal.pone.0098873] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Accepted: 05/08/2014] [Indexed: 11/19/2022] Open
Abstract
Pseudomonas extremaustralis produces mainly polyhydroxybutyrate (PHB), a short chain length polyhydroxyalkanoate (sclPHA) infrequently found in Pseudomonas species. Previous studies with this strain demonstrated that PHB genes are located in a genomic island. In this work, the analysis of the genome of P. extremaustralis revealed the presence of another PHB cluster phbFPX, with high similarity to genes belonging to Burkholderiales, and also a cluster, phaC1ZC2D, coding for medium chain length PHA production (mclPHA). All mclPHA genes showed high similarity to genes from Pseudomonas species and interestingly, this cluster also showed a natural insertion of seven ORFs not related to mclPHA metabolism. Besides PHB, P. extremaustralis is able to produce mclPHA although in minor amounts. Complementation analysis demonstrated that both mclPHA synthases, PhaC1 and PhaC2, were functional. RT-qPCR analysis showed different levels of expression for the PHB synthase, phbC, and the mclPHA synthases. The expression level of phbC, was significantly higher than the obtained for phaC1 and phaC2, in late exponential phase cultures. The analysis of the proteins bound to the PHA granules showed the presence of PhbC and PhaC1, whilst PhaC2 could not be detected. In addition, two phasin like proteins (PhbP and PhaI) associated with the production of scl and mcl PHAs, respectively, were detected. The results of this work show the high efficiency of a foreign gene (phbC) in comparison with the mclPHA core genome genes (phaC1 and phaC2) indicating that the ability of P. extremaustralis to produce high amounts of PHB could be explained by the different expression levels of the genes encoding the scl and mcl PHA synthases.
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Affiliation(s)
- Mariela V. Catone
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Jimena A. Ruiz
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Investigaciones en Biociencias Agrícolas y Ambientales, CONICET, Buenos Aires, Argentina
| | - Mildred Castellanos
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Daniel Segura
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Guadalupe Espin
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Nancy I. López
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- IQUIBICEN, CONICET, Buenos Aires, Argentina
- * E-mail:
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Phukon P, Phukan MM, Phukan S, Konwar BK. Polyhydroxyalkanoate production by indigenously isolated Pseudomonas aeruginosa using glycerol by-product of KCDL biodiesel as an inexpensive carbon source. ANN MICROBIOL 2014. [DOI: 10.1007/s13213-014-0800-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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30
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Jiang XJ, Sun Z, Ramsay JA, Ramsay BA. Fed-batch production of MCL-PHA with elevated 3-hydroxynonanoate content. AMB Express 2013; 3:50. [PMID: 23987136 PMCID: PMC3846598 DOI: 10.1186/2191-0855-3-50] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 08/24/2013] [Indexed: 11/23/2022] Open
Abstract
With no inhibition of β-oxidation, Pseudomonas putida KT2440 produces medium-chain-length poly(3-hydroxyalkanoate) (MCL-PHA) with approximately 65 mol% 3-hydroxynonanoate (HN) from nonanoic acid. Production of PHA with higher HN content and an adjustable monomeric composition was obtained using acrylic acid, a fatty acid β-oxidation inhibitor, together with nonanoic acid and glucose as co-substrates in fed-batch fermentations. Different monomeric compositions were obtained by varying the feeding conditions to impose different specific growth rates and inhibitor feed concentrations. At a nonanoic acid: glucose: acrylic acid feed mass ratio of 1.25: 1: 0.05 and a specific growth rate of 0.15 h-1, 71.4 g L-1 biomass was produced containing 75.5% PHA with 89 mol% HN at a cumulative PHA productivity of 1.8 g L-1 h-1.
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Sarkar J, Chowdhury PP, Dutta TK. Complete degradation of di-n-octyl phthalate by Gordonia sp. strain Dop5. CHEMOSPHERE 2013; 90:2571-2577. [PMID: 23211327 DOI: 10.1016/j.chemosphere.2012.10.101] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 10/26/2012] [Accepted: 10/29/2012] [Indexed: 06/01/2023]
Abstract
The present study describes the assimilation of di-n-octyl phthalate by an aerobic bacterium, isolated from municipal waste-contaminated soil sample utilizing di-n-octyl phthalate as the sole source of carbon and energy. The isolate was identified as Gordonia sp. based on the morphological, nutritional and biochemical characteristics as well as 16S rRNA gene sequence analysis. A combination of chromatographic and spectrometric analyses revealed a complete di-n-octyl assimilation pathway. In the degradation process, mono-n-octyl phthalate, phthalic acid, protocatechuic acid and 1-octanol were identified as the degradation products of di-n-octyl phthalate. Furthermore, phthalic acid was metabolized via protocatechuic acid involving protocatechuate 3,4-dioxygenase while 1-octanol was metabolized by NAD(+)-dependent dehydrogenases to 1-octanoic acid, which was subsequently degraded via β-oxidation, ultimately, leading to tricarboxylic acid cycle intermediates. Apart from phthalic acid and 1-octanol metabolizing pathway enzymes, two esterases, di-n-octyl phthalate hydrolase and mono-n-octyl phthalate hydrolase involved in di-n-octyl phthalate degradation were found to be inducible in nature. This is the first report on the metabolic pathway involved in the complete degradation of di-n-octyl phthalate by a single bacterial isolate, which is also capable of efficiently degrading other phthalate esters of environmental concern having either shorter or longer alkyl chains.
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Affiliation(s)
- Jayita Sarkar
- Department of Microbiology, Bose Institute, P-1/12, C.I.T. Scheme VII M, Kolkata, India
| | - Piyali Pal Chowdhury
- Department of Microbiology, Bose Institute, P-1/12, C.I.T. Scheme VII M, Kolkata, India
| | - Tapan K Dutta
- Department of Microbiology, Bose Institute, P-1/12, C.I.T. Scheme VII M, Kolkata, India.
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Jiang X, Sun Z, Marchessault RH, Ramsay JA, Ramsay BA. Biosynthesis and Properties of Medium-Chain-Length Polyhydroxyalkanoates with Enriched Content of the Dominant Monomer. Biomacromolecules 2012; 13:2926-32. [DOI: 10.1021/bm3009507] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Xuan Jiang
- Department of Chemical
Engineering, Queen’s University, Kingston, Ontario, Canada K7L 3N6,
| | - Zhiyong Sun
- Chemistry Department, McGill University, Montreal, Quebec
H3A 2A7, Canada
| | | | - Juliana A. Ramsay
- Department of Chemical
Engineering, Queen’s University, Kingston, Ontario, Canada K7L 3N6,
| | - Bruce A. Ramsay
- Polyferm Canada, Inc., 4530 CamdenE-Portland Bdry Rd. RR1, Harrowsmith,
Ontario K0H 1V0, Canada
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33
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Theodorou EC, Theodorou MC, Kyriakidis DA. Involvement of the AtoSCDAEB regulon in the high molecular weight poly-(R)-3-hydroxybutyrate biosynthesis in phaCAB+ Escherichia coli. Metab Eng 2012; 14:354-65. [DOI: 10.1016/j.ymben.2012.03.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 03/14/2012] [Accepted: 03/19/2012] [Indexed: 11/16/2022]
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Development of a three-steps derivatization assay for the localization of double bond in monounsaturated monomers of poly-beta-hydroxyalkanoates by GC–MS. J Chromatogr B Analyt Technol Biomed Life Sci 2012; 900:64-70. [DOI: 10.1016/j.jchromb.2012.05.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 05/15/2012] [Accepted: 05/25/2012] [Indexed: 11/21/2022]
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Ngo HL, Ashby RD, Nuñez A. Selective Microbial Degradation of Saturated Methyl Branched-Chain Fatty Acid Isomers. J AM OIL CHEM SOC 2012. [DOI: 10.1007/s11746-012-2092-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Goh YS, Tan IKP. Polyhydroxyalkanoate production by antarctic soil bacteria isolated from Casey Station and Signy Island. Microbiol Res 2012; 167:211-9. [DOI: 10.1016/j.micres.2011.08.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 08/12/2011] [Accepted: 08/22/2011] [Indexed: 10/17/2022]
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Poblete-Castro I, Escapa IF, Jäger C, Puchalka J, Lam CMC, Schomburg D, Prieto MA, Martins dos Santos VAP. The metabolic response of P. putida KT2442 producing high levels of polyhydroxyalkanoate under single- and multiple-nutrient-limited growth: highlights from a multi-level omics approach. Microb Cell Fact 2012; 11:34. [PMID: 22433058 PMCID: PMC3325844 DOI: 10.1186/1475-2859-11-34] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 03/20/2012] [Indexed: 11/10/2022] Open
Abstract
Background Pseudomonas putida KT2442 is a natural producer of polyhydroxyalkanoates (PHAs), which can substitute petroleum-based non-renewable plastics and form the basis for the production of tailor-made biopolymers. However, despite the substantial body of work on PHA production by P. putida strains, it is not yet clear how the bacterium re-arranges its whole metabolism when it senses the limitation of nitrogen and the excess of fatty acids as carbon source, to result in a large accumulation of PHAs within the cell. In the present study we investigated the metabolic response of KT2442 using a systems biology approach to highlight the differences between single- and multiple-nutrient-limited growth in chemostat cultures. Results We found that 26, 62, and 81% of the cell dry weight consist of PHA under conditions of carbon, dual, and nitrogen limitation, respectively. Under nitrogen limitation a specific PHA production rate of 0.43 (g·(g·h)-1) was obtained. The residual biomass was not constant for dual- and strict nitrogen-limiting growth, showing a different feature in comparison to other P. putida strains. Dual limitation resulted in patterns of gene expression, protein level, and metabolite concentrations that substantially differ from those observed under exclusive carbon or nitrogen limitation. The most pronounced differences were found in the energy metabolism, fatty acid metabolism, as well as stress proteins and enzymes belonging to the transport system. Conclusion This is the first study where the interrelationship between nutrient limitations and PHA synthesis has been investigated under well-controlled conditions using a system level approach. The knowledge generated will be of great assistance for the development of bioprocesses and further metabolic engineering work in this versatile organism to both enhance and diversify the industrial production of PHAs.
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Javers J, Karunanithy C. Polyhydroxyalkanoate Production by <i>Pseudomonas putida</i> KT217 on a Condensed Corn Solubles Based Medium Fed with Glycerol Water or Sunflower Soapstock. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/aim.2012.23029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Akaraonye E, Moreno C, Knowles JC, Keshavarz T, Roy I. Poly(3-hydroxybutyrate) production by Bacillus cereus SPV using sugarcane molasses as the main carbon source. Biotechnol J 2011; 7:293-303. [DOI: 10.1002/biot.201100122] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 06/06/2011] [Accepted: 08/25/2011] [Indexed: 11/07/2022]
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Theodorou EC, Theodorou MC, Kyriakidis DA. AtoSC two-component system is involved in cPHB biosynthesis through fatty acid metabolism in E. coli. Biochim Biophys Acta Gen Subj 2011; 1810:561-8. [DOI: 10.1016/j.bbagen.2011.01.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 01/18/2011] [Accepted: 01/25/2011] [Indexed: 10/18/2022]
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Engineering of polyhydroxyalkanoate (PHA) synthase PhaC2Ps of Pseudomonas stutzeri via site-specific mutation for efficient production of PHA copolymers. Appl Microbiol Biotechnol 2011; 91:655-65. [DOI: 10.1007/s00253-011-3274-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 03/21/2011] [Accepted: 03/23/2011] [Indexed: 10/18/2022]
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Sato S, Kanazawa H, Tsuge T. Expression and characterization of (R)-specific enoyl coenzyme A hydratases making a channeling route to polyhydroxyalkanoate biosynthesis in Pseudomonas putida. Appl Microbiol Biotechnol 2011; 90:951-9. [DOI: 10.1007/s00253-011-3150-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 01/20/2011] [Accepted: 01/20/2011] [Indexed: 11/29/2022]
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Choi MH, Xu J, Gutierrez M, Yoo T, Cho YH, Yoon SC. Metabolic relationship between polyhydroxyalkanoic acid and rhamnolipid synthesis in Pseudomonas aeruginosa: Comparative 13C NMR analysis of the products in wild-type and mutants. J Biotechnol 2011; 151:30-42. [DOI: 10.1016/j.jbiotec.2010.10.072] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 09/16/2010] [Accepted: 10/19/2010] [Indexed: 11/28/2022]
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Sohn SB, Kim TY, Park JM, Lee SY. In silico genome-scale metabolic analysis of Pseudomonas putida KT2440 for polyhydroxyalkanoate synthesis, degradation of aromatics and anaerobic survival. Biotechnol J 2010; 5:739-50. [PMID: 20540110 DOI: 10.1002/biot.201000124] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Genome-scale metabolic models have been appearing with increasing frequency and have been employed in a wide range of biotechnological applications as well as in biological studies. With the metabolic model as a platform, engineering strategies have become more systematic and focused, unlike the random shotgun approach used in the past. Here we present the genome-scale metabolic model of the versatile Gram-negative bacterium Pseudomonas putida, which has gained widespread interest for various biotechnological applications. With the construction of the genome-scale metabolic model of P. putida KT2440, PpuMBEL1071, we investigated various characteristics of P. putida, such as its capacity for synthesizing polyhydroxyalkanoates (PHA) and degrading aromatics. Although P. putida has been characterized as a strict aerobic bacterium, the physiological characteristics required to achieve anaerobic survival were investigated. Through analysis of PpuMBEL1071, extended survival of P. putida under anaerobic stress was achieved by introducing the ackA gene from Pseudomonas aeruginosa and Escherichia coli.
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Affiliation(s)
- Seung Bum Sohn
- Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 program), Center for Systems and Synthetic Biotechnology, Institute for the BioCentury, KAIST, Daejeon, Republic of Korea
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Vraspir JM, Holt PD, Butler A. Identification of new members within suites of amphiphilic marine siderophores. Biometals 2010; 24:85-92. [PMID: 20853137 DOI: 10.1007/s10534-010-9378-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 09/01/2010] [Indexed: 01/11/2023]
Abstract
Marine bacterial isolates Vibrio sp. HC0601C5 and Halomonas meridiana str. HC4321C1 were isolated off the coast of southern California and were found to produce an expanded suite of previously identified amphiphilic siderophores. Specifically two new members of the amphibactin family, amphibactins S and T, which have a C14:1 ω-7 fatty acid and a saturated C12 fatty acid, respectively, were produced by Vibrio sp. HC0601C5. These siderophores are produced in addition to a number of previously described amphibactins and are excreted into the culture supernatant. Two new members of the aquachelin family of siderophores, aquachelins I and J, which have an hydroxylated C12 fatty acid and a saturated C10 fatty acid, respectively, were produced by Halomonas meridiana str. HC4321C1. These four new siderophores are more hydrophilic than their previously reported relatives, aquachelins A-D and the amphibactin suite of siderophores.
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Affiliation(s)
- Julia M Vraspir
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106-9510, USA
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Establishment of a metabolic pathway to introduce the 3-hydroxyhexanoate unit into LA-based polyesters via a reverse reaction of β-oxidation in Escherichia coli LS5218. Polym Degrad Stab 2010. [DOI: 10.1016/j.polymdegradstab.2010.01.029] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Ren Q, de Roo G, Ruth K, Witholt B, Zinn M, Thöny-Meyer L. Simultaneous accumulation and degradation of polyhydroxyalkanoates: futile cycle or clever regulation? Biomacromolecules 2010; 10:916-22. [PMID: 19267463 DOI: 10.1021/bm801431c] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The regulation of medium-chain-length polyhydroxyalkanoates (mcl-PHA) metabolism in Pseudomonas putida GPo1 was studied by analysis of enzymes bound to PHA granules and enzymes involved in fatty acid oxidation. N-terminal sequencing of granule-bound enzymes revealed the presence of PHA polymerase (PhaC) and PHA depolymerase (PhaZ) and an acyl-CoA synthetase (ACS1), which recently was found to be associated with PHA granules by in vivo study. The acs1 knockout mutant accumulated 30-50% less PHA than its parental strain, confirming the involvement of ACS1 in PHA metabolism. Isolated PHA granules showed both PhaC and PhaZ activities. PhaC activity was found to be sensitive to the ratio of [R-3-hydroxyacyl-CoA]/[CoA] in which free CoA was a mild competitive inhibitor. Fatty acid oxidation was regulated by the [acetyl-CoA]/[CoA] and [NADH]/[NAD] ratios, with high ratios resulting in accumulation and low ratios leading to rapid oxidation of 3-hydroxyacyl-CoA. These results suggest that PHA metabolism is likely to be controlled by the [acetyl-CoA]/[CoA] and [NADH]/[NAD] ratios. The physiological roles of simultaneous PHA accumulation and degradation are also discussed.
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Affiliation(s)
- Qun Ren
- Laboratory of Biomaterials, Swiss Federal Laboratories for Materials Testing and Research (Empa), CH-9014 St. Gallen, Switzerland.
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A marine bacterium accumulates polyhydroxyalkanoate consisting of mainly 3-hydroxydodecanoate and 3-hydroxydecanoate. World J Microbiol Biotechnol 2009. [DOI: 10.1007/s11274-009-0282-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Abstract
Polyhydroxyalkanoates (PHAs) are polyesters of hydroxyalkanoates (HAs) synthesized by numerous bacteria as intracellular carbon and energy storage compounds and accumulated as granules in the cytoplasm of cells. More than 80 HAs have been detected as constituents of PHAs, which allows these thermoplastic materials to have various mechanical properties resembling hard crystalline polymer or elastic rubber depending on the incorporated monomer units. Even though PHAs have been recognized as good candidates for biodegradable plastics, their high price compared with conventional plastics has limited their use in a wide range of applications. A number of bacteria including Alcaligenes eutrophus, Alcaligenes latus, Azotobacter vinelandii, methylotrophs, pseudomonads, and recombinant Escherichia coli have been employed for the production of PHAs, and the productivity of greater than 2 g PHA/L/h has been achieved. Recent advances in understanding metabolism, molecular biology, and genetics of the PHA-synthesizing bacteria and cloning of more than 20 different PHA biosynthesis genes allowed construction of various recombinant strains that were able to synthesize polyesters having different monomer units and/or to accumulate much more polymers. Also, genetically engineered plants harboring the bacterial PHA biosynthesis genes are being developed for the economical production of PHAs. Improvements in fermentation/separation technology and the development of bacterial strains or plants that more efficiently synthesize PHAs will bring the costs down to make PHAs competitive with the conventional plastics.
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Affiliation(s)
- S Y Lee
- Department of Chemical Engineering and BioProcess Engineering Research Center, Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusong-gu, Taejon 305-701, Korea. leesy@sorak. kaist.ac. kr
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