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Pang AP, Wang Y, Zhang T, Gao F, Shen JD, Huang L, Zhou J, Zhang B, Liu ZQ, Zheng YG. Highly efficient production of rhamnolipid in P. putida using a novel sacB-based system and mixed carbon source. BIORESOURCE TECHNOLOGY 2024; 394:130220. [PMID: 38109979 DOI: 10.1016/j.biortech.2023.130220] [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: 10/30/2023] [Revised: 12/15/2023] [Accepted: 12/15/2023] [Indexed: 12/20/2023]
Abstract
Pseudomonas putida KT2440, a GRAS strain, has been used for synthesizing bulk and fine chemicals. However, the gene editing tool to metabolically engineer KT2440 showed low efficiency. In this study, a novel sacB-based system pK51mobsacB was established to improve the efficiency for marker-free gene disruption. Then the rhamnolipid synthetic pathway was introduced in KT2440 and genes of the competitive pathways were deleted to lower the metabolic burden based on pK51mobsacB. A series of endogenous and synthetic promoters were used for fine tuning rhlAB expression. The limited supply of dTDP-L-rhamnose was enhanced by heterologous rmlBDAC expression. Cell growth and rhamnolipid production were well balanced by using glucose/glycerol as mixed carbon sources. The final strain produced 3.64 g/L at shake-flask and 19.77 g/L rhamnolipid in a 5 L fermenter, the highest obtained among metabolically engineered KT2440, which implied the potential of KT2440 as a promising microbial cell factory for industrial rhamnolipid production.
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Affiliation(s)
- Ai-Ping Pang
- National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
| | - Yun Wang
- National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
| | - Teng Zhang
- National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
| | - Feng Gao
- National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
| | - Ji-Dong Shen
- National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
| | - Lianggang Huang
- National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
| | - Junping Zhou
- National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
| | - Bo Zhang
- National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
| | - Zhi-Qiang Liu
- National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China.
| | - Yu-Guo Zheng
- National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China
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Cyanophycin Granule Polypeptide: a Neglected High Value-Added Biopolymer, Synthesized in Activated Sludge on a Large Scale. Appl Environ Microbiol 2022; 88:e0074222. [PMID: 35862662 PMCID: PMC9317870 DOI: 10.1128/aem.00742-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Recovery of microbial synthetic polymers with high economic value and market demand in activated sludge has attracted extensive attention. This work analyzed the synthesis of cyanophycin granule peptide (CGP) in activated sludge and its adsorption capacity for heavy metals and dyes. The distribution and expression of synthetic genes for eight biopolymers in two wastewater treatment plants (WWTPs) were analyzed by metagenomics and metatranscriptomics. The results indicate that the abundance and expression level of CGP synthase (cphA) are similar to those of polyhydroxyalkanoate polymerase, implying high synthesis of CGP in activated sludges. CGP in activated sludge is mainly polymerized from aspartic acid and arginine, and its secondary structure is mainly β-sheet. The crude yields of CGP are as high as 104 ± 26 and 76 ± 13 mg/g dry sludge in winter and in summer, respectively, comparable to those of polyhydroxyalkanoate and alginate. CGP has a stronger adsorption capacity for anionic pollutants (Cr (VI) and methyl orange) than for cationic pollutants because it is rich in guanidine groups. This study highlights prospects for recovery and application of CGP from WWTPs. IMPORTANCE The conversion of organic pollutants into bioresources by activated sludge can reduce the carbon dioxide emission of wastewater treatment plants. Identification of new high value-added biopolymers produced by activated sludge is beneficial to recover bioresources. Cyanophycin granule polypeptide (CGP), first discovered in cyanobacteria, has unique chemical and material properties suitable for industrial food, medicine, cosmetics, water treatment, and agriculture applications. Here, we revealed for the first time that activated sludge has a remarkable ability to produce CGP. These findings could further facilitate the conversion of wastewater treatment plants into resource recycling plants.
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Kim D, Lee SK. Metabolic Engineering of Escherichia coli for Production of Polyhydroxyalkanoates with Hydroxyvaleric Acid Derived from Levulinic Acid. J Microbiol Biotechnol 2022; 32:110-116. [PMID: 34675141 PMCID: PMC9628823 DOI: 10.4014/jmb.2108.08016] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 10/01/2021] [Accepted: 10/12/2021] [Indexed: 12/15/2022]
Abstract
Polyhydroxyalkanoates (PHAs) are emerging as alternatives to plastics by replacing fossil fuels with renewable raw substrates. Herein, we present the construction of engineered Escherichia coli strains to produce short-chain-length PHAs (scl-PHAs), including the monomers 4-hydroxyvalerate (4HV) and 3-hydroxyvalerate (3HV) produced from levulinic acid (LA). First, an E. coli strain expressing genes (lvaEDABC) from the LA metabolic pathway of Pseudomonas putida KT2440 was constructed to generate 4HV-CoA and 3HV-CoA. Second, both PhaAB enzymes from Cupriavidus necator H16 were expressed to supply 3-hydroxybutyrate (3HB)-CoA from acetyl-CoA. Finally, PHA synthase (PhaCCv) from Chromobacterium violaceum was introduced for the subsequent polymerization of these three monomers. The resulting E. coli strains produced four PHAs (w/w% of dry cell weight): 9.1 wt% P(4HV), 1.7 wt% P(3HV-co-4HV), 24.2 wt% P(3HB-co-4HV), and 35.6 wt% P(3HB-co-3HV-co-4HV).
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Affiliation(s)
- Doyun Kim
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Sung Kuk Lee
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea,Department of Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea,Department of Energy Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea,Corresponding author Phone: +82-52-217-2514 Fax: +82-52-217-3009 E-mail:
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Microbial cell factories for the production of polyhydroxyalkanoates. Essays Biochem 2021; 65:337-353. [PMID: 34132340 DOI: 10.1042/ebc20200142] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/14/2021] [Accepted: 05/26/2021] [Indexed: 12/20/2022]
Abstract
Pollution caused by persistent petro-plastics is the most pressing problem currently, with 8 million tons of plastic waste dumped annually in the oceans. Plastic waste management is not systematized in many countries, because it is laborious and expensive with secondary pollution hazards. Bioplastics, synthesized by microorganisms, are viable alternatives to petrochemical-based thermoplastics due to their biodegradable nature. Polyhydroxyalkanoates (PHAs) are a structurally and functionally diverse group of storage polymers synthesized by many microorganisms, including bacteria and Archaea. Some of the most important PHA accumulating bacteria include Cupriavidus necator, Burkholderia sacchari, Pseudomonas sp., Bacillus sp., recombinant Escherichia coli, and certain halophilic extremophiles. PHAs are synthesized by specialized PHA polymerases with assorted monomers derived from the cellular metabolite pool. In the natural cycle of cellular growth, PHAs are depolymerized by the native host for carbon and energy. The presence of these microbial PHA depolymerases in natural niches is responsible for the degradation of bioplastics. Polyhydroxybutyrate (PHB) is the most common PHA with desirable thermoplastic-like properties. PHAs have widespread applications in various industries including biomedicine, fine chemicals production, drug delivery, packaging, and agriculture. This review provides the updated knowledge on the metabolic pathways for PHAs synthesis in bacteria, and the major microbial hosts for PHAs production. Yeasts are presented as a potential candidate for industrial PHAs production, with their high amenability to genetic engineering and the availability of industrial-scale technology. The major bottlenecks in the commercialization of PHAs as an alternative for plastics and future perspectives are also critically discussed.
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Dutt Tripathi A, Paul V, Agarwal A, Sharma R, Hashempour-Baltork F, Rashidi L, Khosravi Darani K. Production of polyhydroxyalkanoates using dairy processing waste - A review. BIORESOURCE TECHNOLOGY 2021; 326:124735. [PMID: 33508643 DOI: 10.1016/j.biortech.2021.124735] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/12/2021] [Accepted: 01/14/2021] [Indexed: 06/12/2023]
Abstract
Bio-plastics are eco-friendly biopolymers finding tremendous application in the food and pharmaceutical industries. Bio-plastics have suitable physicochemical, mechanical properties, and do not cause any type of hazardous pollution upon disposal but have a high production cost. This can be minimized by screening potential bio-polymers producing strains, selecting inexpensive raw material, optimized cultivation conditions, and upstream processing. These bio-plastics specifically microbial-produced bio-polymers such as polyhydroxyalkanoates (PHAs) find application in food industries as packaging material owing to their desirable water barrier and gas permeability properties. The present review deals with the production, recovery, purification, characterization, and applications of PHAs. This is a comprehensive first review will also focus on different strategies adopted for efficient PHA production using dairy processing waste, its biosynthetic mechanism, metabolic engineering, kinetic aspects, and also biodegradability testing at the lab and pilot plant level. In addition to that, the authors will be emphasizing more on novel PHAs nanocomposites synthesis strategies and their commercial applicability.
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Affiliation(s)
- Abhishek Dutt Tripathi
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Uttar Pradesh, India
| | - Veena Paul
- Department of Dairy Science and Food Technology, Institute of Agricultural Sciences, Banaras Hindu University, Uttar Pradesh, India
| | - Aparna Agarwal
- Department of Food & Nutrition and Food Technology, Lady Irwin College, Sikandra Road, New Delhi 110001, India
| | - Ruchi Sharma
- Department of Agriculture and Environmental Sciences, National Institute of Food Technology Entrepreneurship and Management, Kundli, Sonepat, Haryana 131028, India
| | - Fataneh Hashempour-Baltork
- Department of Food Technology Research, National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Science, P. O. Box: 19395-4741, Tehran, Iran
| | - Ladan Rashidi
- Department of Food and Agricultural Products, Food Technology and Agricultural Products Research Center, Standard Research Institute, Karaj, Iran
| | - Kianoush Khosravi Darani
- Department of Food Technology Research, National Nutrition and Food Technology Research Institute, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Science, P. O. Box: 19395-4741, Tehran, Iran.
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Fidan O, Zhan J. Discovery and engineering of an endophytic Pseudomonas strain from Taxus chinensis for efficient production of zeaxanthin diglucoside. J Biol Eng 2019; 13:66. [PMID: 31388354 PMCID: PMC6676639 DOI: 10.1186/s13036-019-0196-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Accepted: 07/24/2019] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Endophytic microorganisms are a rich source of bioactive natural products. They are considered as promising biofertilizers and biocontrol agents due to their growth-promoting interactions with the host plants and their bioactive secondary metabolites that can help manage plant pathogens. Identification of new endophytes may lead to the discovery of novel molecules or provide new strains for production of valuable compounds. RESULTS In this study, we isolated an endophytic bacterium from the leaves of Taxus chinensis, which was identified as Pseudomonas sp. 102515 based on the 16S rRNA gene sequence and physiological characteristics. Analysis of its secondary metabolites revealed that this endophytic strain produces a major product zeaxanthin diglucoside, a promising antioxidant natural product that belongs to the family of carotenoids. A carotenoid (Pscrt) biosynthetic gene cluster was amplified from this strain, and the functions of PsCrtI and PsCrtY in the biosynthesis of zeaxanthin diglucoside were characterized in Escherichia coli BL21(DE3). The entire Pscrt biosynthetic gene cluster was successfully reconstituted in E. coli BL21(DE3) and Pseudomonas putida KT2440. The production of zeaxanthin diglucoside in Pseudomonas sp. 102515 was improved through the optimization of fermentation conditions such as medium, cultivation temperature and culture time. The highest yield under the optimized conditions reached 206 mg/L. The engineered strain of P. putida KT2440 produced zeaxanthin diglucoside at 121 mg/L in SOC medium supplemented with 0.5% glycerol at 18 °C, while the yield of zeaxanthin diglucoside in E. coli BL21(DE3) was only 2 mg/L. To further enhance the production, we introduced an expression plasmid harboring the Pscrt biosynthetic gene cluster into Pseudomonas sp. 102515. The yield in this engineered strain reached 380 mg/L, 85% higher than the wild type. Through PCR, we also discovered the presence of a turnerbactin biosynthetic gene cluster in Pseudomonas sp. 102515. Because turnerbactin is involved in nitrogen fixation, this endophytic strain might have a role in promoting growth of the host plant. CONCLUSIONS We isolated and identified an endophytic strain of Pseudomonas from T. chinensis. A zeaxanthin diglucoside biosynthetic gene cluster was discovered and characterized in this bacterium. Through fermentation and genetic engineering, the engineered strain produced zeaxanthin diglucoside at 380 ± 12 mg/L, representing a promising strain for the production of this antioxidant natural product. Additionally, Pseudomonas sp. 102515 might also be utilized as a plant-promoting strain for agricultural applications.
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Affiliation(s)
- Ozkan Fidan
- Department of Biological Engineering, Utah State University, 4105 Old Main Hill, Logan, UT 84322-4105 USA
| | - Jixun Zhan
- Department of Biological Engineering, Utah State University, 4105 Old Main Hill, Logan, UT 84322-4105 USA
- TCM and Ethnomedicine Innovation & Development Laboratory, School of Pharmacy, Hunan University of Chinese Medicine, Changsha, 410208 Hunan China
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Abedi D, Moazen F, Akbari V, Mirzaalian F, Sadeghi HMM. Optimization of the expression of phaC2 encoding poly (3-hydroxyalkanoate) synthase from Pseudomonas aeruginosa PTCC1310 in Fad B deleted Escherichia coli. Adv Biomed Res 2016; 5:50. [PMID: 27110547 PMCID: PMC4817391 DOI: 10.4103/2277-9175.178790] [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: 06/01/2013] [Accepted: 12/09/2014] [Indexed: 11/19/2022] Open
Abstract
Background: Poly3-hydroxyalkanoates (PHAs) are potential candidates for the industrial production of biodegradable plastics. Therefore, in the present study, expression and activity of one of the enzymes involved in the PHA synthesis, phaC2 (isolated from Pseudomonas aeruginosa PTCC1310), were investigated in Fad B deleted Escherichia coli. Materials and Methods: The inserts obtained from recombinant pTZ57R plasmids were ligated into the pGEX-5x-1 expression vector and then transformed into Fad B deleted E. coli cells using the heat shock method. This protein was then expressed using isopropyl beta-d-thiogalactoside (IPTG) as an inducer. By changing expression conditions such as IPTG and glucose concentration, time and temperature of incubation with IPTG, the expression conditions were optimized. Results: The optimum condition for the expression of this enzyme was: 1.5 mM IPTG, 1 mM glucose, incubated at 37°C for 2 hours. Conclusion: We obtained functional expression of the phaC2 gene and investigated various conditions that could influence the expression of protein to optimize production of PHA synthase enzymes. This would allow us to study PHA production in large quantities.
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Affiliation(s)
- Daryoush Abedi
- Department of Pharmaceutical Biotechnology and Isfahan Pharmaceutical Sciences Research Center, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Fatemeh Moazen
- Department of Pharmaceutical Biotechnology and Isfahan Pharmaceutical Sciences Research Center, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Vajihe Akbari
- Department of Pharmaceutical Biotechnology and Isfahan Pharmaceutical Sciences Research Center, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Farnoush Mirzaalian
- Department of Pharmaceutical Biotechnology and Isfahan Pharmaceutical Sciences Research Center, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Hamid Mir Mohammad Sadeghi
- Department of Pharmaceutical Biotechnology and Isfahan Pharmaceutical Sciences Research Center, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
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Kadoya R, Matsumoto K, Ooi T, Taguchi S. MtgA Deletion-Triggered Cell Enlargement of Escherichia coli for Enhanced Intracellular Polyester Accumulation. PLoS One 2015; 10:e0125163. [PMID: 26039058 PMCID: PMC4454544 DOI: 10.1371/journal.pone.0125163] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Accepted: 03/12/2015] [Indexed: 11/18/2022] Open
Abstract
Bacterial polyester polyhydroxyalkanoates (PHAs) have been produced in engineered Escherichia coli, which turned into an efficient and versatile platform by applying metabolic and enzyme engineering approaches. The present study aimed at drawing out the latent potential of this organism using genome-wide mutagenesis. To meet this goal, a transposon-based mutagenesis was carried out on E. coli, which was transformed to produce poly(lactate-co-3-hydroxybutyrate) from glucose. A high-throughput screening of polymer-accumulating cells on Nile red-containing plates isolated one mutant that produced 1.8-fold higher quantity of polymer without severe disadvantages in the cell growth and monomer composition of the polymer. The transposon was inserted into the locus within the gene encoding MtgA that takes part, as a non-lethal component, in the formation of the peptidoglycan backbone. Accordingly, the mtgA-deleted strain E. coli JW3175, which was a derivate of superior PHA-producing strain BW25113, was examined for polymer production, and exhibited an enhanced accumulation of the polymer (7.0 g/l) compared to the control (5.2 g/l). Interestingly, an enlargement in cell width associated with polymer accumulation was observed in this strain, resulting in a 1.6-fold greater polymer accumulation per cell compared to the control. This result suggests that the increase in volumetric capacity for accumulating intracellular material contributed to the enhanced polymer production. The mtgA deletion should be combined with conventional engineering approaches, and thus, is a promising strategy for improved production of intracellularly accumulated biopolymers.
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Affiliation(s)
- Ryosuke Kadoya
- Division of Biotechnology and Macromolecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan; CREST, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Ken'ichiro Matsumoto
- Division of Biotechnology and Macromolecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Toshihiko Ooi
- Division of Biotechnology and Macromolecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Seiichi Taguchi
- Division of Biotechnology and Macromolecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, Japan; CREST, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
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Jendrossek D, Pfeiffer D. New insights in the formation of polyhydroxyalkanoate granules (carbonosomes) and novel functions of poly(3-hydroxybutyrate). Environ Microbiol 2014; 16:2357-73. [PMID: 24329995 DOI: 10.1111/1462-2920.12356] [Citation(s) in RCA: 173] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 11/27/2013] [Accepted: 12/05/2013] [Indexed: 12/18/2022]
Abstract
The metabolism of polyhydroxybutyrate (PHB) and related polyhydroxyalkanoates (PHAs) has been investigated by many groups for about three decades, and good progress was obtained in understanding the mechanisms of biosynthesis and biodegradation of this class of storage molecules. However, the molecular events that happen at the onset of PHB synthesis and the details of the initiation of PHB/PHA granule formation, as well as the complex composition of the proteinaceous surface layer of PHB/PHA granules, have only recently come into the focus of research and were not reviewed yet. In this contribution, we summarize the progress in understanding the initiation and formation of the PHA granule complex at the example of Ralstonia eutropha H16 (model organism of PHB-accumulating bacteria). Where appropriate, we include information on PHA granules of Pseudomonas putida as a representative species for medium-chain-length PHA-accumulating bacteria. We suggest to replace the previous micelle mode of PHB granule formation by the Scaffold Model in which the PHB synthase initiation complex is bound to the bacterial nucleoid. In the second part, we highlight data on other forms of PHB: oligo-PHB with ≈100 to 200 3-hydroxybutyrate (3HB) units and covalently bound PHB (cPHB) are unrelated in function to storage PHB but are presumably present in all living organisms, and therefore must be of fundamental importance.
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Arias S, Sandoval A, Arcos M, Cañedo LM, Maestro B, Sanz JM, Naharro G, Luengo JM. Poly-3-hydroxyalkanoate synthases from Pseudomonas putida U: substrate specificity and ultrastructural studies. Microb Biotechnol 2011; 1:170-6. [PMID: 21261834 PMCID: PMC3864450 DOI: 10.1111/j.1751-7915.2007.00016.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The substrate specificity of the two polymerases (PhaC1 and PhaC2) involved in the biosynthesis of medium-chain-length poly-hydroxyalkanoates (mcl PHAs) in Pseudomonas putida U has been studied in vivo. For these kind of experiments, two recombinant strains derived from a genetically engineered mutant in which the whole pha locus had been deleted (P. putida U Δpha) were employed. These bacteria, which expresses only phaC1 (P. putida U Δpha pMC-phaC1) or only phaC2 (P. putida U Δpha pMC-phaC2), accumulated different PHAs in function of the precursor supplemented to the culture broth. Thus, the P. putida U Δpha pMC-phaC1 strain was able to synthesize several aliphatic and aromatic PHAs when hexanoic, heptanoic, octanoic decanoic, 5-phenylvaleric, 6-phenylhexanoic, 7-phenylheptanoic, 8-phenyloctanoic or 9-phenylnonanoic acid were used as precursors; the highest accumulation of polymers was observed when the precursor used were decanoic acid (aliphatic PHAs) or 6-phenylhexanoic acid (aromatic PHAs). However, although it synthesizes similar aliphatic PHAs (the highest accumulation was observed when hexanoic acid was the precursor) the other recombinant strain (P. putida U Δpha pMC-phaC2) only accumulated aromatic PHAs when the monomer to be polymerized was 3-hydroxy-5-phenylvaleryl-CoA. The possible influence of the putative three-dimensional structures on the different catalytic behaviour of PhaC1 and PhaC2 is discussed.
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Affiliation(s)
- Sagrario Arias
- Departamento de Biología Molecular, Facultades de Veterinaria y de Biología, Universidad de León, 24071 León, España
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Höfer P, Choi YJ, Osborne MJ, Miguez CB, Vermette P, Groleau D. Production of functionalized polyhydroxyalkanoates by genetically modified Methylobacterium extorquens strains. Microb Cell Fact 2010; 9:70. [PMID: 20846434 PMCID: PMC2954876 DOI: 10.1186/1475-2859-9-70] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Accepted: 09/16/2010] [Indexed: 11/16/2022] Open
Abstract
Background Methylotrophic (methanol-utilizing) bacteria offer great potential as cell factories in the production of numerous products from biomass-derived methanol. Bio-methanol is essentially a non-food substrate, an advantage over sugar-utilizing cell factories. Low-value products as well as fine chemicals and advanced materials are envisageable from methanol. For example, several methylotrophic bacteria, including Methylobacterium extorquens, can produce large quantities of the biodegradable polyester polyhydroxybutyric acid (PHB), the best known polyhydroxyalkanoate (PHA). With the purpose of producing second-generation PHAs with increased value, we have explored the feasibility of using M. extorquens for producing functionalized PHAs containing C-C double bonds, thus, making them amenable to future chemical/biochemical modifications for high value applications. Results Our proprietary M. extorquens ATCC 55366 was found unable to yield functionalized PHAs when fed methanol and selected unsaturated carboxylic acids as secondary substrates. However, cloning of either the phaC1 or the phaC2 gene from P. fluorescens GK13, using an inducible and regulated expression system based on cumate as inducer (the cumate switch), yielded recombinant M. extorquens strains capable of incorporating modest quantities of C-C double bonds into PHA, starting from either C6= and/or C8=. The two recombinant strains gave poor results with C11=. The strain containing the phaC2 gene was better at using C8= and at incorporating C-C double bonds into PHA. Solvent fractioning indicated that the produced polymers were PHA blends that consequently originated from independent actions of the native and the recombinant PHA synthases. Conclusions This work constitutes an example of metabolic engineering applied to the construction of a methanol-utilizing bacterium capable of producing functionalized PHAs containing C-C double bonds. In this regard, the PhaC2 synthase appeared superior to the PhaC1 synthase at utilizing C8= as source of C-C double bonds and at incorporating C-C double bonds into PHA from either C6= or C8=. The M. ex-phaC2 strain is, therefore, a promising biocatalyst for generating advanced (functionalized) PHAs for future high value applications in various fields.
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Affiliation(s)
- Philipp Höfer
- Microbial and Enzymatic Technology Group, Bioprocess Centre, Biotechnology Research Institute, National Research Council Canada, 6100 Royalmount Avenue, Montréal, Québec, H4P 2R2, Canada
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Ren Q, de Roo G, Witholt B, Zinn M, Thöny-Meyer L. Overexpression and characterization of medium-chain-length polyhydroxyalkanoate granule bound polymerases from Pseudomonas putida GPo1. Microb Cell Fact 2009; 8:60. [PMID: 19925642 PMCID: PMC2788523 DOI: 10.1186/1475-2859-8-60] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Accepted: 11/19/2009] [Indexed: 11/10/2022] Open
Abstract
Background Polyhydroxyalkanoates (PHA) are synthesized by many bacteria in the cytoplasm as storage compounds for energy and carbon. The key enzymes for PHA biosynthesis are PHA polymerases, which catalyze the covalent linkage of 3-hydroxyacyl coenzymeA thioesters by transesterification with concomitant release of CoA. Pseudomonas putida GPo1 and many other Pseudomonas species contain two different class II polymerases, encoded by phaC1 and phaC2. Although numerous studies have been carried out on PHA polymerases and they are well characterized at the molecular level, the biochemical properties of the class II polymerases have not been studied in detail. Previously we and other groups purified the polymerases, however, the activities of the purified enzymes were several magnitude lower than the granule-bound enzymes. It is problematic to study the intrinsic properties of these enzymes with such low activities, although they are pure. Results PHA polymerase 1 (PhaC1) and PHA polymerase 2 (PhaC2) from P. putida GPo1 were overexpressed in the PHA-negative host P. putida GPp104 and purified from isolated PHA granules. Only minor activity (two to three orders of magnitude lower than that of the granule bound proteins) could be recovered when the enzymes were purified to homogeneity. Therefore, kinetic properties and substrate ranges were determined for the granule bound polymerases. The polymerases differed significantly with respect to their association with PHA granules, enzyme kinetics and substrate specificity. PhaC2 appeared to bind PHA granules more tightly than PhaC1. When R-3-hydroxyoctanoic acid was used as substrate, the granule-bound PhaC1 exhibited a Km of 125 (± 35) μM and a Vmax of 40.8 (± 6.2) U/mg PhaC1, while a Km of 37 (± 10) μM and a Vmax of 2.7 (± 0.7) U/mg PhaC2 could be derived for the granule-bound PhaC2. Granule-bound PhaC1 showed a strong preference for medium chain length (mcl-) 3-hydroxyacly-CoAs, with highest affinity towards 3-hydroxydecanoyl-CoA (40 U/mg PhaC1). Granule-bound PhaC2 demonstrated a far broader specificity ranging from short chain length up to long chain length substrates. Activity increased with increasing chain length with a maximum activity for 3-hydroxyacyl-CoAs containing 12 or more C-atoms. Conclusion The kinetic properties and substrate ranges were determined for both granule bound polymerases. Evidence was provided for the first time that two PHA polymerases exhibited significant differences in granule release and in vitro activity profiles, suggesting that there are substantial functional differences between granule bound PhaC1 and PhaC2.
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Affiliation(s)
- Qun Ren
- Laboratory for Biomaterials, Swiss Federal Laboratories for Materials Testing and Research (Empa), CH-9014 St, Gallen, Switzerland.
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Davis R, Chandrashekar A, Shamala TR. Role of (R)-specific enoyl coenzyme A hydratases of Pseudomonas sp in the production of polyhydroxyalkanoates. Antonie van Leeuwenhoek 2007; 93:285-96. [PMID: 17906975 DOI: 10.1007/s10482-007-9203-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Accepted: 09/13/2007] [Indexed: 10/22/2022]
Abstract
Four (R)-specific enoyl CoA hydratases (PhaJ) interconnect the beta-oxidation pathway with PHA biosynthesis in Pseudomonas aeruginosa. The use of antisense technique and over-expression to delineate the role of two of these enzymes, PhaJ1 and PhaJ4 forms the basis of this study. It has been observed that P. aeruginosa recombinant with phaJ1 antisense construct, fed with different fatty acids, produces PHA with less hydroxy octanoate (7-11% reduction) and a proportionate increase in other monomer fractions, compared to that of the control. Recombinants bearing phaJ4 antisense construct are found to contain less hydroxy decanoate (10-11% reduction) and more or less equal amount of hydroxy octanoate, compared to that of the control. P. aeruginosa has produced PHA with more hydroxy octanoate and decanoate (6-17% increase), respectively, when PhaJ1 and PhaJ4 have been over-expressed individually or along with PhaC1. PhaJ1 and PhaJ4 are found to be involved mainly in the production of hydroxy octanoyl CoA and hydroxy decanoyl CoA, respectively, in P. aeruginosa. The strongest accumulation of hydroxy octanoate and hydroxy decanoate has been observed along with hydroxy butyrate, in PHA, produced by E. coli, when PhaC1 has been co-expressed with PhaJ1 and PhaJ4, respectively. We have demonstrated, for the first time, the polymerization of hydroxy butyryl CoA monomers in recombinant E. coli by PhaC1 of P. aeruginosa.
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Affiliation(s)
- Reeta Davis
- Department of Plant Cell Biotechnology, Central Food Technological Research Institute, Mysore, India.
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Ren Q, de Roo G, van Beilen JB, Zinn M, Kessler B, Witholt B. Poly(3-hydroxyalkanoate) polymerase synthesis and in vitro activity in recombinant Escherichia coli and Pseudomonas putida. Appl Microbiol Biotechnol 2005; 69:286-92. [PMID: 15846484 DOI: 10.1007/s00253-005-1995-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2005] [Revised: 04/05/2005] [Accepted: 04/05/2005] [Indexed: 10/25/2022]
Abstract
We tested the synthesis and in vitro activity of the poly(3-hydroxyalkanoate) (PHA) polymerase 1 from Pseudomonas putida GPo1 in both P. putida GPp104 and Escherichia coli JMU193. The polymerase encoding gene phaC1 was expressed using the inducible PalkB promoter. It was found that the production of polymerase could be modulated over a wide range of protein levels by varying inducer concentrations. The optimal inducer dicyclopropylketone concentrations for PHA production were at 0.03% (v/v) for P. putida and 0.005% (v/v) for E. coli. Under these concentrations the maximal polymerase level synthesized in the E. coli host (6% of total protein) was about three- to fourfold less than that in P. putida (20%), whereas the maximal level of PHA synthesized in the E. coli host (8% of total cell dry weight) was about fourfold less than that in P. putida (30%). In P. putida, the highest specific activity of polymerase was found in the mid-exponential growth phase with a maximum of 40 U/g polymerase, whereas in E. coli, the maximal specific polymerase activity was found in the early stationary growth phase (2 U/g polymerase). Our results suggest that optimal functioning of the PHA polymerase requires factors or a molecular environment that is available in P. putida but not in E. coli.
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Affiliation(s)
- Qun Ren
- Biocompatible Materials, Materials Science and Technology (EMPA), 9014 St. Gallen, Switzerland.
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