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Miralles-Robledillo JM, Martínez-Espinosa RM, Pire C. Transcriptomic profiling of haloarchaeal denitrification through RNA-Seq analysis. Appl Environ Microbiol 2024; 90:e0057124. [PMID: 38814058 DOI: 10.1128/aem.00571-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 04/26/2024] [Indexed: 05/31/2024] Open
Abstract
Denitrification, a crucial biochemical pathway prevalent among haloarchaea in hypersaline ecosystems, has garnered considerable attention in recent years due to its ecological implications. Nevertheless, the underlying molecular mechanisms and genetic regulation governing this respiration/detoxification process in haloarchaea remain largely unexplored. In this study, RNA-sequencing was used to compare the transcriptomes of the haloarchaeon Haloferax mediterranei under oxic and denitrifying conditions, shedding light on the intricate metabolic alterations occurring within the cell, such as the accurate control of the metal homeostasis. Furthermore, the investigation identifies several genes encoding transcriptional regulators and potential accessory proteins with putative roles in denitrification. Among these are bacterioopsin-like transcriptional activators, proteins harboring a domain of unknown function (DUF2249), and cyanoglobin. In addition, the study delves into the genetic regulation of denitrification, finding a regulatory motif within promoter regions that activates numerous denitrification-related genes. This research serves as a starting point for future molecular biology studies in haloarchaea, offering a promising avenue to unravel the intricate mechanisms governing haloarchaeal denitrification, a pathway of paramount ecological importance.IMPORTANCEDenitrification, a fundamental process within the nitrogen cycle, has been subject to extensive investigation due to its close association with anthropogenic activities, and its contribution to the global warming issue, mainly through the release of N2O emissions. Although our comprehension of denitrification and its implications is generally well established, most studies have been conducted in non-extreme environments with mesophilic microorganisms. Consequently, there is a significant knowledge gap concerning extremophilic denitrifiers, particularly those inhabiting hypersaline environments. The significance of this research was to delve into the process of haloarchaeal denitrification, utilizing the complete denitrifier haloarchaeon Haloferax mediterranei as a model organism. This research led to the analysis of the metabolic state of this microorganism under denitrifying conditions and the identification of regulatory signals and genes encoding proteins potentially involved in this pathway, serving as a valuable resource for future molecular studies.
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Affiliation(s)
- Jose María Miralles-Robledillo
- Biochemistry, Molecular Biology, Edaphology and Agricultural Chemistry Department, Faculty of Sciences, Universitat d'Alacant, Alicante, Spain
| | - Rosa María Martínez-Espinosa
- Biochemistry, Molecular Biology, Edaphology and Agricultural Chemistry Department, Faculty of Sciences, Universitat d'Alacant, Alicante, Spain
- Multidisciplinary Institute for Environmental Studies "Ramón Margalef", University of Alicante, Alicante, Spain
| | - Carmen Pire
- Biochemistry, Molecular Biology, Edaphology and Agricultural Chemistry Department, Faculty of Sciences, Universitat d'Alacant, Alicante, Spain
- Multidisciplinary Institute for Environmental Studies "Ramón Margalef", University of Alicante, Alicante, Spain
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Longo A, Fanelli F, Villano M, Montemurro M, Rizzello CG. Bioplastic Production from Agri-Food Waste through the Use of Haloferax mediterranei: A Comprehensive Initial Overview. Microorganisms 2024; 12:1038. [PMID: 38930420 PMCID: PMC11205408 DOI: 10.3390/microorganisms12061038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 05/06/2024] [Accepted: 05/16/2024] [Indexed: 06/28/2024] Open
Abstract
The research on bioplastics (both biobased and biodegradable) is steadily growing and discovering environmentally friendly substitutes for conventional plastic. This review highlights the significance of bioplastics, analyzing, for the first time, the state of the art concerning the use of agri-food waste as an alternative substrate for biopolymer generation using Haloferax mediterranei. H. mediterranei is a highly researched strain able to produce polyhydroxybutyrate (PHB) since it can grow and produce bioplastic in high-salinity environments without requiring sterilization. Extensive research has been conducted on the genes and pathways responsible for PHB production using H. mediterranei to find out how fermentation parameters can be regulated to enhance cell growth and increase PHB accumulation. This review focuses on the current advancements in utilizing food waste as a substitute for costly substrates to reduce feedstock expenses. Specifically, it examines the production of biomass and the recovery of PHB from agri-food waste. Furthermore, it emphasizes the characterization of PHB and the significance of hydroxyvalerate (HV) abundance in the formation of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymer. The downstream processing options are described, and the crucial factors associated with industrial scale-up are assessed, including substrates, bioreactors, process parameters, and bioplastic extraction and purification. Additionally, the economic implications of various options are discussed.
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Affiliation(s)
- Angela Longo
- Department of Environmental Biology, Sapienza University of Rome, 00185 Rome, Italy; (A.L.); (C.G.R.)
| | - Francesca Fanelli
- Institute of Sciences of Food Production (CNR-ISPA), National Research Council of Italy, 70126 Bari, Italy;
| | - Marianna Villano
- Department of Chemistry, Sapienza University of Rome, 00185 Rome, Italy;
- Research Center for Applied Sciences to the Safeguard of Environment and Cultural Heritage (CIABC), Sapienza University of Rome, 00185 Rome, Italy
| | - Marco Montemurro
- Institute of Sciences of Food Production (CNR-ISPA), National Research Council of Italy, 70126 Bari, Italy;
| | - Carlo Giuseppe Rizzello
- Department of Environmental Biology, Sapienza University of Rome, 00185 Rome, Italy; (A.L.); (C.G.R.)
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Hou J, Li XX, Sun Y, Li Y, Yang XY, Sun YP, Cui HL. Novel Archaeal Histamine Oxidase from Natronobeatus ordinarius: Insights into Histamine Degradation for Enhancing Food Safety. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:6519-6525. [PMID: 38497614 DOI: 10.1021/acs.jafc.4c00695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Histamine, found abundantly in salt-fermented foods, poses a risk of food poisoning. Natronobeatus ordinarius, a halophilic archaeon isolated from a salt lake, displayed a strong histamine degradation ability. Its histamine oxidase (HOD) gene was identified (hodNbs). This is the first report of an archaeal HOD. The HODNbs protein was determined to be a tetramer with a molecular weight of 307 kDa. HODNbs displayed optimum activity at 60-65 °C, 1.5-2.0 M NaCl, and pH 6.5. Notably, within the broad NaCl range between 0.5 and 2.5 M, HODNbs retained above 50% of its maximum activity. HODNbs exhibited good thermal stability, pH stability, and salinity tolerance. HODNbs was able to degrade various biogenic amines. The Vmax of HODNbs for histamine was 0.29 μmol/min/mg, and the Km was 0.56 mM. HODNbs exhibited high efficiency in histamine removal from fish sauce, namely, 100 μg of HODNbs degraded 5.63 mg of histamine (37.9%) in 10 g of fish sauce within 24 h at 50 °C. This study showed that HODNbs with excellent enzymatic properties has promising application potentials to degrade histamine in high-salt foods.
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Affiliation(s)
- Jing Hou
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Jingkou District, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Xin-Xin Li
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Jingkou District, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Yu Sun
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Jingkou District, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Yang Li
- School of Oceanography, Zhejiang University, 1 Zheda Road, Dinghai District, Zhoushan 316021, Zhejiang, People's Republic of China
| | - Xiao-Yan Yang
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Jingkou District, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Ya-Ping Sun
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Jingkou District, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Heng-Lin Cui
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Jingkou District, Zhenjiang 212013, Jiangsu, People's Republic of China
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4
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Chen J, Cui Y, Zhang S, Wu B, Han J, Xiang H. Unveiling the repressive mechanism of a PPS-like regulator (PspR) in polyhydroxyalkanoates biosynthesis network. Appl Microbiol Biotechnol 2024; 108:265. [PMID: 38498113 PMCID: PMC10948481 DOI: 10.1007/s00253-024-13100-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 02/23/2024] [Accepted: 02/28/2024] [Indexed: 03/20/2024]
Abstract
Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a type of polyhydroxyalkanoates (PHA) that exhibits numerous outstanding properties and is naturally synthesized and elaborately regulated in various microorganisms. However, the regulatory mechanism involving the specific regulator PhaR in Haloferax mediterranei, a major PHBV production model among Haloarchaea, is not well understood. In our previous study, we showed that deletion of the phosphoenolpyruvate (PEP) synthetase-like (pps-like) gene activates the cryptic phaC genes in H. mediterranei, resulting in enhanced PHBV accumulation. In this study, we demonstrated the specific function of the PPS-like protein as a negative regulator of phaR gene expression and PHBV synthesis. Chromatin immunoprecipitation (ChIP), in situ fluorescence reporting system, and in vitro electrophoretic mobility shift assay (EMSA) showed that the PPS-like protein can bind to the promoter region of phaRP. Computational modeling revealed a high structural similarity between the rifampin phosphotransferase (RPH) protein and the PPS-like protein, which has a conserved ATP-binding domain, a His domain, and a predicted DNA-binding domain. Key residues within this unique DNA-binding domain were subsequently validated through point mutation and functional evaluations. Based on these findings, we concluded that PPS-like protein, which we now renamed as PspR, has evolved into a repressor capable of regulating the key regulator PhaR, and thereby modulating PHBV synthesis. This regulatory network (PspR-PhaR) for PHA biosynthesis is likely widespread among haloarchaea, providing a novel approach to manipulate haloarchaea as a production platform for high-yielding PHA. KEY POINTS: • The repressive mechanism of a novel inhibitor PspR in the PHBV biosynthesis was demonstrated • PspR is widespread among the PHA accumulating haloarchaea • It is the first report of functional conversion from an enzyme to a trans-acting regulator in haloarchaea.
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Affiliation(s)
- Junyu Chen
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China
| | - Yinglu Cui
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China
- College of Life Science, University of Chinese Academy of Sciences, 100049, Beijing, People's Republic of China
| | - Shengjie Zhang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China
| | - Bian Wu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China
- College of Life Science, University of Chinese Academy of Sciences, 100049, Beijing, People's Republic of China
| | - Jing Han
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China.
- College of Life Science, University of Chinese Academy of Sciences, 100049, Beijing, People's Republic of China.
| | - Hua Xiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China.
- College of Life Science, University of Chinese Academy of Sciences, 100049, Beijing, People's Republic of China.
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Hou J, Li SY, Zhao YJ, Cui HL. A novel halolysin without C-terminal extension from an extremely halophilic archaeon. Appl Microbiol Biotechnol 2022; 106:3009-3019. [PMID: 35435453 DOI: 10.1007/s00253-022-11903-4] [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: 01/13/2022] [Revised: 03/28/2022] [Accepted: 03/29/2022] [Indexed: 11/29/2022]
Abstract
Halolysins are extracellular proteases secreted by halophilic archaea for nutritional purposes. They bear great application potentials in various industries. Yet the diversity of halolysins remains underexplored. In this study, a halolysin from the extremely halophilic archaeon Haladaptatus sp. DYF46 (HlyHap) was identified to be a novel type of halolysin without C-terminal extension (CTE). Addition of the CTE of a halolysin from Halococcus salifodinae to HlyHap did not significantly affect its extracellular proteolytic activity. Mature HlyHap was generated from recombinant HlyHap precursor by high-affinity column refolding. HlyHap displayed optimal activity at 0.25-0.50 M NaCl, 45 °C and pH 8.5-9.0. Interestingly, HlyHap preferred a low salinity and was stable in a broad range of salinity, albeit from an extremely halophilic archaeon. Ca2+ and Mg2+ significantly promoted HlyHap activity. HlyHap activity was stable with organic solvents and detergents. The Km and Vmax values of HlyHap against azocasein were 0.018 mM and 7,179 U/mg, and those against succinyl-Ala-Ala-Pro-Phe-pNA were 0.32 mM and 3×106 μmol/min/μg, respectively. The unusual traits of HlyHap, a novel type of halolysin without CTE, may endow it with strong potential for various industrial uses, such as biocatalysis in fluctuating salinities and aqueous-organic solvent. KEY POINTS: • This is the first report of a novel type of halolysin without C-terminal extension • HlyHap was obtained by heterologous expression and high-affinity column refolding • HlyHap exhibited good salinity tolerance.
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Affiliation(s)
- Jing Hou
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Jingkou District, Zhenjiang, 212013, Jiangsu, People's Republic of China
| | - Si-Ya Li
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Jingkou District, Zhenjiang, 212013, Jiangsu, People's Republic of China
| | - Yang-Jie Zhao
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Jingkou District, Zhenjiang, 212013, Jiangsu, People's Republic of China
| | - Heng-Lin Cui
- School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Jingkou District, Zhenjiang, 212013, Jiangsu, People's Republic of China.
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6
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Sato S, Ino K, Ushimaru K, Wada K, Saika A, Fukuoka T, Ohshiman K, Morita T. Evaluating haloarchaeal culture media for ultrahigh-molecular-weight polyhydroxyalkanoate biosynthesis by Haloferax mediterranei. Appl Microbiol Biotechnol 2021; 105:6679-6689. [PMID: 34459953 DOI: 10.1007/s00253-021-11508-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 08/03/2021] [Accepted: 08/06/2021] [Indexed: 10/20/2022]
Abstract
A series of culture media for haloarchaea were evaluated to optimize the production of ultrahigh-molecular-weight (UHMW) poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by Haloferax mediterranei. Cells of H. mediterranei grew (> 1 g/L of dry cell weight) and accumulated PHBV upon flask cultivation in 10 medium types with neutral pH and NaCl concentration > 100 g/L. Molecular weight and compositional analysis revealed that the number-average molecular weight (Mn) of PHBV produced with six selected types of media ranged from 0.8 to 3.5 × 106 g/mol and the 3-hydroxyvalerate (3HV) composition ranged from 8 to 36 mol%. Cultivation in two NBRC media, 1214 and 1380, resulted in the production of PHBV with an Mn of more than 3.0 × 106 g/mol and a weight-average molecular weight of more than 5.0 × 106 g/mol, indicating the production of UHMW-PHBV. These culture media contained small amount of complex nutrients like yeast extract and casamino acids, suggesting that H. mediterranei likely produced UHMW-PHBV on poor nutrient condition. Haloferax mediterranei grown in NBRC medium 1380 produced PHBV with the highest 3HV composition. A solvent-cast film of UHMW-PHBV with 26.4 mol% 3HV produced from 1-L flask cultivation with NBRC medium 1380 was found to be flexible and semi-transparent. Thermal analysis of the UHMW-PHBV cast film revealed melting and glass-transition temperatures of 90.5 °C and - 2.7 °C, respectively. KEY POINTS: • Haloarchaeal culture media were evaluated to produce UHMW-PHBV by H. mediterranei. • UHMW-PHBV with varied molecular weight was produced dependent on culture media. • Semi-transparent film could be made from UHMW-PHBV with 26.4 mol% 3HV.
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Affiliation(s)
- Shun Sato
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan.
| | - Kotaro Ino
- Sumitomo Forestry Co., LTD., 3-2 Midorigahara, Tsukuba, Ibaraki, 300-2646, Japan
| | - Kazunori Ushimaru
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
| | - Keisuke Wada
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
| | - Azusa Saika
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
| | - Tokuma Fukuoka
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
| | - Koichi Ohshiman
- Sumitomo Forestry Co., LTD., 3-2 Midorigahara, Tsukuba, Ibaraki, 300-2646, Japan
| | - Tomotake Morita
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
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Müller-Santos M, Koskimäki JJ, Alves LPS, de Souza EM, Jendrossek D, Pirttilä AM. The protective role of PHB and its degradation products against stress situations in bacteria. FEMS Microbiol Rev 2021; 45:fuaa058. [PMID: 33118006 DOI: 10.1093/femsre/fuaa058] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 10/26/2020] [Indexed: 12/15/2022] Open
Abstract
Many bacteria produce storage biopolymers that are mobilized under conditions of metabolic adaptation, for example, low nutrient availability and cellular stress. Polyhydroxyalkanoates are often found as carbon storage in Bacteria or Archaea, and of these polyhydroxybutyrate (PHB) is the most frequently occurring PHA type. Bacteria usually produce PHB upon availability of a carbon source and limitation of another essential nutrient. Therefore, it is widely believed that the function of PHB is to serve as a mobilizable carbon repository when bacteria face carbon limitation, supporting their survival. However, recent findings indicate that bacteria switch from PHB synthesis to mobilization under stress conditions such as thermal and oxidative shock. The mobilization products, 3-hydroxybutyrate and its oligomers, show a protective effect against protein aggregation and cellular damage caused by reactive oxygen species and heat shock. Thus, bacteria should have an environmental monitoring mechanism directly connected to the regulation of the PHB metabolism. Here, we review the current knowledge on PHB physiology together with a summary of recent findings on novel functions of PHB in stress resistance. Potential applications of these new functions are also presented.
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Affiliation(s)
- Marcelo Müller-Santos
- Department of Biochemistry and Molecular Biology, Federal University of Paraná - UFPR, Setor de Ciências Biológicas, Centro Politécnico, Jardim da Américas, CEP: 81531-990, Caixa Postal: 190-46, Curitiba, Paraná, Brazil
| | - Janne J Koskimäki
- Ecology and Genetics Research Unit, University of Oulu, Pentti Kaiteran katu 1, P.O. Box 3000, FI-90014 Oulu, Finland
| | - Luis Paulo Silveira Alves
- Department of Biochemistry and Molecular Biology, Federal University of Paraná - UFPR, Setor de Ciências Biológicas, Centro Politécnico, Jardim da Américas, CEP: 81531-990, Caixa Postal: 190-46, Curitiba, Paraná, Brazil
| | - Emanuel Maltempi de Souza
- Department of Biochemistry and Molecular Biology, Federal University of Paraná - UFPR, Setor de Ciências Biológicas, Centro Politécnico, Jardim da Américas, CEP: 81531-990, Caixa Postal: 190-46, Curitiba, Paraná, Brazil
| | - Dieter Jendrossek
- Institute of Microbiology, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
| | - Anna Maria Pirttilä
- Ecology and Genetics Research Unit, University of Oulu, Pentti Kaiteran katu 1, P.O. Box 3000, FI-90014 Oulu, Finland
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Obulisamy PK, Mehariya S. Polyhydroxyalkanoates from extremophiles: A review. BIORESOURCE TECHNOLOGY 2021; 325:124653. [PMID: 33465644 DOI: 10.1016/j.biortech.2020.124653] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/27/2020] [Accepted: 12/29/2020] [Indexed: 06/12/2023]
Abstract
Polyhydroxyalkanoates (PHAs) are group monomers/heteropolymers that are biodegradable and widely used in biomedical applications. They are considered as alternatives to fossil derived polymers and accumulated by microbes including extremophilic archaea as energy storage inclusions under nutrient limitations. The use of extremophilic archaea for PHA production is an economically viable option for conventional aerobic processes, but less is known about their pathways and PHA accumulation capacities. This review summarized: (a) specific adaptive mechanisms towards extreme environments by extremophiles and specific role of PHAs; (b) understanding of PHA synthesis/metabolism in archaea and specific functional genes; (c) genetic engineering and process engineering approaches required for high-rate PHA production using extremophilic archaea. To conclude, the future studies are suggested to understand the membrane lipids and PHAs accumulation to explain the adaptation mechanism of extremophiles and exploiting it for commercial production of PHAs.
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Affiliation(s)
| | - Sanjeet Mehariya
- Department of Engineering, University of Campania "Luigi Vanvitelli", Real Casa dell'Annunziata, Italy
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9
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Tools for the discovery of biopolymer producing cysteine relays. Biophys Rev 2021; 13:247-258. [PMID: 33927786 DOI: 10.1007/s12551-021-00792-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 03/02/2021] [Indexed: 12/30/2022] Open
Abstract
Cysteine relays, where a protein or small molecule is transferred multiple times via transthiolation, are central to the production of biological polymers. Enzymes that utilise relay mechanisms display broad substrate specificity and are readily engineered to produce new polymers. In this review, I discuss recent advances in the discovery, engineering and biophysical characterisation of cysteine relays. I will focus on eukaryotic ubiquitin (Ub) cascades and prokaryotic polyhydroxyalkanoate (PHA) synthesis. These evolutionarily distinct processes employ similar chemistry and are readily modified for biotechnological applications. Both processes have been studied intensively for decades, yet recent studies suggest we do not fully understand their mechanistic diversity or plasticity. I will discuss the important role that activity-based probes (ABPs) and other chemical tools have had in identifying and delineating Ub cysteine-relays and the potential for ABPs to be applied to PHA synthases. Finally, I will offer a personal perspective on the potential of engineering cysteine-relays for non-native polymer production.
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10
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Kasirajan L, Maupin-Furlow JA. Halophilic archaea and their potential to generate renewable fuels and chemicals. Biotechnol Bioeng 2020; 118:1066-1090. [PMID: 33241850 DOI: 10.1002/bit.27639] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 10/27/2020] [Accepted: 11/17/2020] [Indexed: 12/16/2022]
Abstract
Lignocellulosic biofuels and chemicals have great potential to reduce our dependence on fossil fuels and mitigate air pollution by cutting down on greenhouse gas emissions. Chemical, thermal, and enzymatic processes are used to release the sugars from the lignocellulosic biomass for conversion to biofuels. These processes often operate at extreme pH conditions, high salt concentrations, and/or high temperature. These harsh treatments add to the cost of the biofuels, as most known biocatalysts do not operate under these conditions. To increase the economic feasibility of biofuel production, microorganisms that thrive in extreme conditions are considered as ideal resources to generate biofuels and value-added products. Halophilic archaea (haloarchaea) are isolated from hypersaline ecosystems with high salt concentrations approaching saturation (1.5-5 M salt concentration) including environments with extremes in pH and/or temperature. The unique traits of haloarchaea and their enzymes that enable them to sustain catalytic activity in these environments make them attractive resources for use in bioconversion processes that must occur across a wide range of industrial conditions. Biocatalysts (enzymes) derived from haloarchaea occupy a unique niche in organic solvent, salt-based, and detergent industries. This review focuses on the use of haloarchaea and their enzymes to develop and improve biofuel production. The review also highlights how haloarchaea produce value-added products, such as antibiotics, carotenoids, and bioplastic precursors, and can do so using feedstocks considered "too salty" for most microbial processes including wastes from the olive-mill, shell fish, and biodiesel industries.
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Affiliation(s)
- Lakshmi Kasirajan
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA.,Division of Crop Improvement, ICAR Sugarcane Breeding Institute, Coimbatore, India
| | - Julie A Maupin-Furlow
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, USA.,Genetics Institute, University of Florida, Gainesville, Florida, USA
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11
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Deletion of the pps-like gene activates the cryptic phaC genes in Haloferax mediterranei. Appl Microbiol Biotechnol 2020; 104:9759-9771. [PMID: 32918583 DOI: 10.1007/s00253-020-10898-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 09/01/2020] [Accepted: 09/07/2020] [Indexed: 10/23/2022]
Abstract
Haloferax mediterranei, a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) producing haloarchaeon, possesses four PHA synthase encoding genes, phaC, phaC1, phaC2, and phaC3. In the wild-type strain, except phaC, the other three genes are cryptic and not transcribed under PHA-accumulating conditions. The PhaC protein together with PhaE subunit forms the active PHA synthase and catalyzes PHBV polymerization. Previously, it was observed that the deletion of a gene named pps-like significantly enhanced PHBV accumulation probably resulted from the upregulation of pha cluster genes (phaR-phaP-phaE-phaC). The present study demonstrated the influence of pps-like gene deletion on the cryptic phaC genes. As revealed by qRT-PCR, the expression level of the three cryptic genes was upregulated in the ΔEPSΔpps-like geneΔphaC mutant. Sequential knockout of the cryptic phaC genes and fermentation experiments showed that PhaC1 followed by PhaC3 had the ability to synthesize PHBV in ΔEPSΔpps-like geneΔphaC mutant. Both PhaC1 and PhaC3 could complex with PhaE to form functionally active PHA synthase. However, the expression of phaC2 did not lead to PHBV synthesis. Moreover, PhaC, PhaC1, and PhaC3 exhibited distinct substrate specificity as the 3HV content in PHBV copolymers was different. The EMSA result showed that PPS-like protein might be a negative regulator of phaC1 gene by binding to its promoter region. Taken together, PhaC1 had the most pronounced effect on PHBV synthesis in ΔEPSΔpps-like geneΔphaC mutant and deletion of pps-like gene released the negative effect from phaC1 expression and thereby restored PHBV accumulating ability in ΔphaC mutant. KEY POINTS: • Cryptic phaC genes were activated by pps-like gene deletion. • PPS-like protein probably regulated phaC1 expression by binding to its promoter. • Both PhaC1 and PhaC3 formed active PHA synthase with PhaE.
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Hou J, Han D, Zhou Y, Li Y, Cui HL. Identification and characterization of the gene encoding an extracellular protease from haloarchaeon Halococcus salifodinae. Microbiol Res 2020; 236:126468. [DOI: 10.1016/j.micres.2020.126468] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/10/2020] [Accepted: 03/15/2020] [Indexed: 10/24/2022]
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Mitra R, Xu T, Xiang H, Han J. Current developments on polyhydroxyalkanoates synthesis by using halophiles as a promising cell factory. Microb Cell Fact 2020; 19:86. [PMID: 32264891 PMCID: PMC7137286 DOI: 10.1186/s12934-020-01342-z] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 03/26/2020] [Indexed: 11/17/2022] Open
Abstract
Plastic pollution is a severe threat to our environment which necessitates implementation of bioplastics to realize sustainable development for a green world. Polyhydroxyalkanoates (PHA) represent one of the potential candidates for these bioplastics. However, a major challenge faced by PHA is the high production cost which limits its commercial application. Halophiles are considered to be a promising cell factory for PHA synthesis due to its several unique characteristics including high salinity requirement preventing microbial contamination, high intracellular osmotic pressure allowing easy cell lysis for PHA recovery, and capability to utilize wide spectrum of low-cost substrates. Optimization of fermentation parameters has made it plausible to achieve large-scale production at low cost by using halophiles. Further deeper insights into halophiles have revealed the existence of diversified and even novel PHA synthetic pathways within different halophilic species that greatly affects PHA type. Thus, precise metabolic engineering of halophiles with the help of advanced tools and strategies have led to more efficient microbial cell factory for PHA production. This review is an endeavour to summarize the various research achievements in these areas which will help the readers to understand the current developments as well as the future efforts in PHA research.
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Affiliation(s)
- Ruchira Mitra
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China.,International College, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Tong Xu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China
| | - Hua Xiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China. .,College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
| | - Jing Han
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China. .,College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
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Characterization of a novel Cu-containing dissimilatory nitrite reductase from the haloarchaeon Halorussus sp. YCN54. Extremophiles 2020; 24:403-411. [DOI: 10.1007/s00792-020-01164-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Accepted: 03/09/2020] [Indexed: 11/26/2022]
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Unusual Phosphoenolpyruvate (PEP) Synthetase-Like Protein Crucial to Enhancement of Polyhydroxyalkanoate Accumulation in Haloferax mediterranei Revealed by Dissection of PEP-Pyruvate Interconversion Mechanism. Appl Environ Microbiol 2019; 85:AEM.00984-19. [PMID: 31350314 DOI: 10.1128/aem.00984-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 07/08/2019] [Indexed: 12/21/2022] Open
Abstract
Phosphoenolpyruvate (PEP)/pyruvate interconversion is a major metabolic point in glycolysis and gluconeogenesis and is catalyzed by various sets of enzymes in different Archaea groups. In this study, we report the key enzymes that catalyze the anabolic and catabolic directions of the PEP/pyruvate interconversion in Haloferax mediterranei The in silico analysis showed the presence of a potassium-dependent pyruvate kinase (PYKHm [HFX_0773]) and two phosphoenol pyruvate synthetase (PPS) candidates (PPSHm [HFX_0782] and a PPS homolog protein named PPS-like [HFX_2676]) in this strain. Expression of the pyk Hm gene and pps Hm was induced by glycerol and pyruvate, respectively; whereas the pps-like gene was not induced at all. Similarly, genetic analysis and enzyme activities of purified proteins showed that PYKHm catalyzed the conversion from PEP to pyruvate and that PPSHm catalyzed the reverse reaction, while PPS-like protein displayed no function in PEP/pyruvate interconversion. Interestingly, knockout of the pps-like gene led to a 70.46% increase in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) production. The transcriptome sequencing (RNA-Seq) and quantitative reverse transcription-PCR (qRT-PCR) results showed that many genes responsible for PHBV monomer supply and for PHBV synthesis were upregulated in a pps-like gene deletion strain and thereby improved PHBV accumulation. Additionally, our phylogenetic evidence suggested that PPS-like protein diverged from PPS enzyme and evolved as a distinct protein with novel function in haloarchaea. Our findings attempt to fill the gaps in central metabolism of Archaea by providing comprehensive information about key enzymes involved in the haloarchaeal PEP/pyruvate interconversion, and we also report a high-yielding PHBV strain with great future potentials.IMPORTANCE Archaea, the third domain of life, have evolved diversified metabolic pathways to cope with their extreme habitats. Phosphoenol pyruvate (PEP)/pyruvate interconversion during carbohydrate metabolism is one such important metabolic process that is highly differentiated among Archaea However, this process is still uncharacterized in the haloarchaeal group. Haloferax mediterranei is a well-studied haloarchaeon that has the ability to produce polyhydroxyalkanoates (PHAs) under unbalanced nutritional conditions. In this study, we identified the key enzymes involved in this interconversion and discussed their differences with their counterparts from other members of the Archaea and Bacteria domains. Notably, we found a novel protein, phosphoenolpyruvate synthetase-like (PPS-like), which exhibited high homology to PPS enzyme. However, PPS-like protein has evolved some distinct sequence features and functions, and strikingly the corresponding gene deletion helped to enhance poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) synthesis significantly. Overall, we have filled the gap in knowledge about PEP/pyruvate interconversion in haloarchaea and reported an efficient strategy for improving PHBV production in H. mediterranei.
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Lim CK, Villada JC, Chalifour A, Duran MF, Lu H, Lee PKH. Designing and Engineering Methylorubrum extorquens AM1 for Itaconic Acid Production. Front Microbiol 2019; 10:1027. [PMID: 31143170 PMCID: PMC6520949 DOI: 10.3389/fmicb.2019.01027] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 04/24/2019] [Indexed: 01/05/2023] Open
Abstract
Methylorubrum extorquens (formerly Methylobacterium extorquens) AM1 is a methylotrophic bacterium with a versatile lifestyle. Various carbon sources including acetate, succinate and methanol are utilized by M. extorquens AM1 with the latter being a promising inexpensive substrate for use in the biotechnology industry. Itaconic acid (ITA) is a high-value building block widely used in various industries. Given that no wildtype methylotrophic bacteria are able to utilize methanol to produce ITA, we tested the potential of M. extorquens AM1 as an engineered host for this purpose. In this study, we successfully engineered M. extorquens AM1 to express a heterologous codon-optimized gene encoding cis-aconitic acid decarboxylase. The engineered strain produced ITA using acetate, succinate and methanol as the carbon feedstock. The highest ITA titer in batch culture with methanol as the carbon source was 31.6 ± 5.5 mg/L, while the titer and productivity were 5.4 ± 0.2 mg/L and 0.056 ± 0.002 mg/L/h, respectively, in a scaled-up fed-batch bioreactor under 60% dissolved oxygen saturation. We attempted to enhance the carbon flux toward ITA production by impeding poly-β-hydroxybutyrate accumulation, which is used as carbon and energy storage, via mutation of the regulator gene phaR. Unexpectedly, ITA production by the phaR mutant strain was not higher even though poly-β-hydroxybutyrate concentration was lower. Genome-wide transcriptomic analysis revealed that phaR mutation in the ITA-producing strain led to complex rewiring of gene transcription, which might result in a reduced carbon flux toward ITA production. Besides poly-β-hydroxybutyrate metabolism, we found evidence that PhaR might regulate the transcription of many other genes including those encoding other regulatory proteins, methanol dehydrogenases, formate dehydrogenases, malate:quinone oxidoreductase, and those synthesizing pyrroloquinoline quinone and thiamine co-factors. Overall, M. extorquens AM1 was successfully engineered to produce ITA using acetate, succinate and methanol as feedstock, further supporting this bacterium as a feasible host for use in the biotechnology industry. This study showed that PhaR could have a broader regulatory role than previously anticipated, and increased our knowledge of this regulator and its influence on the physiology of M. extorquens AM1.
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Affiliation(s)
- Chee Kent Lim
- School of Energy and Environment, City University of Hong Kong, Hong Kong, China
| | - Juan C Villada
- School of Energy and Environment, City University of Hong Kong, Hong Kong, China
| | - Annie Chalifour
- Department of Chemistry, City University of Hong Kong, Hong Kong, China
| | - Maria F Duran
- School of Energy and Environment, City University of Hong Kong, Hong Kong, China
| | - Hongyuan Lu
- School of Energy and Environment, City University of Hong Kong, Hong Kong, China
| | - Patrick K H Lee
- School of Energy and Environment, City University of Hong Kong, Hong Kong, China
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Koller M. Polyhydroxyalkanoate Biosynthesis at the Edge of Water Activitiy-Haloarchaea as Biopolyester Factories. Bioengineering (Basel) 2019; 6:bioengineering6020034. [PMID: 30995811 PMCID: PMC6631277 DOI: 10.3390/bioengineering6020034] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/03/2019] [Accepted: 04/04/2019] [Indexed: 11/16/2022] Open
Abstract
Haloarchaea, the extremely halophilic branch of the Archaea domain, encompass a steadily increasing number of genera and associated species which accumulate polyhydroxyalkanoate biopolyesters in their cytoplasm. Such ancient organisms, which thrive in highly challenging, often hostile habitats characterized by salinities between 100 and 300 g/L NaCl, have the potential to outperform established polyhydroxyalkanoate production strains. As detailed in the review, this optimization presents due to multifarious reasons, including: cultivation setups at extreme salinities can be performed at minimized sterility precautions by excluding the growth of microbial contaminants; the high inner-osmotic pressure in haloarchaea cells facilitates the recovery of intracellular biopolyester granules by cell disintegration in hypo-osmotic media; many haloarchaea utilize carbon-rich waste streams as main substrates for growth and polyhydroxyalkanoate biosynthesis, which allows coupling polyhydroxyalkanoate production with bio-economic waste management; finally, in many cases, haloarchaea are reported to produce copolyesters from structurally unrelated inexpensive substrates, and polyhydroxyalkanoate biosynthesis often occurs in parallel to the production of additional marketable bio-products like pigments or polysaccharides. This review summarizes the current knowledge about polyhydroxyalkanoate production by diverse haloarchaea; this covers the detection of new haloarchaea producing polyhydroxyalkanoates, understanding the genetic and enzymatic particularities of such organisms, kinetic aspects, material characterization, upscaling and techno-economic and life cycle assessment.
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Affiliation(s)
- Martin Koller
- University of Graz, Office of Research Management and Service, c/o Institute of Chemistry, NAWI Graz, Heinrichstrasse 28/III, 8010 Graz, Austria.
- ARENA-Association for Resource Efficient and Sustainable Technologies, Inffeldgasse 21b, 8010 Graz, Austria.
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Ferre-Guell A, Winterburn J. Biosynthesis and Characterization of Polyhydroxyalkanoates with Controlled Composition and Microstructure. Biomacromolecules 2018; 19:996-1005. [DOI: 10.1021/acs.biomac.7b01788] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Anna Ferre-Guell
- School of Chemical Engineering and Analytical Science, The Mill, The University of Manchester, Manchester M13 9PL, U.K
| | - James Winterburn
- School of Chemical Engineering and Analytical Science, The Mill, The University of Manchester, Manchester M13 9PL, U.K
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Environmental biodegradation of haloarchaea-produced poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in activated sludge. Appl Microbiol Biotechnol 2016; 100:6893-6902. [DOI: 10.1007/s00253-016-7528-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 03/30/2016] [Accepted: 04/05/2016] [Indexed: 01/19/2023]
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Enoyl-CoA hydratase mediates polyhydroxyalkanoate mobilization in Haloferax mediterranei. Sci Rep 2016; 6:24015. [PMID: 27052994 PMCID: PMC4823750 DOI: 10.1038/srep24015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 03/17/2016] [Indexed: 02/08/2023] Open
Abstract
Although polyhydroxyalkanoate (PHA) accumulation and mobilization are one of the most general mechanisms for haloarchaea to adapt to the hypersaline environments with changeable carbon sources, the PHA mobilization pathways are still not clear for any haloarchaea. In this study, the functions of five putative (R)-specific enoyl-CoA hydratases (R-ECHs) in Haloferax mediterranei, named PhaJ1 to PhaJ5, respectively, were thoroughly investigated. Through gene deletion and complementation, we demonstrated that only certain of these ECHs had a slight contribution to poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biosynthesis. But significantly, PhaJ1, the only R-ECH that is associated with PHA granules, was shown to be involved in PHA mobilization in this haloarchaeon. PhaJ1 catalyzes the dehydration of (R)-3-hydroxyacyl-CoA, the common product of PHA degradation, to enoyl-CoA, the intermediate of the β-oxidation cycle, thus could link PHA mobilization to β-oxidation pathway in H. mediterranei. This linkage was further indicated from the up-regulation of the key genes of β-oxidation under the PHA mobilization condition, as well as the obvious inhibition of PHA degradation upon inhibition of the β-oxidation pathway. Interestingly, 96% of phaJ-containing haloarchaeal species possess both phaC (encoding PHA synthase) and the full set genes of β-oxidation, implying that the mobilization of carbon storage in PHA through the β-oxidation cycle would be general in haloarchaea.
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