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Wang X, Wang Q, Hong Y, Wang Z. A whole process study of dual microalgae cultivation coupled to domestic wastewater treatment and wheat growth. ENVIRONMENTAL RESEARCH 2024; 254:119168. [PMID: 38762007 DOI: 10.1016/j.envres.2024.119168] [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: 03/16/2024] [Revised: 05/14/2024] [Accepted: 05/15/2024] [Indexed: 05/20/2024]
Abstract
The multiple microalgal collaborative treatment of domestic wastewater has been extensively investigated, but its whole life cycle tracking and consequent potential have not been fully explored. Herein, a dual microalgal system was employed for domestic wastewater treatment, tracking the variation in microalgal growth and pollutants removal from shake flask scale to 18 L photobioreactors scales. The results showed that Chlorella sp. HL and Scenedesmus sp. LX1 combination had superior growth and water purification performance, and the interspecies soluble algal products promoted their growth. Through microalgae mixing ratio and inoculum size optimized, the highest biomass yield (0.42 ± 0.03 g/L) and over 91 % N, P removal rates were achieved in 18 L photobioreactor. Harvested microalgae treated in different forms all promoted wheat growth and suppressed yellow leaf rate. This study provided data support for the whole process tracking of dual microalgal system in treating domestic wastewater and improving wheat growth.
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Affiliation(s)
- Xiaoyan Wang
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China
| | - Qiao Wang
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China
| | - Yu Hong
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China.
| | - Zeyuan Wang
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China
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Rodero MDR, Pérez V, Muñoz R. Optimization of methane gas-liquid mass transfer during biogas-based ectoine production in bubble column bioreactors. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 366:121811. [PMID: 39002456 DOI: 10.1016/j.jenvman.2024.121811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 06/26/2024] [Accepted: 07/07/2024] [Indexed: 07/15/2024]
Abstract
Nowadays, the utilization of biogas for energy generation is hindered by the declining production costs of solar and wind power. A shift towards the valorization of biogas into ectoine, a highly valuable bioproduct priced at 1000 €⸱kg-1, offers a novel approach to fostering a more competitive biogas market while contributing to carbon neutrality. This study evaluated the optimization of CH4 gas-liquid mass transfer in 10 L bubble column bioreactors for CH4 conversion into ectoine and hydroxyectoine using a mixed methanotrophic culture. The influence of the empty bed residence time (EBRTs of 27, 54, and 104 min) at different membrane diffuser pore sizes (0.3 and 0.6 mm) was investigated. Despite achieving CH4 elimination capacities (CH4-ECs) of 10-12 g⸱m-3⸱h-1, an EBRT of 104 min mediated CH4 limitation within the cultivation broth, resulting in a negligible biomass growth. Reducing the EBRT to 54 min entailed CH4-ECs of 21-24 g⸱m-3⸱h-1, concomitant to a significant increase in biomass growth (up to 0.17 g⸱L⸱d-1) and reaching maximum ectoine and hydroxyectoine accumulation of 79 and 13 mg⸱gVSS-1, respectively. Conversely, process operation at an EBRT of 27 min lead to microbial inhibition, resulting in a reduced biomass growth of 0.09 g⸱L⸱d-1 and an ectoine content of 47 mg⸱gVSS-1. While the influence of diffuser pore size was less pronounced compared to EBRT, the optimal process performance was observed with a diffuser pore size of 0.6 mm.
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Affiliation(s)
- María Del Rosario Rodero
- Institute of Sustainable Processes, University of Valladolid, 47011, Valladolid, Spain; Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering. University of Valladolid, Dr. Mergelina s/n., 47011, Valladolid, Spain
| | - Víctor Pérez
- Institute of Sustainable Processes, University of Valladolid, 47011, Valladolid, Spain; Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering. University of Valladolid, Dr. Mergelina s/n., 47011, Valladolid, Spain
| | - Raúl Muñoz
- Institute of Sustainable Processes, University of Valladolid, 47011, Valladolid, Spain; Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering. University of Valladolid, Dr. Mergelina s/n., 47011, Valladolid, Spain.
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Lim SE, Cho S, Choi Y, Na JG, Lee J. High production of ectoine from methane in genetically engineered Methylomicrobium alcaliphilum 20Z by preventing ectoine degradation. Microb Cell Fact 2024; 23:127. [PMID: 38698430 PMCID: PMC11067125 DOI: 10.1186/s12934-024-02404-2] [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: 03/19/2024] [Accepted: 04/24/2024] [Indexed: 05/05/2024] Open
Abstract
BACKGROUND Methane is a greenhouse gas with a significant potential to contribute to global warming. The biological conversion of methane to ectoine using methanotrophs represents an environmentally and economically beneficial technology, combining the reduction of methane that would otherwise be combusted and released into the atmosphere with the production of value-added products. RESULTS In this study, high ectoine production was achieved using genetically engineered Methylomicrobium alcaliphilum 20Z, a methanotrophic ectoine-producing bacterium, by knocking out doeA, which encodes a putative ectoine hydrolase, resulting in complete inhibition of ectoine degradation. Ectoine was confirmed to be degraded by doeA to N-α-acetyl-L-2,4-diaminobutyrate under nitrogen depletion conditions. Optimal copper and nitrogen concentrations enhanced biomass and ectoine production, respectively. Under optimal fed-batch fermentation conditions, ectoine production proportionate with biomass production was achieved, resulting in 1.0 g/L of ectoine with 16 g/L of biomass. Upon applying a hyperosmotic shock after high-cell-density culture, 1.5 g/L of ectoine was obtained without further cell growth from methane. CONCLUSIONS This study suggests the optimization of a method for the high production of ectoine from methane by preventing ectoine degradation. To our knowledge, the final titer of ectoine obtained by M. alcaliphilum 20ZDP3 was the highest in the ectoine production from methane to date. This is the first study to propose ectoine production from methane applying high cell density culture by preventing ectoine degradation.
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Affiliation(s)
- Sang Eun Lim
- Department of Chemical and Biomolecular Engineering, Sogang University, Seoul, Republic of Korea
| | - Sukhyeong Cho
- C1 Gas Refinery R&D Center, Sogang University, Seoul, Republic of Korea
| | - Yejin Choi
- Department of Chemical and Biomolecular Engineering, Sogang University, Seoul, Republic of Korea
| | - Jeong-Geol Na
- Department of Chemical and Biomolecular Engineering, Sogang University, Seoul, Republic of Korea
| | - Jinwon Lee
- Department of Chemical and Biomolecular Engineering, Sogang University, Seoul, Republic of Korea.
- C1 Gas Refinery R&D Center, Sogang University, Seoul, Republic of Korea.
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Hu Q, Sun S, Zhang Z, Liu W, Yi X, He H, Scrutton NS, Chen GQ. Ectoine hyperproduction by engineered Halomonas bluephagenesis. Metab Eng 2024; 82:238-249. [PMID: 38401747 DOI: 10.1016/j.ymben.2024.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Accepted: 02/19/2024] [Indexed: 02/26/2024]
Abstract
Ectoine, a crucial osmoprotectant for salt adaptation in halophiles, has gained growing interest in cosmetics and medical industries. However, its production remains challenged by stringent fermentation process in model microorganisms and low production level in its native producers. Here, we systematically engineered the native ectoine producer Halomonas bluephagenesis for ectoine production by overexpressing ectABC operon, increasing precursors availability, enhancing product transport system and optimizing its growth medium. The final engineered H. bluephagenesis produced 85 g/L ectoine in 52 h under open unsterile incubation in a 7 L bioreactor in the absence of plasmid, antibiotic or inducer. Furthermore, it was successfully demonstrated the feasibility of decoupling salt concentration with ectoine synthesis and co-production with bioplastic P(3HB-co-4HB) by the engineered H. bluephagenesis. The unsterile fermentation process and significantly increased ectoine titer indicate that H. bluephagenesis as the chassis of Next-Generation Industrial Biotechnology (NGIB), is promising for the biomanufacturing of not only intracellular bioplastic PHA but also small molecular compound such as ectoine.
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Affiliation(s)
- Qitiao Hu
- School of Life Sciences, Tsinghua University, Beijing, 100084, China; Manchester Institute of Biotechnology, Department of Chemistry, The University of Manchester, Manchester, M1 7DN, UK
| | - Simian Sun
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Zhongnan Zhang
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Wei Liu
- PhaBuilder Biotechnology Co. Ltd., Shunyi District, Beijing 101309, China
| | - Xueqing Yi
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Hongtao He
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Nigel S Scrutton
- Manchester Institute of Biotechnology, Department of Chemistry, The University of Manchester, Manchester, M1 7DN, UK
| | - Guo-Qiang Chen
- School of Life Sciences, Tsinghua University, Beijing, 100084, China; Manchester Institute of Biotechnology, Department of Chemistry, The University of Manchester, Manchester, M1 7DN, UK; Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China.
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Feng Y, Qiu M, Shao L, Jiang Y, Zhang W, Jiang W, Xin F, Jiang M. Strategies for the biological production of ectoine by using different chassis strains. Biotechnol Adv 2024; 70:108306. [PMID: 38157997 DOI: 10.1016/j.biotechadv.2023.108306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 11/27/2023] [Accepted: 12/23/2023] [Indexed: 01/03/2024]
Abstract
As an amino acid derivative and a typical compatible solute, ectoine can assist microorganisms in resisting high osmotic pressure. Own to its long-term moisturizing effects, ectoine shows extensive applications in cosmetics, medicine and other fields. With the rapid development of synthetic biology and fermentation engineering, many biological strategies have been developed to improve the ectoine production and simplify the production process. Currently, the microbial fermentation has been widely used for large scaling ectoine production. Accordingly, this review will introduce the metabolic pathway for ectoine synthesis and also comprehensively evaluate both wild-type and genetically modified strains for ectoine production. Furthermore, process parameters affecting the ectoine production efficiency and adoption of low cost substrates will be evaluated. Lastly, future prospects on the improvement of ectoine production will be proposed.
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Affiliation(s)
- Yifan Feng
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, PR China
| | - Min Qiu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, PR China
| | - Lei Shao
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, PR China
| | - Yujia Jiang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, PR China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing 211816, PR China
| | - Wenming Zhang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, PR China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing 211816, PR China
| | - Wankui Jiang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, PR China.
| | - Fengxue Xin
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, PR China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing 211816, PR China.
| | - Min Jiang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, PR China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing 211816, PR China
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Wang Z, Li Y, Gao X, Xing J, Wang R, Zhu D, Shen G. Comparative genomic analysis of Halomonas campaniensis wild-type and ultraviolet radiation-mutated strains reveal genomic differences associated with increased ectoine production. Int Microbiol 2023; 26:1009-1020. [PMID: 37067733 PMCID: PMC10622362 DOI: 10.1007/s10123-023-00356-y] [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: 11/01/2022] [Revised: 04/01/2023] [Accepted: 04/05/2023] [Indexed: 04/18/2023]
Abstract
Ectoine is a natural amino acid derivative and one of the most widely used compatible solutes produced by Halomonas species that affects both cellular growth and osmotic equilibrium. The positive effects of UV mutagenesis on both biomass and ectoine content production in ectoine-producing strains have yet to be reported. In this study, the wild-type H. campaniensis strain XH26 (CCTCCM2019776) was subjected to UV mutagenesis to increase ectoine production. Eight rounds of mutagenesis were used to generate mutated XH26 strains with different UV-irradiation exposure times. Ectoine extract concentrations were then evaluated among all strains using high-performance liquid chromatography analysis, alongside whole genome sequencing with the PacBio RS II platform and comparison of the wild-type strain XH26 and the mutant strain G8-52 genomes. The mutant strain G8-52 (CCTCCM2019777) exhibited the highest cell growth rate and ectoine yields among mutated strains in comparison with strain XH26. Further, ectoine levels in the aforementioned strain significantly increased to 1.51 ± 0.01 g L-1 (0.65 g g-1 of cell dry weight), representing a twofold increase compared to wild-type cells (0.51 ± 0.01 g L-1) when grown in culture medium for ectoine accumulation. Concomitantly, electron microscopy revealed that mutated strain G8-52 cells were obviously shorter than wild-type strain XH26 cells. Moreover, strain G8-52 produced a relatively stable ectoine yield (1.50 g L-1) after 40 days of continuous subculture. Comparative genomics analysis suggested that strain XH26 harbored 24 mutations, including 10 nucleotide insertions, 10 nucleotide deletions, and unique single nucleotide polymorphisms. Notably, the genes orf00723 and orf02403 (lipA) of the wild-type strain mutated to davT and gabD in strain G8-52 that encoded for 4-aminobutyrate-2-oxoglutarate transaminase and NAD-dependent succinate-semialdehyde dehydrogenase, respectively. Consequently, these genes may be involved in increased ectoine yields. These results suggest that continuous multiple rounds of UV mutation represent a successful strategy for increasing ectoine production, and that the mutant strain G8-52 is suitable for large-scale fermentation applications.
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Affiliation(s)
- Zhibo Wang
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Yongzhen Li
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Xiang Gao
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Jiangwa Xing
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Rong Wang
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Derui Zhu
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China
| | - Guoping Shen
- Research Center of Basic Medical Science, Medical College of Qinghai University, Xining, 810016, China.
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Rodero MDR, Carmona-Martínez AA, Martínez-Fraile C, Herrero-Lobo R, Rodríguez E, García-Encina PA, Peña M, Muñoz R. Ectoines production from biogas in pilot bubble column bioreactors and their subsequent extraction via bio-milking. WATER RESEARCH 2023; 245:120665. [PMID: 37801795 DOI: 10.1016/j.watres.2023.120665] [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: 04/11/2023] [Revised: 09/17/2023] [Accepted: 09/22/2023] [Indexed: 10/08/2023]
Abstract
Despite the potential of biogas from waste/wastewater treatment as a renewable energy source, the presence of pollutants and the rapid decrease in the levelized cost of solar and wind power constrain the use of biogas for energy generation. Biogas conversion into ectoine, one of the most valuable bioproducts (1000 €/kg), constitutes a new strategy to promote a competitive biogas market. The potential for a stand-alone 20 L bubble column bioreactor operating at 6% NaCl and two 10 L interconnected bioreactors (at 0 and 6% NaCl, respectively) for ectoine production from biogas was comparatively assessed. The stand-alone reactor supported the best process performance due to its highest robustness and efficiency for ectoine accumulation (20-52 mgectoine/gVSS) and CH4 degradation (up to 84%). The increase in N availability and internal gas recirculation did not enhance ectoine synthesis. However, a 2-fold increase in the internal gas recirculation resulted in an approximately 1.3-fold increase in CH4 removal efficiency. Finally, the recovery of ectoine through bacterial bio-milking resulted in efficiencies of >70% without any negative impact of methanotrophic cell recycling to the bioreactors on CH4 biodegradation or ectoine synthesis.
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Affiliation(s)
- María Del Rosario Rodero
- Institute of Sustainable Processes, University of Valladolid, Valladolid 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain
| | - Alessandro A Carmona-Martínez
- Institute of Sustainable Processes, University of Valladolid, Valladolid 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain
| | - Cristina Martínez-Fraile
- Institute of Sustainable Processes, University of Valladolid, Valladolid 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain
| | - Raquel Herrero-Lobo
- Institute of Sustainable Processes, University of Valladolid, Valladolid 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain
| | - Elisa Rodríguez
- Institute of Sustainable Processes, University of Valladolid, Valladolid 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain
| | - Pedro A García-Encina
- Institute of Sustainable Processes, University of Valladolid, Valladolid 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain
| | - Mar Peña
- Institute of Sustainable Processes, University of Valladolid, Valladolid 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain
| | - Raúl Muñoz
- Institute of Sustainable Processes, University of Valladolid, Valladolid 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain.
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Orhan F, Ceyran E, Akincioğlu A. Optimization of ectoine production from Nesterenkonia xinjiangensis and one-step ectoine purification. BIORESOURCE TECHNOLOGY 2023; 371:128646. [PMID: 36681344 DOI: 10.1016/j.biortech.2023.128646] [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: 12/07/2022] [Revised: 01/13/2023] [Accepted: 01/16/2023] [Indexed: 06/17/2023]
Abstract
In the current study, the optimization of ectoine production byNesterenkonia xinjiangensisand purification of ectoine from the bacterial cell extract were performed for the first time. Various carbon sources (glucose, sucrose, maltose, lactose, mannitol, and xylose) and nitrogen sources (ammonium nitrate, ammonium phosphate, ammonium chloride, ammonium oxalate, ammonium sulphate, and ammonium acetate), were used to optimize ectoine production. Subsequently, the effects of salt, pH and, concentrations of carbon and nitrogen source on ectoine production were optimized by response surface methodology (RSM). Ultimately, high pure (over 99%) and yield (98%) of ectoine from bacterial cells extracted was obtained by a single-step process using cation exchange chromatography. This study provides information that higher ectoine production can be achieved from this bacterial isolate by optimizing the factors influencing ectoine production and thus can be used as a new and alternative ectoine producer.
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Affiliation(s)
- Furkan Orhan
- Agri Ibrahim Cecen University, Art and Science Faculty, Department of Molecular Biology and Genetics, 4100 Agri, Turkey; Central Research and Application Laboratory, Agri Ibrahim Cecen University, Agri, Turkey.
| | - Ertuğrul Ceyran
- Central Research and Application Laboratory, Agri Ibrahim Cecen University, Agri, Turkey
| | - Akın Akincioğlu
- Central Research and Application Laboratory, Agri Ibrahim Cecen University, Agri, Turkey; Vocational School, Agri Ibrahim Cecen University, Agri, Turkey
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Molecular Dynamics Simulations for the Michaelis Complex of Ectoine Synthase (EctC). Catalysts 2023. [DOI: 10.3390/catal13010124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Ectoine is a chemical chaperone synthesised and used by bacteria to defend against osmotic stress. Although it has already gained attention from the pharmaceutical and cosmetic industries, thanks to its hydrating and cell-protecting properties, the reaction mechanism of its final synthesis step is still not fully understood. The ultimate step of ectoine biosynthesis is catalysed by the ectoine synthase enzyme (EctC), which requires an iron ion for substrate binding and overall enzymatic activity. Even though a crystal structure for Paenibacillus lautus EctC—substrate complex is available (PDB: 5ONN), it is not very informative with respect to the geometry of the active site because: (1) the crystal was obtained at a pH value far from the enzyme’s pH optimum, (2) the electron density at the Fe position is weak, and (3) the Fe-ligand distances are too long. To fill this gap, in this work we have used classical molecular dynamics simulations to model the enzyme-substrate (N-gamma-acetyl-L-2,4-diaminobutyric acid) complex of Paenibacillus lautus EctC (PlEctC). Since PlEctC is a homodimeric protein, MD simulations were carried out for a dimer with various plausible occupancies by the substrate and for two plausible coordination geometries around the catalytic Fe ion: tetrahedral and octahedral. MD results revealed that the presence of the ligand has a stabilising effect on the protein structure, most notably on a short helix 112–118, which flanks the entrance to the active site. The most important amino acids for substrate binding are Trp21, Arg25, Asn38, Thr40, and Tyr52, which were also identified in the crystal structure. Importantly, the substrate can easily adopt a conformation suitable for the progress of the catalytic reaction, and it does so spontaneously for the octahedral 6-coordinate geometry of the iron cofactor or with a low energy penalty (ca. 3 kcal/mol) in the case of 4-coordinate tetrahedral geometry. Simulations for different substrate occupancy states did not reveal any signs of cooperativity between the two monomers.
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Rodero MDR, Herrero-Lobo R, Pérez V, Muñoz R. Influence of operational conditions on the performance of biogas bioconversion into ectoines in pilot bubble column bioreactors. BIORESOURCE TECHNOLOGY 2022; 358:127398. [PMID: 35640813 DOI: 10.1016/j.biortech.2022.127398] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 06/15/2023]
Abstract
The application of biogas as a low-priced substrate for the production of ectoines constitutes an opportunity to decrease their production costs and to enhance the viability of anaerobic digestion. The influence of operational conditions on CH4-biogas biodegradation and on ectoines production yields was assessed in continuous pilot bubble column bioreactors. The rise in biomass concentration from 1 to 3 g L-1 resulted in a decrease in the specific ectoine content from 42 ± 8 to 30 ± 4 mgectoine gVSS-1. The concentration of Cu2+ and Mg2+ did not impact process performance, while the use of ammonium as N source resulted in low CH4 biodegradation and ectoine yields (13 ± 7 mgectoine gVSS-1). The increase in CH4 content from 4.5 to 9 %v·v-1 enhanced CH4 removal efficiency. Process operation at NaCl concentrations of 3 %w·w-1 instead of 6 %w·w-1 decreased the ectoine yield to 17 mgectoine gVSS-1. Finally, Methylomicrobiumburyatense was identified as the dominant species.
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Affiliation(s)
- María Del Rosario Rodero
- Institute of Sustainable Processes, University of Valladolid, 47011, Valladolid, Spain; Department of Chemical Engineering and Environmental Technology, School of Industrial Engineerings. University of Valladolid, Dr. Mergelina s/n., 47011, Valladolid, Spain
| | - Raquel Herrero-Lobo
- Institute of Sustainable Processes, University of Valladolid, 47011, Valladolid, Spain; Department of Chemical Engineering and Environmental Technology, School of Industrial Engineerings. University of Valladolid, Dr. Mergelina s/n., 47011, Valladolid, Spain
| | - Víctor Pérez
- Institute of Sustainable Processes, University of Valladolid, 47011, Valladolid, Spain; Department of Chemical Engineering and Environmental Technology, School of Industrial Engineerings. University of Valladolid, Dr. Mergelina s/n., 47011, Valladolid, Spain
| | - Raúl Muñoz
- Institute of Sustainable Processes, University of Valladolid, 47011, Valladolid, Spain; Department of Chemical Engineering and Environmental Technology, School of Industrial Engineerings. University of Valladolid, Dr. Mergelina s/n., 47011, Valladolid, Spain.
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