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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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2
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Orhan F, Akıncıoğlu A, Ceyran E. Ectoine production from a novel bacterial strain and high-purity purification with a cost-effective and single-step method. J Biotechnol 2024; 388:24-34. [PMID: 38599284 DOI: 10.1016/j.jbiotec.2024.04.003] [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: 11/24/2023] [Revised: 03/08/2024] [Accepted: 04/05/2024] [Indexed: 04/12/2024]
Abstract
This study marks the exploration into the production of ectoine, a valuable compound with significant potential as an antioxidant, osmoprotectant, anti-inflammatory agent, and stabilizer of cell membranes, proteins, and DNA integrity. Our focus centred on investigating the presence of ectoine and optimizing its production by the novel ectoine producer bacterial strain, Piscibacillus halophilus. For the optimization of ectoine production the effects of carbon and nitrogen sources, salt, pH, agitation and incubation period were optimized by one-factor-at-a-time. We started with an initial ectoine content of 46.92 mg/L, and through a series of optimization processes, we achieved a remarkable increase, resulting in an ectoine content of 1498.2 mg/L. The bacterial species P. halophilus achieved its highest ectoine production after 48 h of incubation, with conditions set at 10 % (w/v) salinity, pH of 7.50, and an agitation speed of 160 rpm. These precise conditions were found to be the most favourable for maximizing ectoine production by this strain. Besides, we have achieved successful purification of ectoine from the crude extract through a streamlined single-step process. This purification method has delivered an exceptional level of purity, surpassing 99.15 %, and an impressive yield of over 99 %. Importantly, we accomplished this using readily available and cost-effective strong acids (HCl) and strong bases (NaOH) to arrange pH gradients. The use of acid and base in the purification process of ectoine reflects an innovative and sustainable methodology.
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Affiliation(s)
- Furkan Orhan
- Agri Ibrahim Cecen University, Art and Science Faculty, Department of Molecular Biology and Genetics, Agri 4100, Turkey; Central Research and Application Laboratory, Agri Ibrahim Cecen University, Agri, Turkey.
| | - Akın Akıncıoğlu
- Central Research and Application Laboratory, Agri Ibrahim Cecen University, Agri, Turkey; Vocational School, Agri Ibrahim Cecen University, Agri, Turkey
| | - Ertuğrul Ceyran
- Central Research and Application Laboratory, Agri Ibrahim Cecen University, Agri, Turkey
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3
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Yang N, Liu M, Han J, Jiang M, Zeng Y, Liu Y, Xiang H, Zheng Y. Rational engineering of Halomonas salifodinae to enhance hydroxyectoine production under lower-salt conditions. Appl Microbiol Biotechnol 2024; 108:353. [PMID: 38819481 PMCID: PMC11142988 DOI: 10.1007/s00253-024-13197-0] [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: 12/28/2023] [Revised: 05/01/2024] [Accepted: 05/21/2024] [Indexed: 06/01/2024]
Abstract
Hydroxyectoine is an important compatible solute that holds potential for development into a high-value chemical with broad applications. However, the traditional high-salt fermentation for hydroxyectoine production presents challenges in treating the high-salt wastewater. Here, we report the rational engineering of Halomonas salifodinae to improve the bioproduction of hydroxyectoine under lower-salt conditions. The comparative transcriptomic analysis suggested that the increased expression of ectD gene encoding ectoine hydroxylase (EctD) and the decreased expressions of genes responsible for tricarboxylic acid (TCA) cycle contributed to the increased hydroxyectoine production in H. salifodinae IM328 grown under high-salt conditions. By blocking the degradation pathway of ectoine and hydroxyectoine, enhancing the expression of ectD, and increasing the supply of 2-oxoglutarate, the engineered H. salifodinae strain HS328-YNP15 (ΔdoeA::PUP119-ectD p-gdh) produced 8.3-fold higher hydroxyectoine production than the wild-type strain and finally achieved a hydroxyectoine titer of 4.9 g/L in fed-batch fermentation without any detailed process optimization. This study shows the potential to integrate hydroxyectoine production into open unsterile fermentation process that operates under low-salinity and high-alkalinity conditions, paving the way for next-generation industrial biotechnology. KEY POINTS: • Hydroxyectoine production in H. salifodinae correlates with the salinity of medium • Transcriptomic analysis reveals the limiting factors for hydroxyectoine production • The engineered strain produced 8.3-fold more hydroxyectoine than the wild type.
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Affiliation(s)
- Niping Yang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
- School of Life Sciences, Hebei University, Baoding, 071002, China
| | - Mengshuang Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jing Han
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Mingyue Jiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yan Zeng
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Ying Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Hua Xiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yanning Zheng
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, 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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Bianco F, Race M, Papirio S, Esposito G. Phenanthrene removal from a spent sediment washing solution in a continuous-flow stirred-tank reactor. ENVIRONMENTAL RESEARCH 2023; 228:115889. [PMID: 37054831 DOI: 10.1016/j.envres.2023.115889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/05/2023] [Accepted: 04/11/2023] [Indexed: 05/16/2023]
Abstract
The issue of polycyclic aromatic hydrocarbons (PAHs) is widespread in marine sediments involving ecological systems and human health. Sediment washing (SW) has proven to be the most effective remediation approach for sediments polluted by PAHs, such as phenanthrene (PHE). However, SW still raises waste handling concerns due to a considerable amount of effluents generated downstream. In this context, the biological treatment of a PHE- and ethanol-containing spent SW solution can represent a highly efficient and environmentally-friendly strategy, but its knowledge is still scarce in scientific literature and no studies have so far been conducted in continuous mode. Therefore, a synthetic PHE-polluted SW solution was biologically treated in a 1 L aerated continuous-flow stirred-tank reactor for 129 days by evaluating the effect of different pH values, aeration flowrates and hydraulic retention times as operating parameters over five successive phases. A PHE removal efficiency of up to 75-94% was achieved by an acclimated PHE-degrading consortium mainly composed of Proteobacteria, Bacteroidota and Firmicutes phyla through biodegradation following the adsorption mechanism. PHE biodegradation, mainly occurring via the benzoate route due to the presence of PAH-related-degrading functional genes and a phthalate accumulation up to 46 mg/L, was also accompanied by a reduction of dissolved organic carbon and ammonia nitrogen above 99% in the treated SW solution.
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Affiliation(s)
- Francesco Bianco
- Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via Di Biasio 43, 03043, Cassino, Italy.
| | - Marco Race
- Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via Di Biasio 43, 03043, Cassino, Italy
| | - Stefano Papirio
- Department of Civil, Architectural and Environmental Engineering, University of Napoli Federico II, Via Claudio 21, 80125, Napoli, Italy
| | - Giovanni Esposito
- Department of Civil, Architectural and Environmental Engineering, University of Napoli Federico II, Via Claudio 21, 80125, Napoli, Italy
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Cantera S, Di Benedetto F, Tumulero BF, Sousa DZ. Microbial conversion of carbon dioxide and hydrogen into the fine chemicals hydroxyectoine and ectoine. BIORESOURCE TECHNOLOGY 2023; 374:128753. [PMID: 36801441 DOI: 10.1016/j.biortech.2023.128753] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 02/11/2023] [Accepted: 02/14/2023] [Indexed: 06/18/2023]
Abstract
This study explores a novel conversion of CO2 into the chemicals hydroxyectoine and ectoine, which are compounds with high retail values in the pharmaceutical industry. Firstly, 11 species of microbes able to use CO2 and H2 and that have the genes for ectoines synthesis (ectABCD) were identified through literature search and genomic mining. Laboratory tests were then conducted to ascertain the capacity of these microbes to produce ectoines from CO2. Results showed that the most promising bacteria for CO2 to ectoines bioconversion areHydrogenovibrio marinus, Rhodococcus opacus, and Hydrogenibacillus schlegelii.Upon salinity and H2/CO2/O2 ratio optimization,H. marinus accumulated 85 mg of ectoine g biomass-1. Interestingly, R.opacusand H. schlegelii mainly produced hydroxyectoine (53 and 62 mg g biomass-1), which has a higher commercial value. Overall, these results constitute the first proof of a novel valorization platform of CO2 and lay the foundation for a new economic niche aimed at CO2 recircularization into pharmaceuticals.
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Affiliation(s)
- Sara Cantera
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE, Wageningen, the Netherlands.
| | - Francesca Di Benedetto
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE, Wageningen, the Netherlands
| | - Ben F Tumulero
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE, Wageningen, the Netherlands
| | - Diana Z Sousa
- Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE, Wageningen, the Netherlands
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7
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Production and Recovery of Ectoine: A Review of Current State and Future Prospects. Processes (Basel) 2023. [DOI: 10.3390/pr11020339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid) is a revolutionizing substance with vast applications in the cosmetic and food industries. Ectoine is often sourced from halobacteria. The increasing market demand for ectoine has urged the development of cost-effective and sustainable large-scale production of ectoine from microbial sources. This review describes the existing and potential microbial sources of ectoine and its derivatives, as well as microbial production and fermentation approaches for ectoine recovery. In addition, conventional methods and emerging technologies for enhanced production and recovery of ectoine from microbial fermentation with a focus on the aqueous biphasic system (ABS) are discussed. The ABS is a practically feasible approach for the integration of fermentation, cell disruption, bioconversion, and clarification of various biomolecules in a single-step operation. Nonetheless, the implementation of the ABS on an industrial-scale basis for the enhanced production and recovery of ectoine is yet to be exploited. Therefore, the feasibility of the ABS to integrate the production and direct recovery of ectoine from microbial sources is also highlighted in this review.
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Jungmann L, Hoffmann SL, Lang C, De Agazio R, Becker J, Kohlstedt M, Wittmann C. High-efficiency production of 5-hydroxyectoine using metabolically engineered Corynebacterium glutamicum. Microb Cell Fact 2022; 21:274. [PMID: 36578077 PMCID: PMC9798599 DOI: 10.1186/s12934-022-02003-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 12/17/2022] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Extremolytes enable microbes to withstand even the most extreme conditions in nature. Due to their unique protective properties, the small organic molecules, more and more, become high-value active ingredients for the cosmetics and the pharmaceutical industries. While ectoine, the industrial extremolyte flagship, has been successfully commercialized before, an economically viable route to its highly interesting derivative 5-hydroxyectoine (hydroxyectoine) is not existing. RESULTS Here, we demonstrate high-level hydroxyectoine production, using metabolically engineered strains of C. glutamicum that express a codon-optimized, heterologous ectD gene, encoding for ectoine hydroxylase, to convert supplemented ectoine in the presence of sucrose as growth substrate into the desired derivative. Fourteen out of sixteen codon-optimized ectD variants from phylogenetically diverse bacterial and archaeal donors enabled hydroxyectoine production, showing the strategy to work almost regardless of the origin of the gene. The genes from Pseudomonas stutzeri (PST) and Mycobacterium smegmatis (MSM) worked best and enabled hydroxyectoine production up to 97% yield. Metabolic analyses revealed high enrichment of the ectoines inside the cells, which, inter alia, reduced the synthesis of other compatible solutes, including proline and trehalose. After further optimization, C. glutamicum Ptuf ectDPST achieved a titre of 74 g L-1 hydroxyectoine at 70% selectivity within 12 h, using a simple batch process. In a two-step procedure, hydroxyectoine production from ectoine, previously synthesized fermentatively with C. glutamicum ectABCopt, was successfully achieved without intermediate purification. CONCLUSIONS C. glutamicum is a well-known and industrially proven host, allowing the synthesis of commercial products with granted GRAS status, a great benefit for a safe production of hydroxyectoine as active ingredient for cosmetic and pharmaceutical applications. Because ectoine is already available at commercial scale, its use as precursor appears straightforward. In the future, two-step processes might provide hydroxyectoine de novo from sugar.
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Affiliation(s)
- Lukas Jungmann
- grid.11749.3a0000 0001 2167 7588Institute of Systems Biotechnology, Saarland University, Campus A1.5, Saarbrücken, Germany
| | - Sarah Lisa Hoffmann
- grid.11749.3a0000 0001 2167 7588Institute of Systems Biotechnology, Saarland University, Campus A1.5, Saarbrücken, Germany
| | - Caroline Lang
- grid.11749.3a0000 0001 2167 7588Institute of Systems Biotechnology, Saarland University, Campus A1.5, Saarbrücken, Germany
| | - Raphaela De Agazio
- grid.11749.3a0000 0001 2167 7588Institute of Systems Biotechnology, Saarland University, Campus A1.5, Saarbrücken, Germany
| | - Judith Becker
- grid.11749.3a0000 0001 2167 7588Institute of Systems Biotechnology, Saarland University, Campus A1.5, Saarbrücken, Germany
| | - Michael Kohlstedt
- grid.11749.3a0000 0001 2167 7588Institute of Systems Biotechnology, Saarland University, Campus A1.5, Saarbrücken, Germany
| | - Christoph Wittmann
- grid.11749.3a0000 0001 2167 7588Institute of Systems Biotechnology, Saarland University, Campus A1.5, Saarbrücken, Germany
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Establishment of a salt-induced bioremediation platform from marine Vibrio natriegens. Commun Biol 2022; 5:1352. [PMID: 36494435 PMCID: PMC9734156 DOI: 10.1038/s42003-022-04319-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 11/29/2022] [Indexed: 12/13/2022] Open
Abstract
Industrial wastewater discharge, agricultural production, marine shipping, oil extraction, and other activities have caused serious marine pollution, including microplastics, petroleum and its products, heavy metals, pesticides, and other organics. Efficiency of bioremediation of marine pollutions may be limited by high salt concentrations (>1%, w/v), which can cause an apparent loss of microbial activities. In this study, functional promoters P1, P2-1, and P2-2 censoring salt stress were isolated and identified from a Vibrio natriegens strain Vmax. Three salt-induced degradation models were constructed to degrade polyethylene terephthalate (PET), chlorpyrifos (CP), and hexabromocyclododecanes (HBCDs) using the marine strain Vmax. The engineered strains are efficient for degradation of the corresponding substrates, with the degradation rates at 15 mg/L PET in 8 d, 50 mg/L CP in 24 h, and 1 mg/L HBCDs in 4 h, respectively. In addition, an immobilization strategy for recycling and reusing of engineered strains was realized by expressing the chitin-binding protein GbpA. This study may help answer the usage of rapidly growing marine bacteria such as V. natriegens Vmax to degrade marine pollution efficiently.
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Ma Z, Wu C, Zhu L, Chang R, Ma W, Deng Y, Chen X. Bioactivity profiling of the extremolyte ectoine as a promising protectant and its heterologous production. 3 Biotech 2022; 12:331. [PMID: 36311375 PMCID: PMC9606177 DOI: 10.1007/s13205-022-03370-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 09/20/2022] [Indexed: 11/28/2022] Open
Abstract
Ectoine is a compatible solutes that is diffusely dispersed in bacteria and archaea. It plays a significant role as protectant against various external pressures, such as high temperature, high osmolarity, dryness and radiation, in cells. Ectoine can be utilized in cosmetics due to its properties of moisturizing and antiultraviolet. It can also be used in the pharmaceutical industry for treating various diseases. Therefore, strong protection of ectoine creates a high commercial value. Its current market value is approximately US$1000 kg-1. However, traditional ectoine production in high-salinity media causes high costs of equipment loss and wastewater treatment. There is a growing attention to reduce the salinity of the fermentation broth without sacrificing the production of ectoine. Thus, heterologous production of ectoine in nonhalophilic microorganisms may represent the new generation of the industrial production of ectoine. In this review, we summarized and discussed the biological activities of ectoine on cell and human health protection and its heterologous production.
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Affiliation(s)
- Zhi Ma
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Chutian Wu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Linjiang Zhu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Renjie Chang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Weilin Ma
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Yanfeng Deng
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Xiaolong Chen
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
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11
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Orhan F, Ceyran E. Identification of novel halophilic/halotolerant bacterial species producing compatible solutes. Int Microbiol 2022; 26:219-229. [PMID: 36342583 DOI: 10.1007/s10123-022-00289-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 10/15/2022] [Accepted: 10/25/2022] [Indexed: 11/09/2022]
Abstract
Ectoine and hydroxyectoine are compatible solutes with enormous potential for use in the medical and cosmetic industries. Considering the excellent osmoprotective properties of these compatible solutes, we investigate the presence of four compatible solutes (ectoine, hydroxyectoine, proline, and glutamic acid) quantitatively by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in forty-five halophilic/halotolerant bacterial isolates. We determined ectoine production by Marinibacillus sp., Nesterenkonia xinjiangensis, Halobacillus sp., Bacillus patagoniensis, Virgibacillus picturae, Halomonas neptunia, Bacillus patagoniensis, Gracilibacillus sp., Thalassobacillus devorans, Microbacterium sp., Nesterenkonia sp., and Bacillus agaradhaerens, and this production was NaCl dependent. Additionally, the production of hydroxyectoine was observed in six bacterial isolates (Nesterenkonia xinjiangensis, Halobacillus sp., Halomonas neptunia, Thalassobacillus devorans, Nesterenkonia sp., and Bacillus agaradhaerens) which was NaCl and temperature dependent. The study identified new bacterial isolates producing ectoine or hydroxyectoine. While the ectoine production in many different Bacillus members and a few Nesterenkonia have been documented before, ectoine production by Bacillus patagoniensis and Nesterenkonia xinjiangensis has not been shown so far. Further, ectoine production by a member of the genus Thalassobacillus (Thalassobacillus devorans) was demonstrated experimentally for the first time. The findings reported in the study may serve as a basis for the large-scale production of ectoine and hydroxyectoine in the future.
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Affiliation(s)
- Furkan Orhan
- Department of Molecular Biology and Genetics, Agri İbrahim Cecen University, Agri, 04200, Turkey.
- Central Research and Application Laboratory, Agri Ibrahim Cecen University, Agri, 04200, Turkey.
| | - Ertuğrul Ceyran
- Central Research and Application Laboratory, Agri Ibrahim Cecen University, Agri, 04200, Turkey
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12
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Czech L, Gertzen C, Smits SHJ, Bremer E. Guilty by association: importers, exporters and
MscS
‐type mechanosensitive channels encoded in biosynthetic gene clusters for the stress‐protectant ectoine. Environ Microbiol 2022; 24:5306-5331. [DOI: 10.1111/1462-2920.16203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 09/07/2022] [Indexed: 11/28/2022]
Affiliation(s)
- Laura Czech
- Department of Biology, Laboratory for Microbiology and Center for Synthetic Microbiology (SYNMIKRO) Philipps‐University Marburg Marburg Germany
- Department of Chemistry and Center for Synthetic Microbiology (SYNMIKRO) Philipps‐University Marburg Marburg Germany
| | - Christoph Gertzen
- Center for Structural Studies (CSS) Heinrich‐Heine‐University Düsseldorf Düsseldorf Germany
- Institute of Pharmaceutical and Medicinal Chemistry Heinrich‐Heine‐University Düsseldorf Düsseldorf Germany
| | - Sander H. J. Smits
- Center for Structural Studies (CSS) Heinrich‐Heine‐University Düsseldorf Düsseldorf Germany
- Institute of Biochemistry Heinrich Heine University Düsseldorf Düsseldorf Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology and Center for Synthetic Microbiology (SYNMIKRO) Philipps‐University Marburg Marburg Germany
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13
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Bhutani N, Maheshwari R, Sharma N, Kumar P, Dang AS, Suneja P. Characterization of halo-tolerant plant growth promoting endophytic Bacillus licheniformis MHN 12. J Genet Eng Biotechnol 2022; 20:113. [PMID: 35920988 PMCID: PMC9349330 DOI: 10.1186/s43141-022-00407-3] [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: 09/10/2021] [Accepted: 07/22/2022] [Indexed: 11/24/2022]
Abstract
Background Endophytic bacteria overlay significant role in plant growth promotion, eliminating phyto-pathogens and combating stress-conditions. In the present study, we aimed to screen high salt tolerant bacteria and study their adaptive response to elevated salt concentrations. A total of 46 endophytic bacterial isolates from Vigna radiata were screened for salt tolerance. The high salt tolerant endophytic isolate was characterized for alteration in morphology, growth rate, protein profiling, and compatible solute concentrations. Results The isolate MHN12, based upon biochemical characterization and partial 16S rDNA sequencing identified as B. licheniformis (accession number MG273753) was able to tolerate up to 15% NaCl (Sodium Chloride) (2.6 M) concentration. The isolate possessed 1-aminocyclopropane-1-carboxylic acid deaminase (ACCD) activity along with indole acetic acid (IAA), siderophore, ammonia, organic acid and hydrogen cyanide (HCN) production. Accumulation of proline was apparent up to 7.5% NaCl concentration and declined afterwards. Ultrastructure analysis using TEM (transmission electron microscopy) revealed the morphological alteration from rods to filaments. Conclusion Acclimatization to salt stress and plant growth promoting activities could contribute to utilization of this bacterium as bioinoculant to enhance the crop yield and discourage the application of chemical fertilizers.
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Affiliation(s)
- Namita Bhutani
- Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana, 124001, India
| | - Rajat Maheshwari
- Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana, 124001, India
| | - Nidhi Sharma
- Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana, 124001, India
| | - Pradeep Kumar
- Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana, 124001, India
| | - Amita Suneja Dang
- Centre for Medical Biotechnology, Maharshi Dayanand University, Rohtak, Haryana, 124001, India
| | - Pooja Suneja
- Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana, 124001, India.
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14
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Stecker D, Hoffmann T, Link H, Commichau FM, Bremer E. L-Proline Synthesis Mutants of Bacillus subtilis Overcome Osmotic Sensitivity by Genetically Adapting L-Arginine Metabolism. Front Microbiol 2022; 13:908304. [PMID: 35783388 PMCID: PMC9245794 DOI: 10.3389/fmicb.2022.908304] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 05/17/2022] [Indexed: 11/30/2022] Open
Abstract
The accumulation of the compatible solute L-proline by Bacillus subtilis via synthesis is a cornerstone in the cell’s defense against high salinity as the genetic disruption of this biosynthetic process causes osmotic sensitivity. To understand how B. subtilis could potentially cope with high osmolarity surroundings without the functioning of its natural osmostress adaptive L-proline biosynthetic route (ProJ-ProA-ProH), we isolated suppressor strains of proA mutants under high-salinity growth conditions. These osmostress-tolerant strains carried mutations affecting either the AhrC transcriptional regulator or its operator positioned in front of the argCJBD-carAB-argF L-ornithine/L-citrulline/L-arginine biosynthetic operon. Osmostress protection assays, molecular analysis and targeted metabolomics showed that these mutations, in conjunction with regulatory mutations affecting rocR-rocDEF expression, connect and re-purpose three different physiological processes: (i) the biosynthetic pathway for L-arginine, (ii) the RocD-dependent degradation route for L-ornithine, and (iii) the last step in L-proline biosynthesis. Hence, osmostress adaptation without a functional ProJ-ProA-ProH route is made possible through a naturally existing, but inefficient, metabolic shunt that allows to substitute the enzyme activity of ProA by feeding the RocD-formed metabolite γ-glutamate-semialdehyde/Δ1-pyrroline-5-carboxylate into the biosynthetic route for the compatible solute L-proline. Notably, in one class of mutants, not only substantial L-proline pools but also large pools of L-citrulline were accumulated, a rather uncommon compatible solute in microorganisms. Collectively, our data provide an example of the considerable genetic plasticity and metabolic resourcefulness of B. subtilis to cope with everchanging environmental conditions.
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Affiliation(s)
- Daniela Stecker
- Faculty of Biology, Philipps-University Marburg, Marburg, Germany
| | - Tamara Hoffmann
- Faculty of Biology, Philipps-University Marburg, Marburg, Germany
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
| | - Hannes Link
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Fabian M. Commichau
- Insitute of Microbiology and Genetics, Georg-August-University Göttingen, Göttingen, Germany
- Institute for Biotechnology, BTU Cottbus-Senftenberg, Senftenberg, Germany
| | - Erhard Bremer
- Faculty of Biology, Philipps-University Marburg, Marburg, Germany
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
- *Correspondence: Erhard Bremer,
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15
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Chen SY, Peng TC, Huang SZ, Chien CC. Isolation of an ectoine-producing Sinobaca sp. and identification of genes that are involved in ectoine biosynthesis. FEMS Microbiol Lett 2022; 369:6596284. [PMID: 35641156 DOI: 10.1093/femsle/fnac046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Revised: 04/07/2022] [Accepted: 05/26/2022] [Indexed: 11/13/2022] Open
Abstract
A moderate halophilic bacterium that could accumulate ectoine and hydroxyectoine was isolated from soil near a salt mine and was identified as a Sinobaca sp. (designed strain H24) according to 16S rRNA gene sequence analysis. The bacterium grew well in the presence of 1 to 2 M NaCl, while growth in a medium that contained 2 M NaCl led to higher accumulation of ectoines. The yields of ectoine and hydroxyectoine by Sinobaca sp. H24 reached 11.27 mg/L and 1.34 mg/L, respectively, when cultured in the following medium: NaCl (2 M), peptone (5 g/L), yeast extract (1 g/L), NH4Cl (0.02 M), KH2PO4 (1 M), K2HPO4 (0.1 M) and glycerol (1% w/v). Genes that are involved in ectoine biosynthesis of Sinobaca sp. H24 were also identified, and their sequences were determined by a metagenomics approach. The results demonstrated that Sinobaca sp. H24 possesses ectoine metabolism genes for both ectoine biosynthesis (ectA, ectB, ectC and ectD) and ectoine degradation (doeA). Genes that are related to ectoine biosynthesis, such as lysC and asd, were also characterized. The identification and characterization results for ectoine/hydroxyectoine biosynthesis genes are in agreement with the physiology of Sinobaca sp. H24 as a potential candidate for ectoine production for industrial applications. This report established for the first time the accumulation of ectoine/hydroxyectoine in Sinobaca sp. and characterized the genes that are involved in ectoine/hydroxyectoine biosynthesis in Sinobaca sp. H24.
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Affiliation(s)
- Shan-Yu Chen
- Graduate School of Biotechnology and Bioengineering, Yuan Ze University, Taoyuan, Taiwan
| | - Tzu-Chia Peng
- Graduate School of Biotechnology and Bioengineering, Yuan Ze University, Taoyuan, Taiwan
| | - Shan-Ze Huang
- Graduate School of Biotechnology and Bioengineering, Yuan Ze University, Taoyuan, Taiwan
| | - Chih-Ching Chien
- Graduate School of Biotechnology and Bioengineering, Yuan Ze University, Taoyuan, Taiwan
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16
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Zhang T, Zhang X, Li Y, Yang N, Qiao L, Miao Z, Xing J, Zhu D. Study of osmoadaptation mechanisms of halophilic Halomonas alkaliphila XH26 under salt stress by transcriptome and ectoine analysis. Extremophiles 2022; 26:14. [PMID: 35229247 DOI: 10.1007/s00792-022-01256-1] [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: 04/07/2021] [Accepted: 01/04/2022] [Indexed: 11/04/2022]
Abstract
Halophilic bacteria such as the genus Halomonas are promising candidates in diverse industrial, agricultural and biomedical applications. Here, we successfully isolated a halophilic Halomonas alkaliphila strain XH26 from Xiaochaidan Salt Lake, and studied its osmoadaptation strategies using transcriptome and ectoine analysis. Divergent mechanisms were involved in osmoadaptation at different salinities in H. alkaliphila XH26. At moderate salinity (6% NaCl), increased transcriptions of ABC transporters related to iron (III), phosphate, phosphonate, monosaccharide and oligosaccharide import were observed. At high salinity (15% NaCl), transcriptions of flagellum assembly and cell motility were significantly inhibited. The transcriptional levels of ABC transporter genes related to iron (III) and iron3+-hydroxamate import, glycine betaine and putrescine uptake, and cytochrome biogenesis and assembly were significantly up-regulated. Ectoine synthesis and accumulation was significantly increased under salt stress, and the increased transcriptional expressions of ectoine synthesis genes ectB and ectC may play a key role in high salinity induced osmoadaptation. At extreme high salinity (18% NaCl), 5-hydroxyectoine and ectoine worked together to maintain cell survival. Together these results give valuable insights into the osmoadaptation mechanisms of H. alkaliphila XH26, and provide useful information for further engineering this specific strain for increased ectoine synthesis and related applications.
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Affiliation(s)
- Tiantian Zhang
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, People's Republic of China
| | - Xin Zhang
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, People's Republic of China
| | - Yongzhen Li
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, People's Republic of China
| | - Ning Yang
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, People's Republic of China
| | - Lijuan Qiao
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, People's Republic of China
| | - Zengqiang Miao
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, People's Republic of China
| | - Jiangwa Xing
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, People's Republic of China.
| | - Derui Zhu
- Research Centre of Basic Medical Sciences, Medical College, Qinghai University, Xining, 810016, People's Republic of China.
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17
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Sun X, Zhao J, Zhou X, Bei Q, Xia W, Zhao B, Zhang J, Jia Z. Salt tolerance-based niche differentiation of soil ammonia oxidizers. THE ISME JOURNAL 2022; 16:412-422. [PMID: 34389794 PMCID: PMC8776802 DOI: 10.1038/s41396-021-01079-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 07/20/2021] [Accepted: 07/26/2021] [Indexed: 02/03/2023]
Abstract
Ammonia oxidizers are key players in the global nitrogen cycle, yet little is known about their ecological performances and adaptation strategies for growth in saline terrestrial ecosystems. This study combined 13C-DNA stable-isotope probing (SIP) microcosms with amplicon and shotgun sequencing to reveal the composition and genomic adaptations of active ammonia oxidizers in a saline-sodic (solonetz) soil with high salinity and pH (20.9 cmolc exchangeable Na+ kg-1 soil and pH 9.64). Both ammonia-oxidizing archaea (AOA) and bacteria (AOB) exhibited strong nitrification activities, although AOB performed most of the ammonia oxidation observed in the solonetz soil and in the farmland soil converted from solonetz soil. Members of the Nitrosococcus, which are more often associated with aquatic habitats, were identified as the dominant ammonia oxidizers in the solonetz soil with the first direct labeling evidence, while members of the Nitrosospira were the dominant ammonia oxidizers in the farmland soil, which had much lower salinity and pH. Metagenomic analysis of "Candidatus Nitrosococcus sp. Sol14", a new species within the Nitrosococcus lineage, revealed multiple genomic adaptations predicted to facilitate osmotic and pH homeostasis in this extreme habitat, including direct Na+ extrusion/H+ import and the ability to increase intracellular osmotic pressure by accumulating compatible solutes. Comparative genomic analysis revealed that variation in salt-tolerance mechanisms was the primary driver for the niche differentiation of ammonia oxidizers in saline-sodic soils. These results demonstrate how ammonia oxidizers can adapt to saline-sodic soil with excessive Na+ content and provide new insights on the nitrogen cycle in extreme terrestrial ecosystems.
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Affiliation(s)
- Xiangxin Sun
- grid.9227.e0000000119573309State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
| | - Jun Zhao
- grid.15276.370000 0004 1936 8091Institute for Food and Agricultural Sciences (IFAS), Department of Microbiology & Cell Science, Fort Lauderdale Research and Education Center, University of Florida, Davie, FL USA
| | - Xue Zhou
- grid.257065.30000 0004 1760 3465College of Agricultural Science and Engineering, Hohai University, Nanjing, Jiangsu Province China
| | - Qicheng Bei
- grid.419554.80000 0004 0491 8361Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Weiwei Xia
- grid.260478.f0000 0000 9249 2313College of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, Jiangsu Province China
| | - Bingzi Zhao
- grid.9227.e0000000119573309State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
| | - Jiabao Zhang
- grid.9227.e0000000119573309State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
| | - Zhongjun Jia
- grid.9227.e0000000119573309State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, China
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18
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HU Q, ZHAO J, LUO R, YOU L, ZHAO X, SU C, ZHANG H. The influence of microbial bacterial proteins on metabolites in the chilled tan sheep meat. FOOD SCIENCE AND TECHNOLOGY 2022. [DOI: 10.1590/fst.24822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Mantas MJQ, Nunn PB, Ke Z, Codd GA, Barker D. Genomic insights into the biosynthesis and physiology of the cyanobacterial neurotoxin 2,4-diaminobutanoic acid (2,4-DAB). PHYTOCHEMISTRY 2021; 192:112953. [PMID: 34598041 DOI: 10.1016/j.phytochem.2021.112953] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 09/09/2021] [Accepted: 09/11/2021] [Indexed: 06/13/2023]
Abstract
Cyanobacteria are an ancient clade of photosynthetic prokaryotes, whose worldwide occurrence, especially in water, presents health hazards to humans and animals due to the production of a range of toxins (cyanotoxins). These include the sometimes co-occurring, non-encoded diaminoacid neurotoxins 2,4-diaminobutanoic acid (2,4-DAB) and its structural analogue β-N-methylaminoalanine (BMAA). Knowledge of the biosynthetic pathway for 2,4-DAB, and its role in cyanobacteria, is lacking. The aspartate 4-phosphate pathway is a known route of 2,4-DAB biosynthesis in other bacteria and in some plant species. Another pathway to 2,4-DAB has been described in Lathyrus species. Here, we use bioinformatics analyses to investigate hypotheses concerning 2,4-DAB biosynthesis in cyanobacteria. We assessed the presence or absence of each enzyme in candidate biosynthesis routes, the aspartate 4-phosphate pathway and a pathway to 2,4-DAB derived from S-adenosyl-L-methionine (SAM), in 130 cyanobacterial genomes using sequence alignment, profile hidden Markov models, substrate specificity/active site identification and the reconstruction of gene phylogenies. In the aspartate 4-phosphate pathway, for the 18 species encoding diaminobutanoate-2-oxo-glutarate transaminase, the co-localisation of genes encoding the transaminase with the downstream decarboxylase or ectoine synthase - often within hybrid non-ribosomal peptide synthetase (NRPS)-polyketide synthases (PKS) clusters, NRPS-independent siderophore (NIS) clusters and incomplete ectoine clusters - is compatible with the hypothesis that some cyanobacteria use the aspartate 4-phosphate pathway for 2,4-DAB production. Through this route, in cyanobacteria, 2,4-DAB may be functionally associated with environmental iron-scavenging, via the production of siderophores of the schizokinen/synechobactin type and of some polyamines. In the pathway to 2,4-DAB derived from SAM, eight cyanobacterial species encode homologs of SAM-dependent 3-amino-3-carboxypropyl transferases. Other enzymes in this pathway have not yet been purified or sequenced. Ultimately, the biosynthesis of 2,4-DAB appears to be either restricted to some cyanobacterial species, or there may be multiple and additional routes, and roles, for the synthesis of this neurotoxin.
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Affiliation(s)
- Maria José Q Mantas
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, The King's Buildings, Edinburgh, EH9 3FL, United Kingdom.
| | - Peter B Nunn
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, United Kingdom.
| | - Ziying Ke
- School of Biological Sciences, Roger Land Building, The King's Buildings, Alexander Crum Brown Road, Edinburgh, EH9 3FF, United Kingdom; Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, United Kingdom.
| | - Geoffrey A Codd
- School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, United Kingdom; School of Life Sciences, University of Dundee, Dow Street, Dundee, DD1 5EH, United Kingdom.
| | - Daniel Barker
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, The King's Buildings, Edinburgh, EH9 3FL, United Kingdom.
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20
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Ma Q, Xia L, Wu H, Zhuo M, Yang M, Zhang Y, Tan M, Zhao K, Sun Q, Xu Q, Chen N, Xie X. Metabolic engineering of Escherichia coli for efficient osmotic stress-free production of compatible solute hydroxyectoine. Biotechnol Bioeng 2021; 119:89-101. [PMID: 34612520 DOI: 10.1002/bit.27952] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/22/2021] [Accepted: 09/28/2021] [Indexed: 11/08/2022]
Abstract
Compatible solutes are key for the ability of halophilic bacteria to resist high osmotic stress. They have received wide attention from researchers for their excellent osmotic protection properties. Hydroxyectoine is a particularly important compatible solute, but its production by microbes faces several challenges, including low titer/yield, the presence of the byproduct ectoine, and the requirement of high salinity. Here, we aimed to metabolically engineer Escherichia coli to efficiently produce hydroxyectoine in the absence of osmotic stress without accumulating the byproduct ectoine. First, combinatorial optimization of the expression strength of key genes in the ectoine synthesis module and hydroxyectoine synthesis module was conducted. After optimization of the expression of these genes, 12.12 g/L hydroxyectoine and 0.24 g/L ectoine were obtained at 36 h in shake-flask fermentation with the addition of the co-substrate α-ketoglutarate. Further optimization of the addition of α-ketoglutarate achieved the sole production of hydroxyectoine (i.e., no ectoine accumulation), indicating that the supply of α-ketoglutarate is critically important for sole hydroxyectoine production. Finally, quorum sensing-based auto-regulation of intracellular α-ketoglutarate pool was implemented as an alternative to α-ketoglutarate addition by coupling the expression of sucA with the esaI/esaR circuit, which led to 14.93 g/L hydroxyectoine with a unit cell yield of 1.678 g/g and no ectoine accumulation in the absence of osmotic stress. This is the highest reported titer of sole hydroxyectoine production under salinity-free fermentation to date.
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Affiliation(s)
- Qian Ma
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China.,College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China.,National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology, Tianjin, China
| | - Li Xia
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China.,College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Heyun Wu
- College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin, China
| | - Mingyang Zhuo
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China.,College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Mengya Yang
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China.,College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Ying Zhang
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China.,College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Miao Tan
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China.,College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Kexin Zhao
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China.,College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Quanwei Sun
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China.,College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Qingyang Xu
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China.,College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China.,National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology, Tianjin, China
| | - Ning Chen
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China.,College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China.,National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology, Tianjin, China
| | - Xixian Xie
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin University of Science and Technology, Tianjin, China.,College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China.,National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology, Tianjin, China
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21
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Argandoña M, Piubeli F, Reina‐Bueno M, Nieto JJ, Vargas C. New insights into hydroxyectoine synthesis and its transcriptional regulation in the broad-salt growing halophilic bacterium Chromohalobacter salexigens. Microb Biotechnol 2021; 14:1472-1493. [PMID: 33955667 PMCID: PMC8313267 DOI: 10.1111/1751-7915.13799] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/15/2021] [Accepted: 02/28/2021] [Indexed: 11/28/2022] Open
Abstract
Elucidating the mechanisms controlling the synthesis of hydroxyectoine is important to design novel genetic engineering strategies for optimizing the production of this biotechnologically relevant compatible solute. The genome of the halophilic bacterium Chromohalobacter salexigens carries two ectoine hydroxylase genes, namely ectD and ectE, whose encoded proteins share the characteristic consensus motif of ectoine hydroxylases but showed only a 51.9% identity between them. In this work, we have shown that ectE encodes a secondary functional ectoine hydroxylase and that the hydroxyectoine synthesis mediated by this enzyme contributes to C.␣salexigens thermoprotection. The evolutionary pattern of EctD and EctE and related proteins suggests that they may have arisen from duplication of an ancestral gene preceding the directional divergence that gave origin to the orders Oceanospirillales and Alteromonadales. Osmoregulated expression of ectD at exponential phase, as well as the thermoregulated expression of ectD at the stationary phase, seemed to be dependent on the general stress factor RpoS. In contrast, expression of ectE was always RpoS-dependent regardless of the growth phase and osmotic or heat stress conditions tested. The data presented here suggest that the AraC-GlxA-like EctZ transcriptional regulator, whose encoding gene lies upstream of ectD, plays a dual function under exponential growth as both a transcriptional activator of osmoregulated ectD expression and a repressor of ectE transcription, privileging the synthesis of the main ectoine hydroxylase EctD. Inactivation of ectZ resulted in a higher amount of the total ectoines pool at the expenses of a higher accumulation of ectoine, with maintenance of the hydroxyectoine levels. In addition to the transcriptional control, our results suggest a strong post-transcriptional regulation of hydroxyectoine synthesis. Data on the accumulation of ectoine and hydroxyectoine in rpoS and ectZ strains pave the way for using these genetic backgrounds for metabolic engineering for hydroxyectoine production.
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Affiliation(s)
- Montserrat Argandoña
- Department of Microbiology and ParasitologyFaculty of PharmacyUniversity of SevillaC/ Profesor García González, 2Sevilla41012Spain
| | - Francine Piubeli
- Department of Microbiology and ParasitologyFaculty of PharmacyUniversity of SevillaC/ Profesor García González, 2Sevilla41012Spain
| | - Mercedes Reina‐Bueno
- Department of Microbiology and ParasitologyFaculty of PharmacyUniversity of SevillaC/ Profesor García González, 2Sevilla41012Spain
| | - Joaquín J. Nieto
- Department of Microbiology and ParasitologyFaculty of PharmacyUniversity of SevillaC/ Profesor García González, 2Sevilla41012Spain
| | - Carmen Vargas
- Department of Microbiology and ParasitologyFaculty of PharmacyUniversity of SevillaC/ Profesor García González, 2Sevilla41012Spain
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22
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Hermann L, Mais CN, Czech L, Smits SHJ, Bange G, Bremer E. The ups and downs of ectoine: structural enzymology of a major microbial stress protectant and versatile nutrient. Biol Chem 2021; 401:1443-1468. [PMID: 32755967 DOI: 10.1515/hsz-2020-0223] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 07/22/2020] [Indexed: 12/13/2022]
Abstract
Ectoine and its derivative 5-hydroxyectoine are compatible solutes and chemical chaperones widely synthesized by Bacteria and some Archaea as cytoprotectants during osmotic stress and high- or low-growth temperature extremes. The function-preserving attributes of ectoines led to numerous biotechnological and biomedical applications and fostered the development of an industrial scale production process. Synthesis of ectoines requires the expenditure of considerable energetic and biosynthetic resources. Hence, microorganisms have developed ways to exploit ectoines as nutrients when they are no longer needed as stress protectants. Here, we summarize our current knowledge on the phylogenomic distribution of ectoine producing and consuming microorganisms. We emphasize the structural enzymology of the pathways underlying ectoine biosynthesis and consumption, an understanding that has been achieved only recently. The synthesis and degradation pathways critically differ in the isomeric form of the key metabolite N-acetyldiaminobutyric acid (ADABA). γ-ADABA serves as preferred substrate for the ectoine synthase, while the α-ADABA isomer is produced by the ectoine hydrolase as an intermediate in catabolism. It can serve as internal inducer for the genetic control of ectoine catabolic genes via the GabR/MocR-type regulator EnuR. Our review highlights the importance of structural enzymology to inspire the mechanistic understanding of metabolic networks at the biological scale.
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Affiliation(s)
- Lucas Hermann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Biochemistry and Synthetic Biology of Microbial Metabolism Group, Max Planck Institute for Terrestrial Microbiology, Karl-von Frisch Str. 10, D-35043 Marburg, Germany
| | - Christopher-Nils Mais
- Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Laura Czech
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Sander H J Smits
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany.,Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
| | - Gert Bange
- Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Center for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
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23
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Frank C, Hoffmann T, Zelder O, Felle MF, Bremer E. Enhanced Glutamate Synthesis and Export by the Thermotolerant Emerging Industrial Workhorse Bacillus methanolicus in Response to High Osmolarity. Front Microbiol 2021; 12:640980. [PMID: 33897645 PMCID: PMC8060640 DOI: 10.3389/fmicb.2021.640980] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Accepted: 03/01/2021] [Indexed: 11/13/2022] Open
Abstract
The thermotolerant methylotroph Bacillus methanolicus MGA3 was originally isolated from freshwater marsh soil. Due to its ability to use methanol as sole carbon and energy source, B. methanolicus is increasingly explored as a cell factory for the production of amino acids, fine chemicals, and proteins of biotechnological interest. During high cell density fermentation in industrial settings with the membrane-permeable methanol as the feed, the excretion of low molecular weight products synthesized from it will increase the osmotic pressure of the medium. This in turn will impair cell growth and productivity of the overall biotechnological production process. With this in mind, we have analyzed the core of the physiological adjustment process of B. methanolicus MGA3 to sustained high osmolarity surroundings. Through growth assays, we found that B. methanolicus MGA3 possesses only a restricted ability to cope with sustained osmotic stress. This finding is consistent with the ecophysiological conditions in the habitat from which it was originally isolated. None of the externally provided compatible solutes and proline-containing peptides affording osmostress protection for Bacillus subtilis were able to stimulate growth of B. methanolicus MGA3 at high salinity. B. methanolicus MGA3 synthesized the moderately effective compatible solute L-glutamate in a pattern such that the cellular pool increased concomitantly with increases in the external osmolarity. Counterintuitively, a large portion of the newly synthesized L-glutamate was excreted. The expression of the genes (gltAB and gltA2) for two L-glutamate synthases were upregulated in response to high salinity along with that of the gltC regulatory gene. Such a regulatory pattern of the system(s) for L-glutamate synthesis in Bacilli is new. Our findings might thus be generally relevant to understand the production of the osmostress protectant L-glutamate by those Bacilli that exclusively rely on this compatible solute for their physiological adjustment to high osmolarity surroundings.
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Affiliation(s)
- Christine Frank
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Marburg, Germany
| | - Tamara Hoffmann
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Marburg, Germany.,Center for Synthetic Microbiology (SYNMIKRO), Philipps-University Marburg, Marburg, Germany
| | - Oskar Zelder
- BASF SE, RWB/EC - A030 - L3/10, Ludwigshafen, Germany
| | - Max F Felle
- BASF SE, RWB/EC - A030 - L3/10, Ludwigshafen, Germany
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Marburg, Germany.,Center for Synthetic Microbiology (SYNMIKRO), Philipps-University Marburg, Marburg, Germany
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24
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Liu M, Liu H, Shi M, Jiang M, Li L, Zheng Y. Microbial production of ectoine and hydroxyectoine as high-value chemicals. Microb Cell Fact 2021; 20:76. [PMID: 33771157 PMCID: PMC7995798 DOI: 10.1186/s12934-021-01567-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 03/16/2021] [Indexed: 12/20/2022] Open
Abstract
Ectoine and hydroxyectoine as typical representatives of compatible solutes are not only essential for extremophiles to survive in extreme environments, but also widely used in cosmetic and medical industries. Ectoine was traditionally produced by Halomonas elongata through a "bacterial milking" process, of which the marked feature is using a high-salt medium to stimulate ectoine biosynthesis and then excreting ectoine into a low-salt medium by osmotic shock. The optimal hydroxyectoine production was achieved by optimizing the fermentation process of Halomonas salina. However, high-salinity broth exacerbates the corrosion to fermenters, and more importantly, brings a big challenge to the subsequent wastewater treatment. Therefore, increasing attention has been paid to reducing the salinity of the fermentation broth but without a sacrifice of ectoine/hydroxyectoine production. With the fast development of functional genomics and synthetic biology, quite a lot of progress on the bioproduction of ectoine/hydroxyectoine has been achieved in recent years. The importation and expression of an ectoine producing pathway in a non-halophilic chassis has so far achieved the highest titer of ectoine (~ 65 g/L), while rational flux-tuning of halophilic chassis represents a promising strategy for the next-generation of ectoine industrial production. However, efficient conversion of ectoine to hydroxyectoine, which could benefit from a clearer understanding of the ectoine hydroxylase, is still a challenge to date.
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Affiliation(s)
- Mengshuang Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Hui Liu
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Meng Shi
- Department of Microbiology, University of Washington, Seattle, USA
| | - Mingyue Jiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Lingling Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Yanning Zheng
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China.
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25
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Ayadi H, Frikha-Dammak D, Fakhfakh J, Chamkha M, Hassairi I, Allouche N, Sayadi S, Maalej S. The saltern-derived Paludifilum halophilum DSM 102817 T is a new high-yield ectoines producer in minimal medium and under salt stress conditions. 3 Biotech 2020; 10:533. [PMID: 33214980 DOI: 10.1007/s13205-020-02512-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 10/27/2020] [Indexed: 02/07/2023] Open
Abstract
In the present study, the growth conditions and accumulation of ectoines (ectoine and hydroxyectoine) by Paludifilum halophilum DSM 102817T under salt stress conditions have been investigated. The productivity assay of this strain for ectoines revealed that the highest cellular content was reached in the minimal glucose sea water medium (SW-15) within 15% salinity. The addition of 0.1% (w/v) aspartic acid to the medium allowed an average of four times higher biomass production, and a dry mycelial biomass of 1.76 g L-1 was obtained after 6 days of growth in shake flasks at 40 °C and 200 rpm. Among the inorganic cations supplemented to the glucose SW-15 medium, the addition of 1 mM Fe2+ yielded the highest amount of mycelial biomass (3.45 g L-1) and total ectoines content (119 mg g-1), resulting in about 410 mg L-1 of products at the end of exponential growth phase. After 1 h of incubation in an osmotic downshock solution containing 2% NaCl, 70% of this content was released by the mycelium, and recovering cells maintained a high survival, with a maximal growth rate (µ max) of about 93% of the control population exposed to 15% NaCl. During growth at optimal salinity and temperature (15% NaCl and 40 °C), P. halophilum developed a compact and circular pellets that were easy to separate by simple decantation from both fermentation media and after hypoosmotic shock. Overall, the ectoines excreting P. halophilum could be a promising resource for ectoines production in a commercially valuable culture medium and at a large-scale fermentation process.
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Affiliation(s)
- Houda Ayadi
- Laboratoire de Biodiversité Marine et Environment (LR18ES/30), Université de Sfax, BP 1171, 3000 Sfax, Tunisia
| | - Donyez Frikha-Dammak
- Laboratoire de Biodiversité Marine et Environment (LR18ES/30), Université de Sfax, BP 1171, 3000 Sfax, Tunisia
| | - Jawhar Fakhfakh
- Laboratore de Chimie Organique (LR17ES/08), Unité des Substances Naturelles, Université de Sfax, BP 1171, 3000 Sfax, Tunisia
| | - Mohamed Chamkha
- Laboratore des Bioprocédés Environnementaux, Centre de Biotechnologie de Sfax, BP 1177, 3018 Sfax, Tunisia
| | - Ilem Hassairi
- Unité de Valorisation des résultats de la Recherche, Centre de Biotechnologie de Sfax, BP 1177, 3018 Sfax, Tunisia
| | - Noureddine Allouche
- Laboratore de Chimie Organique (LR17ES/08), Unité des Substances Naturelles, Université de Sfax, BP 1171, 3000 Sfax, Tunisia
| | - Sami Sayadi
- Center for Sustainable Development, College of Arts and Sciences, Qatar University, 2713 Doha, Qatar
| | - Sami Maalej
- Laboratoire de Biodiversité Marine et Environment (LR18ES/30), Université de Sfax, BP 1171, 3000 Sfax, Tunisia
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26
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Becker J, Wittmann C. Microbial production of extremolytes — high-value active ingredients for nutrition, health care, and well-being. Curr Opin Biotechnol 2020; 65:118-128. [DOI: 10.1016/j.copbio.2020.02.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 01/09/2023]
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27
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Fatollahi P, Ghasemi M, Yazdian F, Sadeghi A. Ectoine production in bioreactor by Halomonas elongata DSM2581: Using MWCNT and Fe-nanoparticle. Biotechnol Prog 2020; 37:e3073. [PMID: 32862555 DOI: 10.1002/btpr.3073] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 08/06/2020] [Accepted: 08/07/2020] [Indexed: 12/27/2022]
Abstract
Halomonas elongate produces ectoine to protect itselt from environmental stresses. In this research, important factors in the production of ectoine were optimized using statistical methods to achieve the best production efficiency in bioreactor. Screening important variables (ectoine, hydroxyectoine, l-aspartic acid, and glutamate) on H. elongate growth showed that ectoine and l-aspartic acid directly affect ectoine production. Two nanostructures, multiwalled carbon nanotube (MWCNT) and iron oxide nanoparticle (Fe2 O3 NPs), were used to increase the availability of substrate for the microorganism. The results showed that Fe2 O3 nanoparticles and MWCNT could have a negative or positive effect on bacterial growth and ectoine production depending on the concentration of nanoparticles. At optimized conditions, the amounts of bacterial growth and ectoine production in fermenter were 10.4 g/L and 14.25 g/L, respectively. Therefore, it could be concluded that nanoparticles improve bacterial growth and ectoine production at optimized concentrations.
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Affiliation(s)
- Parvaneh Fatollahi
- Department of Life Science Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran
| | - Mina Ghasemi
- Faculty of Engineering, Islamic Azad University, West Tehran Branch, Tehran, Iran
| | - Fatemeh Yazdian
- Department of Life Science Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran
| | - Akram Sadeghi
- Microbial Biotechnology and Biosafety Department, Agricultural Biotechnology Research Institute of Iran (ABRII), AREEO, Karaj, Iran
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28
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Bethlehem L, Moritz KD. Boosting Escherichia coli's heterologous production rate of ectoines by exploiting the non-halophilic gene cluster from Acidiphilium cryptum. Extremophiles 2020; 24:733-747. [PMID: 32699914 PMCID: PMC7445199 DOI: 10.1007/s00792-020-01188-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/06/2020] [Indexed: 12/26/2022]
Abstract
The compatible solutes ectoine and hydroxyectoine are synthesized by many microorganisms as potent osmostress and desiccation protectants. Besides their successful implementation into various skincare products, they are of increasing biotechnological interest due to new applications in the healthcare sector. To meet this growing demand, efficient heterologous overproduction solutions for ectoines need to be found. This study is the first report on the utilization of the non-halophilic biosynthesis enzymes from Acidiphilium cryptum DSM 2389T for efficient heterologous production of ectoines in Escherichia coli. When grown at low salt conditions (≤ 0.5% NaCl) and utilizing the cheap carbon source glycerol, the production was characterized by the highest specific production of ectoine [2.9 g/g dry cell weight (dcw)] and hydroxyectoine (2.2 g/g dcw) reported so far and occurred at rapid specific production rates of up to 345 mg/(g dcw × h). This efficiency in production was related to an unprecedented carbon source conversion rate of approx. 60% of the theoretical maximum. These findings confirm the unique potential of the here implemented non-halophilic enzymes for ectoine production processes in E. coli and demonstrate the first efficient heterologous solution for hydroxyectoine production, as well as an extraordinary efficient low-salt ectoine production.
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Affiliation(s)
- Lukas Bethlehem
- Institute for Microbiology and Biotechnology, University Bonn, Meckenheimer Allee 168, 53115, Bonn, Germany.
| | - Katharina D Moritz
- Institute for Microbiology and Biotechnology, University Bonn, Meckenheimer Allee 168, 53115, Bonn, Germany
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29
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Mais CN, Hermann L, Altegoer F, Seubert A, Richter AA, Wernersbach I, Czech L, Bremer E, Bange G. Degradation of the microbial stress protectants and chemical chaperones ectoine and hydroxyectoine by a bacterial hydrolase-deacetylase complex. J Biol Chem 2020; 295:9087-9104. [PMID: 32404365 PMCID: PMC7335791 DOI: 10.1074/jbc.ra120.012722] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 05/06/2020] [Indexed: 12/12/2022] Open
Abstract
When faced with increased osmolarity in the environment, many bacterial cells accumulate the compatible solute ectoine and its derivative 5-hydroxyectoine. Both compounds are not only potent osmostress protectants, but also serve as effective chemical chaperones stabilizing protein functionality. Ectoines are energy-rich nitrogen and carbon sources that have an ecological impact that shapes microbial communities. Although the biochemistry of ectoine and 5-hydroxyectoine biosynthesis is well understood, our understanding of their catabolism is only rudimentary. Here, we combined biochemical and structural approaches to unravel the core of ectoine and 5-hydroxy-ectoine catabolisms. We show that a conserved enzyme bimodule consisting of the EutD ectoine/5-hydroxyectoine hydrolase and the EutE deacetylase degrades both ectoines. We determined the high-resolution crystal structures of both enzymes, derived from the salt-tolerant bacteria Ruegeria pomeroyi and Halomonas elongata These structures, either in their apo-forms or in forms capturing substrates or intermediates, provided detailed insights into the catalytic cores of the EutD and EutE enzymes. The combined biochemical and structural results indicate that the EutD homodimer opens the pyrimidine ring of ectoine through an unusual covalent intermediate, N-α-2 acetyl-l-2,4-diaminobutyrate (α-ADABA). We found that α-ADABA is then deacetylated by the zinc-dependent EutE monomer into diaminobutyric acid (DABA), which is further catabolized to l-aspartate. We observed that the EutD-EutE bimodule synthesizes exclusively the α-, but not the γ-isomers of ADABA or hydroxy-ADABA. Of note, α-ADABA is known to induce the MocR/GabR-type repressor EnuR, which controls the expression of many ectoine catabolic genes clusters. We conclude that hydroxy-α-ADABA might serve a similar function.
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Affiliation(s)
- Christopher-Nils Mais
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Marburg, Germany
| | - Lucas Hermann
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Biology, Marburg, Germany
| | - Florian Altegoer
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Marburg, Germany
| | - Andreas Seubert
- Philipps-University Marburg, Faculty of Chemistry, Marburg, Germany
| | - Alexandra A Richter
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Biology, Marburg, Germany
| | - Isa Wernersbach
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Marburg, Germany
| | - Laura Czech
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Biology, Marburg, Germany
| | - Erhard Bremer
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Biology, Marburg, Germany.
| | - Gert Bange
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Marburg, Germany.
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30
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Hillier HT, Altermark B, Leiros I. The crystal structure of the tetrameric DABA-aminotransferase EctB, a rate-limiting enzyme in the ectoine biosynthesis pathway. FEBS J 2020; 287:4641-4658. [PMID: 32112674 DOI: 10.1111/febs.15265] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 01/30/2020] [Accepted: 02/26/2020] [Indexed: 01/13/2023]
Abstract
l-2,4-diaminobutyric acid (DABA) aminotransferases can catalyze the formation of amines at the distal ω-position of substrates, and is the intial and rate-limiting enzyme in the biosynthesis pathway of the cytoprotecting molecule (S)-2-methyl-1,4,5,6-tetrahydro-4-pyrimidine carboxylic acid (ectoine). Although there is an industrial interest in the biosynthesis of ectoine, the DABA aminotransferases remain poorly characterized. Herein, we present the crystal structure of EctB (2.45 Å), a DABA aminotransferase from Chromohalobacter salexigens DSM 3043, a well-studied organism with respect to osmoadaptation by ectoine biosynthesis. We investigate the enzyme's oligomeric state to show that EctB from C. salexigens is a tetramer of two functional dimers, and suggest conserved recognition sites for dimerization that also includes the characteristic gating loop that helps shape the active site of the neighboring monomer. Although ω-transaminases are known to have two binding pockets to accommodate for their dual substrate specificity, we herein provide the first description of two binding pockets in the active site that may account for the catalytic character of DABA aminotransferases. Furthermore, our biochemical data reveal that the EctB enzyme from C. salexigens is a thermostable, halotolerant enzyme with a broad pH tolerance which may be linked to its tetrameric state. Put together, this study creates a solid foundation for a deeper structural understanding of DABA aminotransferases and opening up for future downstream studies of EctB's catalytic character and its redesign as a better catalyst for ectoine biosynthesis. In summary, we believe that the EctB enzyme from C. salexigens can serve as a benchmark enzyme for characterization of DABA aminotransferases. DATABASE: Structural data are available in PDB database under the accession number 6RL5.
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Affiliation(s)
- Heidi Therese Hillier
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, Faculty of Science and Technology, UiT the Arctic University of Norway, Tromsø, Norway
| | - Bjørn Altermark
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, Faculty of Science and Technology, UiT the Arctic University of Norway, Tromsø, Norway
| | - Ingar Leiros
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, Faculty of Science and Technology, UiT the Arctic University of Norway, Tromsø, Norway
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31
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Zeidler S, Müller V. Unusual deprivation of compatible solutes in Acinetobacter baumannii. Environ Microbiol 2020; 22:1370-1380. [PMID: 32079040 DOI: 10.1111/1462-2920.14951] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/27/2020] [Accepted: 02/18/2020] [Indexed: 11/30/2022]
Abstract
The opportunistic human pathogen Acinetobacter baumannii is one of the leading causes of nosocomial infections. The high prevalence of multidrug-resistant strains, a high adaptability to changing environments and an overall pronounced stress resistance contribute to persistence and spread of the bacteria in hospitals and thereby promote repeated outbreaks. Altogether, the success of A. baumannii is mainly built on adaptation and stress resistance mechanisms, rather than relying on 'true' virulence factors. One of the stress factors that pathogens must cope with is osmolarity, which can differ between the external environment and different body parts of the human host. A. baumannii ATCC 19606T accumulates the compatible solutes glutamate, mannitol and trehalose in response to high salinities. In this work, it was found that most of the solutes vanish immediately after reaching stationary phase, a very unusual phenomenon. While glutamate can be metabolized, mannitol produced by MtlD is excreted to the medium in high amounts. First results indicate that A. baumannii ATCC 19606T undergoes a rapid switch to a dormant state (viable but non-culturable) after disappearance of the compatible solutes. Resuscitation from this state could easily be achieved in PBS or fresh medium.
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Affiliation(s)
- Sabine Zeidler
- Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, Germany
| | - Volker Müller
- Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, Germany
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32
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Richter AA, Kobus S, Czech L, Hoeppner A, Zarzycki J, Erb TJ, Lauterbach L, Dickschat JS, Bremer E, Smits SHJ. The architecture of the diaminobutyrate acetyltransferase active site provides mechanistic insight into the biosynthesis of the chemical chaperone ectoine. J Biol Chem 2020; 295:2822-2838. [PMID: 31969391 DOI: 10.1074/jbc.ra119.011277] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 01/19/2020] [Indexed: 12/17/2022] Open
Abstract
Ectoine is a solute compatible with the physiologies of both prokaryotic and eukaryotic cells and is widely synthesized by bacteria as an osmotic stress protectant. Because it preserves functional attributes of proteins and macromolecular complexes, it is considered a chemical chaperone and has found numerous practical applications. However, the mechanism of its biosynthesis is incompletely understood. The second step in ectoine biosynthesis is catalyzed by l-2,4-diaminobutyrate acetyltransferase (EctA; EC 2.3.1.178), which transfers the acetyl group from acetyl-CoA to EctB-formed l-2,4-diaminobutyrate (DAB), yielding N-γ-acetyl-l-2,4-diaminobutyrate (N-γ-ADABA), the substrate of ectoine synthase (EctC). Here, we report the biochemical and structural characterization of the EctA enzyme from the thermotolerant bacterium Paenibacillus lautus (Pl). We found that (Pl)EctA forms a homodimer whose enzyme activity is highly regiospecific by producing N-γ-ADABA but not the ectoine catabolic intermediate N-α-acetyl-l-2,4-diaminobutyric acid. High-resolution crystal structures of (Pl)EctA (at 1.2-2.2 Å resolution) (i) for its apo-form, (ii) in complex with CoA, (iii) in complex with DAB, (iv) in complex with both CoA and DAB, and (v) in the presence of the product N-γ-ADABA were obtained. To pinpoint residues involved in DAB binding, we probed the structure-function relationship of (Pl)EctA by site-directed mutagenesis. Phylogenomics shows that EctA-type proteins from both Bacteria and Archaea are evolutionarily highly conserved, including catalytically important residues. Collectively, our biochemical and structural findings yielded detailed insights into the catalytic core of the EctA enzyme that laid the foundation for unraveling its reaction mechanism.
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Affiliation(s)
- Alexandra A Richter
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, D-35043 Marburg, Germany; SYNMIKRO Research Center, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Stefanie Kobus
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Laura Czech
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, D-35043 Marburg, Germany; SYNMIKRO Research Center, Philipps-University Marburg, D-35043 Marburg, Germany
| | - Astrid Hoeppner
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Jan Zarzycki
- Department of Biochemistry and Synthetic Metabolism, Max-Planck-Institute for Terrestrial Microbiology, D-35043 Marburg, Germany
| | - Tobias J Erb
- SYNMIKRO Research Center, Philipps-University Marburg, D-35043 Marburg, Germany; Department of Biochemistry and Synthetic Metabolism, Max-Planck-Institute for Terrestrial Microbiology, D-35043 Marburg, Germany
| | - Lukas Lauterbach
- Kekulé-Institute for Organic Chemistry and Biochemistry, Friedrich-Wilhelms-University Bonn, D-53121 Bonn, Germany
| | - Jeroen S Dickschat
- Kekulé-Institute for Organic Chemistry and Biochemistry, Friedrich-Wilhelms-University Bonn, D-53121 Bonn, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, D-35043 Marburg, Germany; SYNMIKRO Research Center, Philipps-University Marburg, D-35043 Marburg, Germany.
| | - Sander H J Smits
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, D-40225 Düsseldorf, Germany; Institute of Biochemistry, Heinrich-Heine University Düsseldorf, D-40225 Düsseldorf, Germany.
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Richter AA, Mais CN, Czech L, Geyer K, Hoeppner A, Smits SHJ, Erb TJ, Bange G, Bremer E. Biosynthesis of the Stress-Protectant and Chemical Chaperon Ectoine: Biochemistry of the Transaminase EctB. Front Microbiol 2019; 10:2811. [PMID: 31921013 PMCID: PMC6915088 DOI: 10.3389/fmicb.2019.02811] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 11/20/2019] [Indexed: 12/20/2022] Open
Abstract
Bacteria frequently adapt to high osmolarity surroundings through the accumulation of compatible solutes. Ectoine is a prominent member of these types of stress protectants and is produced via an evolutionarily conserved biosynthetic pathway beginning with the L-2,4-diaminobutyrate (DAB) transaminase (TA) EctB. Here, we studied EctB from the thermo-tolerant Gram-positive bacterium Paenibacillus lautus (Pl) and show that this tetrameric enzyme is highly tolerant to salt, pH, and temperature. During ectoine biosynthesis, EctB converts L-glutamate and L-aspartate-beta-semialdehyde into 2-oxoglutarate and DAB, but it also catalyzes the reverse reaction. Our analysis unravels that EctB enzymes are mechanistically identical to the PLP-dependent gamma-aminobutyrate TAs (GABA-TAs) and only differ with respect to substrate binding. Inspection of the genomic context of the ectB gene in P. lautus identifies an unusual arrangement of juxtapositioned genes for ectoine biosynthesis and import via an Ehu-type binding-protein-dependent ABC transporter. This operon-like structure suggests the operation of a highly coordinated system for ectoine synthesis and import to maintain physiologically adequate cellular ectoine pools under osmotic stress conditions in a resource-efficient manner. Taken together, our study provides an in-depth mechanistic and physiological description of EctB, the first enzyme of the ectoine biosynthetic pathway.
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Affiliation(s)
- Alexandra A Richter
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Marburg, Germany.,SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
| | - Christopher-Nils Mais
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany.,Department of Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Laura Czech
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Marburg, Germany.,SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
| | - Kyra Geyer
- Department of Biochemistry and Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Astrid Hoeppner
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sander H J Smits
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Tobias J Erb
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany.,Department of Biochemistry and Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Gert Bange
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany.,Department of Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Marburg, Germany.,SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
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Mustakhimov II, Reshetnikov AS, But SY, Rozova ON, Khmelenina VN, Trotsenko YA. Engineering of Hydroxyectoine Production based on the Methylomicrobium alcaliphilum. APPL BIOCHEM MICRO+ 2019. [DOI: 10.1134/s0003683819130015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Czech L, Wilcken S, Czech O, Linne U, Brauner J, Smits SHJ, Galinski EA, Bremer E. Exploiting Substrate Promiscuity of Ectoine Hydroxylase for Regio- and Stereoselective Modification of Homoectoine. Front Microbiol 2019; 10:2745. [PMID: 31827466 PMCID: PMC6890836 DOI: 10.3389/fmicb.2019.02745] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 11/12/2019] [Indexed: 11/13/2022] Open
Abstract
Extant enzymes are not only highly efficient biocatalysts for a single, or a group of chemically closely related substrates but often have retained, as a mark of their evolutionary history, a certain degree of substrate ambiguity. We have exploited the substrate ambiguity of the ectoine hydroxylase (EctD), a member of the non-heme Fe(II)-containing and 2-oxoglutarate-dependent dioxygenase superfamily, for such a task. Naturally, the EctD enzyme performs a precise regio- and stereoselective hydroxylation of the ubiquitous stress protectant and chemical chaperone ectoine (possessing a six-membered pyrimidine ring structure) to yield trans-5-hydroxyectoine. Using a synthetic ectoine derivative, homoectoine, which possesses an expanded seven-membered diazepine ring structure, we were able to selectively generate, both in vitro and in vivo, trans-5-hydroxyhomoectoine. For this transformation, we specifically used the EctD enzyme from Pseudomonas stutzeri in a whole cell biocatalyst approach, as this enzyme exhibits high catalytic efficiency not only for its natural substrate ectoine but also for homoectoine. Molecular docking approaches with the crystal structure of the Sphingopyxis alaskensis EctD protein predicted the formation of trans-5-hydroxyhomoectoine, a stereochemical configuration that we experimentally verified by nuclear-magnetic resonance spectroscopy. An Escherichia coli cell factory expressing the P. stutzeri ectD gene from a synthetic promoter imported homoectoine via the ProU and ProP compatible solute transporters, hydroxylated it, and secreted the formed trans-5-hydroxyhomoectoine, independent from all currently known mechanosensitive channels, into the growth medium from which it could be purified by high-pressure liquid chromatography.
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Affiliation(s)
- Laura Czech
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Sarah Wilcken
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Oliver Czech
- Department of Chemistry, Philipps-Universität Marburg, Marburg, Germany
| | - Uwe Linne
- Department of Chemistry, Philipps-Universität Marburg, Marburg, Germany
| | - Jarryd Brauner
- Institute of Microbiology and Biotechnology, Rheinische Friedrich-Wilhelms-Universität, Bonn, Germany
| | - Sander H J Smits
- Institute of Biochemistry, Heinrich-Heine Universität Düsseldorf, Düsseldorf, Germany.,Center for Structural Studies, Heinrich-Heine Universität Düsseldorf, Düsseldorf, Germany
| | - Erwin A Galinski
- Institute of Microbiology and Biotechnology, Rheinische Friedrich-Wilhelms-Universität, Bonn, Germany
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany.,SYNMIKRO Research Center, Philipps-Universität Marburg, Marburg, Germany
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High ectoine production by an engineered Halomonas hydrothermalis Y2 in a reduced salinity medium. Microb Cell Fact 2019; 18:184. [PMID: 31655591 PMCID: PMC6815383 DOI: 10.1186/s12934-019-1230-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 10/11/2019] [Indexed: 12/02/2022] Open
Abstract
Background As an attracted compatible solute, 1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid (ectoine) showed great potentials in various field. However, lower productivity and high saline medium seriously hinder its wide applications. Results The entire ectoine metabolism, including pathways for ectoine synthesis and catabolism, was identified in the genome of an ectoine-excreting strain Halomonas hydrothermalis Y2. By in-frame deletion of genes encoding ectoine hydroxylase (EctD) and (or) ectoine hydrolase (DoeA) that responsible for ectoine catabolism, the pathways for ectoine utilization were disrupted and resulted in an obviously enhanced productivity. Using an optimized medium containing 100 g L−1 NaCl in a 500-mL flask, the double mutant of Y2/ΔectD/ΔdoeA synthesized 3.13 g L−1 ectoine after 30 h cultivation. This is much higher than that of the wild type strain (1.91 g L−1), and also exceeds the production of Y2/ΔectD (2.21 g L−1). The remarkably enhanced accumulation of ectoine by Y2/ΔectD/ΔdoeA implied a critical function of Doe pathway in the ectoine catabolism. Furthermore, to reduce the salinity of fermentation medium and overcome the wastewater treatment difficulty, mutants that lacking key Na+/H+ antiporter, Mrp and (or) NhaD2, were constructed based on strain Y2/ΔectD/ΔdoeA. As a result, the Mrp-deficient strain could synthesize equal amount of ectoine (around 7 g L−1 or 500 mg (g DCW) −1) in the medium containing lower concentration of NaCl. During a fed-batch fermentation process with 60 g L−1 NaCl stress, a maximum 10.5 g L−1 ectoine was accumulated by the Mrp-deficient strain, with a specific production of 765 mg (g DCW)−1 and a yield of 0.21 g g−1 monosodium glutamate. Conclusion The remarkably enhanced production of ectoine by Y2/ΔectD/ΔdoeA implied the critical function of Doe pathway in the ectoine catabolism. Moreover, the reduced salinity requirement of Mrp-deficient strain implied a feasible protocol for many compatible solute biosynthesis, i.e., by silencing some Na+/H+ antiporters in their halophilic producers and thus lowering the medium salinity.![]()
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Hara R, Nishikawa T, Okuhara T, Koketsu K, Kino K. Ectoine hydroxylase displays selective trans-3-hydroxylation activity towards L-proline. Appl Microbiol Biotechnol 2019; 103:5689-5698. [PMID: 31106391 DOI: 10.1007/s00253-019-09868-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 04/18/2019] [Accepted: 04/26/2019] [Indexed: 11/25/2022]
Abstract
L-Hydroxyproline (Hyp) is a valuable intermediate for the synthesis of pharmaceuticals; consequently, a practical process for its production has been in high demand. To date, industrial processes have been developed by using L-Pro hydroxylases. However, a process for the synthesis of trans-3-Hyp has not yet been established, because of the lack of highly selective enzymes that can convert L-Pro to trans-3-Hyp. The present study was designed to develop a biocatalytic trans-3-Hyp production process. We speculated that ectoine hydroxylase (EctD), which is involved in the hydroxylation of the known compatible solute ectoine, may possess the ability to hydroxylate L-Pro, since the structures of ectoine and 5-hydroxyectoine resemble those of L-Pro and trans-3-Hyp, respectively. Consequently, we discovered that ectoine hydroxylases from Halomonas elongata, as well as some actinobacteria, catalyzed L-Pro hydroxylation to form trans-3-Hyp. Of these, ectoine hydroxylase from Streptomyces cattleya also utilized 3,4-dehydro-L-Pro, 2-methyl-L-Pro, and L-pipecolic acid as substrates. In the whole-cell bioconversion of L-Pro into trans-3-Hyp using Escherichia coli expressing the ectD gene from S. cattleya, only 12.4 mM trans-3-Hyp was produced from 30 mM L-Pro, suggesting a rapid depletion of 2-oxoglutarate, an essential component of enzyme activity as a cosubstrate, in the host. Therefore, the endogenous 2-oxoglutarate dehydrogenase gene was deleted. Using this deletion mutant as the host, trans-3-Hyp production was enhanced up to 26.8 mM from 30 mM L-Pro, with minimal loss of 2-oxoglutarate. This finding is not only beneficial for trans-3-Hyp production, but also for other E. coli bioconversion processes involving 2-oxoglutarate-utilizing enzymes.
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Affiliation(s)
- Ryotaro Hara
- Research Institute for Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo, 169-8555, Japan
| | - Takeyuki Nishikawa
- Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo, 169-8555, Japan
| | - Takuya Okuhara
- Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo, 169-8555, Japan
| | - Kento Koketsu
- Bioprocess Development Center, Kyowa Hakko Bio Co., Ltd., 2, Miyukigaoka, Tsukuba, Ibaraki, 305-0841, Japan
| | - Kuniki Kino
- Research Institute for Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo, 169-8555, Japan.
- Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo, 169-8555, Japan.
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Illuminating the catalytic core of ectoine synthase through structural and biochemical analysis. Sci Rep 2019; 9:364. [PMID: 30674920 PMCID: PMC6344544 DOI: 10.1038/s41598-018-36247-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 11/16/2018] [Indexed: 11/26/2022] Open
Abstract
Ectoine synthase (EctC) is the signature enzyme for the production of ectoine, a compatible solute and chemical chaperone widely synthesized by bacteria as a cellular defense against the detrimental effects of osmotic stress. EctC catalyzes the last step in ectoine synthesis through cyclo-condensation of the EctA-formed substrate N-gamma-acetyl-L-2,4-diaminobutyric acid via a water elimination reaction. We have biochemically and structurally characterized the EctC enzyme from the thermo-tolerant bacterium Paenibacillus lautus (Pl). EctC is a member of the cupin superfamily and forms dimers, both in solution and in crystals. We obtained high-resolution crystal structures of the (Pl)EctC protein in forms that contain (i) the catalytically important iron, (ii) iron and the substrate N-gamma-acetyl-L-2,4-diaminobutyric acid, and (iii) iron and the enzyme reaction product ectoine. These crystal structures lay the framework for a proposal for the EctC-mediated water-elimination reaction mechanism. Residues involved in coordinating the metal, the substrate, or the product within the active site of ectoine synthase are highly conserved among a large group of EctC-type proteins. Collectively, the biochemical, mutational, and structural data reported here yielded detailed insight into the structure-function relationship of the (Pl)EctC enzyme and are relevant for a deeper understanding of the ectoine synthase family as a whole.
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Cantera S, Sánchez-Andrea I, Lebrero R, García-Encina PA, Stams AJM, Muñoz R. Multi-production of high added market value metabolites from diluted methane emissions via methanotrophic extremophiles. BIORESOURCE TECHNOLOGY 2018; 267:401-407. [PMID: 30031279 DOI: 10.1016/j.biortech.2018.07.057] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/09/2018] [Accepted: 07/11/2018] [Indexed: 05/12/2023]
Abstract
This study constitutes the first-proof-of-concept of a methane biorefinery based on the multi-production of high profit margin substances (ectoine, hydroxyectoine, polyhydroxyalkanoates (PHAs) and exopolysaccharides (EPS)) using methane as the sole carbon and energy source. Two bubble column bioreactors were operated under different magnesium concentrations (0.2, 0.02 and 0.002 g L-1) to validate and optimize this innovative strategy for valorization of CH4 emissions. High Mg2+ concentrations promoted the accumulation of ectoine (79.7-94.2 mg g biomass-1), together with high hydroxyectoine yields (up to 13 mg g biomass-1) and EPS concentrations (up to 2.6 g L culture broth-1). Unfortunately, PHA synthesis was almost negligible (14.3 mg L-1) and only found at the lowest Mg2+ concentration tested. Halomonas, Marinobacter, Methylophaga and Methylomicrobium, previously described as ectoine producers, were dominant in both bioreactors, Methylomicrobium being the only described methanotroph. This study encourages further research on CH4 biorefineries capable of creating value out of GHG mitigation.
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Affiliation(s)
- S Cantera
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, Valladolid University, Dr. Mergelina, s/n, Valladolid, Spain
| | - I Sánchez-Andrea
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - R Lebrero
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, Valladolid University, Dr. Mergelina, s/n, Valladolid, Spain
| | - P A García-Encina
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, Valladolid University, Dr. Mergelina, s/n, Valladolid, Spain
| | - Alfons J M Stams
- Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - R Muñoz
- Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, Valladolid University, Dr. Mergelina, s/n, Valladolid, Spain.
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OpuF, a New Bacillus Compatible Solute ABC Transporter with a Substrate-Binding Protein Fused to the Transmembrane Domain. Appl Environ Microbiol 2018; 84:AEM.01728-18. [PMID: 30097444 DOI: 10.1128/aem.01728-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Accepted: 08/08/2018] [Indexed: 01/20/2023] Open
Abstract
The accumulation of compatible solutes is a common defense of bacteria against the detrimental effects of high osmolarity. Uptake systems for these compounds are cornerstones in cellular osmostress responses because they allow the energy-preserving scavenging of osmostress protectants from environmental sources. Bacillus subtilis is well studied with respect to the import of compatible solutes and its five transport systems (OpuA, OpuB, OpuC, OpuD, and OpuE), for these stress protectants have previously been comprehensively studied. Building on this knowledge and taking advantage of the unabated appearance of new genome sequences of members of the genus Bacillus, we report here the discovery, physiological characterization, and phylogenomics of a new member of the Opu family of transporters, OpuF (OpuFA-OpuFB). OpuF is not present in B. subtilis but it is widely distributed in members of the large genus Bacillus OpuF is a representative of a subgroup of ATP-binding cassette (ABC) transporters in which the substrate-binding protein (SBP) is fused to the transmembrane domain (TMD). We studied the salient features of the OpuF transporters from Bacillus infantis and Bacillus panaciterrae by functional reconstitution in a B. subtilis chassis strain lacking known Opu transporters. A common property of the examined OpuF systems is their substrate profile; OpuF mediates the import of glycine betaine, proline betaine, homobetaine, and the marine osmolyte dimethylsulfoniopropionate (DMSP). An in silico model of the SBP domain of the TMD-SBP hybrid protein OpuFB was established. It revealed the presence of an aromatic cage, a structural feature commonly present in ligand-binding sites of compatible solute importers.IMPORTANCE The high-affinity import of compatible solutes from environmental sources is an important aspect of the cellular defense of many bacteria and archaea against the harmful effects of high external osmolarity. The accumulation of these osmostress protectants counteracts high-osmolarity-instigated water efflux, a drop in turgor to nonphysiological values, and an undue increase in molecular crowding of the cytoplasm; they thereby foster microbial growth under osmotically unfavorable conditions. Importers for compatible solutes allow the energy-preserving scavenging of osmoprotective and physiologically compliant organic solutes from environmental sources. We report here the discovery, exemplary physiological characterization, and phylogenomics of a new compatible solute importer, OpuF, widely found in members of the Bacillus genus. The OpuF system is a representative of a growing subgroup of ABC transporters in which the substrate-scavenging function of the substrate-binding protein (SBP) and the membrane-embedded substrate translocating subunit (TMD) are fused into a single polypeptide chain.
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Chatterjee P, Samaddar S, Niinemets Ü, Sa TM. Brevibacterium linens RS16 confers salt tolerance to Oryza sativa genotypes by regulating antioxidant defense and H + ATPase activity. Microbiol Res 2018; 215:89-101. [PMID: 30172313 DOI: 10.1016/j.micres.2018.06.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 05/01/2018] [Accepted: 06/16/2018] [Indexed: 01/07/2023]
Abstract
Soil salinity is one of the major limitations that affects both plant and its soil environment, leading to reduced agricultural production. Evaluation of stress severity by plant physical and biochemical characteristics is an established way to study plant-salt stress interaction, but the halotolerant properties of plant growth promoting bacteria (PGPB) along with plant growth promotion is less studied till date. The aim of the present study was to elucidate the strategy, used by ACC deaminase-containing halotolerant Brevibacterium linens RS16 to confer salt stress tolerance in moderately salt-tolerant (FL478) and salt-sensitive (IR29) rice (Oryza sativa L.) cultivars. The plants were exposed to salt stress using 0, 50, and 100 mM of NaCl with and without bacteria. Plant physiological and biochemical characteristics were estimated after 1, 5, 10 days of stress application. H+ ATPase activity and the presence of hydroxyectoine gene (ectD) that is responsible for compatible solute accumulation were also analyzed in bacteria. The height and dry mass of bacteria inoculated plants significantly increased compared to salt-stressed plants, and the differences increased in time dependent manner. Bacteria priming reduced the plant antioxidant enzyme activity, lipid peroxidation and it also regulated the salt accumulation by modulating vacuolar H+ ATPase activity. ATPase activity and presence of hydroxyectoine gene in RS16 might have played a vital role in providing salt tolerance in bacteria inoculated rice cultivars. We conclude that dual benefits provided by the halotolerant plant growth promoting bacteria (PGPB) can provide a major way to improve rice yields in saline soil.
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Affiliation(s)
- Poulami Chatterjee
- Department of Environmental and Biological Chemistry, Chungbuk National University, Cheongju, Chungbuk, 28644, Republic of Korea
| | - Sandipan Samaddar
- Department of Environmental and Biological Chemistry, Chungbuk National University, Cheongju, Chungbuk, 28644, Republic of Korea
| | - Ülo Niinemets
- Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, Tartu, 51006, Estonia; Estonian Academy of Sciences, Kohtu 6, 10130, Tallinn, Estonia
| | - Tong-Min Sa
- Department of Environmental and Biological Chemistry, Chungbuk National University, Cheongju, Chungbuk, 28644, Republic of Korea.
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Developing a colorimetric assay for Fe(II)/2-oxoglutarate-dependent dioxygenase. Anal Biochem 2018; 548:109-114. [DOI: 10.1016/j.ab.2018.02.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 02/09/2018] [Accepted: 02/12/2018] [Indexed: 01/27/2023]
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Czech L, Hermann L, Stöveken N, Richter AA, Höppner A, Smits SHJ, Heider J, Bremer E. Role of the Extremolytes Ectoine and Hydroxyectoine as Stress Protectants and Nutrients: Genetics, Phylogenomics, Biochemistry, and Structural Analysis. Genes (Basel) 2018; 9:genes9040177. [PMID: 29565833 PMCID: PMC5924519 DOI: 10.3390/genes9040177] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 03/13/2018] [Accepted: 03/15/2018] [Indexed: 01/26/2023] Open
Abstract
Fluctuations in environmental osmolarity are ubiquitous stress factors in many natural habitats of microorganisms, as they inevitably trigger osmotically instigated fluxes of water across the semi-permeable cytoplasmic membrane. Under hyperosmotic conditions, many microorganisms fend off the detrimental effects of water efflux and the ensuing dehydration of the cytoplasm and drop in turgor through the accumulation of a restricted class of organic osmolytes, the compatible solutes. Ectoine and its derivative 5-hydroxyectoine are prominent members of these compounds and are synthesized widely by members of the Bacteria and a few Archaea and Eukarya in response to high salinity/osmolarity and/or growth temperature extremes. Ectoines have excellent function-preserving properties, attributes that have led to their description as chemical chaperones and fostered the development of an industrial-scale biotechnological production process for their exploitation in biotechnology, skin care, and medicine. We review, here, the current knowledge on the biochemistry of the ectoine/hydroxyectoine biosynthetic enzymes and the available crystal structures of some of them, explore the genetics of the underlying biosynthetic genes and their transcriptional regulation, and present an extensive phylogenomic analysis of the ectoine/hydroxyectoine biosynthetic genes. In addition, we address the biochemistry, phylogenomics, and genetic regulation for the alternative use of ectoines as nutrients.
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Affiliation(s)
- Laura Czech
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Lucas Hermann
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Nadine Stöveken
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
| | - Alexandra A Richter
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Astrid Höppner
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
| | - Sander H J Smits
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
- Institute of Biochemistry, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
| | - Johann Heider
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
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Abstract
2-Oxoglutarate (2OG)-dependent oxygenases (2OGXs) catalyze a remarkably diverse range of oxidative reactions. In animals, these comprise hydroxylations and N-demethylations proceeding via hydroxylation; in plants and microbes, they catalyze a wider range including ring formations, rearrangements, desaturations, and halogenations. The catalytic flexibility of 2OGXs is reflected in their biological functions. After pioneering work identified the roles of 2OGXs in collagen biosynthesis, research revealed they also function in plant and animal development, transcriptional regulation, nucleic acid modification/repair, fatty acid metabolism, and secondary metabolite biosynthesis, including of medicinally important antibiotics. In plants, 2OGXs are important agrochemical targets and catalyze herbicide degradation. Human 2OGXs, particularly those regulating transcription, are current therapeutic targets for anemia and cancer. Here, we give an overview of the biochemistry of 2OGXs, providing examples linking to biological function, and outline how knowledge of their enzymology is being exploited in medicine, agrochemistry, and biocatalysis.
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Affiliation(s)
- Md Saiful Islam
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom;
| | - Thomas M Leissing
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom;
| | - Rasheduzzaman Chowdhury
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom;
| | - Richard J Hopkinson
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom; .,Current affiliation for Richard J. Hopkinson: Leicester Institute of Structural and Chemical Biology and Department of Chemistry, University of Leicester, Leicester LE1 7RH, United Kingdom;
| | - Christopher J Schofield
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom;
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45
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León MJ, Hoffmann T, Sánchez-Porro C, Heider J, Ventosa A, Bremer E. Compatible Solute Synthesis and Import by the Moderate Halophile Spiribacter salinus: Physiology and Genomics. Front Microbiol 2018; 9:108. [PMID: 29497403 PMCID: PMC5818414 DOI: 10.3389/fmicb.2018.00108] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 01/17/2018] [Indexed: 11/13/2022] Open
Abstract
Members of the genus Spiribacter are found worldwide and are abundant in ecosystems possessing intermediate salinities between seawater and saturated salt concentrations. Spiribacter salinus M19-40 is the type species of this genus and its first cultivated representative. In the habitats of S. salinus M19-40, high salinity is a key determinant for growth and we therefore focused on the cellular adjustment strategy to this persistent environmental challenge. We coupled these experimental studies to the in silico mining of the genome sequence of this moderate halophile with respect to systems allowing this bacterium to control its potassium and sodium pools, and its ability to import and synthesize compatible solutes. S. salinus M19-40 produces enhanced levels of the compatible solute ectoine, both under optimal and growth-challenging salt concentrations, but the genes encoding the corresponding biosynthetic enzymes are not organized in a canonical ectABC operon. Instead, they are scrambled (ectAC; ectB) and are physically separated from each other on the S. salinus M19-40 genome. Genomes of many phylogenetically related bacteria also exhibit a non-canonical organization of the ect genes. S. salinus M19-40 also synthesizes trehalose, but this compatible solute seems to make only a minor contribution to the cytoplasmic solute pool under osmotic stress conditions. However, its cellular levels increase substantially in stationary phase cells grown under optimal salt concentrations. In silico genome mining revealed that S. salinus M19-40 possesses different types of uptake systems for compatible solutes. Among the set of compatible solutes tested in an osmostress protection growth assay, glycine betaine and arsenobetaine were the most effective. Transport studies with radiolabeled glycine betaine showed that S. salinus M19-40 increases the pool size of this osmolyte in a fashion that is sensitively tied to the prevalent salinity of the growth medium. It was amassed in salt-stressed cells in unmodified form and suppressed the synthesis of ectoine. In conclusion, the data presented here allow us to derive a genome-scale picture of the cellular adjustment strategy of a species that represents an environmentally abundant group of ecophysiologically important halophilic microorganisms.
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Affiliation(s)
- María J León
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Seville, Spain
| | - Tamara Hoffmann
- Laboratory for Microbiology, Department of Biology, Philipps University of Marburg, Marburg, Germany
| | - Cristina Sánchez-Porro
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Seville, Spain
| | - Johann Heider
- Laboratory for Microbiology, Department of Biology, Philipps University of Marburg, Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps University of Marburg, Marburg, Germany
| | - Antonio Ventosa
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Seville, Spain
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps University of Marburg, Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps University of Marburg, Marburg, Germany
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46
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Tinkering with Osmotically Controlled Transcription Allows Enhanced Production and Excretion of Ectoine and Hydroxyectoine from a Microbial Cell Factory. Appl Environ Microbiol 2018; 84:AEM.01772-17. [PMID: 29101191 DOI: 10.1128/aem.01772-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 10/28/2017] [Indexed: 12/21/2022] Open
Abstract
Ectoine and hydroxyectoine are widely synthesized by members of the Bacteria and a few members of the Archaea as potent osmostress protectants. We have studied the salient features of the osmostress-responsive promoter directing the transcription of the ectoine/hydroxyectoine biosynthetic gene cluster from the plant-root-associated bacterium Pseudomonas stutzeri by transferring it into Escherichia coli, an enterobacterium that does not produce ectoines naturally. Using ect-lacZ reporter fusions, we found that the heterologous ect promoter reacted with exquisite sensitivity in its transcriptional profile to graded increases in sustained high salinity, responded to a true osmotic signal, and required the buildup of an osmotically effective gradient across the cytoplasmic membrane for its induction. The involvement of the -10, -35, and spacer regions of the sigma-70-type ect promoter in setting promoter strength and response to osmotic stress was assessed through site-directed mutagenesis. Moderate changes in the ect promoter sequence that increase its resemblance to housekeeping sigma-70-type promoters of E. coli afforded substantially enhanced expression, both in the absence and in the presence of osmotic stress. Building on this set of ect promoter mutants, we engineered an E. coli chassis strain for the heterologous production of ectoines. This synthetic cell factory lacks the genes for the osmostress-responsive synthesis of trehalose and the compatible solute importers ProP and ProU, and it continuously excretes ectoines into the growth medium. By combining appropriate host strains and different plasmid variants, excretion of ectoine, hydroxyectoine, or a mixture of both compounds was achieved under mild osmotic stress conditions.IMPORTANCE Ectoines are compatible solutes, organic osmolytes that are used by microorganisms to fend off the negative consequences of high environmental osmolarity on cellular physiology. An understanding of the salient features of osmostress-responsive promoters directing the expression of the ectoine/hydroxyectoine biosynthetic gene clusters is lacking. We exploited the ect promoter from an ectoine/hydroxyectoine-producing soil bacterium for such a study by transferring it into a surrogate bacterial host. Despite the fact that E. coli does not synthesize ectoines naturally, the ect promoter retained its exquisitely sensitive osmotic control, indicating that osmoregulation of ect transcription is an inherent feature of the promoter and its flanking sequences. These sequences were narrowed to a 116-bp DNA fragment. Ectoines have interesting commercial applications. Building on data from a site-directed mutagenesis study of the ect promoter, we designed a synthetic cell factory that secretes ectoine, hydroxyectoine, or a mixture of both compounds into the growth medium.
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47
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Sahle CJ, Schroer MA, Jeffries CM, Niskanen J. Hydration in aqueous solutions of ectoine and hydroxyectoine. Phys Chem Chem Phys 2018; 20:27917-27923. [DOI: 10.1039/c8cp05308a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We explore the influence of the two osmolytes ectoine and hydroxyectoine on the structure of pure water and aqueous NaCl solutions using non-resonant X-ray Raman scattering spectroscopy at the oxygen K-edge.
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Affiliation(s)
- Christoph J. Sahle
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs
- 38000 Grenoble
- France
| | - Martin A. Schroer
- European Molecular Biology Laboratory (EMBL)
- Hamburg Outstation c/o DESY
- 22607 Hamburg
- Germany
| | - Cy M. Jeffries
- European Molecular Biology Laboratory (EMBL)
- Hamburg Outstation c/o DESY
- 22607 Hamburg
- Germany
| | - Johannes Niskanen
- University of Turku
- Department of Physics and Astronomy
- FI-20014 Turun yliopisto
- Finland
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48
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Kim KH, Jia B, Jeon CO. Identification of Trans-4-Hydroxy-L-Proline as a Compatible Solute and Its Biosynthesis and Molecular Characterization in Halobacillus halophilus. Front Microbiol 2017; 8:2054. [PMID: 29104571 PMCID: PMC5655121 DOI: 10.3389/fmicb.2017.02054] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 10/06/2017] [Indexed: 12/17/2022] Open
Abstract
Halobacillus halophilus, a moderately halophilic bacterium, accumulates a variety of compatible solutes including glycine betaine, glutamate, glutamine, proline, and ectoine to cope with osmotic stress. Non-targeted analysis of intracellular organic compounds using 1H-NMR showed that a large amount of trans-4-hydroxy-L-proline (Hyp), which has not been reported as a compatible solute in H. halophilus, was accumulated in response to high NaCl salinity, suggesting that Hyp may be an important compatible solute in H. halophilus. Candidate genes encoding proline 4-hydroxylase (PH-4), which hydroxylates L-proline to generate Hyp, were retrieved from the genome of H. halophilus through domain searches based on the sequences of known PH-4 proteins. A gene, HBHAL_RS11735, which was annotated as a multidrug DMT transporter permease in GenBank, was identified as the PH-4 gene through protein expression analysis in Escherichia coli. The PH-4 gene constituted a transcriptional unit with a promoter and a rho-independent terminator, and it was distantly located from the proline biosynthetic gene cluster (pro operon). Transcriptional analysis showed that PH-4 gene expression was NaCl concentration-dependent, and was specifically induced by chloride anion, similar to the pro operon. Accumulation of intracellular Hyp was also observed in other bacteria, suggesting that Hyp may be a widespread compatible solute in halophilic and halotolerant bacteria.
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Affiliation(s)
| | | | - Che Ok Jeon
- Department of Life Science, Chung-Ang University, Seoul, South Korea
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49
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Schulz A, Hermann L, Freibert SA, Bönig T, Hoffmann T, Riclea R, Dickschat JS, Heider J, Bremer E. Transcriptional regulation of ectoine catabolism in response to multiple metabolic and environmental cues. Environ Microbiol 2017; 19:4599-4619. [PMID: 28892254 DOI: 10.1111/1462-2920.13924] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 08/29/2017] [Accepted: 08/31/2017] [Indexed: 01/04/2023]
Abstract
Ectoine and hydroxyectoine are effective microbial osmostress protectants, but can also serve as versatile nutrients for bacteria. We have studied the genetic regulation of ectoine and hydroxyectoine import and catabolism in the marine Roseobacter species Ruegeria pomeroyi and identified three transcriptional regulators involved in these processes: the GabR/MocR-type repressor EnuR, the feast and famine-type regulator AsnC and the two-component system NtrYX. The corresponding genes are widely associated with ectoine and hydroxyectoine uptake and catabolic gene clusters (enuR, asnC), and with microorganisms predicted to consume ectoines (ntrYX). EnuR contains a covalently bound pyridoxal-5'-phosphate as a co-factor and the chemistry underlying the functioning of MocR/GabR-type regulators typically requires a system-specific low molecular mass effector molecule. Through ligand binding studies with purified EnuR, we identified N-(alpha)-L-acetyl-2,4-diaminobutyric acid and L-2,4-diaminobutyric acid as inducers for EnuR that are generated through ectoine catabolism. AsnC/Lrp-type proteins can wrap DNA into nucleosome-like structures, and we found that the asnC gene was essential for use of ectoines as nutrients. Furthermore, we discovered through transposon mutagenesis that the NtrYX two-component system is required for their catabolism. Database searches suggest that our findings have important ramifications for an understanding of the molecular biology of most microbial consumers of ectoines.
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Affiliation(s)
- Annina Schulz
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Lucas Hermann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Sven-Andreas Freibert
- Department of Medicine, Institute for Cytobiology and Cytopathology, Philipps-University Marburg, Robert-Koch Str. 6, D-35032 Marburg, Germany
| | - Tobias Bönig
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Tamara Hoffmann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Ramona Riclea
- Institute of Organic Chemistry, Technical University Braunschweig, D-38106 Braunschweig, Germany.,Kekulé-Institute for Organic Chemistry and Biochemistry, Friedrich-Wilhelms-Universität Bonn, D-53121 Bonn, Germany
| | - Jeroen S Dickschat
- Institute of Organic Chemistry, Technical University Braunschweig, D-38106 Braunschweig, Germany.,Kekulé-Institute for Organic Chemistry and Biochemistry, Friedrich-Wilhelms-Universität Bonn, D-53121 Bonn, Germany
| | - Johann Heider
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
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50
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Hoffmann T, Bleisteiner M, Sappa PK, Steil L, Mäder U, Völker U, Bremer E. Synthesis of the compatible solute proline by Bacillus subtilis: point mutations rendering the osmotically controlled proHJ promoter hyperactive. Environ Microbiol 2017; 19:3700-3720. [PMID: 28752945 DOI: 10.1111/1462-2920.13870] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 07/09/2017] [Accepted: 07/24/2017] [Indexed: 01/29/2023]
Abstract
The ProJ and ProH enzymes of Bacillus subtilis catalyse together with ProA (ProJ-ProA-ProH), osmostress-adaptive synthesis of the compatible solute proline. The proA-encoded gamma-glutamyl phosphate reductase is also used for anabolic proline synthesis (ProB-ProA-ProI). Transcription of the proHJ operon is osmotically inducible whereas that of the proBA operon is not. Targeted and quantitative proteome analysis revealed that the amount of ProA is not limiting for the interconnected anabolic and osmostress-responsive proline production routes. A key player for enhanced osmostress-adaptive proline production is the osmotically regulated proHJ promoter. We used site-directed mutagenesis to study the salient features of this stress-responsive promoter. Two important features were identified: (i) deviations of the proHJ promoter from the consensus sequence of SigA-type promoters serve to keep transcription low under non-inducing growth conditions, while still allowing a finely tuned induction of transcriptional activity when the external osmolarity is increased and (ii) a suboptimal spacer length for SigA-type promoters of either 16-bp (the natural proHJ promoter), or 18-bp (a synthetic promoter variant) is strictly required to allow regulation of promoter activity in proportion to the external salinity. Collectively, our data suggest that changes in the local DNA structure at the proHJ promoter are important determinants for osmostress-inducibility of transcription.
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Affiliation(s)
- Tamara Hoffmann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg D-35043, Germany
| | - Monika Bleisteiner
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg D-35043, Germany
| | - Praveen Kumar Sappa
- Interfaculty Institute of Genetics and Functional Genomics, Department Functional Genomics, University Medicine Greifswald, Friedrich-Ludwig-Jahn-Str. 15, Greifswald D-17475, Germany
| | - Leif Steil
- Interfaculty Institute of Genetics and Functional Genomics, Department Functional Genomics, University Medicine Greifswald, Friedrich-Ludwig-Jahn-Str. 15, Greifswald D-17475, Germany
| | - Ulrike Mäder
- Interfaculty Institute of Genetics and Functional Genomics, Department Functional Genomics, University Medicine Greifswald, Friedrich-Ludwig-Jahn-Str. 15, Greifswald D-17475, Germany
| | - Uwe Völker
- Interfaculty Institute of Genetics and Functional Genomics, Department Functional Genomics, University Medicine Greifswald, Friedrich-Ludwig-Jahn-Str. 15, Greifswald D-17475, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg D-35043, Germany
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerweinstr. 6, Marburg D-35043, Germany
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