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Dobruchowska JM, Bjornsdottir B, Fridjonsson OH, Altenbuchner J, Watzlawick H, Gerwig GJ, Dijkhuizen L, Kamerling JP, Hreggvidsson GO. Enzymatic depolymerization of alginate by two novel thermostable alginate lyases from Rhodothermus marinus. FRONTIERS IN PLANT SCIENCE 2022; 13:981602. [PMID: 36204061 PMCID: PMC9530828 DOI: 10.3389/fpls.2022.981602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/17/2022] [Indexed: 06/16/2023]
Abstract
Alginate (alginic acid) is a linear polysaccharide, wherein (1→4)-linked β-D-mannuronic acid and its C5 epimer, α-L-guluronic acid, are arranged in varying sequences. Alginate lyases catalyze the depolymerization of alginate, thereby cleaving the (1→4) glycosidic linkages between the monomers by a β-elimination mechanism, to yield unsaturated 4-deoxy-L-erythro-hex-4-enopyranosyluronic acid (Δ) at the non-reducing end of resulting oligosaccharides (α-L-erythro configuration) or, depending on the enzyme, the unsaturated monosaccharide itself. In solution, the released free unsaturated monomer product is further hydrated in a spontaneous (keto-enol tautomerization) process to form two cyclic stereoisomers. In this study, two alginate lyase genes, designated alyRm3 and alyRm4, from the marine thermophilic bacterium Rhodothermus marinus (strain MAT378), were cloned and expressed in Escherichia coli. The recombinant enzymes were characterized, and their substrate specificity and product structures determined. AlyRm3 (PL39) and AlyRm4 (PL17) are among the most thermophilic and thermostable alginate lyases described to date with temperature optimum of activity at ∼75 and 81°C, respectively. The pH optimum of activity of AlyRm3 is ∼5.5 and AlyRm4 at pH 6.5. Detailed NMR analysis of the incubation products demonstrated that AlyRm3 is an endolytic lyase, while AlyRm4 is an exolytic lyase, cleaving monomers from the non-reducing end of oligo/poly-alginates.
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Affiliation(s)
- Justyna M. Dobruchowska
- Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Groningen, Netherlands
| | | | | | - Josef Altenbuchner
- Institute for Industrial Genetics, University of Stuttgart, Stuttgart, Germany
| | | | - Gerrit J. Gerwig
- Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Groningen, Netherlands
| | - Lubbert Dijkhuizen
- Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Groningen, Netherlands
| | - Johannis P. Kamerling
- Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Groningen, Netherlands
| | - Gudmundur O. Hreggvidsson
- Matís Ltd., Reykjavík, Iceland
- Faculty of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland
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A Survey of Spontaneous Antibiotic-Resistant Mutants of the Halophilic, Thermophilic Bacterium Rhodothermus marinus. Antibiotics (Basel) 2021; 10:antibiotics10111384. [PMID: 34827322 PMCID: PMC8614978 DOI: 10.3390/antibiotics10111384] [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: 09/19/2021] [Revised: 11/08/2021] [Accepted: 11/10/2021] [Indexed: 11/17/2022] Open
Abstract
Rhodothermus marinus is a halophilic extreme thermophile, with potential as a model organism for studies of the structural basis of antibiotic resistance. In order to facilitate genetic studies of this organism, we have surveyed the antibiotic sensitivity spectrum of R. marinus and identified spontaneous antibiotic-resistant mutants. R. marinus is naturally insensitive to aminoglycosides, aminocylitols and tuberactinomycins that target the 30S ribosomal subunit, but is sensitive to all 50S ribosomal subunit-targeting antibiotics examined, including macrolides, lincosamides, streptogramin B, chloramphenicol, and thiostrepton. It is also sensitive to kirromycin and fusidic acid, which target protein synthesis factors. It is sensitive to rifampicin (RNA polymerase inhibitor) and to the fluoroquinolones ofloxacin and ciprofloxacin (DNA gyrase inhibitors), but insensitive to nalidixic acid. Drug-resistant mutants were identified using rifampicin, thiostrepton, erythromycin, spiramycin, tylosin, lincomycin, and chloramphenicol. The majority of these were found to have mutations that are similar or identical to those previously found in other species, while several novel mutations were identified. This study provides potential selectable markers for genetic manipulations and demonstrates the feasibility of using R. marinus as a model system for studies of ribosome and RNA polymerase structure, function, and evolution.
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Kristjansdottir T, Ron EYC, Molins-Delgado D, Fridjonsson OH, Turner C, Bjornsdottir SH, Gudmundsson S, van Niel EWJ, Karlsson EN, Hreggvidsson GO. Engineering the carotenoid biosynthetic pathway in Rhodothermus marinus for lycopene production. Metab Eng Commun 2020; 11:e00140. [PMID: 32793416 PMCID: PMC7414004 DOI: 10.1016/j.mec.2020.e00140] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/25/2020] [Accepted: 07/20/2020] [Indexed: 11/20/2022] Open
Abstract
Rhodothermus marinus has the potential to be well suited for biorefineries, as an aerobic thermophile that produces thermostable enzymes and is able to utilize polysaccharides from different 2nd and 3rd generation biomass. The bacterium produces valuable chemicals such as carotenoids. However, the native carotenoids are not established for industrial production and R. marinus needs to be genetically modified to produce higher value carotenoids. Here we genetically modified the carotenoid biosynthetic gene cluster resulting in three different mutants, most importantly the lycopene producing mutant TK-3 (ΔtrpBΔpurAΔcruFcrtB::trpBcrtBT.thermophilus). The genetic modifications and subsequent structural analysis of carotenoids helped clarify the carotenoid biosynthetic pathway in R. marinus. The nucleotide sequences encoding the enzymes phytoene synthase (CrtB) and the previously unidentified 1′,2′-hydratase (CruF) were found fused together and encoded by a single gene in R. marinus. Deleting only the cruF part of the gene did not result in an active CrtB enzyme. However, by deleting the entire gene and inserting the crtB gene from Thermus thermophilus, a mutant strain was obtained, producing lycopene as the sole carotenoid. The lycopene produced by TK-3 was quantified as 0.49 g/kg CDW (cell dry weight). Genetically engineered Rhodothermus marinus produces lycopene instead of native γ-carotenoids. A gene encoding 1′,2′-hydratase (cruF) was identified in the genome, fused with the gene encoding phytoene synthase (crtB). Marker-replacement of the cruF-crtB gene with the crtB from Thermus thermophilus resulted in the R. marinus mutant TK-3. The mutant strain TK-3 produced lycopene as the sole carotenoid (0.49 g/kg CDW).
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Affiliation(s)
- Thordis Kristjansdottir
- Matis, Vinlandsleid 12, 113 Reykjavik, Iceland.,University of Iceland, Department of Computer Science, School of Engineering and Natural Sciences, Dunhagi 5, 107 Reykjavik, Iceland
| | - Emanuel Y C Ron
- Lund University, Department of Chemistry, Division of Biotechnology, Box 124, 221 00, Lund, Sweden
| | - Daniel Molins-Delgado
- Lund University, Department of Chemistry, Centre for Analysis and Synthesis, Box 124, 221 00, Lund, Sweden
| | | | - Charlotta Turner
- Lund University, Department of Chemistry, Centre for Analysis and Synthesis, Box 124, 221 00, Lund, Sweden
| | - Snaedis H Bjornsdottir
- University of Iceland, Department of Biology, School of Engineering and Natural Sciences, Sturlugata 7, 102 Reykjavík, Iceland
| | - Steinn Gudmundsson
- University of Iceland, Department of Computer Science, School of Engineering and Natural Sciences, Dunhagi 5, 107 Reykjavik, Iceland
| | - Ed W J van Niel
- Lund University, Department of Chemistry, Division of Applied Microbiology, Box 124, 221 00, Lund, Sweden
| | - Eva Nordberg Karlsson
- Lund University, Department of Chemistry, Division of Biotechnology, Box 124, 221 00, Lund, Sweden
| | - Gudmundur O Hreggvidsson
- Matis, Vinlandsleid 12, 113 Reykjavik, Iceland.,University of Iceland, Department of Biology, School of Engineering and Natural Sciences, Sturlugata 7, 102 Reykjavík, Iceland
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Edrada-Ebel R, Ævarsson A, Polymenakou P, Hentschel U, Carettoni D, Day J, Green D, Hreggviðsson GÓ, Harvey L, McNeil B. SeaBioTech: From Seabed to Test-Bed: Harvesting the Potential of Marine Biodiversity for Industrial Biotechnology. GRAND CHALLENGES IN MARINE BIOTECHNOLOGY 2018. [DOI: 10.1007/978-3-319-69075-9_12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Ron EYC, Plaza M, Kristjansdottir T, Sardari RRR, Bjornsdottir SH, Gudmundsson S, Hreggvidsson GO, Turner C, van Niel EWJ, Nordberg-Karlsson E. Characterization of carotenoids in Rhodothermus marinus. Microbiologyopen 2017; 7. [PMID: 29045010 PMCID: PMC5822342 DOI: 10.1002/mbo3.536] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 08/10/2017] [Accepted: 08/18/2017] [Indexed: 11/13/2022] Open
Abstract
Rhodothermus marinus, a marine aerobic thermophile, was first isolated from an intertidal hot spring in Iceland. In recent years, the R. marinus strain PRI 493 has been genetically modified, which opens up possibilities for targeted metabolic engineering of the species, such as of the carotenoid biosynthetic pathway. In this study, the carotenoids of the R. marinus type‐strain DSM 4252T, strain DSM 4253, and strain PRI 493 were characterized. Bioreactor cultivations were used for pressurized liquid extraction and analyzed by ultra‐high performance supercritical fluid chromatography with diode array and quadropole time‐of‐flight mass spectrometry detection (UHPSFC‐DAD‐QTOF/MS). Salinixanthin, a carotenoid originally found in Salinibacter ruber and previously detected in strain DSM 4253, was identified in all three R. marinus strains, both in the hydroxylated and nonhydroxylated form. Furthermore, an additional and structurally distinct carotenoid was detected in the three strains. MS/MS fragmentation implied that the mass difference between salinixanthin and the novel carotenoid structure corresponded to the absence of a 4‐keto group on the ß‐ionone ring. The study confirmed the lack of carotenoids for the strain SB‐71 (ΔtrpBΔpurAcrtBI’::trpB) in which genes encoding two enzymes of the proposed pathway are partially deleted. Moreover, antioxidant capacity was detected in extracts of all the examined R. marinus strains and found to be 2–4 times lower for the knock‐out strain SB‐71. A gene cluster with 11 genes in two operons in the R. marinusDSM 4252T genome was identified and analyzed, in which several genes were matched with carotenoid biosynthetic pathway genes in other organisms.
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Affiliation(s)
- Emanuel Y C Ron
- Division of Biotechnology, Department of Chemistry, Lund University, Lund, Sweden
| | - Merichel Plaza
- Division of Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Lund, Sweden
| | | | - Roya R R Sardari
- Division of Biotechnology, Department of Chemistry, Lund University, Lund, Sweden
| | | | | | | | - Charlotta Turner
- Division of Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Lund, Sweden
| | - Ed W J van Niel
- Division of Applied Microbiology, Department of Chemistry, Lund University, Lund, Sweden
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Waldhauer MC, Schmitz SN, Ahlmann-Eltze C, Gleixner JG, Schmelas CC, Huhn AG, Bunne C, Büscher M, Horn M, Klughammer N, Kreft J, Schäfer E, Bayer PA, Krämer SG, Neugebauer J, Wehler P, Mayer MP, Eils R, Di Ventura B. Backbone circularization of Bacillus subtilis family 11 xylanase increases its thermostability and its resistance against aggregation. MOLECULAR BIOSYSTEMS 2015; 11:3231-43. [DOI: 10.1039/c5mb00341e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
While using a serine (S) as linker for circularization increases the thermostability, a longer linker (RGKCWE) leads to reduced aggregation after heat shock at elevated temperatures.
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Generation of targeted deletions in the genome of Rhodothermus marinus. Appl Environ Microbiol 2011; 77:5505-12. [PMID: 21705543 DOI: 10.1128/aem.02070-10] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The aim of this work was to develop an approach for chromosomal engineering of the thermophile Rhodothermus marinus. A selection strategy for R. marinus had previously been developed; this strategy was based on complementing a restriction-negative trpB strain with the R. marinus trpB gene. The current work identified an additional selective marker, purA, which encodes adenylosuccinate synthase and confers adenine prototrophy. In a two-step procedure, the available Trp(+) selection was used during the deletion of purA from the R. marinus chromosome. The alternative Ade(+) selection was in turn used while deleting the endogenous trpB gene. Since both deletions are unmarked, the purA and trpB markers may be reused. Through the double deletant SB-62 (ΔtrpB ΔpurA), the difficulties that are associated with spontaneous revertants and unintended chromosomal integration of marker-containing molecules are circumvented. The selection efficiency in R. marinus strain SB-62 (ΔtrpB ΔpurA) was demonstrated by targeting putative carotenoid biosynthesis genes, crtBI, using a linear molecule containing a marked deletion with 717 and 810 bp of 5' and 3' homologous sequences, respectively. The resulting Trp(+) transformants were colorless rather than orange-red. The correct replacement of an internal crtBI fragment with the trpB marker was confirmed by Southern hybridization analysis of the transformants. Thus, it appears that target genes in the R. marinus chromosome can be readily replaced with linear molecules in a single step by double-crossover recombination.
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Taylor MP, van Zyl L, Tuffin IM, Leak DJ, Cowan DA. Genetic tool development underpins recent advances in thermophilic whole-cell biocatalysts. Microb Biotechnol 2011; 4:438-48. [PMID: 21310009 PMCID: PMC3815256 DOI: 10.1111/j.1751-7915.2010.00246.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The environmental value of sustainably producing bioproducts from biomass is now widely appreciated, with a primary target being the economic production of fuels such as bioethanol from lignocellulose. The application of thermophilic prokaryotes is a rapidly developing niche in this field, driven by their known catabolic versatility with lignocellulose-derived carbohydrates. Fundamental to the success of this work has been the development of reliable genetic and molecular systems. These technical tools are now available to assist in the development of other (hyper)thermophilic strains with diverse phenotypes such as hemicellulolytic and cellulolytic properties, branched chain alcohol production and other 'valuable bioproduct' synthetic capabilities. Here we present an insight into the historical limitations, recent developments and current status of a number of genetic systems for thermophiles. We also highlight the value of reliable genetic methods for increasing our knowledge of thermophile physiology. We argue that the development of robust genetic systems is paramount in the evolution of future thermophilic based bioprocesses and make suggestions for future approaches and genetic targets that will facilitate this process.
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Affiliation(s)
- M P Taylor
- Institute for Microbial Biotechnology and Metagenomics (IMBM), University of the Western Cape, Modderdam Road, Bellville 7535, Cape Town, South Africa
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