1
|
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.
Collapse
|
2
|
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).
Collapse
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
| |
Collapse
|
3
|
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]
|
4
|
Sardari RR, Kulcinskaja E, Ron EY, Björnsdóttir S, Friðjónsson ÓH, Hreggviðsson GÓ, Karlsson EN. Evaluation of the production of exopolysaccharides by two strains of the thermophilic bacterium Rhodothermus marinus. Carbohydr Polym 2017; 156:1-8. [DOI: 10.1016/j.carbpol.2016.08.062] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 08/18/2016] [Accepted: 08/18/2016] [Indexed: 01/27/2023]
|
5
|
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.
Collapse
|
6
|
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.
Collapse
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
| | | | | | | | | |
Collapse
|
7
|
Nolan M, Tindall BJ, Pomrenke H, Lapidus A, Copeland A, Glavina Del Rio T, Lucas S, Chen F, Tice H, Cheng JF, Saunders E, Han C, Bruce D, Goodwin L, Chain P, Pitluck S, Ovchinikova G, Pati A, Ivanova N, Mavromatis K, Chen A, Palaniappan K, Land M, Hauser L, Chang YJ, Jeffries CD, Brettin T, Göker M, Bristow J, Eisen JA, Markowitz V, Hugenholtz P, Kyrpides NC, Klenk HP, Detter JC. Complete genome sequence of Rhodothermus marinus type strain (R-10). Stand Genomic Sci 2009; 1:283-90. [PMID: 21304669 PMCID: PMC3035238 DOI: 10.4056/sigs.46736] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Rhodothermus marinus Alfredsson et al. 1995 is the type species of the genus and is of phylogenetic interest because the Rhodothermaceae represent the deepest lineage in the phylum Bacteroidetes. R. marinus R-10T is a Gram-negative, non-motile, non-spore-forming bacterium isolated from marine hot springs off the coast of Iceland. Strain R-10T is strictly aerobic and requires slightly halophilic conditions for growth. Here we describe the features of this organism, together with the complete genome sequence, and annotation. This is the first complete genome sequence of the genus Rhodothermus, and only the second sequence from members of the family Rhodothermaceae. The 3,386,737 bp genome (including a 125 kb plasmid) with its 2914 protein-coding and 48 RNA genes is part of the Genomic Encyclopedia of Bacteria and Archaea project.
Collapse
|
8
|
Turner P, Mamo G, Karlsson EN. Potential and utilization of thermophiles and thermostable enzymes in biorefining. Microb Cell Fact 2007; 6:9. [PMID: 17359551 PMCID: PMC1851020 DOI: 10.1186/1475-2859-6-9] [Citation(s) in RCA: 317] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Accepted: 03/15/2007] [Indexed: 11/10/2022] Open
Abstract
In today's world, there is an increasing trend towards the use of renewable, cheap and readily available biomass in the production of a wide variety of fine and bulk chemicals in different biorefineries. Biorefineries utilize the activities of microbial cells and their enzymes to convert biomass into target products. Many of these processes require enzymes which are operationally stable at high temperature thus allowing e.g. easy mixing, better substrate solubility, high mass transfer rate, and lowered risk of contamination. Thermophiles have often been proposed as sources of industrially relevant thermostable enzymes. Here we discuss existing and potential applications of thermophiles and thermostable enzymes with focus on conversion of carbohydrate containing raw materials. Their importance in biorefineries is explained using examples of lignocellulose and starch conversions to desired products. Strategies that enhance thermostablity of enzymes both in vivo and in vitro are also assessed. Moreover, this review deals with efforts made on developing vectors for expressing recombinant enzymes in thermophilic hosts.
Collapse
Affiliation(s)
- Pernilla Turner
- Dept Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Gashaw Mamo
- Dept Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Eva Nordberg Karlsson
- Dept Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| |
Collapse
|
9
|
Bjornsdottir SH, Fridjonsson OH, Kristjansson JK, Eggertsson G. Cloning and expression of heterologous genes in Rhodothermus marinus. Extremophiles 2006; 11:283-93. [PMID: 17124556 DOI: 10.1007/s00792-006-0037-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Accepted: 10/01/2006] [Indexed: 10/23/2022]
Abstract
The construction of a shuttle cloning system for Rhodothermus marinus and Escherichia coli is described. It is based on the shuttle vector pRM3000, which contains a multiple cloning site as well as the shuttle marker trpB and TrpB(-) recipients of both species. The vector is stable and in 25 +/- 2 and 91 +/- 3 copies in R. marinus SB-1 and E. coli SDH-1, respectively. Three different R. marinus regulatory sequences of the dnaJ, dnaK and recA genes were integrated into pRM3000 to make the expression vectors pRM5100, pRM5200 and pRM5300, respectively. Genes encoding alpha- and beta-galactosidase (agaT and bgaT) from Thermus brockianus were cloned in R. marinus. Expression of both recombinant genes in R. marinus was demonstrated. The agaT gene was used as a reporter to study transcription from the expression vectors. Induced expression by ten- and twentyfold was observed from the dnaK and dnaJ regulatory sequences, respectively, after a temperature shift from 63 to 77 degrees C. This is the first report of cloning and expression of heterologous genes in R. marinus and the first study of promoter activity in the species.
Collapse
|
10
|
Fernández-López R, Garcillán-Barcia MP, Revilla C, Lázaro M, Vielva L, de la Cruz F. Dynamics of the IncW genetic backbone imply general trends in conjugative plasmid evolution. FEMS Microbiol Rev 2006; 30:942-66. [PMID: 17026718 DOI: 10.1111/j.1574-6976.2006.00042.x] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Plasmids cannot be understood as mere tools for genetic exchange: they are themselves subject to the forces of evolution. Their genomic and phylogenetic features have been less studied in this respect. Focusing on the IncW incompatibility group, which includes the smallest known conjugative plasmids, we attempt to unveil some common trends in plasmid evolution. The functional modules of IncW genetic backbone are described, with emphasis on their architecture and relationships to other plasmid groups. Some plasmid regions exhibit strong phylogenetic mosaicism, in striking contrast to others of unusual synteny conservation. The presence of genes of unknown function that are widely distributed in plasmid genomes is also emphasized, exposing the existence of ill-defined yet conserved plasmid functions. Conjugation is an essential hallmark of IncW plasmid biology and special attention is given to the organization and evolution of its transfer modules. Genetic exchange between plasmids and their hosts is analysed by following the evolution of the type IV secretion system. Adaptation of the trw conjugative machinery to pathogenicity functions in Bartonella is discussed as an example of how plasmids can change their host modus vivendi. Starting from the phage paradigm, our analysis articulates novel concepts that apply to plasmid evolution.
Collapse
Affiliation(s)
- Raúl Fernández-López
- Departamento de Biología Molecular (Unidad Asociada al C.I.B., C.S.I.C.), Universidad de Cantabria, Santander, Spain
| | | | | | | | | | | |
Collapse
|
11
|
Bjornsdottir SH, Blondal T, Hreggvidsson GO, Eggertsson G, Petursdottir S, Hjorleifsdottir S, Thorbjarnardottir SH, Kristjansson JK. Rhodothermus marinus: physiology and molecular biology. Extremophiles 2005; 10:1-16. [PMID: 16075163 DOI: 10.1007/s00792-005-0466-z] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Accepted: 06/17/2005] [Indexed: 11/24/2022]
Abstract
Rhodothermus marinus has been the subject of many studies in recent years. It is a thermohalophilic bacterium and is the only validly described species in the genus Rhodothermus. It is not closely related to other well-known thermophiles and is the only thermophile within the family Crenotrichaceae. R. marinus has been isolated from several similar but distantly located geothermal habitats, many of which are subject to large fluctuations in environmental conditions. This presumably affects the physiology of R. marinus. Many of its enzymes show optimum activity at temperatures considerably higher than 65 degrees C, the optimum for growth, and some are active over a broad temperature range. Studies have found distinguishing components in the R. marinus electron transport chain as well as in its pool of intracellular solutes, which accumulate during osmotic stress. The species hosts both bacteriophages and plasmids and a functional intein has been isolated from its chromosome. Despite these interesting features and its unknown genetics, interest in R. marinus has been mostly stimulated by its thermostable enzymes, particularly polysaccharide hydrolysing enzymes and enzymes of DNA synthesis which may be useful in industry and in the laboratory. R. marinus has not been amenable to genetic analysis until recently when a system for gene transfer was established. Here, we review the current literature on R. marinus.
Collapse
|