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Madigan MT, Bender KS, Sanguedolce SA, Parenteau MN, Mayer MH, Kimura Y, Wang-Otomo ZY, Sattley WM. Genomic basis for the unique phenotype of the alkaliphilic purple nonsulfur bacterium Rhodobaca bogoriensis. Extremophiles 2023; 27:19. [PMID: 37481751 DOI: 10.1007/s00792-023-01304-4] [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: 04/07/2023] [Accepted: 07/14/2023] [Indexed: 07/25/2023]
Abstract
Although several species of purple sulfur bacteria inhabit soda lakes, Rhodobaca bogoriensis is the first purple nonsulfur bacterium cultured from such highly alkaline environments. Rhodobaca bogoriensis strain LBB1T was isolated from Lake Bogoria, a soda lake in the African Rift Valley. The phenotype of Rhodobaca bogoriensis is unique among purple bacteria; the organism is alkaliphilic but not halophilic, produces carotenoids absent from other purple nonsulfur bacteria, and is unable to grow autotrophically or fix molecular nitrogen. Here we analyze the draft genome sequence of Rhodobaca bogoriensis to gain further insight into the biology of this extremophilic purple bacterium. The strain LBB1T genome consists of 3.91 Mbp with no plasmids. The genome sequence supports the defining characteristics of strain LBB1T, including its (1) production of a light-harvesting 1-reaction center (LH1-RC) complex but lack of a peripheral (LH2) complex, (2) ability to synthesize unusual carotenoids, (3) capacity for both phototrophic (anoxic/light) and chemotrophic (oxic/dark) energy metabolisms, (4) utilization of a wide variety of organic compounds (including acetate in the absence of a glyoxylate cycle), (5) ability to oxidize both sulfide and thiosulfate despite lacking the capacity for autotrophic growth, and (6) absence of a functional nitrogen-fixation system for diazotrophic growth. The assortment of properties in Rhodobaca bogoriensis has no precedent among phototrophic purple bacteria, and the results are discussed in relation to the organism's soda lake habitat and evolutionary history.
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Affiliation(s)
- Michael T Madigan
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, 62901, USA
| | - Kelly S Bender
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, 62901, USA
| | - Sophia A Sanguedolce
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, 62901, USA
| | - Mary N Parenteau
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, 94035, USA
| | - Marisa H Mayer
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, 94035, USA
| | - Yukihiro Kimura
- Department of Agrobioscience, Kobe University, Kobe, 657-8501, Japan
| | | | - W Matthew Sattley
- Division of Natural Sciences, Indiana Wesleyan University, Marion, IN, 46953, USA.
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Bender KS, Madigan MT, Williamson KL, Mayer MH, Parenteau MN, Jahnke LL, Welander PV, Sanguedolce SA, Brown AC, Sattley WM. Genomic Features of the Bundle-Forming Heliobacterium Heliophilum fasciatum. Microorganisms 2022; 10:microorganisms10050869. [PMID: 35630314 PMCID: PMC9147875 DOI: 10.3390/microorganisms10050869] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/18/2022] [Accepted: 04/19/2022] [Indexed: 02/01/2023] Open
Abstract
Eight species of heliobacteria have had their genomes sequenced. However, only two of these genomes have been analyzed in detail, those from the thermophilic Heliomicrobium (Hmi.) modesticaldum and the alkaliphilic Heliorestis (Hrs.) convoluta. Here we present analyses of the draft genome sequence of a species of heliobacterium that grows optimally at a moderate temperature and neutral pH. The organism, Heliophilum (Hph.) fasciatum, is phylogenetically unique among cultured heliobacteria and was isolated from rice soil, a common habitat for heliobacteria. The Hph. fasciatum genome contains 3.14 Mbp—similar to that of other reported heliobacteria—but has a G+C base ratio that lies between that of Hmi. modesticaldum and Hrs. convoluta. Many of the genomic features of Hmi. modesticaldum and Hrs. convoluta, such as the absence of genes encoding autotrophic pathways, the presence of a superoperonal cluster of photosynthesis-related genes, and genes encoding endospore-specific proteins, are also characteristic of the Hph. fasciatum genome. However, despite the fact that Hph. fasciatum is diazotrophic, classical nif genes encoding the alpha and beta subunits of dinitrogenase (nifDK) present in other heliobacteria could not be identified. Instead, genes encoding several highly divergent NifDK homologs were present, at least one of which likely encodes a functional dinitrogenase and another a methylthio-alkane reductase (MarDK) for sulfur assimilation. A classical NifH (dinitrogenase reductase) homolog was also absent in Hph. fasciatum, but a related protein was identified that likely carries out this function as well as electron delivery to MarDK. The N2-fixing system of Hph. fasciatum is therefore distinct from that of other heliobacteria and may have unusual properties.
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Affiliation(s)
- Kelly S. Bender
- Microbiology Program, School of Biological Sciences, Southern Illinois University, Carbondale, IL 62901, USA; (K.S.B.); (M.T.M.); (K.L.W.)
| | - Michael T. Madigan
- Microbiology Program, School of Biological Sciences, Southern Illinois University, Carbondale, IL 62901, USA; (K.S.B.); (M.T.M.); (K.L.W.)
| | - Kyleigh L. Williamson
- Microbiology Program, School of Biological Sciences, Southern Illinois University, Carbondale, IL 62901, USA; (K.S.B.); (M.T.M.); (K.L.W.)
| | - Marisa H. Mayer
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA 94035, USA; (M.H.M.); (M.N.P.); (L.L.J.)
| | - Mary N. Parenteau
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA 94035, USA; (M.H.M.); (M.N.P.); (L.L.J.)
| | - Linda L. Jahnke
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA 94035, USA; (M.H.M.); (M.N.P.); (L.L.J.)
| | - Paula V. Welander
- Department of Earth System Science, Stanford University, Stanford, CA 94305, USA;
| | - Sophia A. Sanguedolce
- Division of Natural Sciences, Indiana Wesleyan University, Marion, IN 46953, USA; (S.A.S.); (A.C.B.)
| | - Abigail C. Brown
- Division of Natural Sciences, Indiana Wesleyan University, Marion, IN 46953, USA; (S.A.S.); (A.C.B.)
| | - W. Matthew Sattley
- Division of Natural Sciences, Indiana Wesleyan University, Marion, IN 46953, USA; (S.A.S.); (A.C.B.)
- Correspondence: ; Tel.: +1-765-677-2128
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3
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Kyndt JA, Montano Salama D, Meyer TE, Imhoff JF. Phylogenetic relationship of phototrophic heliobacteria and systematic reconsideration of species and genus assignments based on genome sequences of eight species. Int J Syst Evol Microbiol 2021; 71. [PMID: 33881982 DOI: 10.1099/ijsem.0.004729] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The draft genome sequences of five species of named phototrophic heliobacteria in the order Clostridiales were determined. Whole genome phylogenetic and average nucleotide identity comparison for the heliobacteria suggests that Heliobacterium chlorum and Heliobacillus mobilis are closely related to one another and belong to the same genus. The three species Heliobacterium modesticaldum, Heliobacterium undosum and Heliobacterium gestii all belong in the same genus, but are more divergent from Hbt. chlorum and belong in a separate genus, which we suggest to be called Heliomicrobium. Heliorestis convoluta is properly recognized to be in the same genus as Heliorestis acidaminivorans. Heliophilum fasciatum is clearly unlike any other and rightfully belongs in a separate genus.
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Affiliation(s)
- John A Kyndt
- College of Science and Technology, Bellevue University, Bellevue, Nebraska 68005, USA
| | - Dayana Montano Salama
- College of Science and Technology, Bellevue University, Bellevue, Nebraska 68005, USA
| | - Terrance E Meyer
- Department of Biochemistry, University of Arizona, Tucson, AZ, USA
| | - Johannes F Imhoff
- GEOMAR Helmholtz Centre for Ocean Research Kiel, RU Marine Symbioses, Düsternbrooker Weg 20, 24105 Kiel, Germany
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Nature and bioprospecting of haloalkaliphilics: a review. World J Microbiol Biotechnol 2020; 36:66. [DOI: 10.1007/s11274-020-02841-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 04/14/2020] [Indexed: 01/07/2023]
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Dewey ED, Stokes LM, Burchell BM, Shaffer KN, Huntington AM, Baker JM, Nadendla S, Giglio MG, Bender KS, Touchman JW, Blankenship RE, Madigan MT, Sattley WM. Analysis of the Complete Genome of the Alkaliphilic and Phototrophic Firmicute Heliorestis convoluta Strain HH T. Microorganisms 2020; 8:E313. [PMID: 32106460 PMCID: PMC7143216 DOI: 10.3390/microorganisms8030313] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 02/16/2020] [Accepted: 02/22/2020] [Indexed: 11/16/2022] Open
Abstract
Despite significant interest and past work to elucidate the phylogeny and photochemistry of species of the Heliobacteriaceae, genomic analyses of heliobacteria to date have been limited to just one published genome, that of the thermophilic species Heliobacterium (Hbt.) modesticaldum str. Ice1T. Here we present an analysis of the complete genome of a second heliobacterium, Heliorestis (Hrs.) convoluta str. HHT, an alkaliphilic, mesophilic, and morphologically distinct heliobacterium isolated from an Egyptian soda lake. The genome of Hrs. convoluta is a single circular chromosome of 3.22 Mb with a GC content of 43.1% and 3263 protein-encoding genes. In addition to culture-based observations and insights gleaned from the Hbt. modesticaldum genome, an analysis of enzyme-encoding genes from key metabolic pathways supports an obligately photoheterotrophic lifestyle for Hrs. convoluta. A complete set of genes encoding enzymes for propionate and butyrate catabolism and the absence of a gene encoding lactate dehydrogenase distinguishes the carbon metabolism of Hrs. convoluta from its close relatives. Comparative analyses of key proteins in Hrs. convoluta, including cytochrome c553 and the Fo alpha subunit of ATP synthase, with those of related species reveal variations in specific amino acid residues that likely contribute to the success of Hrs. convoluta in its highly alkaline environment.
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Affiliation(s)
- Emma D. Dewey
- Division of Natural Sciences, Indiana Wesleyan University, Marion, IN 46953, USA; (E.D.D.); (L.M.S.); (B.M.B.); (K.N.S.); (A.M.H.); (J.M.B.)
| | - Lynn M. Stokes
- Division of Natural Sciences, Indiana Wesleyan University, Marion, IN 46953, USA; (E.D.D.); (L.M.S.); (B.M.B.); (K.N.S.); (A.M.H.); (J.M.B.)
| | - Brad M. Burchell
- Division of Natural Sciences, Indiana Wesleyan University, Marion, IN 46953, USA; (E.D.D.); (L.M.S.); (B.M.B.); (K.N.S.); (A.M.H.); (J.M.B.)
| | - Kathryn N. Shaffer
- Division of Natural Sciences, Indiana Wesleyan University, Marion, IN 46953, USA; (E.D.D.); (L.M.S.); (B.M.B.); (K.N.S.); (A.M.H.); (J.M.B.)
| | - Austin M. Huntington
- Division of Natural Sciences, Indiana Wesleyan University, Marion, IN 46953, USA; (E.D.D.); (L.M.S.); (B.M.B.); (K.N.S.); (A.M.H.); (J.M.B.)
| | - Jennifer M. Baker
- Division of Natural Sciences, Indiana Wesleyan University, Marion, IN 46953, USA; (E.D.D.); (L.M.S.); (B.M.B.); (K.N.S.); (A.M.H.); (J.M.B.)
| | - Suvarna Nadendla
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (S.N.); (M.G.G.)
| | - Michelle G. Giglio
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (S.N.); (M.G.G.)
| | - Kelly S. Bender
- Department of Microbiology, Southern Illinois University, Carbondale, IL 62901, USA; (K.S.B.); (M.T.M.)
| | | | - Robert E. Blankenship
- Departments of Biology and Chemistry, Washington University in Saint Louis, St. Louis, MO 63130, USA;
| | - Michael T. Madigan
- Department of Microbiology, Southern Illinois University, Carbondale, IL 62901, USA; (K.S.B.); (M.T.M.)
| | - W. Matthew Sattley
- Division of Natural Sciences, Indiana Wesleyan University, Marion, IN 46953, USA; (E.D.D.); (L.M.S.); (B.M.B.); (K.N.S.); (A.M.H.); (J.M.B.)
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6
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Ward LM, Cardona T, Holland-Moritz H. Evolutionary Implications of Anoxygenic Phototrophy in the Bacterial Phylum Candidatus Eremiobacterota (WPS-2). Front Microbiol 2019; 10:1658. [PMID: 31396180 PMCID: PMC6664022 DOI: 10.3389/fmicb.2019.01658] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 07/04/2019] [Indexed: 12/15/2022] Open
Abstract
Genome-resolved environmental metagenomic sequencing has uncovered substantial previously unrecognized microbial diversity relevant for understanding the ecology and evolution of the biosphere, providing a more nuanced view of the distribution and ecological significance of traits including phototrophy across diverse niches. Recently, the capacity for bacteriochlorophyll-based anoxygenic photosynthesis has been proposed in the uncultured bacterial WPS-2 phylum (recently proposed as Candidatus Eremiobacterota) that are in close association with boreal moss. Here, we use phylogenomic analysis to investigate the diversity and evolution of phototrophic WPS-2. We demonstrate that phototrophic WPS-2 show significant genetic and metabolic divergence from other phototrophic and non-phototrophic lineages. The genomes of these organisms encode a new family of anoxygenic Type II photochemical reaction centers and other phototrophy-related proteins that are both phylogenetically and structurally distinct from those found in previously described phototrophs. We propose the name Candidatus Baltobacterales for the order-level aerobic WPS-2 clade which contains phototrophic lineages, from the Greek for "bog" or "swamp," in reference to the typical habitat of phototrophic members of this clade.
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Affiliation(s)
- Lewis M. Ward
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, United States
| | - Tanai Cardona
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Hannah Holland-Moritz
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO, United States
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, CO, United States
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7
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Oren A, Garrity GM. List of new names and new combinations that have appeared in effective publications outside of the IJSEM and are submitted for valid publication. Int J Syst Evol Microbiol 2019; 71. [PMID: 33787483 DOI: 10.1099/ijsem.0.004688] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- Aharon Oren
- The Institute of Life Sciences, The Hebrew University of Jerusalem, The Edmond J. Safra Campus, 9190401 Jerusalem, Israel
| | - George M Garrity
- Department of Microbiology & Molecular Genetics, Biomedical Physical Sciences, Michigan State University, East Lansing, MI 48824-4320, USA
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8
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Energy Conservation in Heliobacteria: Photosynthesis and Central Carbon Metabolism. THE STRUCTURAL BASIS OF BIOLOGICAL ENERGY GENERATION 2014. [DOI: 10.1007/978-94-017-8742-0_13] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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9
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Guo S, Mahillon J. pGIAK1, a heavy metal resistant plasmid from an obligate alkaliphilic and halotolerant bacterium isolated from the Antarctic Concordia station confined environment. PLoS One 2013; 8:e72461. [PMID: 24009682 PMCID: PMC3756968 DOI: 10.1371/journal.pone.0072461] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 07/14/2013] [Indexed: 11/18/2022] Open
Abstract
pGIAK1 is a 38-kb plasmid originating from the obligate alkaliphilic and halotolerant Bacillaceae strain JMAK1. The strain was originally isolated from the confined environments of the Antarctic Concordia station. Analysis of the pGIAK1 38,362-bp sequence revealed that, in addition to its replication region, this plasmid contains the genetic determinants for cadmium and arsenic resistances, putative methyltransferase, tyrosine recombinase, spore coat protein and potassium transport protein, as well as several hypothetical proteins. Cloning the pGIAK1 cad operon in Bacillus cereus H3081.97 and its ars operon in Bacillus subtilis 1A280 conferred to these hosts cadmium and arsenic resistances, respectively, therefore confirming their bona fide activities. The pGIAK1 replicon region was also shown to be functional in Bacillus thuringiensis, Bacillus subtilis and Staphylococcus aureus, but was only stably maintained in B. subtilis. Finally, using an Escherichia coli - B. thuringiensis shuttle BAC vector, pGIAK1 was shown to display conjugative properties since it was able to transfer the BAC plasmid among B. thuringiensis strains.
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Affiliation(s)
- Suxia Guo
- Laboratory of Food and Environmental Microbiology, Université Catholique de Louvain, Croix du Sud, Louvain-la-Neuve, Belgium
| | - Jacques Mahillon
- Laboratory of Food and Environmental Microbiology, Université Catholique de Louvain, Croix du Sud, Louvain-la-Neuve, Belgium
- * E-mail:
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10
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Adaptation in Haloalkaliphiles and Natronophilic Bacteria. CELLULAR ORIGIN, LIFE IN EXTREME HABITATS AND ASTROBIOLOGY 2013. [DOI: 10.1007/978-94-007-6488-0_5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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11
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Amino acid-assimilating phototrophic heliobacteria from soda lake environments: Heliorestis acidaminivorans sp. nov. and ‘Candidatus Heliomonas lunata’. Extremophiles 2012; 16:585-95. [DOI: 10.1007/s00792-012-0458-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 04/19/2012] [Indexed: 10/28/2022]
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Girija KR, Vinay B, Sasikala C, Ramana CV. Novel heliobacteria of a few semi-arid tropical soils. Indian J Microbiol 2010; 50:17-20. [PMID: 22815566 DOI: 10.1007/s12088-010-0069-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Accepted: 06/01/2008] [Indexed: 10/18/2022] Open
Abstract
Out of forty rhizosphere soils collected from semi arid tropical regions of Andhra Pradesh, India, 30 gave positive enrichments for heliobacteria. These bacteria were recognized by the presence of bacteriochlorophyll-g together with endospores in the initial enrichments. Using group specific primers of 16S rRNA gene, ten monoheliobacterial cultures were sequenced. They were finally grouped into 3 clusters based on the 16S rRNA gene similarity. Based on a few phenotypic characters, in addition to genetic characterization, we identified them as potential novel species and the 16S rRNA gene sequences were deposited with EMBL.
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Asao M, Madigan MT. Taxonomy, phylogeny, and ecology of the heliobacteria. PHOTOSYNTHESIS RESEARCH 2010; 104:103-111. [PMID: 20094790 DOI: 10.1007/s11120-009-9516-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Accepted: 12/07/2009] [Indexed: 05/28/2023]
Abstract
Heliobacteria are a recently discovered group of anoxygenic phototrophic bacteria, first described in 1983. Heliobacteria contain bacteriochlorophyll g, a pigment unique to species of this group, and synthesize the simplest photosynthetic complexes of all known phototrophs. Also, unlike all other phototrophs, heliobacteria lack a mechanism for autotrophy and produce endospores. Four genera of heliobacteria containing a total of 10 species are known. Species of the genera Heliobacterium, Heliobacillus, and Heliophilum grow best at neutral pH, whereas species of Heliorestis are alkaliphilic. Heliobacterium, Heliobacillus, and Heliophilum species form one phylogenetic clade of heliobacteria, while Heliorestis species form a second within the phylum Firmicutes of the domain Bacteria. Heliobacteria have a unique ecology, being primarily terrestrial rather than aquatic phototrophs, and may have evolved a mutualistic relationship with plants, in particular, rice plants. The genome sequence of the thermophile Heliobacterium modesticaldum supports the hypothesis that heliobacteria are "minimalist phototrophs" and that they may have played a key role in the evolution of phototrophic bacteria.
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Affiliation(s)
- Marie Asao
- Department of Microbiology, Southern Illinois University, Carbondale, IL 62901, USA
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14
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The genome of Heliobacterium modesticaldum, a phototrophic representative of the Firmicutes containing the simplest photosynthetic apparatus. J Bacteriol 2008; 190:4687-96. [PMID: 18441057 DOI: 10.1128/jb.00299-08] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Despite the fact that heliobacteria are the only phototrophic representatives of the bacterial phylum Firmicutes, genomic analyses of these organisms have yet to be reported. Here we describe the complete sequence and analysis of the genome of Heliobacterium modesticaldum, a thermophilic species belonging to this unique group of phototrophs. The genome is a single 3.1-Mb circular chromosome containing 3,138 open reading frames. As suspected from physiological studies of heliobacteria that have failed to show photoautotrophic growth, genes encoding enzymes for known autotrophic pathways in other phototrophic organisms, including ribulose bisphosphate carboxylase (Calvin cycle), citrate lyase (reverse citric acid cycle), and malyl coenzyme A lyase (3-hydroxypropionate pathway), are not present in the H. modesticaldum genome. Thus, heliobacteria appear to be the only known anaerobic anoxygenic phototrophs that are not capable of autotrophy. Although for some cellular activities, such as nitrogen fixation, there is a full complement of genes in H. modesticaldum, other processes, including carbon metabolism and endosporulation, are more genetically streamlined than they are in most other low-G+C gram-positive bacteria. Moreover, several genes encoding photosynthetic functions in phototrophic purple bacteria are not present in the heliobacteria. In contrast to the nutritional flexibility of many anoxygenic phototrophs, the complete genome sequence of H. modesticaldum reveals an organism with a notable degree of metabolic specialization and genomic reduction.
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Asao M, Takaichi S, Madigan MT. Thiocapsa imhoffii, sp. nov., an alkaliphilic purple sulfur bacterium of the family Chromatiaceae from Soap Lake, Washington (USA). Arch Microbiol 2007; 188:665-75. [PMID: 17661016 DOI: 10.1007/s00203-007-0287-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Revised: 07/05/2007] [Accepted: 07/11/2007] [Indexed: 11/30/2022]
Abstract
An alkaliphilic purple sulfur bacterium, strain SC5, was isolated from Soap Lake, a soda lake located in east central Washington state (USA). Cells of strain SC5 were gram-negative, non-motile, and non-gas vesiculate cocci, often observed in pairs or tetrads. In the presence of sulfide, elemental sulfur was deposited internally. Liquid cultures were pink to rose red in color. Cells contained bacteriochlorophyll a and spirilloxanthin as major photosynthetic pigments. Internal photosynthetic membranes were of the vesicular type. Optimal growth of strain SC5 occurred in the absence of NaCl (range 0-4%), pH 8.5 (range pH 7.5-9.5), and 32 degrees C. Photoheterotrophic growth occurred in the presence of sulfide or thiosulfate with only a limited number of organic carbon sources. Growth factors were not required, and cells could fix N2. Dark, microaerobic growth occurred in the presence of both an organic carbon source and thiosulfate. Sulfide and thiosulfate served as electron donors for photoautotrophy, which required elevated levels of CO2. Phylogenetic analysis placed strain SC5 basal to the clade of the genus Thiocapsa in the family Chromatiaceae with a 96.7% sequence similarity to its closest relative, Thiocapsa roseopersicina strain 1711T (DSM217T). The unique assemblage of physiological and phylogenetic properties of strain SC5 defines it as a new species of the genus Thiocapsa, and we describe strain SC5 herein as Tca. imhoffii, sp. nov.
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Affiliation(s)
- Marie Asao
- Department of Microbiology, Southern Illinois University, Carbondale, IL 62901-6508, USA
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Romano I, Lama L, Orlando P, Nicolaus B, Giordano A, Gambacorta A. Halomonas sinaiensis sp. nov., a novel halophilic bacterium isolated from a salt lake inside Ras Muhammad Park, Egypt. Extremophiles 2007; 11:789-96. [PMID: 17618404 DOI: 10.1007/s00792-007-0100-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Accepted: 06/15/2007] [Indexed: 11/26/2022]
Abstract
An alkalitolerant and halotolerant bacterium, designated strain Sharm was isolated from a salt lake inside Ras Muhammad. The morphological, physiological and genetic characteristics were compared with those of related species of the genus Halomonas. The isolate grew optimally at pH 7.0, 5-15% NaCl at 35 degrees C. The cells were Gram-negative rods, facultative anaerobes. They accumulated glycine-betaine, as a major osmolyte, and ectoine and glutamate as minor components. The strain Sharm(T) biosynthetised alpha-glucosidase. The polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, and a novel phosphoglycolipid as major components. Ubiquinone with nine repetitive unities (Q9) was the only quinone found and, nC16:0 and C19:0 with cyclopropane were the main cellular fatty acids, accounting for 87.3% of total fatty acids. The G + C content of the genomic DNA was 64.7 mol %. The 16S rRNA sequence analysis indicated that strain Sharm was a member of the genus Halomonas. The closest relatives of the strain Sharm were Halomonas elongata and Halomonas eurihalina. However, DNA-DNA hybridisation results clearly indicated that strain Sham was a distinct species of Halomonas. On the basis of the evidence, we propose to assign strain Sharm as a new species of the genus Halomonas, H. sinaiensis sp. nov, with strain Sharm(T) as the type strain (DSM 18067(T); ATCC BAA-1308(T)).
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Affiliation(s)
- Ida Romano
- Istituto di Chimica Biomolecolare, Comprensorio ex Olivetti, via Campi Flegrei 34, 80078, Pozzuoli, Napoli, Italy
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