Phylogenetic and physiological characterization of a filamentous anoxygenic photoautotrophic bacterium ?Candidatus Chlorothrix halophila? gen. nov., sp. nov., recovered from hypersaline microbial mats (original) (raw)
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Microbiology, 2014
Five phylogenetically similar monocultures of mesophilic filamentous anoxygenic phototrophic bacteria (FAPB) were isolated from microbial mats of low mineral (5-28 g/L) alkaline lakes in Buryat Republic, Transbaikalia and Mongolia, as well as from biofilms of an alkaline sulfide spring (3 g/L) of the Umhei hydrothermal system (Buryat Republic). New isolates were characterized by short trichomes (15-30 μm long and ~1 μm in diameter), straight, curved, or wavy, surrounded by a thin iron sorbing mucous sheath. Gliding motion of the trichomes was not observed. The trichomes formed bunches consisting of sev eral filaments. Trichomes multiply by the separation of short fragments or single cells from the parental tri chome. The cells in the filaments were elongated; they contained chlorosomes, gas vesicles, poly β hydrox ybutyrate granules, and small polyphosphate inclusions. Bacteria contained bacteriochlorophylls c and a and γ carotene. Absorption maxima of the pigments in the cells were observed at 462, (shoulder at 515), 742, 805, and 863 nm. The organisms were strict anaerobes capable of photoautotrophic growth with sulfide as an elec tron donor. Elemental sulfur emerged into the medium as a result of sulfide photooxidation. The organisms were tolerant to sulfide (up to 8 mM). Best growth occurred at pH 8.0, 3-15 g/L NaCl, and 1-5 g/L sodium bicarbonate. According to phylogenetic analysis, the 16S rRNA gene sequences of the FAPB isolates formed a separate cluster most closely related to the species cluster of the family Oscillochloridaceae, suborder Chlo roflexinae, order Chloroflexales, class Chloroflexi. The differences with the closest 16S rRNA gene sequences of the known FAPB were 9-10%. The formal description of a new taxon, Candidatus 'Chloroploca asiatica' gen. nov., sp. nov., is provided.
Recommended standards for the description of new species of anoxygenic phototrophic bacteria
INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 2004
Recommended standards for the description of new species of the anoxygenic phototrophic bacteria are proposed in accordance with Recommendation 30b of the International Code of Nomenclature of Bacteria. These standards include information on the natural habitat, ecology and phenotypic properties including morphology, physiology and pigments and on genetic information and nucleic acid data. The recommended standards were supported by the Subcommittee on the taxonomy of phototrophic bacteria of the International Committee on Systematics of Prokaryotes. They are considered as guidelines for authors to prepare descriptions of new species.
Candidatus Chloracidobacterium thermophilum: an aerobic phototrophic Acidobacterium
Science (New York, N.Y.), 2007
Only five bacterial phyla with members capable of chlorophyll (Chl)-based phototrophy are presently known. Metagenomic data from the phototrophic microbial mats of alkaline siliceous hot springs in Yellowstone National Park revealed the existence of a distinctive bacteriochlorophyll (BChl)-synthesizing, phototrophic bacterium. A highly enriched culture of this bacterium grew photoheterotrophically, synthesized BChls a and c under oxic conditions, and had chlorosomes and type 1 reaction centers. "Candidatus Chloracidobacterium thermophilum" is a BChl-producing member of the poorly characterized phylum Acidobacteria.
FEMS microbiology …, 2008
Israel Anschrift: 31 Rambam St. Petach-Tiqwa (49542), Israel ERKLÄRUNG Hiermit erkläre ich, dass ich die Arbeit mit dem Titel: Phototrophic Chloroflexus-like bacteria and their role in hypersaline microbial mats selbstständing verfasst und geschrieben habe und auβer den angegebenen Quellen keine weiteren Hilfsmittel verwendet habe. Ebenfalls erkläre ich hiermit eidesstattlich, dass es sich bei den von mir abgegebenen Arbeiten um 3 identische Exemplare handelt. ____________________ (ünterschrift)
Fems Microbiology Ecology, 2008
Pigment analysis in an intact hypersaline microbial mat by hyperspectral imaging revealed very patchy and spatially uncorrelated distributions of photopigments Chl a and BChl a/c, which are characteristic photopigments for oxygenic (diatoms and cyanobacteria) and anoxygenic phototrophs (Chloroflexaceae). This finding is in contrast to the expectation that these biomarker pigments should be spatially correlated, as oxygenic phototrophs are thought to supply the Chloroflexaceae members with organic substrates for growth. We suggest that the heterogeneous occurrence is possibly due to sulfide, whose production by sulfate-reducing bacteria may be spatially heterogeneous in the partially oxic photic zone of the mat. We furthermore mapped the near-infra-red-light controlled respiration of Chloroflexaceae under light and dark conditions and found that Chloroflexaceae are responsible for a major part of oxygen consumption at the lower part of the oxic zone in the mat. The presence of Chloroflexaceae was further confirmed by FISH probe and 16S rRNA gene clone library analysis. We assume that species related to the genera Oscillochloris and ‘Candidatus Chlorothrix’, in contrast to those related to Chloroflexus and Roseiflexus, depend less on excreted photosynthates but more on the presence of free sulfide, which may explain their presence in deeper parts of the mat.
Anoxygenic phototrophic bacteria from extreme environments
Discoveries in Photosynthesis, 2005
A diverse group of anoxygenic phototrophic bacteria thrive in habitats characterized by extremes of temperature, pH, or salinity. These 'extremophilic' anoxygenic phototrophs are optimally adapted to the conditions of their habitats and are ideal model systems for defining the physiochemical limits of photosynthesis. Extremophilic phototrophs have provided new insight into the evolution of photosynthesis and play ecological roles as primary producers in their unusual habitats.
Microbes and Environments, 2019
Chloroflexus aggregans is a thermophilic filamentous anoxygenic phototrophic bacterium frequently found in microbial mats in natural hot springs. C. aggregans often thrives with cyanobacteria that engage in photosynthesis to provide it with an organic substrate; however, it sometimes appears as the dominant phototroph in microbial mats without cyanobacteria. This suggests that C. aggregans has the ability to grow photoautotrophically. However, photoautotrophic growth has not been observed in any cultured strains of C. aggregans. We herein attempted to isolate a photoautotrophic strain from C. aggregansdominated microbial mats in Nakabusa hot spring in Japan. Using an inorganic medium, we succeeded in isolating a new strain that we designated "ACA-12". A phylogenetic analysis based on 16S rRNA gene and 16S-23S rRNA gene internal transcribed spacer (ITS) region sequences revealed that strain ACA-12 was closely related to known C. aggregans strains. Strain ACA-12 showed sulfide consumption along with autotrophic growth under anaerobic light conditions. The deposited elemental sulfur particles observed by microscopy indicated that sulfide oxidation occurred, similar to that in photoautotrophic strains in the related species, C. aurantiacus. Moreover, we found that other strains of C. aggregans, including the type strain, also exhibited a slight photoautotrophic growing ability, whereas strain ACA-12 showed the fastest growth rate. This is the first demonstration of photoautotrophic growth with sulfide in C. aggregans. The present results strongly indicate that C. aggregans is associated with inorganic carbon incorporation using sulfide as an electron donor in hot spring microbial mats.
Environmental Microbiology Reports, 2009
Agar-based solid media with increasing concentrations of organic matter were used to isolate new members of the Chloroflexaceae (phylum Chloroflexi) from mesophilic environments containing sulfide. Inorganic media yielded less than 10% positive enrichments, which were not able to be maintained after repetitive inoculations in fresh medium. The use of casaminoacids and complex organic acid mixtures increased the number of positive enrichments (up to 45%) from both water and sediment samples. Two different green filamentous bacteria, SisoF2 and SalF, could be stably maintained as co-cultures for long periods and their phylogeny inferred from the analysis of complete sequences of the 16S rRNA gene. Ribotype SalF showed a high homology (95-98%) to previously isolated Oscillochloris trichoides strains. The 16S rRNA gene sequence retrieved from culture SisoF2 was largely divergent (< 92% similarity) from any sequence derived from either cultured representatives or environmental samples, suggesting that ribotype SisoF2 may constitute a new genus within the phylum. The presence of the new morphotypes in the environment from where they were enriched was analysed by high-resolution phylogenetic fingerprinting.