scholarly journals Physiology and Phylogeny of Green Sulfur Bacteria Forming a Monospecific Phototrophic Assemblage at a Depth of 100 Meters in the Black Sea

2005 ◽  
Vol 71 (12) ◽  
pp. 8049-8060 ◽  
Author(s):  
Ann K. Manske ◽  
Jens Glaeser ◽  
Marcel M. M. Kuypers ◽  
Jörg Overmann
Keyword(s):  
Black Sea ◽  
Sulfide Oxidation ◽  
Green Sulfur Bacteria ◽  
The Black Sea ◽  
Rrna Gene ◽  
Green Sulfur Bacterium ◽  
Sulfur Bacteria ◽  
Light Intensities ◽  
Green Sulfur

ABSTRACT The biomass, phylogenetic composition, and photoautotrophic metabolism of green sulfur bacteria in the Black Sea was assessed in situ and in laboratory enrichments. In the center of the western basin, bacteriochlorophyll e (BChl e) was detected between depths of 90 and 120 m and reached maxima of 54 and 68 ng liter−1. High-pressure liquid chromatography analysis revealed a dominance of farnesyl esters and the presence of four unusual geranyl ester homologs of BChl e. Only traces of BChl e (8 ng liter−1) were found at the northwestern slope of the Black Sea basin, where the chemocline was positioned at a significantly greater depth of 140 m. Stable carbon isotope fractionation values of farnesol indicated an autotrophic growth mode of the green sulfur bacteria. For the first time, light intensities in the Black Sea chemocline were determined employing an integrating quantum meter, which yielded maximum values between 0.0022 and 0.00075 μmol quanta m−2 s−1 at the top of the green sulfur bacterial layer around solar noon in December. These values represent by far the lowest values reported for any habitat of photosynthetic organisms. Only one 16S rRNA gene sequence type was detected in the chemocline using PCR primers specific for green sulfur bacteria. This previously unknown phylotype groups with the marine cluster of the Chlorobiaceae and was successfully enriched in a mineral medium containing sulfide, dithionite, and freshly prepared yeast extract. Under precisely controlled laboratory conditions, the enriched green sulfur bacterium proved to be capable of exploiting light intensities as low as 0.015 μmol quanta m−2 s−1 for photosynthetic 14CO2 fixation. Calculated in situ doubling times of the green sulfur bacterium range between 3.1 and 26 years depending on the season, and anoxygenic photosynthesis contributes only 0.002 to 0.01% to total sulfide oxidation in the chemocline. The stable population of green sulfur bacteria in the Black Sea chemocline thus represents the most extremely low-light-adapted and slowest-growing type of phototroph known to date.

scholarly journals Subfossil 16S rRNA Gene Sequences of Green Sulfur Bacteria in the Black Sea and Their Implications for Past Photic Zone Anoxia

2007 ◽  
Vol 74 (3) ◽  
pp. 624-632 ◽  
Author(s):  
Ann K. Manske ◽  
Uta Henßge ◽  
Jens Glaeser ◽  
Jörg Overmann
Keyword(s):  
16S Rrna ◽  
Black Sea ◽  
Dna Sequences ◽  
Green Sulfur Bacteria ◽  
The Black Sea ◽  
Rrna Gene ◽  
Photic Zone ◽  
Low Light ◽  
Sulfur Bacteria ◽  
Green Sulfur

ABSTRACT The Black Sea is the largest extant anoxic water body on Earth. Its oxic-anoxic boundary is located at a depth of 100 m and is populated by a single phylotype of marine green sulfur bacteria. This organism, Chlorobium sp. strain BS-1, is extraordinarily low light adapted and can therefore serve as an indicator of deep photic zone anoxia (A. K. Manske, J. Glaeser, M. M. M. Kuypers, and J. Overmann, Appl. Environ. Microbiol. 71:8049-8060, 2005). In the present study, two sediment cores were retrieved from the bottom of the Black Sea at depths of 2,006 and 2,162 m and were analyzed for the presence of subfossil DNA sequences of BS-1 using ancient-DNA methodology. Using optimized cultivation media, viable cells of the BS-1 phylotype were detected only at the sediment surface and not in deeper layers. In contrast, green sulfur bacterial 16S rRNA gene fragments were amplified from all the sediment layers investigated, including turbidites. After separation by denaturing gradient gel electrophoresis and sequencing, 14 different sequence types were distinguished. The sequence of BS-1 represented only a minor fraction of the amplification products and was found in 6 of 22 and 4 of 26 samples from the 2,006- and 2,162-m stations, respectively. Besides the sequences of BS-1, three additional phylotypes of the marine clade of green sulfur bacteria were detected. However, the majority of sequences clustered with groups from freshwater habitats. Our results suggest that a considerable fraction of green sulfur bacterial chemofossils did not originate in a low-light marine chemocline environment and therefore were likely to have an allochthonous origin. Thus, analysis of subfossil DNA sequences permits a more differentiated interpretation and reconstruction of past environmental conditions if specific chemofossils of stenoec species, like Chlorobium sp. strain BS-1, are employed.

scholarly journals Characterization and In Situ Carbon Metabolism of Phototrophic Consortia

2003 ◽  
Vol 69 (7) ◽  
pp. 3739-3750 ◽  
Author(s):  
Jens Glaeser ◽  
Jörg Overmann
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Stable Carbon Isotope ◽  
Green Sulfur Bacteria ◽  
Purple Sulfur Bacteria ◽  
Rrna Gene ◽  
Sulfur Bacteria ◽  
Green Sulfur

ABSTRACT A dense population of the phototrophic consortium “Pelochromatium roseum” was investigated in the chemocline of a temperate holomictic lake (Lake Dagow, Brandenburg, Germany). Fluorescence in situ hybridization revealed that the brown epibionts of “P. roseum” constituted up to 37% of the total bacterial cell number and up to 88% of all green sulfur bacteria present in the chemocline. Specific amplification of 16S rRNA gene fragments of green sulfur bacteria and denaturing gradient gel electrophoresis fingerprinting yielded a maximum of four different DNA bands depending on the year of study, indicating that the diversity of green sulfur bacteria was low. The 465-bp 16S rRNA gene sequence of the epibiont of “P. roseum” was obtained after sorting of individual consortia by micromanipulation, followed by a highly sensitive PCR. The sequence obtained represents a new phylotype within the radiation of green sulfur bacteria. Maximum light-dependent H14CO3 − fixation in the chemocline in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea suggested that there was anaerobic autotrophic growth of the green sulfur bacteria. The metabolism of the epibionts was further studied by determining stable carbon isotope ratios (δ13C) of their specific biomarkers. Analysis of photosynthetic pigments by high-performance liquid chromatography revealed the presence of high concentrations of bacteriochlorophyll (BChl) e and smaller amounts of BChl a and d and chlorophyll a in the chemocline. Unexpectedly, isorenieratene and β-isorenieratene, carotenoids typical of other brown members of the green sulfur bacteria, were absent. Instead, four different esterifying alcohols of BChl e were isolated as biomarkers of green sulfur bacterial epibionts, and their δ13C values were determined. Farnesol, tetradecanol, hexadecanol, and hexadecenol all were significantly enriched in 13C compared to bulk dissolved and particulate organic carbon and compared to the biomarkers of purple sulfur bacteria. The difference between the δ13C values of farnesol, the major esterifying alcohol of BChl e, and CO2 was −7.1%, which provides clear evidence that the mode of growth of the green sulfur bacterial epibionts of “P. roseum” in situ is photoautotrophic.

scholarly journals Sulfur globule oxidation in green sulfur bacteria is dependent on the dissimilatory sulfite reductase system

Microbiology ◽  
2011 ◽  
Vol 157 (4) ◽  
pp. 1229-1239 ◽  
Author(s):  
Carina Holkenbrink ◽  
Santiago Ocón Barbas ◽  
Anders Mellerup ◽  
Hiroyo Otaki ◽  
Niels-Ulrik Frigaard
Keyword(s):  
Sulfide Oxidation ◽  
Green Sulfur Bacteria ◽  
Substrate Oxidation ◽  
Sulfite Reductase ◽  
Wild Type ◽  
Oxidation Rates ◽  
Dissimilatory Sulfite Reductase ◽  
Sulfur Bacteria ◽  
Sulfur Globules ◽  
Green Sulfur

Green sulfur bacteria (GSB) oxidize sulfide and thiosulfate to sulfate, with extracellular globules of elemental sulfur as an intermediate. Here we investigated which genes are involved in the formation and consumption of these sulfur globules in the green sulfur bacterium Chlorobaculum tepidum. We show that sulfur globule oxidation is strictly dependent on the dissimilatory sulfite reductase (DSR) system. Deletion of dsrM/CT2244 or dsrT/CT2245, or the two dsrCABL clusters (CT0851–CT0854, CT2247–2250), abolished sulfur globule oxidation and prevented formation of sulfate from sulfide, whereas deletion of dsrU/CT2246 had no effect. The DSR system also seems to be involved in the formation of thiosulfate, because thiosulfate was released from wild-type cells during sulfide oxidation, but not from the dsr mutants. The dsr mutants incapable of complete substrate oxidation oxidized sulfide and thiosulfate about twice as fast as the wild-type, while having only slightly lower growth rates (70–80 % of wild-type). The increased oxidation rates seem to compensate for the incomplete substrate oxidation to satisfy the requirement for reducing equivalents during growth. A mutant in which two sulfide : quinone oxidoreductases (sqrD/CT0117 and sqrF/CT1087) were deleted exhibited a decreased sulfide oxidation rate (∼50 % of wild-type), yet formation and consumption of sulfur globules were not affected. The observation that mutants lacking the DSR system maintain efficient growth suggests that the DSR system is dispensable in environments with sufficiently high sulfide concentrations. Thus, the DSR system in GSB may have been acquired by horizontal gene transfer as a response to a need for enhanced substrate utilization in sulfide-limiting habitats.

scholarly journals Genetic Manipulation of Carotenoid Biosynthesis in the Green Sulfur Bacterium Chlorobium tepidum

2004 ◽  
Vol 186 (16) ◽  
pp. 5210-5220 ◽  
Author(s):  
Niels-Ulrik Frigaard ◽  
Julia A. Maresca ◽  
Colleen E. Yunker ◽  
A. Daniel Jones ◽  
Donald A. Bryant
Keyword(s):  
Genetic Manipulation ◽  
Sequence Similarity ◽  
Carotenoid Biosynthesis ◽  
Green Sulfur Bacteria ◽  
Chlorobium Tepidum ◽  
Sequence Motifs ◽  
Green Sulfur Bacterium ◽  
Sulfur Bacteria ◽  
Carotenoid Composition ◽  
Green Sulfur

ABSTRACT The green sulfur bacterium Chlorobium tepidum is a strict anaerobe and an obligate photoautotroph. On the basis of sequence similarity with known enzymes or sequence motifs, nine open reading frames encoding putative enzymes of carotenoid biosynthesis were identified in the genome sequence of C. tepidum, and all nine genes were inactivated. Analysis of the carotenoid composition in the resulting mutants allowed the genes encoding the following six enzymes to be identified: phytoene synthase (crtB/CT1386), phytoene desaturase (crtP/CT0807), ζ-carotene desaturase (crtQ/CT1414), γ-carotene desaturase (crtU/CT0323), carotenoid 1′,2′-hydratase (crtC/CT0301), and carotenoid cis-trans isomerase (crtH/CT0649). Three mutants (CT0180, CT1357, and CT1416 mutants) did not exhibit a discernible phenotype. The carotenoid biosynthetic pathway in C. tepidum is similar to that in cyanobacteria and plants by converting phytoene into lycopene using two plant-like desaturases (CrtP and CrtQ) and a plant-like cis-trans isomerase (CrtH) and thus differs from the pathway known in all other bacteria. In contrast to the situation in cyanobacteria and plants, the construction of a crtB mutant completely lacking carotenoids demonstrates that carotenoids are not essential for photosynthetic growth of green sulfur bacteria. However, the bacteriochlorophyll a contents of mutants lacking colored carotenoids (crtB, crtP, and crtQ mutants) were decreased from that of the wild type, and these mutants exhibited a significant growth rate defect under all light intensities tested. Therefore, colored carotenoids may have both structural and photoprotection roles in green sulfur bacteria. The ability to manipulate the carotenoid composition so dramatically in C. tepidum offers excellent possibilities for studying the roles of carotenoids in the light-harvesting chlorosome antenna and iron-sulfur-type (photosystem I-like) reaction center. The phylogeny of carotenogenic enzymes in green sulfur bacteria and green filamentous bacteria is also discussed.

scholarly journals Two Genes Encoding New Carotenoid-Modifying Enzymes in the Green Sulfur Bacterium Chlorobium tepidum

2006 ◽  
Vol 188 (17) ◽  
pp. 6217-6223 ◽  
Author(s):  
Julia A. Maresca ◽  
Donald A. Bryant
Keyword(s):  
Green Sulfur Bacteria ◽  
The Other ◽  
Chlorobium Tepidum ◽  
Green Sulfur Bacterium ◽  
Gene Encoding ◽  
Anoxygenic Phototrophs ◽  
Sulfur Bacteria ◽  
Genes Encoding ◽  
Green Sulfur ◽  
Predicted Function

ABSTRACT The green sulfur bacterium Chlorobium tepidum produces chlorobactene as its primary carotenoid. Small amounts of chlorobactene are hydroxylated by the enzyme CrtC and then glucosylated and acylated to produce chlorobactene glucoside laurate. The genes encoding the enzymes responsible for these modifications of chlorobactene, CT1987, and CT0967, have been identified by comparative genomics, and these genes were insertionally inactivated in C. tepidum to verify their predicted function. The gene encoding chlorobactene glucosyltransferase (CT1987) has been named cruC, and the gene encoding chlorobactene lauroyltransferase (CT0967) has been named cruD. Homologs of these genes are found in the genomes of all sequenced green sulfur bacteria and filamentous anoxygenic phototrophs as well as in the genomes of several nonphotosynthetic bacteria that produce similarly modified carotenoids. The other bacteria in which these genes are found are not closely related to green sulfur bacteria or to one another. This suggests that the ability to synthesize modified carotenoids has been a frequently transferred trait.

scholarly journals A Green Sulfur Bacterium From Epsomitic Hot Lake, Washington, USA

2020 ◽  
Author(s):  
Michael T. Madigan ◽  
Megan L. Kempher ◽  
Kelly S. Bender ◽  
Deborah O. Jung ◽  
W. Matthew Sattley ◽  
...  
Keyword(s):  
Phylogenetic Analyses ◽  
Late Summer ◽  
Green Sulfur Bacteria ◽  
Hypersaline Lake ◽  
Green Sulfur Bacterium ◽  
Sulfur Bacteria ◽  
Lake Washington ◽  
Pure Cultures ◽  
Green Sulfur ◽  
Anoxic Zones

Hot Lake is a small heliothermal and hypersaline lake in far north-central Washington State (USA) and is limnologically unusual because MgSO4 rather than NaCl is the dominant salt. In late summer, the Hot Lake metalimnion becomes distinctly green from blooms of planktonic phototrophs. In a study undertaken over 60 years ago, these blooms were predicted to include green sulfur bacteria but no cultures were obtained. We sampled Hot Lake and established enrichment cultures for phototrophic sulfur bacteria in MgSO4-rich sulfidic media. Most enrichments turned green or red within two weeks, and from green-colored enrichments, pure cultures of a lobed green sulfur bacterium (Phylum Chlorobi) were isolated. Phylogenetic analyses showed the organism to be a species of the prosthecate green sulfur bacterium Prosthecochloris. Cultures of this Hot Lake phototroph were halophilic and tolerated high levels of sulfide and MgSO4. In addition, unlike all recognized species of Prosthecochloris, the Hot Lake isolates grew at temperatures up to 45°C, indicating an adaptation to the warm summer temperatures of the lake. Photoautotrophy by Hot Lake green sulfur bacteria may contribute dissolved organic matter to anoxic zones of the lake, and their diazotrophic capacity may provide a key source of bioavailable nitrogen, as well.

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