scholarly journals Inhibition of photoferrotrophy by nitric oxide in ferruginous environments

2021 ◽  
Author(s):  
Verena Nikeleit ◽  
Adrian Mellage ◽  
Giorgio Bianchini ◽  
Lea Sauter ◽  
Steffen Buessecker ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Numerical Modelling ◽  
Primary Role ◽  
Photic Zone ◽  
Banded Iron Formations ◽  
Geochemical Conditions ◽  
Sulfur Bacteria ◽  
Green Sulfur ◽  
Iron Formations ◽  
Detoxification Mechanisms

Anoxygenic phototrophic Fe(II)-oxidizers (photoferrotrophs) are thought to have thrived in Earth’s ancient ferruginous oceans and played a primary role in the precipitation of Archean and Paleoproterozoic (3.8-1.85 Ga) banded iron formations (BIF). The end of BIF deposition by photoferrotrophs has often been interpreted as being the result a deepening of water column oxygenation below the photic zone concomitant with the proliferation of cyanobacteria. We suggest here that a potentially overlooked aspect influencing BIF precipitation by photoferrotrophs is competition with another anaerobic Fe(II)-oxidizing metabolism. It is speculated that microorganisms capable of coupling Fe(II) oxidation to the reduction of nitrate were also present early in Earth history when BIF were being deposited, but the extent to which they could compete with photoferrotrophs when favourable geochemical conditions overlapped is unknown. Utilizing microbial incubations and numerical modelling, we show that nitrate-reducing Fe(II)-oxidizers metabolically outcompete photoferrotrophs for dissolved Fe(II). Moreover, the nitrate-reducing Fe(II)-oxidizers inhibit photoferrotrophy via the production of toxic nitric oxide (NO). Four different photoferrotrophs, representing both green sulfur and purple non-sulfur bacteria, are susceptible to this toxic effect despite having genomic capabilities for NO detoxification. Indeed, despite NO detoxification mechanisms being ubiquitous in some groups of phototrophs at the genomic level (e.g. Chlorobi and Cyanobacteria) it is likely they would still be influenced by NO stress. We suggest that the production of NO during nitrate-reducing Fe(II) oxidation in ferruginous environments represents an as yet unreported control on the activity of photoferrotrophs in the ancient oceans and thus the mechanisms driving precipitation of BIF.

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 Signature pigments of green sulfur bacteria in lower Pleistocene deposits from the Banyoles lacustrine area (Spain)

2005 ◽  
Vol 34 (2) ◽  
pp. 271-280 ◽  
Author(s):  
N. Mallorquí ◽  
J.B. Arellano ◽  
C.M. Borrego ◽  
L.J. Garcia-Gil
Keyword(s):  
Green Sulfur Bacteria ◽  
Sulfur Bacteria ◽  
Lower Pleistocene ◽  
Green Sulfur

scholarly journals Differential RNA Sequencing Implicates Sulfide as the Master Regulator of S 0 Metabolism in Chlorobaculum tepidum and Other Green Sulfur Bacteria

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
Jacob M. Hilzinger ◽  
Vidhyavathi Raman ◽  
Kevin E. Shuman ◽  
Brian J. Eddie ◽  
Thomas E. Hanson
Keyword(s):  
Gene Expression ◽  
Elemental Sulfur ◽  
Green Sulfur Bacteria ◽  
Electron Donors ◽  
Reduced Sulfur Compounds ◽  
Promoter Elements ◽  
Content Type ◽  
Sulfur Bacteria ◽  
Chlorobaculum Tepidum ◽  
Green Sulfur

ABSTRACT The green sulfur bacteria ( Chlorobiaceae ) are anaerobes that use electrons from reduced sulfur compounds (sulfide, S 0 , and thiosulfate) as electron donors for photoautotrophic growth. Chlorobaculum tepidum , the model system for the Chlorobiaceae , both produces and consumes extracellular S 0 globules depending on the availability of sulfide in the environment. These physiological changes imply significant changes in gene regulation, which has been observed when sulfide is added to Cba. tepidum growing on thiosulfate. However, the underlying mechanisms driving these gene expression changes, i.e., the specific regulators and promoter elements involved, have not yet been defined. Here, differential RNA sequencing (dRNA-seq) was used to globally identify transcript start sites (TSS) that were present during growth on sulfide, biogenic S 0 , and thiosulfate as sole electron donors. TSS positions were used in combination with RNA-seq data from cultures growing on these same electron donors to identify both basal promoter elements and motifs associated with electron donor-dependent transcriptional regulation. These motifs were conserved across homologous Chlorobiaceae promoters. Two lines of evidence suggest that sulfide-mediated repression is the dominant regulatory mode in Cba. tepidum . First, motifs associated with genes regulated by sulfide overlap key basal promoter elements. Second, deletion of the Cba. tepidum 1277 ( CT1277 ) gene, encoding a putative regulatory protein, leads to constitutive overexpression of the sulfide:quinone oxidoreductase CT1087 in the absence of sulfide. The results suggest that sulfide is the master regulator of sulfur metabolism in Cba. tepidum and the Chlorobiaceae . Finally, the identification of basal promoter elements with differing strengths will further the development of synthetic biology in Cba. tepidum and perhaps other Chlorobiaceae . IMPORTANCE Elemental sulfur is a key intermediate in biogeochemical sulfur cycling. The photoautotrophic green sulfur bacterium Chlorobaculum tepidum either produces or consumes elemental sulfur depending on the availability of sulfide in the environment. Our results reveal transcriptional dynamics of Chlorobaculum tepidum on elemental sulfur and increase our understanding of the mechanisms of transcriptional regulation governing growth on different reduced sulfur compounds. This report identifies genes and sequence motifs that likely play significant roles in the production and consumption of elemental sulfur. Beyond this focused impact, this report paves the way for the development of synthetic biology in Chlorobaculum tepidum and other Chlorobiaceae by providing a comprehensive identification of promoter elements for control of gene expression, a key element of strain engineering.

scholarly journals Iron and Carbon Isotope Constraints on the Formation Pathway of Iron-Rich Carbonates within the Dagushan Iron Formation, North China Craton

Minerals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 94
Author(s):  
Xiaoxue Tong ◽  
Kaarel Mänd ◽  
Yuhao Li ◽  
Lianchang Zhang ◽  
Zidong Peng ◽  
...  
Keyword(s):  
Iron Reduction ◽  
Isotope Composition ◽  
Iron Formation ◽  
Banded Iron Formations ◽  
Organic C ◽  
Formation Pathway ◽  
Wide Range ◽  
Dissimilatory Iron Reduction ◽  
O Isotope ◽  
Iron Formations

Banded iron formations (BIFs) are enigmatic chemical sedimentary rocks that chronicle the geochemical and microbial cycling of iron and carbon in the Precambrian. However, the formation pathways of Fe carbonate, namely siderite, remain disputed. Here, we provide photomicrographs, Fe, C and O isotope of siderite, and organic C isotope of the whole rock from the ~2.52 Ga Dagushan BIF in the Anshan area, China, to discuss the origin of siderite. There are small magnetite grains that occur as inclusions within siderite, suggesting a diagenetic origin of the siderite. Moreover, the siderites have a wide range of iron isotope compositions (δ56FeSd) from −0.180‰ to +0.463‰, and a relatively negative C isotope composition (δ13CSd = −6.20‰ to −1.57‰). These results are compatible with the reduction of an Fe(III)-oxyhydroxide precursor to dissolved Fe(II) through microbial dissimilatory iron reduction (DIR) during early diagenesis. Partial reduction of the precursor and possible mixing with seawater Fe(II) could explain the presence of siderite with negative δ56Fe, while sustained reaction of residual Fe(III)-oxyhydroxide could have produced siderite with positive δ56Fe values. Bicarbonate derived from both DIR and seawater may have provided a C source for siderite formation. Our results suggest that microbial respiration played an important role in the formation of siderite in the late Archean Dagushan BIF.

Linearly polarized light absorption spectra of chlorosomes, light-harvesting antennas of photosynthetic green sulfur bacteria

2010 ◽  
Vol 484 (4-6) ◽  
pp. 333-337 ◽  
Author(s):  
Hitoshi Tamiaki ◽  
Shingo Tateishi ◽  
Shosuke Nakabayashi ◽  
Yutaka Shibata ◽  
Shigeru Itoh
Keyword(s):  
Absorption Spectra ◽  
Light Absorption ◽  
Light Harvesting ◽  
Polarized Light ◽  
Green Sulfur Bacteria ◽  
Sulfur Bacteria ◽  
Linearly Polarized ◽  
Green Sulfur
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