The transition between Aptian and Albian stages of the Lower Cretaceous (∼113 Ma) was a critical moment in the development of the proto–South Atlantic Ocean. At this time, marine ingressions in ...Brazilian sedimentary basins occurred in the northeastern region and deposited organic-rich mudstones and sulfate evaporites. However, the paleogeographic configuration that controlled sedimentation and biota dynamics remains poorly understood. This study presents new paleogeographic insights based on tectonic reconstructed Gplate models and a high-resolution chemostratigraphic framework. We explore new isotopic data of bulk organic carbon and nitrogen as well as saturated fraction biomarkers collected from a well-preserved section in the eastern part of the Brazilian northeastern Parnaíba Basin (Codó Formation). We also present new biomarker data for samples from the Barra Velha Formation from a well in the Santos Basin, which belongs to the same local stage of the Codó Formation (Alagoas Stage). For the Parnaíba Basin section, geochemical proxies subdivide the environmental evolution into five stages. These stages reflect a transition from a highly saline environment (stage A) that experienced transient marine influxes and eventually transitioned into a closed evaporitic system (stage B). A major marine ingression established an epicontinental anoxic sea (Stage C) that subsequently experienced an increase in water circulation and water depth; turning into an oxic marine environment (Stage D). Interruption of the connection with the sea and constant terrestrial input led to a continentalization process establishing a lacustrine/continental environment (Stage E). For the Santos Basin section (Barra Velha Formation), we measured the occurrence of the C30 tetracyclic polyprenoids which are consistent with a dominant lacustrine saline environment. Our paleogeographic model suggests that marine ingressions towards the southern basins, during the first stages of Pangea breakup, occurred through the northern portion of the Borborema Province and produced an interior seaway that possibly connected the Brazilian northeastern with the southeastern basins through the Recôncavo/Tucano rift system. Our findings and the environmental interpretations for stratigraphic correlated units from the southern continental basins infers that the greater marine influence in the northeastern areas shifted from hypersaline environments into restricted marine environments that resulted in the deposition of shales and mesohaline/penesaline salts. Concomitantly, the existence of a Brazilian-African landbridge acted as a barrier point for the first marine inflows towards the south. The restricted marine connection transformed south alkaline environments into extensive areas of superhaline conditions that resulted in giant thick salt successions of the South Atlantic basins. Finally, further tectonic evolution and complete breakup of Pangea terminated the Brazilian-African landbridge and shutoff interior marine routes that later became terrestrial environments. As the continents steadily became rifted-segments, the proto-South Atlantic Ocean expanded leaving a marine record in the southern basins.
•Key record of first Gondwanan marine Cretaceous ingressions are investigated.•Geochemical proxies show a transition from a high saline-alkaline environment into a marine setting.•Environmental correspondences with proto-South Atlantic deposits have been traced.•Tectonic, climate and marine paleo-route controlled sedimentation.
Many hypersaline environments are often contaminated with petroleum compounds. Among these, oil and natural gas production sites all over the world and hundreds of kilometers of coastlines in the ...more arid regions of Gulf countries are of major concern due to the extent and magnitude of contamination. Because conventional microbiological processes do not function well at elevated salinities, bioremediation of hypersaline environments can only be accomplished using high salt-tolerant microorganisms capable of degrading petroleum compounds. In the last two decades, there have been many reports on the biodegradation of hydrocarbons in moderate to high salinity environments. Numerous microorganisms belonging to the domain Bacteria and Archaea have been isolated and their phylogeny and metabolic capacity to degrade a variety of aliphatic and aromatic hydrocarbons in varying salinities have been demonstrated. This article focuses on our growing understanding of bacteria and archaea responsible for the degradation of hydrocarbons under aerobic conditions in moderate to high salinity conditions. Even though organisms belonging to various genera have been shown to degrade hydrocarbons, members of the genera Halomonas Alcanivorax, Marinobacter, Haloferax, Haloarcula, and Halobacterium dominate the published literature. Despite rapid advances in understanding microbial taxa that degrade hydrocarbons under aerobic conditions, not much is known about organisms that carry out similar processes in anaerobic conditions. Also, information on molecular mechanisms and pathways of hydrocarbon degradation in high salinity is scarce and only recently there have been a few reports describing genes, enzymes and breakdown steps for some hydrocarbons. These limited studies have clearly revealed that degradation of oxygenated and non-oxygenated hydrocarbons by halophilic and halotolerant microorganisms occur by pathways similar to those found in non-halophiles.
The genus
is classified on the family
, within the class
and currently includes six species isolated from salterns, saline or soda lakes, and salt mines. All are extremely halophilic (optimal growth ...at 20-25% w/v NaCl) and neutrophilic, except
, the type species of the genus, that is haloalkaliphilic (showing optimal growth at pH 9.0) and possesses distinct phenotypic features, such as a different polar lipid profile than the rest of species of the genus. We have carried out a genome-based study in order to determine the phylogenetic structure of the genus
and elucidate its current taxonomic status. Overall genomic relatedness indexes, i.e., OrthoANI (Average Nucleotide Identity), dDDH (digital DNA-DNA hybridization), and AAI (Average Amino acid Identity), were determined with respect to the species of
and other representative taxa of the class
Our data show that the six species of
constitute a coherent cluster at the genus level. Besides, we have characterized a new haloarchaeon, strain F2-12
, isolated from the brine of a pond of a saltern in Isla Cristina, Huelva, Spain, and we determined that it constitutes a new species of
, for which we propose the name
sp. nov. Besides, the metabolic analysis revealed a heterotrophic lifestyle and a versatile nitrogen metabolism for members of this genus. Finally, metagenomic fragment recruitments from a subset of hypersaline habitats, indicated that the species of
are widely distributed in saline lakes and salterns as well as on saline soils. Species of this haloarchaeal genus can be considered as ubiquitous in intermediate to high salinity habitats.
Members of the genus
are found worldwide and are abundant in ecosystems possessing intermediate salinities between seawater and saturated salt concentrations.
M19-40 is the type species of this genus ...and its first cultivated representative. In the habitats of
M19-40, high salinity is a key determinant for growth and we therefore focused on the cellular adjustment strategy to this persistent environmental challenge. We coupled these experimental studies to the
mining of the genome sequence of this moderate halophile with respect to systems allowing this bacterium to control its potassium and sodium pools, and its ability to import and synthesize compatible solutes.
M19-40 produces enhanced levels of the compatible solute ectoine, both under optimal and growth-challenging salt concentrations, but the genes encoding the corresponding biosynthetic enzymes are not organized in a canonical
operon. Instead, they are scrambled (
;
) and are physically separated from each other on the
M19-40 genome. Genomes of many phylogenetically related bacteria also exhibit a non-canonical organization of the
genes.
M19-40 also synthesizes trehalose, but this compatible solute seems to make only a minor contribution to the cytoplasmic solute pool under osmotic stress conditions. However, its cellular levels increase substantially in stationary phase cells grown under optimal salt concentrations.
genome mining revealed that
M19-40 possesses different types of uptake systems for compatible solutes. Among the set of compatible solutes tested in an osmostress protection growth assay, glycine betaine and arsenobetaine were the most effective. Transport studies with radiolabeled glycine betaine showed that
M19-40 increases the pool size of this osmolyte in a fashion that is sensitively tied to the prevalent salinity of the growth medium. It was amassed in salt-stressed cells in unmodified form and suppressed the synthesis of ectoine. In conclusion, the data presented here allow us to derive a genome-scale picture of the cellular adjustment strategy of a species that represents an environmentally abundant group of ecophysiologically important halophilic microorganisms.
•The genome of halovirus VOLN27B, a new member of myovirus from haloarchaea, was determined to be a linear, dsDNA and 75,891 bp in size, which was predicted to encode 109 proteins and four tRNAs. A ...315 bp LTR (long terminal repeat) was also detected at the both ends of the genome.•VOLN27B, as well as other haloviruses, exhibits a nearly 10% lower DNA G + C content and a distinct difference in frequency of codon usage against its host strain.•The active halovirus VOLN27B as well its host strain, Halorubrum sp. LN27, is isolated from a salt mine located in the central of China, showing a significant genes sequence similarity and synteny with a provirus on the genome of strain Halorubrum sp. Y78 isolated from the south of China and other HF1-like haloviruses isolated from other countries.
Relatively few viruses infecting haloarchaea (haloviruses) have been reported. In this study, the genome sequence of VOLN27B, a recently described archaeal tailed virus (arTV) with a myovirus morphotype was described, along with the sequence of its host, Halorubrum spp. LN27. Halovirus VOLN27B contains a linear, dsDNA genome of 76,891 bp which is predicted to encode 109 proteins and four tRNAs (tRNAThr, tRNAArg, tRNAGly and tRNAAsn). The DNA G + C content of VOLN27B genome is 56.1 mol%, nearly 10% lower than that of its host strain. A 315 bp LTR (long terminal repeat) was detected in the genome. The genome of its host strain LN27 was 3,301,211 bp (chromosome and 1 plasmid) with a DNA G + C content of 68.3 mol% and 3142 annotated protein coding genes. At least two hypothetical proviruses were detected in the genome. It lacked a CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) locus. Sequence similarity and phylogenetic tree reconstructions placed it within the genus Halorubrum as a potential new species. VOLN27B exhibits a distinct difference in the frequency of codon usage against its host strain Halorubrum sp. LN27. The organization of VOLN27B genome shows remarkable synteny and amino acid sequence similarity to the genomes and predicted proteins of HF1-like haloviruses (genus Haloferacalesvirus) and a provirus in the genome of Halorubrum depositum Y78. VOLN27B and its host Halorubrum sp. LN27 comprise a new virus-host system from a hypersaline ecosystem and can be used to further understand the novel biology at extreme salt concentration.
Hypersaline regions are terrestrial analogs of the Earth’s primitive ecosystem and extraterrestrial environment. The salt range in Pakistan is considered among a few of the ancient salt deposits in ...the subcontinent. Karak salt mine is situated at the Northwest end in Pakistan. Despite the fact that halophiles initiated the formation of terrestrial ecosystems, their products and identities remain hidden. Some preliminary studies limited to culture-dependent isolations have been reported. Characterizing the microbiome that spans over centuries of ecosystem development is crucial, given their role in shaping landscape succession and biogeochemical cycles. Here, we used metagenomics techniques to explore the microbial diversity of the Karak salt mine. We used 16S rRNA Illumina amplicon sequencing to characterize the halophilic communities entrapped in Karak mine. The results were interpreted using Illumina Basespace, QIIME, and Cytoscape. Cultures were isolated at 16–25% salinity. Metagenomics data was consistent with our preliminary culturing data, indicating remarkable species to strain-level diversity of unique halophiles. A total of 107,099 (brine) and 122,679 (salt) reads were obtained. 16S rRNA based sequencing revealed a microbiome with bacteria (66% brine and 72% salt) dominated by Bacteroidetes and Proteobacteria with a strikingly high abundance of Archaea (18% brine and 13% salt). Alpha diversity has higher values in salt than in the brine. The study of the halophiles in the Karak salt mine provides clues for species contributing to the maintenance of biogeochemical cycles of the ecosystem. This is the first report of a metagenomic study of any hypersaline region of Pakistan.
Bacteriophages function as a regulator of host communities and metabolism. Many phages have been isolated and sequenced in environments such as the ocean, but very little is known about hypersaline ...environments. Phages infecting members of the genus
remain poorly understood, and no
phage genome has been reported. In this study, a halovirus infecting
sp. F3, YPCBV-1, was isolated from Yipinglang salt mine. YPCBV-1 could only infect host strain F3 with burst size of 6.3 PFU/cell. It could produce progeny in 5%-20% (w/v) NaCl with an optimal concentration of 10% (w/v), but the optimal adsorption NaCl concentration was 5%-8% (w/v). YPCBV-1 is sensitive to pure water and depends on NaCl or KCl solutions to survive. YPCBV-1 stability increased with increasing salinity but decreased in NaCl saturated solutions, and it has a broader salinity adaptation than the host. YPCBV-1 has a double-stranded DNA of 36,002 bp with a G + C content of 67.09% and contains a total of 55 predicted ORFs and no tRNA genes. Phylogenetic analysis and genomic network analysis suggested that YPCBV-1 is a novel Mu-like phage under the class Caudoviricetes. Auxiliary metabolic gene, SUMF1/EgtB/PvdO family non-heme iron enzyme, with possible roles in antioxidant was found in YPCBV-1. Moreover, DGR-associated genes were predicted in YPCBV-1 genome, which potentially produce hypervariable phage tail fiber. These findings shed light on the halovirus-host interaction in hypersaline environments.
Trace metal distribution and speciation studies in hypersaline systems are scarce because of the difficulty in measuring low metal concentrations in high salinity (S) waters. In this study, dissolved ...molybdenum (MoD) was measured in samples collected in the hypersaline Ojo de Liebre Lagoon and evaporation ponds of the Guerrero Negro saltern, Baja California Peninsula, Mexico. MoD was extracted from these hypersaline waters with a modification of a method originally developed to measure this element in natural waters (S < 36). In general, MoD concentrations ranged from 42 to 241 nM along the hypersaline gradient, well below those predicted from simple seawater evaporation, indicating non-conservative behavior of MoD relative to salinity. The magnitude of the removal process was reflected in both the high calculated MoD fluxes toward the sediment/microbial mat (2.2 ton yr−1), and the very short residence time of MoD (4.1 yr) in the water column of the evaporation ponds. These findings suggest that sediments/microbial mats and also gypsum from current hypersaline environments act as important, but as yet unquantified, MoD sinks. Removal of MoD in hypersaline environments may have been especially important during the geological past, when these environments were more prevalent and extensive, and thus capable of influencing the global Mo cycle as well as, indirectly, the nitrogen cycle.
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•Reliable determination of dissolved Mo (MoD) in hypersaline waters is demonstrated.•MoD behaves non-conservatively along a salinity gradient in this hypersaline system.•Annual MoD removal to the underlying sediment/microbial mat of this area is ~2.2 t.•MoD residence time calculated for the entire aquatic hypersaline system is 4.1 y.•A novel method for measuring Mo in endoevaporites by XRF was developed.
Life can persist under severe osmotic stress and low water activity in hypersaline environments. On Mars, evidence for the past presence of saline bodies of water is prevalent and resulted in the ...widespread deposition of sulfate and chloride salts. Here we investigate Spotted Lake (British Columbia, Canada), a hypersaline lake with extreme (>3 M) levels of sulfate salts as an exemplar of the conditions thought to be associated with ancient Mars. We provide the first characterization of microbial structure in Spotted Lake sediments through metagenomic sequencing, and report a bacteria-dominated community with abundant Proteobacteria, Firmicutes, and Bacteroidetes, as well as diverse extremophiles. Microbial abundance and functional comparisons reveal similarities to Ace Lake, a meromictic Antarctic lake with anoxic and sulfidic bottom waters. Our analysis suggests that hypersaline-associated species occupy niches characterized foremost by differential abundance of Archaea, uncharacterized Bacteria, and Cyanobacteria. Potential biosignatures in this environment are discussed, specifically the likelihood of a strong sulfur isotopic fractionation record within the sediments due to the presence of sulfate reducing bacteria. With its high sulfate levels and seasonal freeze-thaw cycles, Spotted Lake is an analog for ancient paleolakes on Mars in which sulfate salt deposits may have offered periodically habitable environments, and could have concentrated and preserved organic materials or their biomarkers over geologic time.
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