Spiribacter
is the most abundant bacterial genus in the intermediate-salinity zones of hypersaline environments. However,
Spiribacter
strains are extremely difficult to isolate in pure culture. ...Therefore, the characteristics, genome features, and adaption mechanisms that allow
Spiribacter
strains to thrive in highly saline conditions are largely unknown. Here, we show that
Spiribacter
is predominant in brines from marine solar salterns and sulfate-type salt lakes with intermediate to saturated salinities. Using a high-salt medium, we isolated a novel strain,
Spiribacter halobius
E85
T
, which possesses a relatively large and distinct genome. The genome of strain E85
T
has a length of 4.17 Mbp, twice that of other
Spiribacter
species genomes and the largest described genome within the family
Ectothiorhodospiraceae
. Comparative genomic analyses indicate that approximately 50% of E85
T
genes are strain-specific, endowing functional differences in its metabolic capabilities, biosynthesis of compatible solutes, and transport and pumping of solutes into the cell from the environment. Hundreds of insertion sequences result in many pseudogenes and frequent gene fragment rearrangements in the E85
T
genome. Dozens of genomic islands, which show a significant preference for replication, recombination and repair, and cell motility and may have been gained from other bacterial species, are scattered in the genome. This study provides important insights into the general genetic basis for the abundance of
Spiribacter
in hypersaline environments and the strain-specific genome evolutionary strategies of strain E85
T
.
Purpose
Hypersaline environments are extremely vulnerable and important ecological niches. Because much knowledge has focused on the distribution of heavy metals in these areas, the detailed behavior ...of key major elements in hypersaline environments has not been elucidated in detail.
This research aims to define the distribution, translocation pathways, and mobility patterns of the major elements in hypersaline sediments and halophytes.
Materials and methods
Samples of
Sarcocornia fruticosa
plants were collected from evaporation (ES) and crystallization (CA) sites in the Sečovlje Salina area (Republic of Slovenia). The major element contents were measured by digestion in HNO
3
then aqua regia and analyzed by ICP-MS for ultra-low detection limits. Rhizo-sediments from EA and CA were processed using sequential extraction analysis to determine the precise fractionation of Al, Ca, Fe, K, Mg, Mn, and Na. To determine the translocation patterns of individual major elements in
S. fruticosa
, two indices were calculated: bioconcentration (BCF) and translocation factor (TF). Differences and similarities between samples and elements were highlighted using Statistica VII and Grapher 8 statistical software and Ward’s method, respectively.
Results and discussion
The obtained results confirmed that halophyte plants take up large amounts of the essential micronutrient Na due to high salinity, and that macronutrients (Ca, Mg, P, and S) are intensively translocated from the roots to the upper parts of the plant. The overall trend in translocation signature for major elements, distinguished by BCF and TF factor calculations, emphasizes that root tissues accumulate a significant amount of major elements and that accumulation depends on individual major elements. It also showed that the major elements Ca, Mg, Na, P, and S are highly translocated within plants, while the mobility of Al, Fe, and K is limited.
Conclusions
Our results suggest that the major elements are vital macronutrients for halophytes, but their accumulation in the roots and further translocation within the plant depend on individual elements and their dynamics. The translocation pattern of the major elements can be justified as follows: Ca is an essential element for plant growth, maintenance, and membrane integrity; Mg is a specific component of chlorophyll; Na is present because of the hypersaline environment; P is a key component of plant metabolic processes; S represents an important component of enzymes and other key proteins; Al and Fe are preferentially accumulated in roots; and plant leaves are generally undersupplied with K. The presented results are of great importance for the general knowledge and use/application of halophytes in agriculture and biotechnology.
The environmental characterization of the Lower Permian mesosaur-bearing strata of the Mangrullo Formation (Paraná Basin, northeastern Uruguay) has been controversial. Historically, marine conditions ...were suggested for this unit, despite the absence of any normal marine fossils. More recently, some authors have argued for freshwater to brackish settings, inferring fluctuating environmental conditions, which would have generated abrupt changes in the composition of the communities. Mesosaurs are the only tetrapods found in this unit, and they colonized the basin at the time of highest isolation, and apparently increased salinity, coincident with a gradual global rise in aridity. An assemblage of extremely low diversity (the “mesosaur community”) developed, with mesosaur reptiles, pygocephalomorph crustaceans, and the vermiform producers of the trace fossil Chondrites as the dominant components. This community may have existed under temporary hypersaline, lagoon-like conditions, as suggested by ecological, anatomical and physiological attributes of its member taxa. This interpretation is supported by sedimentological and mineralogical features of the enclosing rocks, also seen in the correlative Brazilian Iratí and South African Whitehill formations. In the Uruguayan deposits, as well as in their Brazilian correlatives, relatively close volcanic events affected the basin. This particular environment, where bottom waters were depleted of oxygen and hypersaline, retarded decay of the carcasses, and precluded the development of bioturbating organism, and together with bacterial sealing, favoured exquisite preservation of the fossils, including soft tissues. This leads us to consider the fossil-bearing strata of the Mangrullo Formation as a Konservat-Lagerstätte, the oldest known for South America.
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•Higher bacterial diversity and richness found in abandoned salterns.•Higher eukaryotic diversity and richness found in exploited salterns.•Abandoned and exploited salterns own ...specific microorganisms.•Salinity drives bacterial community structures.•Salterns exploitation affects eukaryotic predator composition.
In order to understand the effect of human practices on microbial mats organisation, the study aimed to investigate the biodiversity within microbial mats from exploited and abandoned salterns. Despite several attempts, archaeal 16S rRNA gene fragment sequences were not obtained, indicating that microbial mats were probably dominated by Bacteria with very low abundance of Archaea (< 1%). Thus, the study compared the bacterial and meiofaunal diversity of microbial mats from abandoned and exploited salterns. The higher salinity (101 ± 3.7 psu vs. 51.1 ± 0.7 psu; Welch t-test p < 0.05) of the exploited site maintained lower bacterial diversity in comparison to the abandoned site where the salinity gradient was no longer maintained. However, the microbial mats exhibited similar bacterial class composition while the eukaryotic diversity was significantly higher in the exploited saltern. The abandoned saltern was dominated by sulfate-reducing bacteria and Nematoda, while the exploited saltern was characterized by the presence of halophilic bacteria belonging to Marinobacter, Salinivibrio and Rhodohalobacter genera, and the larger abundance of Hypotrichia (ciliates). Such bacterial and eukaryotic diversity difference might be explained by human actions for salt recovery in exploited salterns such as scraping the surface of microbial mat and increasing salinity renewing the microbial mat each year. Such action decreases the bacterial diversity changing the food web structure that favour the presence of a larger diversity of eukaryotic organisms. Our study provides new insights on microbial mat communities inhabiting salterns, especially the consequences of abandoning saltern exploitation.
Oceanic deep hypersaline anoxic basins (DHABs) are characterized by drastic changes in physico-chemical conditions in the transition from overlaying seawater to brine body. Brine-seawater interfaces ...(BSIs) of several DHABs across the Mediterranean Sea have been shown to possess methanogenic and sulfate-reducing activities, yet no systematic studies have been conducted to address the potential functional diversity of methanogenic and sulfate-reducing communities in the Red Sea DHABs. Here, we evaluated the relative abundance of Bacteria and Archaea using quantitative PCR and conducted phylogenetic analyses of nearly full-length 16S rRNA genes as well as functional marker genes encoding the alpha subunits of methyl-coenzyme M reductase (mcrA) and dissimilatory sulfite reductase (dsrA). Bacteria predominated over Archaea in most locations, the majority of which were affiliated with Deltaproteobacteria, while Thaumarchaeota were the most prevalent Archaea in all sampled locations. The upper convective layers of Atlantis II Deep, which bear increasingly harsh environmental conditions, were dominated by members of the class Thermoplasmata (Marine Benthic Group E and Mediterranean Sea Brine Lakes Group 1). Our study revealed unique microbial compositions, the presence of niche-specific groups, and collectively, a higher diversity of sulfate-reducing communities compared to methanogenic communities in all five studied locations.
Seasonal sampling was carried out at three Argentinian salterns, Salitral Negro (SN), Colorada Grande (CG) and Guatraché (G), to analyze abiotic parameters and microbial diversity and dynamics. ...Microbial assemblages were correlated to environmental factors by statistical analyses. Principal component analysis of the environmental data grouped SN and CG samples separately from G samples owing to G's higher pH values and sulfate concentration. Differences in microbial assemblages were also found. Many archaeal sequences belonged to uncultured members of Haloquadratum and Haloquadratum-related genera, with different environmental optima. Notably, nearly half of the archaeal sequences were affiliated to the recently described ‘Candidatus Haloredividus’ (phylum Nanohaloarchaeota), not previously detected in salt-saturated environments. Most bacterial sequences belonged to Salinibacter representatives, while sequences affiliated to the recently described genus Spiribacter were also found. Seasonal analysis showed at least 40% of the microbiota from the three salterns was prevalent through the year, indicating they are well adapted to environmental fluctuations. On the other hand, a minority of archaeal and bacterial sequences were found to be seasonally distributed. Five viral morphotypes and also eukaryal predators were detected, suggesting different mechanisms for controlling prokaryotic numbers. Notably, Guatraché was the saltern that harbored the highest virus-to-cell ratios reported to date for hypersaline environments.
For the first time the microbial dynamics of three Argentinian extreme environments were analyzed, relating archaeal, bacterial, eukaryal and viral diversity to one another and to abiotic parameters.
A moderately halophilic bacterium designated strain M6-53T was isolated from water of a pond from a marine saltern located in Huelva, south-west Spain. Cells of the strain were Gram-stain-negative, ...strictly aerobic, motile, slightly curved rods, able to grow in media containing 5-25 % (w/v) NaCl (optimal growth at 10 %, w/v), at temperatures from 20 to 40 °C (optimally at 37 °C) and at pH 6.5-9 (optimally at pH 7.0). Phylogenetic analysis based on 16S rRNA gene sequences placed the new isolate within the genus Marinobacter, with the type strains of the most closely related species being Marinobacter persicus IBRC-M 10445T (98.5 % similarity), Marinobacter oulmenensis Set74T (97.2 %) and Marinobacter hydrocarbonoclasticus ATCC 49840T (97.1 %). The major fatty acids present in strain M6-53T were C18 : 1ω9c (29.5 %), C16 : 0 (26.7 %), C12 : 0 3-OH (15.1 %), C18 : 0 (10.2 %) and C16 : ω9c (9.6 %). The G+C content of the genomic DNA for this strain was determined to be 56.4 mol%. The DNA-DNA hybridization values between strain M6-53T and M. persicus CECT 7991T, M. oulmenensis CECT 7499T and M. hydrocarbonoclasticus DSM 50418 were 8, 41 and 38 %, respectively. These values are lower than the accepted 70 % threshold and showed that the new isolate represented a different species within the genus Marinobacter. Phylogenetic analysis based on the 16S rRNA gene sequence and the phenotypic, genotypic and chemotaxonomic features of this new isolate support the placement of strain M6-53T as a representative of a novel species of the genus Marinobacter, for which we propose the name Marinobacter aquaticus sp. nov., with strain M6-53T (=CECT 9228T=LMG 30006T) as the type strain.
Halophiles can be found in hypersaline environments and they can synthesize products of industrial interest.
Method: In this work, 37 bacterial strains were isolated from the sediment of a dried-out ...maar of the “Hoya Rincón de Parangueo” (Mexico) on different culture media with 20% NaCl and pH 9, while potential industrial extracellular enzymes were determined.
Results: Eight genera Salsuginibacillus, Alkalibacillus, Bacillus, Staphylococcus, Oceanobacillus, Halomonas and Nesterenkonia besides 15 distinct species belonging to Actinobacteria, Firmicutes and Proteobacteria were identified. The L371, LTA7 and SU3 isolates produced proteases, M20, L5, L7, L8, Y1, Y2, M3, M9 and RA lipases, LTA4 and SU3 amylases, while LTA7, Y2, M5, M9 and RA caseinases with enzymatic activity at pH 9. Production of siderophore was found in 17 isolates. Discussion or Conclusion: It is reported for the first experimental evidence of siderophores production by N. alba, Alkalibacillus and Oceanobacillus at 6% NaCl (w/v). Isolates RE, RG1, RG2, RH1, RA and I11 showed 2.8% to 4.1% genetic distance with Nesterenkonia species and might represent new species.
The advent of molecular tools, and particularly next-generation sequencing, has dramatically changed our knowledge of the diversity of microbial life on Earth. In recent decades, many studies on ...different terrestrial environments have described the intriguing diversity and abundance of Euzebyales/Euzebyaceae/Euzebya, yet its role in the geochemical cycle of elements is unknown. In addition, as far as we know, no Euzebya isolates have been obtained from terrestrial niches. In this review, it is shown that Euzebya and other haloalkaliphilic bacteria can thrive under harsh conditions, such as high concentrations of sodium and/or calcium, high electric conductivity and alkaline pH, highly variable temperatures, and water fluctuations. These conditions are quasi-extreme in the studied terrestrial environments. However, the culture media used so far for isolation have failed to reproduce the original conditions of these terrestrial ecosystems, and this is likely the reason why strains of Euzebya and other bacteria that inhabit the same niche could not be isolated. It is expected that culture media reproducing the environmental conditions outlined in this review could cope with the isolation of terrestrial Euzebya and other haloalkaliphilic genera.
Saltpans are increasingly being abandoned around the world, leading to the loss of ecosystem services provided by these unique semi-natural wetlands. The desertion of a saltpan at the Swartkops ...Estuary, South Africa has left behind a large area of desiccated hypersaline sediment and a sharp decrease in waterbird abundance and diversity. Here, we explore the potential for restoring this saltpan's wetland function using stormwater inflow to support multiple ecosystem services and improve estuary health. Stormwater will be able to flow into the saltpan as a passive restoration approach that can maintain the site as a wetland habitat. This will contribute to improving the health of a nationally important, yet highly degraded, estuary by retaining 758 ML of stormwater to achieve full capacity, containing an estimated 2908 kg of dissolved inorganic nitrogen and 68 kg of dissolved inorganic nitrogen. Additional ecosystem services such as biodiversity maintenance, carbon storage and societal values can be expected. However, this would create a novel hypersaline stormwater wetland and a strategic adaptive management approach will be required. Management must be guided by monitoring, which should comprise collection of basic environmental data to establish a baseline condition, and against which, long term changes and responses resulting from stochastic events can be assessed and mitigated through the use of achievable ecological restoration targets.
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