Soda Lake Research Articles

Microbialites diversity from the Ediacaran of the Anti-Atlas (Morocco): A snapshot of microbial oases thriving in an alkaline volcanic lake

The Moroccan Anti-Atlas belt preserves an exceptional record of an Ediacaran microbial biosphere. The Amane Tazgart Formation of the Ouarzazate Group corresponds to an Ediacaran volcanic alkaline lake depositional system (ca. 571 Ma) where microbial buildups accreted in an extreme environment. These microbial accumulations are exceptional not only for their diverse range of extreme conditions but also for their significance in understanding the early biosphere and earth's habitability. A description of these buildups provides insights into their Spatio-temporal distribution. The lower part consists of thrombolitic limestones, usually displaying irregular to patchy mesoclots, associated with composite and stromatolitic buildups. The upper part dominated by clastic stromatolites exhibits a variety of morphotypes ranging vertically from planar wrinkly laminated to large domes. The transitional morphotypes are made of linked and vertically oriented or inclined columns, grading upward to cone-shaped domes. The increase in laminated fabrics and the decrease in clotted fabrics toward the top of the section indicate that environmental conditions were likely suitable for coexisting both fabrics during microbial carbonate accretion. The demise of carbonate production at the late stage coincides with riverine input of clastic sediments, subsequently followed during low sediment input by growth of siliciclastic stromatolites.

Characterisation and Antimicrobial Potential of Actinobacteria Isolated from Momela Soda Lakes, Tanzania

Extreme environments such as soda lakes are potential sources of microbes with biotechnological applications in different sectors. This study aimed at isolation, characterization and investigation of antibacterial potential of actinobacteria from Momela Soda Lakes, at Arusha National Park in Tanzania. One hundred and twenty (120) isolates were recovered from soil and water samples using the dilution plate technique. The isolates were morphologically and biochemically characterized, and further, screened for antimicrobial activity by disc diffusion method as well as the micro dilution technique. Cytotoxic effects were determined using the brine shrimp lethality test. Results showed that, all 120 isolates were Gram-positive rod-coccus shaped. Forty-four out of them showed antibacterial activity against Staphylococcus aureus and Escherichia coli. The Streptomyces (101TI) and Dietzia (56BI) strains exhibited exceptionally higher antibacterial activity compared to the rest with inhibition zones of 16.25 and 21.00 mm, respectively. These two strains were toxic against brine shrimp-larvae. Microbacterium (5LI), Hoyosella (113BI), Streptomyces (62BI), Dietzia (117SI), Hoyosella (37SI) and Microbacterium (3BI) strains had low antibacterial and cytotoxic activities. This study therefore revealed that Momela Soda Lakes harbour actinobacteria with antimicrobial potential.
 Keywords: Actinobacteria; antimicrobial activity; extremophiles; Momela soda lakes

Implications From the Meteorological Data Effects on Water Level Fluctuations of the Lake Van (Eastern Anatolia/Türkiye)

Lake Van is located in the eastern part of Türkiye and forms the largest soda lake in the world. In this study, we present the relationship between instrumental data which belongs to Lake Van level changes and meteorological parameters by performing a multilevel analysis. The data set consists of monthly average levels of Lake Van and monthly meteorological parameters (temperature, precipitation and wind speed) between 1944-2019 years. Two different multilevel linear models; random intercept, random intercept and slope model were used. Unstructured (UN) covariance structure and Maximum Likelihood (ML) were used for repeated measurements and estimation, respectively. Log-likelihood (ll), Akaike Information Criteria (AIC), Bayesian Information Criteria (BIC) and AIC Corrected (AICC) were used for the selection of the best model. The random intercept and slope model (Model II) is explained as the best model for the lake level changes in this study. Statistical results in this study indicated that the temperature and wind speed are the key parameters controlling the Lake Van water level fluctuations, whereas the precipitation effect is minimal due to the type of precipitation (snowfall). For this reason, temperature, wind speed and also the type of precipitation (snowfall or rain) must be considered for disaster modelling in settlements of Lake Van and similarly closed basin lakes.

Carotegenic Virgibacillus halodenitrificans from Wadi El-Natrun Salt Lakes: Isolation, Optimization, Characterization and Biological Activities of Carotenoids.

Simple SummaryAs one of the two cases of soda lakes in the world, Wadi El-Natrun salt lakes are the intended isolation source in this study. They encompass a characteristic microbial niche of symbionts producing unique bioactive agents, among them carotenoids. Herein, halophilic carotenoid-producing microbes were isolated and purified. Based on the carotenoids content, the potent isolate, namely Virgibacillus halodenitrificans, was molecularly identified, and characterized physiologically, biochemically and morphologically as well. Its carotenoids content was optimized using statistical methods. Under optimized conditions, the maximum productivity was obtained and the extracted carotenoids were identified by UV-Vis analysis, FTIR, Raman spectroscopy, TLC and LC–MS, which confirmed such halophilic carotenoids composed of β-carotene, lutein and β-Apo-8′-carotenal mixture. Meanwhile, the carotenoids were utilized as a powerful antibacterial and antifungal agent. Notably, they exerted higher antibiofilm potentiality at a concentration of 20 μg/mL. Finally, halophilic carotenoids are competing as new biocidal agents, in particular with their biocompatibility and efficiency.Carotenoids, as phytonutrient pigments, are signified by their unique beneficial features that serve human health and the surrounding ecosystem. Haloalkaliphiles from soda lakes produce different natural bioactive molecules; however, their ability to produce carotenoids has been limited. Therefore, this study focused on the screening and isolation of carotenoid-producing haloalkaliphilic microbes. Out of 10 isolates, a powerful carotigenic bacterium was isolated, characterized phenotypically and identified on the molecular level as Virgibacillus halodenitrificans. By employing statistical approaches like Plackett–Burman design and central composite design, the influence of significant nutritional variables on carotenoids production was screened and optimized. Predictive modeling manifested that carotenoid yield was 36.42 mg/mL, a 2.12-fold enhancement compared to the basal conditions through inoculating 1.8% of bacterial biomass on optimized medium containing yeast extract (2 g/mL), peptone (10 g/mL) and NaCl (233.6 g/mL). The carotenoids content was confirmed by UV-Vis spectrum which detected a characteristic unique peak with left and right shoulders at 461 nm, 490 and 522 nm. However, FTIR and Raman spectroscopy showed the presence of several functional groups. Meanwhile, LC–MS confirmed that the examined carotenoids were composed of β-carotene, lutein and β-Apo-8′-carotenal mixture. As a bioactive agent, the carotenoids of V. halodenitrificans DASH showed characteristic antagonistic potency against a wide spectrum of Gram-positive and Gram-negative pathogens. Interestingly, a potent antifungal capacity was observed against Candida albicans, reflecting promising mycocidal efficacy against COVID-19 white fungal post-infections. Furthermore, carotenoids (20 μg/mL) inhibited the biofilm formation of P. aeruginosa and S. aureus by 54.01 ± 3.97% and 80.082 ± 0.895%, respectively. Our results proposed that haloalkaliphiles of Wadi El-Natrun lakes are promising sources of carotenoids that exhibited efficiency as safe, biocompatible and natural bioactive agents for environmental, medical and industrial applications.

Transcriptomic and proteomic analyses provide insights into the adaptive responses to the combined impact of salinity and alkalinity in Gymnocypris przewalskii

Gymnocypris przewalskii is the only high-land endemic teleost living in Qinghai Lake, the largest saline–alkaline lake in China. Its osmoregulatory physiology remains elusive due to a lack of precise identification of the response proteins. In the present study, DIA/SWATH was used to identify differentially expressed proteins (DEPs) under alkaline (pH = 10.1, carbonate buffer), saline (12‰, sodium chloride), and saline–alkaline [carbonate buffer (pH = 10.1) plus 11‰ sodium chloride] stresses. A total of 66,056 unique peptides representing 7,150 proteins and 230 DEPs [the false discovery rate (FDR) ≤ 0.05, fold change (FC) ≥ 1.5] were identified under different stresses. Comparative analyses of the proteome and transcriptome indicated that over 86% of DEPs did not show consistent trends with mRNA. In addition to consistent enrichment results under different stresses, the specific DEPs involved in saline–alkaline adaptation were primarily enriched in functions of homeostasis, hormone synthesis and reactions of defense response, complement activation and reproductive development. Meanwhile, a protein–protein interaction (PPI) network analysis of these specific DEPs indicated that the hub genes were ITGAX, MMP9, C3, F2, CD74, BTK, ANXA1, NCKAP1L, and CASP8. This study accurately isolated the genes that respond to stress, and the results could be helpful for understanding the physiological regulation mechanisms regarding salinity, alkalinity, and salinity–alkalinity interactions.Graphical

Bacterial and archaeal communities within the alkaline soda Langaco Lake in the Qinghai-Tibet Plateau

PurposeLangaco Lake (LGL) is a soda lake located at an altitude of 4548 m in the Qinghai-Tibet Plateau in China. LGL exhibits unique hydrochemical characteristics among soda lakes, but little is known about the microbial diversity of LGL and the microbial interactions with environmental factors.MethodsThe water samples were filtered using chemical-grade cellulose acetate membrane (pore size of 0.45 μm), and the hydrochemical characteristics were analyzed. Community DNA was extracted, and then high-throughput sequencing of 16S rRNA genes was conducted to evaluate the composition of the microbial community.ResultsThe high-throughput sequencing of 16S rRNA genes revealed that the bacterial diversity in LGL consisted of 327 genera in 24 phyla (4871 operational taxonomic units (OTUs); Shannon index values of 5.20–6.07), with a significantly higher diversity than that of the Archaea (eight phyla and 29 genera comprising 1008 OTUs; Shannon index values of 2.98–3.30). The bacterial communities were dominated by Proteobacteria (relative abundances of 42.79–53.70%), followed by Bacteroidetes (11.13–15.18%), Planctomycetes (4.20–12.82%), Acidobacteria (5.91–9.50%), Actinobacteria (2.60–5.80%), and Verrucomicrobia (2.11–4.08%). Furthermore, the archaeal communities were dominated by Crenarchaeota (35.97–58.29%), Euryarchaeota (33.02–39.89%), and Woesearchaeota (6.50–21.57%). The dominant bacterial genus was Thiobacillus (8.92–16.78%), and its abundances were most strongly correlated with the total phosphorus (TP) content, pH value, CO32− concentration, and temperature. The most abundant archaeal genus was Methanoregula (21.40–28.29%), and its abundances were the most highly correlated with the total organic carbon (TOC) content, total salinity (TS), and K+ and Na+ concentrations.ConclusionsThe results of this study provide valuable insights for developing a more comprehensive understanding of microbial diversity in these unique carbonate alkaline environments, as well as a better understanding of the microbial resources on the Qinghai-Tibet Plateau.

Microcrystalline dolomite in a middle Permian volcanic lake: Insights on primary dolomite formation in a non‐evaporitic environment

AbstractLacustrine dolomite nucleation commonly occurs in modern and Neogene evaporitic alkaline lakes. As a result, ancient lacustrine microcrystalline dolomite has been conventionally interpreted to be formed in evaporitic environments. This study, however, suggests a non‐evaporitic origin of dolomite precipitated in a volcanic–hydrothermal lake, where hydrothermal and volcanic processes interacted. The dolomite occurs in lacustrine fine‐grained sedimentary rocks in the middle Permian Lucaogou Formation in the Santanghu intracontinental rift basin, north‐west China. Dolostones are composed mainly of nano‐sized to micron‐sized dolomite with a euhedral to subhedral shape and a low degree of cation ordering, and are interlaminated and intercalated with tuffaceous shale. Non‐dolomite minerals, including quartz, alkaline feldspars, smectite and magnesite mix with the dolomite in various proportions. The 87Sr/86Sr ratios (0.704528 to 0.705372, average = 0.705004) and δ26Mg values (−0.89 to −0.24‰, average = −0.55‰) of dolostones are similar to those of mantle rocks, indicating that the precipitates mainly originated from fluids that migrated upward from the mantle and were subject to water–rock reactions at a great depth. The δ18O values (−3.1 to −22.7‰, average = −14.0‰) of the dolostones indicate hydrothermal influence. The trace and rare earth element concentrations suggest a saline, anoxic and volcanic–hydrothermally‐influenced subaqueous environment. In this subaqueous environment of Lucaogou lake, locally high temperatures and a supply of abundant Mg2+ from a deep source induced by volcanic–hydrothermal activity formed favourable chemical conditions for direct precipitation of primary dolomite. This study's findings deepen the understanding of the origin and processes of lacustrine primary dolomite formation and provide an alternative possibility for environmental interpretations of ancient dolostones.

Diversity of Culturable Alkaliphilic Nitrogen-Fixing Bacteria from a Soda Lake in the East African Rift Valley.

Lake Chitu is a highly productive soda lake found in the East African Rift Valley, where Arthrospira fusiformis (Spirulina platensis) is the main primary producer. High biomass accumulation requires an adequate supply of nitrogen. However, Lake Chitu is a closed system without any external nutrient input. A recent study has also demonstrated the presence of a diverse group of denitrifying bacteria, indicating a possible loss of nitrate released from the oxidation of organic matter. The aim of this study was to isolate culturable nitrogen-fixing alkaliphiles and evaluate their potential contribution in the nitrogen economy of the soda lake. A total of 118 alkaliphiles belonging to nine different operational taxonomic units (OTUs) were isolated using a nitrogen-free medium. Nineteen isolates were tested for the presence of the nifH gene, and 11 were positive. The ability to fix nitrogen was tested by co-culturing with a non-nitrogen-fixing alkaliphile, Alkalibacterium sp. 3.5*R1. When inoculated alone, Alkalibacterium sp. 3.5*R1 failed to grow on a nitrogen-free medium, but grew very well when co-cultured with the nitrogen-fixing alkaliphile NF10m6 isolated in this study, indicating the availability of nitrogen. These results show that nitrogen fixation by alkaliphiles may have an important contribution as a source of nitrogen in soda lakes.

Natranaeroarchaeum sulfidigenes gen. nov., sp. nov., carbohydrate-utilizing sulfur-respiring haloarchaeon from hypersaline soda lakes, a member of a new family Natronoarchaeaceae fam. nov. in the order Halobacteriales

A pure culture of alkaliphilic haloarchaeon strain AArc-ST capable of anaerobic growth by carbohydrate-dependent sulfur respiration was obtained from hypersaline lakes in southwestern Siberia. According to phylogenetic analysis, AArc-ST formed a new genus level branch most related to the genus Natronoarchaeum in the order Halobacteriales. The strain is facultatively anaerobic with strictly respiratory metabolism growing either by anaerobic respiration with elemental sulfur and thiosulfate as the electron acceptors or by aerobic respiration at microoxic conditions. Thiosulfate is reduced partially to sulfide and sulfite. It is a first sulfur-reducing alkaliphilic haloarchaeon utilizing sugars, starch and glycerol as substrates for anaerobic growth. It is extremely halophilic (optimum at 3.5 M total Na+) and obligately alkaliphilic (optimum at pH 9.5). The dominant polar lipids include PG and PGP-Me with the archaeol (C20-C20) or extended archaeol (C20-C25) cores. The dominant respiratory lipoquinone is MK-8:8. On the basis of unique physiological properties and results of phylogenetic analysis, the soda lake isolate is suggested to be classified into a novel genus and species Natranaeroarchaeum sulfidigenes gen. nov., sp. nov. (=JCM 34033T = UNIQEM U1000T). Furthermore, on the bases of phylogenomic reconstruction, a new family Natronoarchaeaceae fam. nov. is proposed within the order Halobacteriales incorporating Natranaeroarchaeum and three related genera: Natronoarchaeum, Salinarchaeum and Halostella.

Van Gölü’nde Sintine Suyu Kaynaklı Kirliliğin İncelenmesi

Van Gölü’nde faaliyet gösteren gemilerin sintine sularından kaynaklı su kirliliği araştırılmıştır. Gemilerin barındığı on ayrı istasyondaki göl suyunda multimetre ile yerinde ölçümler yapılırken, göl suyunda ve gemilerden alınan sintine sularında kimyasal oksijen ihtiyacı (KOİ) ve yağ-gres analizleri gerçekleştirilmiştir. Göl sularında en düşük ve en yüksek KOİ değerleri sırasıyla 32 ve 240 mg/L, en düşük ve en yüksek yağ-gres değerleri sırasıyla 23 ve 146.5 mg/L olmuştur. Sintine su örneklerinde ise en düşük ve en yüksek KOİ değerleri sırasıyla 22 ve 5890 mg/L, en düşük ve en yüksek yağ-gres değerleri sırasıyla 11.3 ve 10000.0 mg/L bulunmuştur. İstasyonlarda göl suyunda yapılan ölçümlerde Su Kirliliği Kontrolü Yönetmeliği’ne göre genel olarak su sıcaklığının I-II. sınıf, çözünmüş oksijenin I. sınıf, oksijen doygunluğunun I. sınıf ve göl suyunun sodalı özelliğinden dolayı pH’nın IV. sınıfta yer aldığı belirlenmiştir. İstasyon göl sularından alınan örneklerde ortalama KOİ ve yağ-gres değerleri ise IV. sınıfta bulunmuştur. Tüm teknelerdeki yağ-gres değerleri MARPOL 73/78’e göre sınır değerin (15 mg/L) üstünde çıkmıştır. Çalışma sonucunda barınak olarak kullanılan bölgelerin, gemilerin bıraktığı sintine sularından olumsuz etkilendiği belirlenmiştir.

Nutrient Thresholds Required to Control Eutrophication: Does It Work for Natural Alkaline Lakes?

The responses of phytoplankton to nutrients vary for different natural bodies of water, which can finally affect the occurrence of phytoplankton bloom. However, the effect of high alkalinity characteristic on the nutrient thresholds of natural alkaline lake is rarely considered. Bioassay experiments were conducted to investigate the nutrient thresholds and the responses of phytoplankton growth to nutrients for the closed plateau Chenghai Lake, Southwest China, which has a high pH background of up to 9.66. The growth of the phytoplankton community was restricted by phosphorus without obvious correlation with the input of nitrogen sources. This can be explained by the nitrogen fixation function of cyanobacteria, which can meet their growth needs for nitrogen. In addition, nitrate nitrogen (NO3-N) could be utilized more efficiently than ammonia nitrogen (NH4-N) for the phytoplankton in Chenghai Lake. Interestingly, the eutrophication thresholds of soluble reactive phosphorus (SRP), NH4-N, and NO3-N should be targeted at below 0.05 mg/L, 0.30 mg/L, and 0.50 mg/L, respectively, which are higher than the usual standards for eutrophication. This can be explained by the inhibition effect of the high pH background on phytoplankton growth due to the damage to phytoplankton cells. Therefore, the prevention of phytoplankton blooms should be considered from not only the aspect of reducing nutrient input, especially phosphorus input, but also maintaining the high alkalinity characteristic in natural alkaline lake, which was formed due to the geological background of saline-alkali soil.

When distinction matters: Carbonate shrubs from the Aptian Barra Velha Formation of Brazilian's Pre-salt

Branched, bush- or shrub-like crystals are some of the most striking components of carbonate facies from the Cretaceous South Atlantic Pre-salt carbonate reservoirs. Many different analogues have been proposed to help to understand them, including travertines, lacustrine mounds and alkaline lake deposits, amongst others. Interpretation and genesis of these special facies involve discussions about biogenic vs. abiogenic formation of these branched components, relation with Mg-clays, role of microbes and growth of spherulites, amongst others. The present work shows some examples at microscale from a drilled core from Santos Basin (Brazil).The analyses of the shrub-like crystals present in the studied section allowed the distinction between four different types: (i) Type 1: fan-shaped fibrous-radial crystals; (ii) Type 2: fan-shaped, branched fibrous-radial crystals; (iii) Type 3: dendrite crystals; and (iv) Type 4: laminated crusts. All these components show similarities with their counterparts present in travertines, suggesting similar conditions controlling crystal growth in both Pre-salt and travertines. However, microfacies relationships show clear differences between the Pre-salt and those from travertine in the literature. Such Pre-salt microfacies presented here show a clear relationship between the development of the so called shrub-like crystals and the environment's energy, allowing the establishment of a proximal–distal pattern within a lacustrine environment as well as the identification of microfacies that could be related to (subaqueous?) hydrothermal vents.Distinction between the different types of branched components described here as well as their relationships with other microfacies are critical issues for the differentiation of the processes involved and the interpretation of the environments of formation (e.g., spring-related and proximal–distal environments within a lake). The observations made on samples from a drilled core of Brazilian's Pre-salt allow the discussion on some topics and interpretations involving the Pre-salt facies, providing potential research guidelines on these challenging continental carbonates.

Hexavalent Chromium Reduction by a Potent Novel Haloalkaliphilic Nesterenkonia sp strain NRC-Y Isolated from Hypersaline Soda Lakes

Hexavalent Chromium Reduction by a Potent Novel Haloalkaliphilic Nesterenkonia sp strain NRC-Y Isolated from Hypersaline Soda Lakes

Phylogenetic analysis of Arthrospira strains from Ordos based on 16S rRNA

To study the growth rate of different Arthrospira strains, three species of Arthrospira from Ordos alkaline lake, labeled as sp.DD, sp.ER, sp.FB, one species of Arthrospira from Hasu Sea in Hohhot, labeled as sp.HS, another purified strain labeled as sp.QD donated by the Ocean University of China had been collected. The first four need to be further isolated and purified in culture. The growth curves of all strains were plotted. Subsequently, 16S rRNA sequences were amplified and sequenced in an attempt to study taxonomic relationships. The results showed that the growth rate was increased in the first 9 days, and sp.DD had the highest growth rate. Analysis of the sequencing results revealed that sp.HS had 99.79% homology with Arthrospira platensis strain Sp-2, sp.DD had 99.69% homology with Arthrospira platensis FACHB834, sp.QD had 99.54% homology with Arthrospira platensis F3S, sp.ER had 99.79% homology with Arthrospira erdosensis ‘Inner Mongolia’, sp.FB had 99.74% homology with Arthrospira erdosensis ‘Inner Mongolia’. Phylogenetic analysis indicated that sp.HS was closely related to Arthrospira platensis strain Sp-2; sp.DD and sp.QD had a close genetic relationship; sp.ER and sp.FB had a close genetic relationship. In conclusion, these findings provide a theoretical basis for the further development and reproduction of dominant algae species in Inner Mongolia through biological analysis of Arthrospira.

Two new alkali-sink specialist species of Paruroctonus Werner 1934 (Scorpiones, Vaejovidae) from central California.

Herein we describe two new species of Paruroctonus (Werner 1934) from California: Paruroctonussoda sp. nov. from the Soda Lake playa at the center of the Carrizo Plain in San Luis Obispo county and Paruroctonusconclusus sp. nov. from the Koehn Lake playa in the Mojave Desert of Kern County. They can be differentiated from other Paruroctonus by a combination of morphological features including deeply scalloped pedipalp fingers in males, specific patterns of fuscous pigmentation, unique setal counts, and unique morphometric ratios. They can also be separated from one another by the latter three characters. Photographs of a large selection of live scorpions are provided, including detailed images and figures of many morphological features. Their distributions, habitats, and ecologies are discussed; and important steps towards their conservation are described.

The Novel Role of Tyrosinase Enzymes in the Storage of Globally Significant Amounts of Carbon in Wetland Ecosystems.

Over the last millennia, wetlands have been sequestering carbon from the atmosphere via photosynthesis at a higher rate than releasing it and, therefore, have globally accumulated 550 × 1015 g of carbon, which is equivalent to 73% of the atmospheric carbon pool. The accumulation of organic carbon in wetlands is effectuated by phenolic compounds, which suppress the degradation of soil organic matter by inhibiting the activity of organic-matter-degrading enzymes. The enzymatic removal of phenolic compounds by bacterial tyrosinases has historically been blocked by anoxic conditions in wetland soils, resulting from waterlogging. Bacterial tyrosinases are a subgroup of oxidoreductases that oxidatively remove phenolic compounds, coupled to the reduction of molecular oxygen to water. The biochemical properties of bacterial tyrosinases have been investigated thoroughly in vitro within recent decades, while investigations focused on carbon fluxes in wetlands on a macroscopic level have remained a thriving yet separated research area so far. In the wake of climate change, however, anoxic conditions in wetland soils are threatened by reduced rainfall and prolonged summer drought. This potentially allows tyrosinase enzymes to reduce the concentration of phenolic compounds, which in turn will increase the release of stored carbon back into the atmosphere. To offer compelling evidence for the novel concept that bacterial tyrosinases are among the key enzymes influencing carbon cycling in wetland ecosystems first, bacterial organisms indigenous to wetland ecosystems that harbor a TYR gene within their respective genome (tyr+) have been identified, which revealed a phylogenetically diverse community of tyr+ bacteria indigenous to wetlands based on genomic sequencing data. Bacterial TYR host organisms covering seven phyla (Acidobacteria, Actinobacteria, Bacteroidetes, Firmicutes, Nitrospirae, Planctomycetes, and Proteobacteria) have been identified within various wetland ecosystems (peatlands, marshes, mangrove forests, bogs, and alkaline soda lakes) which cover a climatic continuum ranging from high arctic to tropic ecosystems. Second, it is demonstrated that (in vitro) bacterial TYR activity is commonly observed at pH values characteristic for wetland ecosystems (ranging from pH 3.5 in peatlands and freshwater swamps to pH 9.0 in soda lakes and freshwater marshes) and toward phenolic compounds naturally present within wetland environments (p-coumaric acid, gallic acid, protocatechuic acid, p-hydroxybenzoic acid, caffeic acid, catechin, and epicatechin). Third, analyzing the available data confirmed that bacterial host organisms tend to exhibit in vitro growth optima at pH values similar to their respective wetland habitats. Based on these findings, it is concluded that, following increased aeration of previously anoxic wetland soils due to climate change, TYRs are among the enzymes capable of reducing the concentration of phenolic compounds present within wetland ecosystems, which will potentially destabilize vast amounts of carbon stored in these ecosystems. Finally, promising approaches to mitigate the detrimental effects of increased TYR activity in wetland ecosystems and the requirement of future investigations of the abundance and activity of TYRs in an environmental setting are presented.

Nitrogen Fixation Activity and Genome Analysis of a Moderately Haloalkaliphilic Anoxygenic Phototrophic Bacterium Rhodovulum tesquicola

The genome of the moderately haloalkaliphilic diazotrophic anoxygenic phototrophic bacterium Rhodovulum tesquicola A-36sT isolated from an alkaline lake was analyzed and compared to the genomes of the closest species Rhodovulum steppense A-20sT and Rhodovulum strictum DSM 11289T. The genomic features of three organisms are quite similar, reflecting their ecological and physiological role of facultative photoheterotrophs. Nevertheless, the nitrogenase activity of the pure cultures of the studied bacteria differed significantly: the highest rate (4066 nmoles C2H2/mg of dry weight per hour) was demonstrated by Rhodovulum strictum while the rates in Rhodovulum tesquicola and Rhodovulum steppense were an order of magnitude lower (278 and 523 nmoles C2H2/mg of dry weight per hour, respectively). This difference can be attributed to the presence of an additional nitrogenase operon found exclusively in R. strictum and to the structural variation in nitrogenase operon in R. tesquicola.

Bacterial Communities Along Environmental Gradients in Tropical Soda Lakes.

Soda lake environments are known to be variable and can have distinct differences according to geographical location. In this study, we investigated the effects of different environmental conditions of six adjacent soda lakes in the Pantanal biome (Mato Grosso do Sul state, Brazil) on bacterial communities and their functioning using a metagenomic approach combined with flow cytometry and chemical analyses. Ordination analysis using flow cytometry and water chemistry data from two sampling periods (wet and dry) clustered soda lakes into three different profiles: eutrophic turbid (ET), oligotrophic turbid (OT), and clear vegetated oligotrophic (CVO). Analysis of bacterial community composition and functioning corroborated this ordination; the exception was one ET lake, which was similar to one OT lake during the wet season, indicating drastic shifts between seasons. Microbial abundance and diversity increased during the dry period, along with a considerable number of limnological variables, all indicative of a strong effect of the precipitation-evaporation balance in these systems. Cyanobacteria were associated with high electric conductivity, pH, and nutrient availability, whereas Actinobacteria, Alphaproteobacteria, and Betaproteobacteria were correlated with landscape morphology variability (surface water, surface perimeter, and lake volume) and with lower salinity and pH levels. Stress response metabolism was enhanced in OT and ET lakes and underrepresented in CVO lakes. The microbiome dataset of this study can serve as a baseline for restoring impacted soda lakes. Altogether, the results of this study demonstrate the sensitivity of tropical soda lakes to climate change, as slight changes in hydrological regimes might produce drastic shifts in community diversity.

Draft Genome Sequence of the Alkaliphilic, Lithoautotrophic Homoacetogen Fuchsiella alkaliacetigena Z-7100T.

ABSTRACTFuchsiella alkaliacetigena is a spore-forming, alkaliphilic hydrogentrophic homoacetogen that was isolated from the soda lake Lake Tanatar III in Russia. The genome of the type strain Z-7100 (= DSM 24880) is 2.9 Mb, with a G+C content of 36.2%.

Characteristics and Genesis of Alkaline Lacustrine Tight Oil Reservoirs in the Permian Fengcheng Formation in the Mahu Sag, Junggar Basin, NW China

Through optical microscopic examination, scanning electron microscope analysis, whole rock X-ray diffraction analysis, X-ray fluorescence spectrum analysis, carbon and oxygen isotope analysis, and temperature measurement of fluid inclusions, the characteristics and formation mechanism of the alkaline lacustrine tight oil reservoirs of the Permian Fengcheng Formation in the Mahu Sag of the Junggar Basin have been systematically studied, and a genetic model has been proposed. Porosity of tight oil reservoirs of the Fengcheng Formation in the Mahu Sag is mostly less than 4%, with permeability mostly less than 0.1 mD. The lithology of the Fengcheng Formation in the Mahu Sag is mainly tuff, and the authigenic minerals mainly consist of feldspar, quartz, dolomite, and salt minerals (e.g., shortite, trona). The authigenic feldspar and quartz of the Fengcheng Formation in the Mahu Sag mainly originate from devitrification of volcanic glass in pyroclastic rocks. Reservoir space is dominated by dissolution pores of feldspar and salt minerals, followed by intercrystalline pores among feldspar, quartz, and other minerals formed by devitrification. Fractures are mainly comprised of shrinkage fractures, structural fractures, and bedding seans. The Permian Fengcheng Formation was mainly formed in an alkaline lake in the Mahu Sag, and the alkaline lacustrine sedimentary setting plays a decisive role in the formation of the tight oil reservoirs of the Fengcheng Formation. Volcanic glass in the tight oil reservoirs was generally devitrified within the alkaline lacustrine diagenetic fluid in the early diagenetic stage, and the devitrified micropores become an important reservoir space. Feldspars and salt minerals were mainly dissolved by acidic fluids generated by burial thermal evolution of the alkaline lacustrine source rocks of the Fengcheng Formation in the Mahu Sag, which produces the most developed dissolution pores in the tight oil reservoir. The abnormal high pressure formed by the early hydrocarbon generation and expulsion of the alkaline lacustrine source rocks in the Fengcheng Formation is one of the main reasons for porosity preservation. In the alkaline lake sedimentary environment of the Fengcheng Formation, widespread dolomitization and precipitation of a large number of salt minerals in the early diagenetic stage resisted partial compaction, which not only effectively protected early porosity, but also provided material conditions for dissolution porosity enhancement.