Natronorubrum sulfidifaciens sp. nov., an extremely haloalkaliphilic archaeon isolated from Aiding salt lake in Xin-Jiang, China

Cui, Heng‐Lin; Tohty, Dilbr; Liu, Hong‐Can; Liu, Shuang‐Jiang; Oren, Aharon; Zhou, Pengyu

doi:10.1099/ijs.0.64651-0

Cited by 27 publications

(3 citation statements)

References 9 publications

(8 reference statements)

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“…3), which suggested that CO uptake was well-adapted for water stress and the high salt regimes that typify BSF. Additional assays have also revealed CO oxidation by the extremely halophilic euryarchaeotes N. bangense and N. sulfidifaciens, both isolated from Chinese salt lakes (38,39). Collectively, these results suggested that novel extremely halophilic CO oxidizers derived from diverse terrestrial systems might prove suitable as models for metabolism and survival on Mars or elsewhere.…”

Section: Resultsmentioning

confidence: 87%

Carbon monoxide as a metabolic energy source for extremely halophilic microbes: Implications for microbial activity in Mars regolith

King

2015

Proc. Natl. Acad. Sci. U.S.A.

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Carbon monoxide occurs at relatively high concentrations (≥800 parts per million) in Mars' atmosphere, where it represents a potentially significant energy source that could fuel metabolism by a localized putative surface or near-surface microbiota. However, the plausibility of CO oxidation under conditions relevant for Mars in its past or at present has not been evaluated. Results from diverse terrestrial brines and saline soils provide the first documentation, to our knowledge, of active CO uptake at water potentials (−41 MPa to −117 MPa) that might occur in putative brines at recurrent slope lineae (RSL) on Mars. Results from two extremely halophilic isolates complement the field observations. Halorubrum str. BV1, isolated from the Bonneville Salt Flats, Utah (to our knowledge, the first documented extremely halophilic CO-oxidizing member of the Euryarchaeota), consumed CO in a salt-saturated medium with a water potential of −39.6 MPa; activity was reduced by only 28% relative to activity at its optimum water potential of −11 MPa. A proteobacterial isolate from hypersaline Mono Lake, California, Alkalilimnicola ehrlichii MLHE-1, also oxidized CO at low water potentials (−19 MPa), at temperatures within ranges reported for RSL, and under oxic, suboxic (0.2% oxygen), and anoxic conditions (oxygen-free with nitrate). MLHE-1 was unaffected by magnesium perchlorate or low atmospheric pressure (10 mbar). These results collectively establish the potential for microbial CO oxidation under conditions that might obtain at local scales (e.g., RSL) on contemporary Mars and at larger spatial scales earlier in Mars' history. Geological, geochemical, and geomorphological observations have provided definitive evidence for large, ancient fluvial systems that might have been conducive to life (8-13), but the timing, temperature, and composition of surface water have been controversial (14-17). Although unequivocal evidence for contemporary liquid water reservoirs has not yet been obtained, experimental evidence suggests plausible conditions under which brines might form (18), and observations from the Mars Reconnaissance Orbiter suggest that recurring slope lineae (RSL) at latitudes between 32°S and 48°S might develop in association with seasonally moderate conditions during late spring-summer (19-21). McEwen et al. (19) have proposed that these features can be best explained by near-surface liquid water brines that form between temperatures of about −10°C and 25°C during late spring-summer.However, even if liquid water was at one time or is now sufficient to support microbial life, energy sources that could sustain metabolism in near-surface regolith have not been identified. Although the 1976 Viking lander results appeared to exclude surface organic matter (e.g., 22, 23), recent evidence suggests that low organic matter levels might indeed occur in some deposits (e.g., 12). Even so, it is uncertain whether this material exists in a form or concentrations suitable for microbial use.The Martian atmosphere has largely been ign...

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Section: Resultsmentioning

confidence: 87%

Carbon monoxide as a metabolic energy source for extremely halophilic microbes: Implications for microbial activity in Mars regolith

King

2015

Proc. Natl. Acad. Sci. U.S.A.

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“…The traditional tests for catalase, oxidase, reduction of nitrate to nitrite, formation of gas from nitrate, indole formation, and hydrolysis of casein, gelatin, starch, and Tween 80 are maintained. The test for hydrogen sulfide production from thiosulfate that was not mandatory or recommended in the former minimal standards is now required in the description of new taxa [ 38 39 ]. Type strains of related species should be selected as positive and negative controls in the biochemical tests under the same experimental conditions simultaneously.…”

Section: Biochemical Activitiesmentioning

confidence: 99%

Proposed minimal standards for description of new taxa of the class Halobacteria

Cui,

Hou,

Amoozegar

et al. 2024

International Journal of Systematic and Evolutionary Microbiology

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Halophilic archaea of the class Halobacteria are the most salt-requiring prokaryotes within the domain Archaea. In 1997, minimal standards for the description of new taxa in the order Halobacteriales were proposed. From then on, the taxonomy of the class Halobacteria provides an excellent example of how changing concepts on prokaryote taxonomy and the development of new methods were implemented. The last decades have witnessed a rapid expansion of the number of described taxa within the class Halobacteria coinciding with the era of genome sequencing development. The current members of the International Committee on Systematics of Prokaryotes Subcommittee on the Taxonomy of Halobacteria propose these revisions to the recommended minimal standards and encourage the use of advanced technologies in the taxonomic description of members of the Halobacteria. Most previously required and some recommended minimal standards for the description of new taxa in the class Halobacteria were retained in the present revision, but changes have been proposed in line with the new methodologies. In addition to the 16S rRNA gene, the rpoB′ gene is an important molecular marker for the identification of members of the Halobacteria. Phylogenomic analysis based on concatenated conserved, single-copy marker genes is required to infer the taxonomic status of new taxa. The overall genome relatedness indexes have proven to be determinative in the classification of the taxa within the class Halobacteria. Average nucleotide identity, digital DNA–DNA hybridization, and average amino acid identity values should be calculated for rigorous comparison among close relatives.

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“…aibiense (isolated from a salt lake, China) [143], Nrr. sulfidifaciens (isolated from a salt lake, China) [144], Nrr. tibetense (isolated from a soda lake, Tibet) [145] and Nrr.…”

Section: Order Haloferacalesmentioning

confidence: 99%

Systematics of haloarchaea and biotechnological potential of their hydrolytic enzymes

et al. 2017

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Halophilic archaea, also referred to as haloarchaea, dominate hypersaline environments. To survive under such extreme conditions, haloarchaea and their enzymes have evolved to function optimally in environments with high salt concentrations and, sometimes, with extreme pH and temperatures. These features make haloarchaea attractive sources of a wide variety of biotechnological products, such as hydrolytic enzymes, with numerous potential applications in biotechnology. The unique trait of haloarchaeal enzymes, haloenzymes, to sustain activity under hypersaline conditions has extended the range of already-available biocatalysts and industrial processes in which high salt concentrations inhibit the activity of regular enzymes. In addition to their halostable properties, haloenzymes can also withstand other conditions such as extreme pH and temperature. In spite of these benefits, the industrial potential of these natural catalysts remains largely unexplored, with only a few characterized extracellular hydrolases. Because of the applied impact of haloarchaea and their specific ability to live in the presence of high salt concentrations, studies on their systematics have intensified in recent years, identifying many new genera and species. This review summarizes the current status of the haloarchaeal genera and species, and discusses the properties of haloenzymes and their potential industrial applications. SYSTEMATICS OF HALOPHILIC ARCHAEAHalophilic micro-organisms are found in the three domains of life, and are extremophiles living in hypersaline environments in the presence of salt (generally NaCl) as a specific requisite for their growth [1]. Hypersaline environments contain higher salt concentrations than seawater (3.5 % total dissolved salts) [2]. According to the optimum NaCl concentration for growth, micro-organisms fall into one of the following categories: extreme halophiles with optimum growth at 15-30 % (2.5-5.2 M) NaCl; moderate halophiles with optimum growth at 3-15 % (0.5-2.5 M) NaCl; slight halophiles with optimum growth at 1-3 % (0.2-0.5 M) NaCl; non-halophiles with optimum growth at less than 1 % (0.2 M) NaCl; and halotolerant micro-organisms which are non-halophiles showing the ability to tolerate high NaCl concentrations [3]. Halophiles can live in hypersaline environments because they are able to sustain osmotic balance. They use two main strategies to withstand the adverse consequences of water loss when exposed to high salt concentrations. The first strategy used by extremely halophilic archaea (haloarchaea) and halophilic anaerobic bacteria such as members of Halanaerobiales is known as the 'salt-in-cytoplasm' strategy, during which salts such as NaCl or KCl accumulate in the cytoplasm at concentrations similar to the extracellular ones [4,5]. Another mechanism to cope with high salt concentrations is the accumulation of organic molecules such as amino acids, sugars and polyols, known as compatible solutes or osmolytes. Compatible solutes are small and highly soluble molecules that can...

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Natronorubrum sulfidifaciens sp. nov., an extremely haloalkaliphilic archaeon isolated from Aiding salt lake in Xin-Jiang, China

Cited by 27 publications

References 9 publications

Carbon monoxide as a metabolic energy source for extremely halophilic microbes: Implications for microbial activity in Mars regolith

Carbon monoxide as a metabolic energy source for extremely halophilic microbes: Implications for microbial activity in Mars regolith

Proposed minimal standards for description of new taxa of the class Halobacteria

Systematics of haloarchaea and biotechnological potential of their hydrolytic enzymes

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