''Salinibacter ruber'' is an extremely

halophilic A halophile (from the Greek word for 'salt-loving') is an extremophile that thrives in high salt concentrations. In chemical terms, halophile refers to a Lewis acidic species that has some ability to extract halides from other chemical species. ...

red

bacterium Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the ...

, first found in Spain in 2002.

Taxonomy

''Salinibacter ruber'' is most closely related to the genus

Rhodothermus ''Rhodothermus'' is a genus of bacteria. Phylogeny The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI) See also * List of ba ...

which is a

thermophilic A thermophile is a type of extremophile that thrives at relatively high temperatures, between . Many thermophiles are archaea, though some of them are bacteria and fungi. Thermophilic eubacteria are suggested to have been among the earliest bact ...

, slightly halophilic bacterium. Though genetically it is considered to be closest to the Rhodothermus genus, it is most comparable to the family

Halobacteriaceae Halobacteriaceae is a family in the order Halobacteriales and the domain Archaea. ''Halobacteriaceae'' represent a large part of halophilic Archaea, along with members in two other methanogenic families, ''Methanosarcinaceae'' and ''Methanocalcul ...

, because of similarity in protein structure. It is red-pigmented,

motile Motility is the ability of an organism to move independently using metabolic energy. This biological concept encompasses movement at various levels, from whole organisms to cells and subcellular components. Motility is observed in animals, mi ...

rod-shaped Bacterial cellular morphologies are the shapes that are characteristic of various types of bacteria and often key to their identification. Their direct examination under a light microscope enables the classification of these bacteria (and archae ...

, and extremely

. The

type strain The International Code of Nomenclature of Prokaryotes (ICNP) or Prokaryotic Code, formerly the International Code of Nomenclature of Bacteria (ICNB) or Bacteriological Code (BC), governs the scientific names for Bacteria and Archaea.P. H. A. Sneath ...

is strain M31^T(= DSM 13855^T = CECT 5946^T).

Habitat

''Salinibacter ruber'' was found in

saltern A saltern is an area or installation for making salt. Salterns include modern salt-making works (saltworks), as well as hypersaline waters that usually contain high concentrations of Halophile, halophilic microorganisms, primarily haloarchaea but ...

crystallizer ponds in

Alicante Alicante (, , ; ; ; officially: ''/'' ) is a city and municipalities of Spain, municipality in the Valencian Community, Spain. It is the capital of the province of Alicante and a historic Mediterranean Sea, Mediterranean port. The population ...

and

Mallorca Mallorca, or Majorca, is the largest of the Balearic Islands, which are part of Spain, and the List of islands in the Mediterranean#By area, seventh largest island in the Mediterranean Sea. The capital of the island, Palma, Majorca, Palma, i ...

, Spain in 2002 by Antón et al. This environment has very high salt concentrations, and ''Salinibacter ruber'' itself cannot grow at below 15% salt concentration, with an ideal concentration between 20 and 30% (i.e. 200-300 grams of salt per litre, the average concentration in the ocean being around 35 g/L). It has also been found in

pink lake A pink lake is a lake that has a red or pink colour. This is often caused by the presence of salt-tolerant algae that produces carotenoids, such as ''Dunaliella salina'', usually in conjunction with specific bacteria and archaea, which may var ...

s in Australia. This bacterium is notable for its halophilic lifestyle, a trait exhibited primarily by members of

Archaea Archaea ( ) is a Domain (biology), domain of organisms. Traditionally, Archaea only included its Prokaryote, prokaryotic members, but this has since been found to be paraphyletic, as eukaryotes are known to have evolved from archaea. Even thou ...

. In general, bacteria do not play a large role in microbial communities of hypersaline brines at or approaching NaCl saturation. However, with the discovery of ''S. ruber'', this belief was challenged. It was found that ''S. ruber'' made up from 5% to 25% of the total prokaryotic community of the Spanish saltern ponds. Salinibacter ruber in pink lake

Characteristics

In a 2015 study conducted by researchers led by

molecular biologist Molecular biology is a branch of biology that seeks to understand the molecule, molecular basis of biological activity in and between Cell (biology), cells, including biomolecule, biomolecular synthesis, modification, mechanisms, and interactio ...

Ken McGrath at

Lake Hillier Lake Hillier is a saline lake on the edge of Middle Island, the largest of the islands and islets that make up the Recherche Archipelago in the Goldfields-Esperance region, off the south coast of Western Australia. It is particularly notable ...

Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...

, showed that, while the algae ''

Dunaliella salina ''Dunaliella salina'' is a type of halophile unicellular green algae especially found in hypersaline environments, such as salt lakes and salt evaporation ponds. Known for its antioxidant activity because of its ability to create a large amoun ...

'', formerly thought to create the color in this

, was present in only tiny quantities (0.1% of

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

sampled), while ''S. ruber'' formed 20 to 33% of the DNA recovered from the lake. ''Salinibacter ruber'' produces a

pigment A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...

called bacterioruberin, which helps it to trap and use light for energy in the

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

process. While the pigments in algae are contained within the

chloroplast A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

s, bacterioruberin is spread across the whole cell of the bacterium. This makes it more likely that the colour of the lake is that of ''S. ruber''.

Footnotes

References

External links