''Salinibacter ruber'' is an extremely

halophilic The halophiles, named after the Greek word for "salt-loving", are extremophiles that thrive in high salt concentrations. While most halophiles are classified into the domain Archaea, there are also bacterial halophiles and some eukaryotic species, ...

red

bacterium Bacteria (; singular: 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 ...

, first found in Spain in 2002.

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 halophilic microorganisms, primarily haloarchaea but also oth ...

crystallizer ponds in

Alicante Alicante ( ca-valencia, Alacant) is a city and municipality in the Valencian Community, Spain. It is the capital of the province of Alicante and a historic Mediterranean port. The population of the city was 337,482 , the second-largest in t ...

and

Mallorca Mallorca, or Majorca, is the largest island in the Balearic Islands, which are part of Spain and located in the Mediterranean. The capital of the island, Palma, is also the capital of the autonomous community of the Balearic Islands. The Bal ...

, 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%. 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, which may vary from lake ...

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

Archaea Archaea ( ; singular archaeon ) is a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as bacteria, receiving the name archaebacteria (in the Archaebac ...

. 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. ca: ''Salinibacter ruber'' was found in

crystallizer ponds in

and

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

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 The National Center for Bio ...

which is a

thermophilic A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between . Many thermophiles are archaea, though they can be bacteria or fungi. Thermophilic eubacteria are suggested to have been among the earl ...

, slightly halophilic bacterium. Though genetically it is considered to be closest to the Rhodothermus genus, it is most comparable to the family Halobacteriaceae, because of similarity in protein structure. It is red-pigmented,

motile Motility is the ability of an organism to move independently, using metabolic energy. Definitions Motility, the ability of an organism to move independently, using metabolic energy, can be contrasted with sessility, the state of organisms th ...

rod-shaped A bacillus (), also called a bacilliform bacterium or often just a rod (when the context makes the sense clear), is a rod-shaped bacterium or archaeon. Bacilli are found in many different taxonomic groups of bacteria. However, the name ''Bacillu ...

, and extremely

. The

type strain The International Code of Nomenclature of Prokaryotes (ICNP) 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, 2003. A short hist ...

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

Characteristics

In a 2015 study conducted by researchers led by

molecular biologist Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physi ...

Ken McGrath at

Lake Hillier Lake Hillier is a salt lake, saline lake on the edge of Middle Island (Western Australia), 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 We ...

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

, showed that, while the algae ''

Dunaliella salina ''Dunaliella salina'' is a type of halophile green unicellular micro-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 large ...

'', formerly thought to create the color in this

, was present in only tiny quantities (0.1% of DNA sampled), while ''S. ruber'' formed 20 to 33% of the DNA recovered from the lake. ''Salinibacter ruber'' produces a

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...

called

bacterioruberin ''Halobacterium'' (common abbreviation ''Hbt.'') is a genus in the family Halobacteriaceae. The genus ''Halobacterium'' ("salt" or "ocean bacterium") consists of several species of Archaea with an aerobic metabolism which requires an environment ...

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

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

process. While the pigments in algae are contained within the

chloroplast A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...

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