''Acaryochloris marina'' is a symbiotic

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

of the

phylum In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature ...

Cyanobacteria Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, bl ...

that produces chlorophyll d, allowing it to use far-red light, at 770 nm wavelength.

Description

It was first discovered in 1993 from coastal isolates of coral in the

Republic of Palau Palau,, officially the Republic of Palau and historically ''Belau'', ''Palaos'' or ''Pelew'', is an island country and microstate in the western Pacific. The nation has approximately 340 islands and connects the western chain of the Caro ...

in the west

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the conti ...

and announced in 1996. Despite the claim in the 1996 ''Nature'' paper that its formal description was to be published shortly thereafter, a tentative partial description was presented in 2003 due to

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups ...

issues (deep branching cyanobacterium).

Genome

Its

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ...

was sequenced in 2008, revealing a large bacterial genome of 8.3 Mb with nine

plasmid A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria; how ...

Etymology

The name ''Acaryochloris'' is a combination of the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

prefix ''a'' (ἄν) meaning "without", ''caryo'' (κάρυον) meaning "nut" (here intended as "nucleus") and ''chloros'' (χλωρός) meaning green; therefore it is

new Latin New Latin (also called Neo-Latin or Modern Latin) is the revival of Literary Latin used in original, scholarly, and scientific works since about 1500. Modern scholarly and technical nomenclature, such as in zoological and botanical taxonomy ...

''Acaryochloris'' meaning "without nucleus green". The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bo ...

''marina'' is

Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

meaning "marine".

Classification

Due to historical reason, the classification of the Cyanobacteria is problematic and many are not validly published, meaning they have not yet been placed into the classification framework. One of these not officially recognised species is ''Acaryochloris marina'', which technically should be written as "Acaryochloris marina" in official writings, but in effect this is rarely done (cf.)

Exoplanet habitability

Scientists including

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...

's Nancy Kiang have proposed that the existence of ''Acaryochloris marina'' suggests that organisms that use chlorophyll d, rather than chlorophyll a, may be able to perform oxygenic photosynthesis on

exoplanets An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

orbiting

red dwarf stars ''Red Dwarf'' is a British science fiction comedy franchise created by Rob Grant and Doug Naylor, which primarily consists of a television sitcom that aired on BBC Two between 1988 and 1999, and on Dave (TV channel), Dave since 2009, gaining a ...

(which emit much less light than the Sun). Because about 70% of the stars in the

Milky Way galaxy The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...

are red dwarfs, the existence of ''A. marina'' implies that oxygenic photosynthesis may be occurring on far more

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

s than astrobiologists initially thought possible.

References