''Nautilia profundicola'' is a

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wa ...

chemolithoautotrophic

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 amon ...

found around hydrothermal vents in the deep ocean. It was first discovered in 1999 on the

East Pacific Rise The East Pacific Rise is a mid-ocean rise (termed an oceanic rise and not a mid-ocean ridge due to its higher rate of spreading that results in less elevation increase and more regular terrain), a divergent tectonic plate boundary located alon ...

at depth of , on the surface of the

polychaete worm Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made ...

Alvinella pompejana ''Alvinella pompejana'', the Pompeii worm, is a species of deep-sea polychaete worm (commonly referred to as "bristle worms"). It is an extremophile found only at hydrothermal vents in the Pacific Ocean, discovered in the early 1980s off the Gal� ...

''. ''Nautilia profundicola'' lives symbiotically on the dorsal hairs of ''A. pompejana'' but they may also form

biofilm A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular ...

s and live independently on the walls of hydrothermal vents. The ability of ''N. profundicola'' to survive in an

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: * Anaerobic adhesive, a bonding a ...

environment rich in sulfur, H₂ and CO₂ of varying temperature makes it a useful organism to study, as these are the conditions that are theorized to have prevailed around the time of the earliest life on earth.

Morphology

''Nautilia profundicola'' is a motile, rod-shaped bacterium, around 0.4 μm long and 0.3 μm wide. Like most

Campylobacterota Campylobacterota are a phylum of bacteria. All species of this phylum are Gram-negative. The Campylobacterota consist of few known genera, mainly the curved to spirilloid ''Wolinella'' spp., ''Helicobacter'' spp., and ''Campylobacter'' spp. Most ...

(syn. Epsilonproteobacteria), it has an unsheathed polar

flagellum A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have f ...

Physiology

''Nautilia profundicola'' lives among the hydrothermal vents and can grow at temperatures of . It uses

anaerobic respiration Anaerobic respiration is respiration using electron acceptors other than molecular oxygen (O2). Although oxygen is not the final electron acceptor, the process still uses a respiratory electron transport chain. In aerobic organisms undergoing r ...

and is a chemolithoautotroph. ''Nautilia profundicola'' uses hydrogen or formate as an

electron donor In chemistry, an electron donor is a chemical entity that donates electrons to another compound. It is a reducing agent that, by virtue of its donating electrons, is itself oxidized in the process. Typical reducing agents undergo permanent chemi ...

and sulfur an electron acceptor to produce hydrogen sulfide. ''Nautilia profundicola'' contains the protein reverse gyrase, which has been found amongst

thermophilic bacteria 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 ...

, and which helps it survive the large temperature variation associated with its environment. Reverse gyrase is theorized to keep the genome stable and prevent damage by the extreme heat. Along with the ability to fix carbon and sulfur, analysis of the genome of ''Nautilia profundicola'' points to a novel pathway of

nitrogen fixation Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atmo ...

Taxonomy

Analysis of the 16S rRNA gene sequence of ''Nautilia profundicola'' allowed it to be placed in the family Nautiliaceae of the order Nautiliales in the phylum

. Analysis of this gene demonstrated that this organism shared 97.8 percent of its DNA for this gene with the related bacterium '' Nautilia lithotrophica''. Using DNA–DNA hybridization, the total DNA-DNA relatedness of the two organisms was found to be 34.6 percent which, along with differences in

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spe ...

, allowed ''Nautilia profundicola'' to be classified as its own species.

Genomic information

The genome of ''Nautilia profundicola'' consists of one

circular chromosome A circular chromosome is a chromosome in bacteria, archaea, Mitochondrial DNA#Genome structure and diversity, mitochondria, and Chloroplast DNA#Molecular structure, chloroplasts, in the form of a molecule of circular DNA, unlike the linear chromo ...

of 1.7 million base pairs, which is small compared to other free-living Campylobacterota. There is relatively little evidence of the influence of

horizontal gene transfer Horizontal gene transfer (HGT) or lateral gene transfer (LGT) is the movement of genetic material between unicellular and/or multicellular organisms other than by the ("vertical") transmission of DNA from parent to offspring (reproduction). H ...

in the genome of ''Nautilia profundicola'' and this lack of external DNA is theorized to be a product of its own defense mechanisms or the lack of free DNA in the surrounding inhospitable environment.

Ecological function

''Nautilia profundicola'' is a member of the Campylobacterota, which are dominant in the vent ecosystem and are likely to be key players in the cycling of carbon, nitrogen, and sulfur. ''Nautilia profundicola'' has been found to have a symbiotic relationship with ''Alvinella pompejana'', in which the worm secretes edible

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It ...

, possibly in exchange for the bacterium's heat-resistant

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

s. This has the potential to explain how ''Alvinella pompejana'' can survive with one part of its body in water in the vent and the rest of its body in water outside the vent.

References

External links

*
LPSNType strain of ''Nautilia profundicola'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q16756078 Campylobacterota Organisms living on hydrothermal vents Bacteria described in 2008