''Vibrio harveyi'' 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 ...

bioluminescent Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some b ...

marine bacterium Marine prokaryotes are marine bacteria and marine archaea. They are defined by their habitat as prokaryotes that live in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. All cellular ...

in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

Vibrio ''Vibrio'' is a genus of Gram-negative bacteria, possessing a curved-rod (comma) shape, several species of which can cause foodborne infection, usually associated with eating undercooked seafood. Being highly salt tolerant and unable to survive ...

''. ''V. harveyi'' is rod-shaped, motile (via polar

flagella 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 fro ...

), facultatively anaerobic, halophilic, and competent for both fermentative and respiratory metabolism. It does not grow below 4 °C ( optimum growth: 30° to 35 °C). ''V. harveyi'' can be found free-swimming in tropical marine waters, commensally in the gut microflora of

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military ...

animals, and as both a primary and

opportunistic pathogen An opportunistic infection is an infection caused by pathogens (bacteria, fungi, parasites or viruses) that take advantage of an opportunity not normally available. These opportunities can stem from a variety of sources, such as a weakened immune ...

of marine animals, including Gorgonian

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and se ...

oyster Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but not ...

prawn Prawn is a common name for small aquatic crustaceans with an exoskeleton and ten legs (which is a member of the order decapoda), some of which can be eaten. The term "prawn"Mortenson, Philip B (2010''This is not a weasel: a close look at nature' ...

lobster Lobsters are a family (Nephropidae, synonym Homaridae) of marine crustaceans. They have long bodies with muscular tails and live in crevices or burrows on the sea floor. Three of their five pairs of legs have claws, including the first pair, ...

s, the

common snook The common snook (''Centropomus undecimalis'') is a species of marine fish in the family Centropomidae of the order Perciformes. The common snook is also known as the sergeant fish or robalo. It was originally assigned to the sciaenid genus ...

barramundi The barramundi (''Lates calcarifer'') or Asian sea bass, is a species of catadromous fish in the family Latidae of the order Perciformes. The species is widely distributed in the Indo-West Pacific, spanning the waters of the Middle East, Sout ...

, turbot,

milkfish The milkfish (''Chanos chanos'') is the sole living species in the family Chanidae. However, there are at least five extinct genera from the Cretaceous. The repeating scientific name ( tautonym) is from Greek ( ‘mouth’). The species has man ...

, and

seahorse A seahorse (also written ''sea-horse'' and ''sea horse'') is any of 46 species of small marine fish in the genus ''Hippocampus''. "Hippocampus" comes from the Ancient Greek (), itself from () meaning "horse" and () meaning "sea monster" or ...

s. It is responsible for luminous vibriosis, a disease that affects commercially farmed penaeid prawns. Additionally, based on samples taken by ocean-going ships, ''V. harveyi'' is thought to be the cause of the milky seas effect, in which, during the night, a uniform blue glow is emitted from the

seawater Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appro ...

. Some glows can cover nearly .

Quorum sensing

Groups of ''V. harveyi'' bacteria communicate by

quorum sensing In biology, quorum sensing or quorum signalling (QS) is the ability to detect and respond to cell population density by gene regulation. As one example, QS enables bacteria to restrict the expression of specific genes to the high cell densities at ...

to coordinate the production of bioluminescence and virulence factors. Quorum sensing was first studied in ''V. fischeri'' (now '' Aliivibrio fischeri''), a marine bacterium that uses a synthase (LuxI) to produce a species-specific

autoinducer Autoinducers are signaling molecules that are produced in response to changes in cell-population density. As the density of quorum sensing bacterial cells increases so does the concentration of the autoinducer. Detection of signal molecules by ba ...

(AI) that binds a cognate receptor (LuxR) that regulates changes in expression. Coined "LuxI/R" quorum sensing, these systems have been identified in many other species of Gram-negative bacteria. Despite its relatedness to ''A. fischeri'', ''V. harveyi'' lacks a LuxI/R quorum-sensing system, and instead employs a hybrid quorum-sensing circuit, detecting its AI through a membrane-bound

histidine kinase Histidine kinases (HK) are multifunctional, and in non-animal kingdoms, typically transmembrane, proteins of the transferase class of enzymes that play a role in signal transduction across the cellular membrane. The vast majority of HKs are ho ...

and using a phosphorelay to convert information about the population size to changes in gene expression. Since their identification in ''V. harveyi'', such hybrid systems have been identified in many other bacterial species. ''V. harveyi'' uses a second AI, termed

autoinducer-2 Autoinducer-2 (AI-2), a furanosyl borate diester or tetrahydroxy furan (species dependent), is a member of a family of signaling molecules used in quorum sensing. AI-2 is one of only a few known biomolecules incorporating boron. First identified ...

or AI-2, which is unusual because it is made and detected by a variety of different bacteria, both Gram-negative and Gram-positive. Thus, ''V. harveyi'' has been instrumental to the understanding and appreciation of interspecies bacterial communication.

References

External links

''V. harveyi'' at NCBI

Vibrios at NCBIType strain of ''Vibrio harveyi'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q3761158 Vibrionales Bioluminescent bacteria Bacteria described in 1936