The Vibrionaceae are a family of Proteobacteria

Proteobacteria

The Proteobacteria are a major group of bacteria. They include a wide variety of pathogens, such as Escherichia, Salmonella, Vibrio, Helicobacter, and many other notable genera....

, given their own order. Inhabitants of fresh or salt water, several species are pathogenic, including the type species Vibrio cholerae

Vibrio cholerae

Vibrio cholerae is a Gram-negative, comma-shaped bacterium. Some strains of V. cholerae cause the disease cholera. V. cholerae is facultatively anaerobic and has a flagella at one cell pole. V...

, which is the agent responsible for cholera

Cholera

Cholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting. Transmission occurs primarily by drinking or eating water or food that has been contaminated by the diarrhea of an infected person or the feces...

. Most bioluminescent

Bioluminescence

Bioluminescence is the production and emission of light by a living organism. Its name is a hybrid word, originating from the Greek bios for "living" and the Latin lumen "light". Bioluminescence is a naturally occurring form of chemiluminescence where energy is released by a chemical reaction in...

 bacteria belong to this family, and are typically found as symbiote

Symbiosis

Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

s of deep-sea animals.

Vibrionaceae are Gram-negative

Gram-negative

Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...

 organisms and facultative anaerobes, capable of fermentation

Fermentation (biochemistry)

Fermentation is the process of extracting energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. In contrast, respiration is where electrons are donated to an exogenous electron acceptor, such as oxygen,...

. They contain oxidase

Oxidase

An oxidase is any enzyme that catalyzes an oxidation-reduction reaction involving molecular oxygen as the electron acceptor. In these reactions, oxygen is reduced to water or hydrogen peroxide ....

 and have one or more flagella

Flagellum

A flagellum is a tail-like projection that protrudes from the cell body of certain prokaryotic and eukaryotic cells, and plays the dual role of locomotion and sense organ, being sensitive to chemicals and temperatures outside the cell. There are some notable differences between prokaryotic and...

, which are generally polar. Originally these characteristics defined the family, which was divided into four genera. Two of these, Vibrio

Vibrio

Vibrio is a genus of Gram-negative bacteria possessing a curved rod shape, several species of which can cause foodborne infection, usually associated with eating undercooked seafood. Typically found in saltwater, Vibrio are facultative anaerobes that test positive for oxidase and do not form...

and Photobacterium

Photobacterium

Photobacterium is a genus of gram-negative bacteria in the family Vibrionaceae. Members of the genus are bioluminescent, that is they have the ability to emit light....

, correspond to the modern group, although several new genera have been defined. Genetic studies have shown the other two original members—Aeromonas

Aeromonas

Aeromonas is a gram-negative, facultative anaerobic rod that morphologically resembles members of the family Enterobacteriaceae. Fourteen species of Aeromonas have been described, most of which have been associated with human diseases. The most important pathogens are A. hydrophila, A. caviae, and...

and Plesiomonas—belong to separate families. The family Vibrionaceae currently comprises eight validly published genera: Aliivibrio, Catenococcus, Enterovibrio, Grimontia, Listonella, Photobacterium, Salinivibrio, and Vibrio; although the status of Listonella has been questioned.

Members of this family also synthesize Tetrodotoxin

Tetrodotoxin

Tetrodotoxin, also known as "tetrodox" and frequently abbreviated as TTX, sometimes colloquially referred to as "zombie powder" by those who practice Vodou, is a potent neurotoxin with no known antidote. There have been successful tests of a possible antidote in mice, but further tests must be...

 (TTX), an ancient marine alkaloid and powerful neurotoxin (Na+ pump inhibitor, 1 mg can kill an adult) that serves to protect members of an Order (biology)

Order (biology)

In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 of fishes, the Tetraodontiformes

Tetraodontiformes

The Tetraodontiformes are an order of highly derived ray-finned fish, also called the Plectognathi. Sometimes these are classified as a suborder of the Perciformes...

 (tetras-four and odontos-tooth), which include the Puffer Fish (see fugu

Fugu

is the Japanese word for pufferfish and the dish prepared from it, normally species of genus Takifugu, Lagocephalus, or Sphoeroides, or porcupinefish of the genus Diodon. Fugu can be lethally poisonous due to its tetrodotoxin; therefore, it must be carefully prepared to remove toxic parts and to...

, raw puffer fish served in Japan). As mentioned above, Vibrionaceae bacteria are in symbiosis with many marine organisms. In the case of the Puffer fish, and other marine organisms harboring TTX producing Vibrionaceae, the symbiosis is an ancient and powerful one, providing protection against predation for the marine organisms that harbor these bacteria, while providing the bacteria a protected environment with plenty of nutrients for growth. TTX and saxitoxin provide a good example of convergent biochemical evolution: both toxins are extremely toxic at low levels, both are Na⁺ pump inhibitors and both have nearly identical binding constants on the Na⁺ pump in neurons.

Pathology

A characteristic of the family is the broad host range susceptible to infection by vibrios. Pathogens of man, other than V. cholerae, include V. parahaemolyticus, a cause of gastro-enteritis and V. vulnificus that can lead to acute and fatal septicaemia. Other species of Vibrionaceae are associated with disease in a wide variety of finfish, one of the most notable and commonly occurring pathogens being Vibrio anguillarum

Vibrio anguillarum

-Introduction:Vibrio anguillarum is a Gram negative, curved rod bacterium with one polar flagellum. It is an important pathogen of cultured salmonid fish, and causes the disease known as vibriosis or red pest of eels....

, the cause of septicaemia in farmed salmonids such as Atlantic salmon and rainbow trout. Species such as V. tubiashii cause disease in larval stages of Pacific oyster (Crassostrea gigas) while V. harveyi causes luminous vibriosis in penaeid shrimps (prawns). The extent of the host range is seen with species such as V. mediterranei and V. coralliilyticus which can infect zooxanthellae, the plant symbiont of coral. These species of vibrio are thought to be a cause of coral bleaching