Colwellia

Colwellia is a genus of marine bacteria in the family Colwelliaceae, within the Gammaproteobacteria. The cells are Gram-negative and typically rod-shaped, with many strains being motile by polar flagella. Colwellia species are commonly associated with cold marine habitats, including Arctic and Antarctic waters, sea ice, and deep-sea sediments, and many are psychrophilic or psychrotolerant.

The genus was named after American microbiologist Rita R. Colwell. Colwellia psychrerythraea 34H is a well-studied representative and serves as a model organism for cold adaptation; its genome has been sequenced to investigate mechanisms that enable life at low temperatures. Other described species have been isolated from polar, deep-sea, and other cold environments.

Colwellia species are predominantly chemoorganotrophs that derive energy from organic substrates and are generally aerobic, though some members can grow under low-oxygen conditions. They contribute to carbon and nutrient cycling in cold marine ecosystems and reflect the adaptability of marine bacteria to extreme environments.

In addition to ecological roles, certain Colwellia strains have been explored for biotechnological and environmental applications, including potential use in bioremediation of hydrocarbons in cold marine settings and for studying enzymes that function at low temperatures.

Notable species associated with the genus include Colwellia psychrerythraea, Colwellia profunda, and Colwellia piezophila, among others. The genus is part of the broader marine Gammaproteobacteria and comprises organisms from shallow to deep-sea cold environments.