Alteromonadales

Alteromonadales is an order of Gram-negative bacteria within the class Gammaproteobacteria, phylum Proteobacteria. Members are predominantly marine heterotrophs and are found in seawater, coastal sediments, and on surfaces such as algae and invertebrates. They are typically rod-shaped, motile with polar flagella, and mostly aerobic or facultatively anaerobic. Metabolically, they are chemoorganotrophs that utilize a wide range of organic substrates; many members produce extracellular enzymes that enable degradation of complex marine organic matter.

Ecology and physiology: Alteromonadales organisms play roles in marine carbon and nutrient cycles, including degradation of algal polysaccharides and hydrocarbons. Some lineages are psychrophilic or psychrotolerant, reflecting adaptation to cold marine environments. Several isolates associate with marine algae or animals, and some members participate in hydrocarbon degradation or bioremediation processes.

Taxonomy and diversity: The order comprises several families, notably Alteromonadaceae, Oceanospirillaceae, Colwelliaceae, Pseudoalteromonadaceae, Shewanellaceae, Marinomonadaceae, and Moritellaceae. Genera such as Alteromonas, Pseudoalteromonas, Marinomonas, Shewanella, Colwellia, Oceanospirillum, and Moritella are among the better known. Taxonomic assignments within Alteromonadales have been refined with genome-based methods, leading to reorganizations at the family and genus levels in recent years.

Clinical and applied relevance: Most Alteromonadales are environmental in origin. A few species, particularly some Shewanella, can cause opportunistic infections in humans, though they are not common pathogens. Members are of interest for biotechnology due to enzymes and pathways involved in degrading marine polymers and hydrocarbons, with potential applications in bioremediation and industrial biocatalysis.