gammaproteobacterial

Gammaproteobacteria is a large and diverse class of Gram-negative bacteria within the phylum Proteobacteria. It is one of the largest and most studied groups of Proteobacteria, reflecting its broad ecological breadth and medical importance. The class includes many familiar genera and species, ranging from harmless environmental organisms to important human pathogens. The group comprises several orders, such as Enterobacterales (including Escherichia coli, Salmonella enterica, Klebsiella pneumoniae), Vibrionales (Vibrio cholerae), Pseudomonadales (Pseudomonas aeruginosa), Legionellales (Legionella pneumophila), Xanthomonadales (Xanthomonas spp.), Aeromonadales (Aeromonas spp.), and Francisellales (Francisella tularensis).

Gammaproteobacteria are typically Gram-negative and often rod-shaped; many are motile via flagella, though nonmotile species exist. They exhibit broad metabolic diversity, including aerobic respiration, anaerobic respiration with various electron acceptors, and fermentation. They inhabit diverse environments, such as soil, water, plant and animal hosts, and are common members of gut microbiota in humans and other animals.

Several members are significant in medicine and public health. Pathogens include Escherichia coli, Salmonella spp., Shigella spp., Yersinia pestis, Vibrio cholerae, Legionella pneumophila, and Pseudomonas aeruginosa. Others play important ecological roles or industrial applications, such as in bioremediation or nitrogen cycling in environmental settings.

Taxonomy within Gammaproteobacteria is dynamic; advances in genomics continue to reshape the understanding of relationships among lineages, and some lineages may be reclassified as new data emerge.