  legionella pneumophila is a thin, aerobic, pleomorphic, flagellated, non-spore forming, gram-negative bacterium of the genus legionella. l. pneumophila is the primary human pathogenic bacterium in this group and is the causative agent of legionellosis or legionnaires' disease. ==characterization== l. pneumophila is a gram-negative, non-encapsulated, aerobic bacillus with a single, polar flagellum often characterized as being a coccobacillus. it is aerobic and unable to hydrolyse gelatin or produce urease. it is also non-fermentative. l. pneumophila is neither pigmented nor does it autofluoresce. it is oxidase positive- and catalase-negative, and produces beta-lactamase. l. pneumophila has a colony morphology that is gray-white with a textured, cut-glass appearance; it also requires cysteine and iron to thrive. it will grow on yeast extract in "opal-like" colonies. ===cell membrane structure=== while l. pneumophila is categorized as a gram-negative organism, it stains poorly due to its unique lipopolysaccharide-content in the outer leaflet of the outer cell membrane. the bases for the somatic antigen specificity of this organism is located on the side-chains of its cell wall. the chemical composition of these side chains both with respect to components, as well as arrangement of the different sugars, determines the nature of the somatic or o-antigen determinants, which are important means of serologically classifying many gram-negative bacteria. at least 35 different serovars of l. pneumophila have been described, as well as several other species being subdivided into a number of serovars. ===detection=== sera have been used both for slide a
Bacteria_with_sequenced_genomes Gram-negative_bacteria Legionellales