Taxonomic evaluation of amino acid metabolism inLegionella

Legionella utilizes amino acids as the sole source of carbon and energy. We have examined 62 strains of nine species to determine whether their amino acid metabolism correlated with species definition. Neither definitive species differences nor serogroup differences within the speciesLegionella pneumophila were found. Greatest metabolic activity of all strains was observed with glutamate, alanine, aspartate, and proline; anaerobically, the greatest reduction of methylene blue was obtained with glutamate, aspartate, histidine, and lysine. Within the genus, two major groups were observed: those species that showed little endogenous activity and metabolized a select group of amino acids, and those species that showed strong endogenous activity and appeared to actively metabolize virtually all the amino acids.