fluoreszcens

Fluoreszcens is a Latin adjective used in the scientific names of organisms to denote fluorescence, or the emission of light by a substance that has absorbed light. In zoological and botanical nomenclature it is an epithet rather than a taxon, and does not imply a specific lineage by itself. The form fluorescens means fluorescent or glowing, from the verb fluorescere in Latin.

In microbiology, fluorescens is commonly found in species epithets such as Pseudomonas fluorescens, Xanthomonas fluorescens, and related taxa. The epithet indicates that the organism or its colonies exhibit visible fluorescence under ultraviolet or specific excitation light. In many Pseudomonas species, fluorescence is due to the production of fluorescent pigments called siderophores, notably pyoverdine, which emits blue-green light and can be detected under UV in culture plates.

Taxonomic notes: Pseudomonas fluorescens has been subject to taxonomic revision and is now treated as a complex with multiple related species; Xanthomonas fluorescens was used historically but some strains have been reclassified under other genera. The epithet remains in historical literature to describe fluorescence as a phenotypic trait rather than a strict diagnostic feature today.

Other uses: The term is not exclusive to microbes; some plants or algae may be described as fluorescens if they exhibit fluorescence under UV, but such usage is less common. In scientific practice, fluorescence-based naming highlights a measured property rather than a genotype or phylogeny.