Luminescence in Latia involves a specific flavoprotein enzyme ("luciferase"), which has a tightly bound flavin group constituting the light-emitter. The overall reaction includes oxidation of a specific substrate ("luciferin," an enol formate derivative of an aliphatic aldehyde), by 2 O(2) molecules, in the presence of a "purple protein" cofactor, yielding a ketone, HCOOH, CO(2), and light. In Achromobacter, a required aliphatic aldehyde, which is functionally equivalent to Latia luciferin, is oxidized to an acid containing the same hydrocarbon chain as the aldehyde; this reaction proceeds in the presence of bacterial luciferase and reduced flavin mononucleotide with a quantum yield of 0.17 + 0.1 photons per aldehyde molecule that is independent of aldehyde chain length from 9 to at least 14 carbons.