"A. fischeri" is one of many species of bacteria that commonly form symbiotic relationships with marine organisms. Marine organisms contain bacteria that use bioluminescence so they can find mates, ward off predators, attract prey, or communicate with other organisms. In return, the organism the bacteria are living within provides the bacteria with a nutrient-rich environment. The "lux" operon is a 9-kilobase fragment of the "A. fischeri" genome that controls bioluminescence through the catalytic activity of the enzyme luciferase. This operon has a known gene sequence of "luxCDAB(F)E", where "luxA" and "luxB" code for the protein subunits of the luciferase enzyme, and the "luxCDE" codes for a fatty acid reductase complex that makes the fatty acids necessary for the luciferase mechanism." luxC "codes for the enzyme acyl-reductase, "luxD" codes for acyl-transferase, and "luxE" makes the proteins needed for the enzyme acyl-protein synthetase. Luciferase produces blue/green light through the oxidation of reduced flavin mononucleotide and a long-chain aldehyde by diatomic oxygen. The reaction is summarized as: