The nucleotide sequence of the luxC gene (EMBL Accession No. 65156) encoding fatty acid reductase (FAR) of the lux operon from Photobacterium leiognathi PL741 was determined and the encoded amino acid sequence deduced. The fatty acid reductase is a component of the fatty acid reductase complex. The complex is responsible for converting fatty acid to aldehyde which serves as the substrate in the luciferase-catalyzed bioluminescent reaction. The protein comprises 478 amino acid residues and has a calculated M(r) of 53,858. Alignment and comparison of the fatty acid reductase of P. leiognathi with that of Vibrio harveyi B392 and Vibrio fischeri ATCC 7744 shows that there is 70% and 59% amino acid residues identity, respectively.