A novel alpha-pyrone designated as alcanivorone was found in a culture broth of the marine bacterium, Alcanivorax jadensis, and its structure was determined by an analysis of 1D NMR, 2D NMR and MS data. Alcanivorone was produced by A. jadensis only when sodium pyruvate was added to the culture medium as a carbon source. Incorporation experiments using stable isotope-labeled pyruvate indicated that alcanivorone was biosynthesized from four molecules of pyruvate.