A flavoprotein (FAD). Limonene is the most widespread terpene and is formed by more than 300 plants. Rhodococcus erythropolis DCL14, a Gram-positive bacterium, is able to grow on both (S)-limonene and (R)-limonene as the sole source of carbon and energy. NADPH can act instead of NADH, although more slowly. It has not been established if the product formed is optically pure or a mixture of two enantiomers.