The last step in the biosynthesis of aryl carotenoids in the cheese ripening bacteria Brevibacterium linens ATCC 9175 ( Brevibacterium aurantiacum sp. nov.) involves a cytochrome P450-dependent monooxygenase

Bacterial surface-ripened cheeses such as Tilsit, Brick, Limburger, Epoisses, Livarot, Munster, Reblochon, Herve or Taleggio develop a red or orange color during ripening. Color is linked to the production of pigments by bacteria growing on the surface, and Brevibacterium linens is particularly added in milk by cheese manufacturers. Tetcyclacis, a chemical compound known to be an inhibitor of cytochrome P450 dependent monooxygenase inhibited the aerobic biosynthesis of orange hydroxylated carotenoids in the red-smear cheese ripening bacteria B. linens. Growth of the cells in the presence of tetcyclacis reduced to almost zero the level of the 3,3′-dihydroxy-isorenieratene found in stationary-phase cells. According to co-elution with carotenoid standards and LC–MS, the substrate of cytochrome P450 dependent monooxygenase was identified as isorenieratene, a carotene with Φ rings. Up to now, there are only few examples of carotenoid hydroxylases from the P450 superfamily. Moreover this is the first description of a P450 monooxygenase that catalyzes the hydroxylation of non-β-ring carotenoid in bacteria.