Coenzyme Q in Thraustochytrium sp. RT2316-16: Effect of the Medium Composition.

Coenzyme Q (CoQ; ubiquinone) is an essential component of the respiratory chain. It is also a potent antioxidant that prevents oxidative damage to DNA, biological membranes, and lipoproteins. CoQ comprises a six-carbon ring with polar substituents that interact with electron acceptors and donors, and a hydrophobic polyisoprenoid chain that allows for its localization in cellular membranes. Human CoQ has 10 isoprenoid units (CoQ 10 ) within the polyisoprenoid chain. Few microorganisms produce CoQ 10 . This work shows that Thraustochytrium sp. RT2316-16 produces CoQ 10 and CoQ 9 . The CoQ 10 content in RT2316-16 depended strongly on the composition of the growth medium and the age of the culture, whereas the CoQ 9 content was less variable probably because it served a different function in the cell. Adding p -hydroxybenzoic acid to the culture media positively influenced the CoQ 10 content of the cell. The absence of some B vitamins and p -aminobenzoic acid in the culture medium negatively affected the growth of RT2316-16, but reduced the decline in CoQ 10 that otherwise occurred during growth. The highest content of CoQ 9 and CoQ 10 in the biomass were 855 μg g -1 and 10 mg g -1 , respectively. The results presented here suggest that the thraustochytrid RT2316-16 can be a potential vehicle for producing CoQ 10 . Metabolic signals that trigger the synthesis of CoQ 10 in RT2316-16 need to be determined for optimizing culture conditions.