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 (CoQ₁₀) within the polyisoprenoid chain. Few microorganisms produce CoQ₁₀. This work shows that Thraustochytrium sp. RT2316-16 produces CoQ₁₀ and CoQ₉. The CoQ₁₀ content in RT2316-16 depended strongly on the composition of the growth medium and the age of the culture, whereas the CoQ₉ 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 CoQ₁₀ 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 CoQ₁₀ that otherwise occurred during growth. The highest content of CoQ₉ and CoQ₁₀ 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 CoQ₁₀. Metabolic signals that trigger the synthesis of CoQ₁₀ in RT2316-16 need to be determined for optimizing culture conditions.