Involved in the non-oxidative decarboxylation and detoxification of phenolic derivatives under both aerobic and anaerobic conditions, however the precise biochemical function of VdcD in metabolism of phenolic acid is unknown. By vanillate. It is not known, if phenolic acid decarboxylase forms a complex composed of VdcB, VdcC and VdcD. The term subunit is often used in reference to the operon, however there is no experimental evidence to prove the existence of the complex.