The present invention relates to a process for the production of isoprenoids Coenzyme Q-10 by microorganisms. More particularly, the present invention relates to a process for increased production of Coenzyme Q-10 by microorganisms of the genus Rhodobacter, preferably of the species R. sphaeroides which have been transformed with one or more gene(s) of the mevalonate (mev) operon from a different microorganism, preferably of the genus Paracoccus, more preferably of the species P. zeaxanthinifaciens, whereby the mev operon is mutated leading to an increased coenzyme Q-10 production. Sequences carrying such a mutation as well as a microorganism carrying such a mutated mev operon are also included.