Carotenoid Biosynthesis by Aphanocapsa Homogenates Coupled to a Phytoene-generating System from Phycomyces Blakesleeanus

The ability of a cell extract from the C5 carB10(-) (phytoene-accumulating) strain of Phycomyces blakesleeanus to convert [2-(14)C]mevalonic acid into phytoene has been exploited in a coupled assay with a cell homogenate from the cyanobacterium Aphanocapsa 6714 (Pasteur Culture Collection]. Incubations containing both cell extracts convert [2-(14)C]mevalonic acid into unsaturated carotenes and xanthophylls of Aphanocapsa, via the [(14)C]phytoene formed by the C5 preparation. The major advantage of this experimental approach is that it simplifies and shortens the assay procedure, since it eliminates the necessity to initially prepare [(14)C]phytoene and then add it to the incubation with an emulsifying agent.