ASTAXANTHIN SYNTHESIS IN SYNECHOCOCCUS PC7002: OPTIMIZATION AND PRODUCTSECRETIONTO CULTURE MEDIUM

Synechococcus sp. PCC7002 can produce theastaxanthin precursor β-carotene but not astaxanthin.Using a synthetic ketolase-and a synthetic hydroxylase-gene we modifiedSynechococcuscarotene metabolism to produce astaxanthin. The total cellular content of astaxanthin was further increased by over-expressing the intrinsic phytoene synthase. Besides a beneficial step in astaxanthin production our results indicate for some modifications in the suggestedprocess of carotenoid metabolism. In addition, we were expressing an E. coli ABC-transporter to export astaxanthinand decrease intracellular product accumulation. By this, the synthesis was increased further and significant amounts of astaxanthin can be recovered from culture medium without cell destruction.