Figure 1

Scheme of the putative astaxanthin biosynthesis pathway in recombinant E. coli , proceeding from the central intermediates pyruvate (Pyr) and glyceraldehyde-3-phosphate (GAP), highlighting the different possible routes of ketolase and hydroxylase reaction that can take place by the conversion of β-carotene (1) to astaxanthin (10). Dxs 1-deoxyxylulose-5-phosphate synthase, Idi isopentenyl diphosphate isomerise, IspA farnesyl diphosphate synthase, CrtE geranylgeranyl diphosphate synthase, CrtB phytoene synthase, CrtI phytoene desaturase, CrtY lycopene cyclase, W β-carotene ketolase (CrtW), Z β-carotene hydroxylase (CrtZ), IPP isopentenyl diphosphate, DMAPP dimethylallyl diphosphate, DXP 1-deoxyxylulose-5-phosphate, (2) β-cryptoxanthin, (3) echinenone, (4) 3'-hydroxyechinenone, (5) 3-hydroxyechinenone, (6) zeaxanthin, (7) canthaxanthin, (8) adonixanthin, (9) adonirubin.