Production of non-photosynthetic carotenoids, e.g. beta-carotene for use in food or cosmetics etc., involves culturing photosynthetic bacteria which have been genetically modified to produce the required compounds

摘要

The non-photosynthetic carotenoids beta -carotene (IA), canthaxanthin (IB) and astaxanthin (IC) are obtained from photosynthetic bacteria which have been modified by deleting genes involved in the endogenous route after the lycopene stage and inserting the genes crtY, crtY and crtW, or crtY, crtZ and crtW. Method (M1) for the synthesis of non-photosynthetic carotenoids (I) selected from beta -carotene (IA), canthaxanthin (IB) and astaxanthin (IC) with the aid of photosynthetic bacteria producing photosynthetic carotenoid(s) with lycopene as an intermediate. The method involves: (i) deletion of at least part of one or more genes involved in the endogenous synthetic route following that of lycopene so as to stop the synthesis at the lycopene stage; (ii) insertion of the following genes: crtY if the required product is (IA), crtY and crtW if (IA) or (IB) is required, or crtY, crtZ and crtW if (IA) or (IC) is required; (iii) culturing the modified bacteria; and (iv) extraction of the carotenoid(s) (I) from the bacteria. Independent claims are also included for (1) method (M2) for the synthesis of (I) by: (i) using mutant bacteria in which photosynthesis is not inhibited by dioxygen (O 2); (ii) deleting genes as in M1; (iii) inserting genes as in M1; (iv) culturing the modified bacteria under aerobic or micro-aerobic conditions to make (IB) or (IC), or under anaerobic conditions to make (IA); and (v) extracting (I); (2) photosynthetic bacteria obtained by M1 and producing lycopene, (IA), (IB) and/or (IC) (3) photosynthetic bacteria obtained from stages (i) and (ii) in M1 (4) mutant photosynthetic bacteria obtained by stages (i)-(iii) in M2.