THE BIOTECHNOLOGY OF CULTIVATING DUNALIELLA FOR PRODUCTION OF BETA-CAROTENE RICH ALGAE

Dunaliella accumulates massive amounts of beta-carotene when cultivated under high light intensity and growth-limiting conditions. The pathway for biosynthesis of beta-carotene was elucidated by analysis of the effect of selected inhibitors. The presence of the inhibitors elicited the accumulation of the following intermediates: beta-zeacarotene, lycopene, zeta-carotene, phytofluene, phytoene and a few unidentified long-chain isoprenoids. Each of the accumulated intermediates was composed of about equal amounts of two stereoisomers, as is the case for beta-carotene in the untreated algae. It is deduced, therefore, that the isomerization reaction occurs early in the pathway of beta-carotene biosynthesis, at or before phytoene. The unique carotenogenesis properties of Dunaliella led to the development of a new biotechnological process for mass-cultivation of the alga. Commercial production facilities for beta-carotene rich Dunaliella exist today in Israel, USA, Australia, Spain and China. Recent developments, which indicate that the stereoisomeric mixture of beta-carotene present in Dunaliella is preferentially absorbed in animal tissues, coupled with new evidence for the efficacy of beta-carotene in reducing the incidence of cancer, have opened new vistas of potential markets for the high beta-carotene algae.