Carotenoids are a large group of natural pigments, ranging from red, to orange, to yellow colors. Synthesized by plants and some microorganisms (e.g., microalgae, fungi and bacteria), carotenoids have important physiological functions (e.g., light harvesting). Apocarotenoids are carotenoid-derived compounds and play important roles in various biological activities (e.g., plant hormones). Many carotenoids and apocarotenoids have high economic value in feed, food, supplements, cosmetics and pharmaceutical industries. Despite high commercial values, they are severely undersupplied because of low abundance in natural hosts (usually a few milligrams per kilogram of raw materials). Furthermore, plants or microbes usually produce mixtures of these molecules with very similar physical and chemical properties (such as α- and β-carotenes). All these features render the extraction from natural hosts rather difficult and also very costly both from process economics and sustainable land-use viewpoints. Chemical synthesis is also expensive due to structural complexity (e.g., astaxanthin has many unsaturated bonds and two chiral regions). Biotechnology via the rapidly advancing metabolic engineering and synthetic biology approaches has led to alternative ways to attain several carotenoids and apocarotenoids at relatively high titers and yields using fast-growing microorganisms. This chapter briefly reviews the biosynthesis of carotenoids and apocarotenoids by microorganisms and their industrial potential.
Part of the book: Progress in Carotenoid Research