An update on microbial carotenoid production: application of recent metabolic engineering tools

Carotenoids are ubiquitous pigments synthesized by plants, fungi, algae, and bacteria. Industrially, carotenoids are used in pharmaceuticals, neutraceuticals, and animal feed additives, as well as colorants in cosmetics and foods. Scientific interest in dietary carotenoids has increased in recent years because of their beneficial effects on human health, such as lowering the risk of cancer and enhancement of immune system function, which are attributed to their antioxidant potential. The availability of carotenoid genes from carotenogenic microbes has made possible the synthesis of carotenoids in non-carotenogenic microbes. The increasing interest in microbial sources of carotenoid is related to consumer preferences for natural additives and the potential cost effectiveness of creating carotenoids via microbial biotechnology. In this review, we will describe the recent progress made in metabolic engineering of non-carotenogenic microorganisms with particular focus on the potential of Escherichia coli for improved carotenoid productivity.