Microbial platforms to produce commercially vital carotenoids at industrial scale: an updated review of critical issues.

Carotenoids are a diverse group of isoprenoid pigments that play crucial roles in plants, animals, and microorganisms, including body pigmentation, bio-communication, precursors for vitamin A, and potent antioxidant activities. With their potent antioxidant activities, carotenoids are emerging as molecules of vital importance in protecting against chronic degenerative disease, such as aging, cancer, cataract, cardiovascular, and neurodegenerative diseases. Due to countless functions in the cellular system, carotenoids are extensively used in dietary supplements, food colorants, aquaculture and poultry feed, nutraceuticals, and cosmetics. Moreover, the emerging demand for carotenoids in these vast areas has triggered their industrial-scale production. Currently, 80%-90% of carotenoids are produced synthetically by chemical synthesis. However, the demand for naturally produced carotenoids is increasing due to the health concern of synthetic counterparts. This article presents a review of the industrial production of carotenoids utilizing a number of diverse microbes, including microalgae, bacteria, and fungi, some of which have been genetically engineered to improve production titers.