Engineered microbial production of carotenoids and their cleavage products: Recent advances and prospects.

Carotenoids and their cleavage products (referred to as apocarotenoids) have functional properties such as antioxidant activity, fragrance, and color that are important in the pharmaceutical, healthcare, cosmetics, and food industries. Currently, carotenoids and apocarotenoids are primarily obtained through extraction from natural sources or chemical synthesis, both of which are associated with inefficiencies, environmental impact, and product limitations. Ongoing advances in metabolic engineering and synthetic biology have positioned heterologous biosynthesis as a promising, efficient, and sustainable production strategy. This review summarizes recent progress in carotenoid and apocarotenoid biosynthesis, detailing the key biosynthetic pathways originating from mevalonate and methylerythritol phosphate, with a focus on the enzymes involved in carotenoid cleavage. We also highlight significant advancements in microbial production, emphasizing various metabolic engineering strategies aimed at enhancing microbial production efficiency. Lastly, we discuss potential future research directions for the biosynthesis of these compounds.