Advances in biosynthesis of 7-Dehydrocholesterol through de novo cell factory strategies

7-Dehydrocholesterol (7-DHC) is an important sterol for maintaining human health and is present in the skin. After sun exposure, 7-DHC in the skin is converted to vitamin D3 to strengthen the immune system. In recent years, synthetic biology has gained importance due to the effective and efficient production of various important compounds using microorganisms. Despite the understanding of the mechanisms and pathways of 7-DHC biosynthesis, achieving higher production yields remains a significant challenge. This review aims to provide a comprehensive overview of the current state of 7-DHC biosynthesis. Various synthetic strategies including optimization of rate-limiting enzymes, metabolic fluxes, redox balance, and subcellular localization are discussed. Moreover, the role of omics technology in designing important proteins and gene editing techniques for strain modification to efficiently synthesize 7-DHC will also be discussed.