Expression of Synthetic Phytoene Synthase Gene to Enhance β‐Carotene Production in Scenedesmus sp. CPC2

β‐carotene is a valuable pigment abundant in some microalgal species but the low β‐carotene productivity of microalgae has become the major obstacles against its commercialization. This work aims to improve the productivity of algae‐based β‐carotene via genetic engineering approaches. First, a synthetic psy gene construct (891 bp) encoding 297 amino acids is expressed in Scenedesmus sp. CPC2 host to enhance the β‐carotene production. The synthetic psy gene is designed by considering the highest consensus of amino acids (i.e., 62% identity) from Chlamydomonas reinhardtii , Dunaliella salina, and Mariella zofingiensis . The original β‐carotene content in wild‐type Scenedesmus sp. CPC2 is 10.8 mg g −1 ‐cell when grown on BG11 medium under 2% CO 2 aeration, 150 μmol m −2  s −1 light intensity and 25°C. After transformation of the psy gene into the microalgal host, the β‐carotene content of the best recombinant strain (i.e., transformant CPC2‐4) significantly increased to over 30 mg g −1 ‐cell. The optimal production of β‐carotene with the CPC2‐4 recombinant strain was achieved when the strain is grown on BG11 medium amended with 0.075 g of MgSO 4 , giving approximately 3‐fold higher β‐carotene content than that of the wild‐type strain. The best cellular β‐carotene content obtained (i.e., 31.8 mg g −1 ) is superior to most algae‐based β‐carotene production performance reported in the literature.