Astaxanthin Synthesis In Chlamydomonas Reinhardtii Chloroplast

Chlamydomonas reinhardtii is a widely studied model organism with its genetic mechanism clearly understood. This essay is based on the chlamydomonas reinhardtii chloroplast transformation to produce astaxanthin. The key enzymes of astaxanthin biosynthetic pathway include beta lycopene cyclase, beta-carotene, ketone and beta carotene hydroxylase.β-lycopene reacts with cyclase to generate β-carotene, which reacts with both ketone enzyme and hydroxylase. If β-carotene reacts with hydroxylase to generate zeaxanthin first, it will be hard for zeaxanthin to react with ketone enzyme to produce astaxanthin. So we try to fuse proteins together, which enables ketone enzyme to make immediate contact with β-carotene produced by lycopene reacting with cyclase. In this way, lycopene turns into canthaxanthin directly. Because canthaxanthin is easy to turn into astaxanthin, the conversion efficiency of β-lycopene to astaxanthin is improved. In this easy, fusion expression of beta lycopene cyclase and beta carotene ketone enzyme is used to increase productivity of astaxanthin in Chlamydomonas reinhardtii. Further use of biolistic transformation method enables β-carotene ketone enzymes gene and hydroxylase gene to get into the Chlamydomonas reinhardtii chloroplast. Then screen the cells on solid medium containing 100 mg/L spectinomycin to get transformants, shows that target gene expresses successfully in Chlamydomonas reinhardtii transformants.