Perozeni Federico, Angelini Margherita, Ballottari Matteo, Cazzaniga Stefano
Department of Biotechnology, University of Verona, 37134 Verona, Italy.
Life (Basel). 2025 May 20;15(5):813. doi: 10.3390/life15050813.
Microalgae have evolved a diverse carotenoid profile, enabling efficient light harvesting and photoprotection. Previous studies have demonstrated the feasibility of genome editing in the green algal model species , leading to significant modifications in carotenoid accumulation. By overexpressing a fully redesigned β-carotene ketolase (bkt), the metabolic pathway of was successfully redirected toward astaxanthin biosynthesis, a high-value ketocarotenoid with exceptional antioxidant properties, naturally found in only a few microalgal species. In this study, a tailor-made double knockout targeting lycopene ε-cyclase (LCYE) and zeaxanthin epoxidase (ZEP) was introduced as a background for bkt expression to ensure higher substrate availability for bkt enzyme. The increased zeaxanthin availability resulted in a 2-fold increase in ketocarotenoid accumulation compared to the previously engineered bkt1 or bkt5 strain in the UVM4 background. Specifically, the best Δzl--expressing lines reached 2.84 mg/L under low light and 2.58 mg/L under high light, compared to 1.74 mg/L and 1.26 mg/L, respectively, in UVM4- strains. These findings highlight the potential of rationally designed microalgal host strains, developed through genome editing, for biotechnological applications and high-value compound production.
微藻已经进化出多样化的类胡萝卜素谱，能够高效地捕获光能并进行光保护。先前的研究已经证明了在绿藻模式物种中进行基因组编辑的可行性，这导致了类胡萝卜素积累的显著改变。通过过表达完全重新设计的β-胡萝卜素酮酶（bkt），成功地将 的代谢途径重定向到虾青素生物合成，虾青素是一种具有特殊抗氧化特性的高价值酮类胡萝卜素，仅在少数微藻物种中天然存在。在本研究中，引入了针对番茄红素ε-环化酶（LCYE）和玉米黄质环氧化酶（ZEP）的定制双敲除作为bkt表达的背景，以确保bkt酶有更高的底物可用性。与UVM4背景下先前工程改造的bkt1或bkt5菌株相比，玉米黄质可用性的增加导致酮类胡萝卜素积累增加了2倍。具体而言，最佳的Δzl - - 表达系在低光下达到2.84 mg/L，在高光下达到2.58 mg/L，而UVM4 - 菌株分别为1.74 mg/L和1.26 mg/L。这些发现突出了通过基因组编辑开发的合理设计的微藻宿主菌株在生物技术应用和高价值化合物生产方面的潜力。
