Algae emerge as leading actors for the development of new strategies to cope oxidative stress, thanks to their availability for genetic manipulation and simple cultivation. This study reports the design of novel mutant strains of the green photosynthetic alga Chlamydomonas reinhardtii, as a model system, able to produce bioactive peptides with high antioxidant capacity by means of a custom-made expression system. The D1 protein of Photosystem II is highly abundant in the chloroplast with a rapid steady-state turnover; the final step of D1 protein processing is thus exploited for the continuous release of antioxidant peptides into the organism. Three antioxidant peptides, isolated from different food sources, were successfully expressed in C. reinhardtii. We show that the in vitro antioxidant activity of algae extract is lower in transgenic lines, while the in vivo antioxidant activity is highly evident towards radical oxygen-generating substances than in the control strain. Moreover, the antioxidant mutant releasing the peptide designed from Hoki fish, showed a longer shelf-life and a better resistance to high light and heat stress than the control. These features can be exploited in the vision of the development of robust biocomponents for bioassay applications. In particular, we described the design of an optical bioassay for herbicides detection, showing the high potential of the proposed mutant strains as robust and sensitive biological recognition elements.

藻类因其可进行基因操作和简单栽培而成为开发应对氧化应激新策略的主要参与者。这项研究报告了绿色光合藻莱茵衣藻的新型突变菌株的设计，该菌株作为模型系统，能够通过定制的表达系统生产具有高抗氧化能力的生物活性肽。光系统II的D1蛋白在叶绿体中高度丰富，具有快速的稳态转换；因此，利用D1蛋白加工的最后一步将抗氧化剂肽连续释放到生物体中。分离自不同食物来源的三种抗氧化剂肽在莱茵衣藻中成功表达。我们表明，藻类提取物的体外抗氧化活性在转基因品系中较低，而体内抗氧化活性对自由基产生氧的物质比在对照菌株中高度明显。而且，释放出由Hoki鱼设计的肽的抗氧化剂突变体显示出比对照组更长的保质期和更好的抗强光和热胁迫的能力。这些特征可以在开发用于生物测定应用的健壮生物组分的视野中加以利用。尤其是，我们描述了用于除草剂检测的光学生物测定法的设计，显示了提出的突变菌株作为健壮和敏感的生物识别元件的巨大潜力。