玫瑰考克氏菌中类胡萝卜素的合成途径及其介导的辐射防护机制研究

Radioresistant bacteria are a kind of microbial resources with important development and utilization prospects. The study of their radioresistant mechanism and radioresistant components is of great significance for environmental remediation and the development of radioprotective drugs. In the early stage of the project, a radioresistant bacterium has been obtained by screening from the irradiated storage bin of the irradiated device and identified as Kocuria rosea. Kocuria is one of the radiation-resistant bacteria and has been employed as a biotechnology tool for several goals. Nevertheless, the radiation-resistant mechanism of the strain has not been reported, which limits its application in bioremediation and radioprotection. The researcher speculated that the carotenoid pigment contained in the strain played an important role in its radioresistance. However, the biosynthetic pathway of the carotenoid in Kocuria has not been clarified, as well as the radioprotective role and mechanism. In this project, the key enzymes of carotenoid biosynthetic pathway will be firstly identified through bioinformatics, gene knockout and compensation techniques. Afterwards, the pathway will be reconstructed and verified in E. coli by synthetic biology technique. The radioprotective effect of the carotenoid on bacteria will also be analyzed. Finally, the radioprotective effect and mechanism of the carotenoid on mammals will be analyzed at cell level and animal level. The research results will help to clarify biosynthesis mechanism of carotenoids in Kocuria rosea, and provide scientific examples for the study of the biosynthetic pathways of carotenoids in other bacteria. Meanwhile, it can also lay a theoretical foundation for the application of carotenoids in the development of radioprotective drugs.

耐辐射细菌是一类具有重要开发和利用前景的微生物资源，研究其抗辐射机制和组分，对于环境修复和辐射防护药物的开发具有重要意义。项目前期筛选获得一株耐辐射的玫瑰考克氏菌，但关于该菌的耐辐射机制尚无文献报道，限制了其在生物修复和辐射防护中的应用。研究者推测其含有的色素类胡萝卜素在该菌的辐射抗性中发挥重要作用，然而迄今为止考克氏菌中类胡萝卜素合成途径及其在辐射防护中的作用和机制还未阐明。本项目拟以筛选获得的玫瑰考克氏菌为研究对象，首先利用生物信息学和敲除回补技术鉴定类胡萝卜素合成途径的关键酶；其次在大肠杆菌内重构并验证该途径，解析类胡萝卜素对细菌的辐射防护作用；最后，从细胞水平和动物水平分析类胡萝卜素对哺乳动物的辐射防护作用及机制。研究成果将有助于阐明玫瑰考克氏菌中类胡萝卜素的种类和合成机制，为其他细菌中类胡萝卜素合成途径的研究提供科学例证；同时也可以为类胡萝卜素在辐射防护药物中的应用奠定理论基础。

放射性肠损伤是意外照射及腹腔、盆腔肿瘤患者放疗后常见的辐射损伤，目前尚无有效的治疗手段，寻找安全、有效的防治策略是临床放疗恶性肿瘤中亟需解决的问题。耐辐射细菌是一类具有重要开发和利用前景的微生物资源，研究其抗辐射机制和组分，对于环境修复和辐射防护药物的开发具有重要意义。申请者筛选到一株耐辐射的玫瑰考克氏菌RP1，该菌株具有显著的抗氧化和抗DNA损伤能力，推测其产生的色素类胡萝卜素具有抗辐射功能。基于生物信息学分析，推测该菌中存在类胡萝卜素合成途径。对其产生的类胡萝卜素进行提取、分纯和鉴定，并通过细胞实验和动物实验证实了该菌产生类胡萝卜素的辐射防护作用及机制，发现玫瑰考克氏菌中产生的类胡萝卜素可以通过Nrf2介导的抗氧化通路发挥辐射防护作用，并且可以减轻小鼠的炎症反应，改善小鼠肠道菌群，促进有益菌及短链脂肪酸的产生。该研究成果拓展了类胡萝卜素在辐射防护药物开发中的应用，为其他细菌中类胡萝卜素的合成和鉴定提供科学例证，同时也可以为类胡萝卜素在放射性肠损伤中的临床应用奠定理论基础。