产氢红杆菌类胡萝卜素代谢研究

在不损伤细胞条件下,采用分光光度法探求了产氢红杆菌(Rhod obacter sp.)R 7菌株光合色素合成规律,研究了供氢体、氮源和生长因子对R 7菌株细胞生长、类胡萝卜素表达和合成量的影响.结果表明,光合色素的合成具有时序性,R 7菌株首先合成可吸收近红外光的细菌叶绿素,而370 nm和590 nm组分的细菌叶绿素的合成则晚于类胡萝卜素,426 nm类胡萝卜素含量的变化引起捕光色素复合体和光反应中心复合体比率的改变.与乙酸钠相比,苹果酸钠只在生长初期对细胞生长有促进作用,但最终细胞生物量无明显差异.在乙酸钠体系中,分别用酵母提取物和谷氨酸钠替代生物素和硫酸铵后可使细胞生物量提高37.9%和20.4%.乙酸钠供氢体可诱导细胞进行球形烯和球状菌素类胡萝卜素代谢,苹果酸钠和谷氨酸钠有利于426 nm类胡萝卜素组分的产生,但不利于450 nm类胡萝卜素组分的积累,苹果酸钠还可诱导产生556 nm类胡萝卜素新组分.酵母提取物可显著提高类胡萝卜素产量,并改变了类胡萝卜素合成途径.

Carotenoid Metabolism of Hydrogen-Producing Rhodobacter sp.

The synthesis sequence of photopigment in live cell of hydrogen-producing Rhodobacter sp.was investigated.The effects of different hydrogen donors,different nitrogen sources and different growth factors on metabolic pathway and composition of carotenoids in hydrogen-producing photosynthetic bacteria were also analyzed.The results showed that the biosynthesis of bacteriochlorophylla was earlier than that of carotenoids in the order of 800 nm,850 nm,450 nm,480 nm,512 nm,426 nm,870 nm in hydrogen-producing photosynthetic bacteria Rhodobacter sp.R7 strain,and the synthesis of 426 nm carotenoid changed the ratio of content of the light-harvesting complex and reaction center of Rhodobacter sp.R7 strain.The addition of acetate to the medium instead of malate could induce spheroidene and spheroidenone metabolic pathway of carotenoid bosynthesis.The addition of glutamate and malate to the medium was helpful to accumulate of 426nm carotenoid and enhance cell growth.The addition of yeast extract to the medium could not only enhance cell growth and carotenoid yield remarkably,but also could change the metabolic pathway of carotenoid bosynthesis.