不产氧光合细菌光合色素的光氧调控机制

【目的】为不产氧光合细菌光合色素研究提供可行的较系统规范的研究方法和数据,揭示固氮红细菌(Rhodobacter azotoformans134K20)光合色素光氧适应性机制。【方法】采用光谱法和色谱法对光和氧调控下的类胡萝卜素和细菌叶绿素合成代谢进行了研究。【结果】134K20菌株光照好氧时细胞得率最高。光照厌氧时主要合成3黄、1红、1紫、2绿、2蓝9种色素,黄色素大量表达。有氧时红色素大量表达,且启动2种新的红色素和1种新的紫色素表达,而黄色和蓝绿色素则受氧抑制。黑暗好氧主要合成2黄、3红、2紫、1绿、1蓝9种色素,但不同于光照厌氧。光照好氧时黄色素减少到1种,紫色素含量增加,其余同黑暗好氧。【结论】固氮红细菌(Rhodobacter azotoformans134K20)是通过PpsR调节途径来调节光合基因表达的。黄色和红色素属于类胡萝卜素。黄色素1属于球形烯系列,其余两种黄色素是新的类胡萝卜素组分。红色素为新的球形烯酮组分,3种红色素极性、峰形和峰位差别显著,正己烷能显示其精细结构。紫色为极性较大的细菌脱镁叶绿素,绿色和蓝色为4种极性不同的细菌叶绿素a中间产物。乙醚甲醇法适合类胡萝卜素的提取,丙酮甲醇冰冻研磨法能快速有效完全提取光合色素。溶剂效应可有效鉴别细菌叶绿素a中间产物。

Importance, features and uses of metal oxide catalysts in heterogeneous catalysis

This short review paper aims at assembling the present state of the art of the multiuses of metal oxides in heterogeneous catalysis, concerning liquid and gaseous phases of the reactant mixtures on solid catalysts. It includes the description of the main types of metal oxide catalysts, of their various preparation procedures and of the main reactions catalysed by them (acid-base type, selective and total oxidations, bi-functional catalysis, photocatalysis, biomass treatments, environmental catalysis and some of the numerous industrial applications). Challenges and prospectives are also discussed.