加拿大滑铁卢大学J. D. Neufeld等研究人员合作发现，Chloroflexota的不产氧光养生物使用I型反应中心。相关论文于2024年3月13日在线发表在《自然》杂志上。

通过北盾湖湖水培养，研究人员培养出了一种来自Chloroflexota里一个未知目中的不产氧光养细菌，它代表了光合作用演化过程中的一种高度新颖的过渡形式。与所有其他已知的光养细菌不同，这种细菌使用I型反应中心（RCI）进行光能转换，但与使用II型反应中心（RCII）进行光养的生物属于同一细菌门。利用生理学、系统发生组学和环境元转录组学数据，研究人员证明了该菌株在利用叶绿体和细菌叶绿素进行新陈代谢的同时，还积极利用了RCI。

尽管使用不同的反应中心，但系统发生组数据提供了强有力的证据，证明利用RCI和利用RCII的Chloroflexota成员从最近的共同光养祖先那里继承了光养。Chloroflexota保留了基因相关细菌使用不同光养模式的演化记录，为探索地球上光养的多样化提供了新的背景。

研究人员表示，近200年来对光养细菌的科学探索发现，已知光养菌群之间存在巨大的系统发育差距，这限制了人们对光养菌如何演化和多样化的了解。

附：英文原文

Title: Anoxygenic phototroph of the Chloroflexota uses a type I reaction centre

Author: Tsuji, J. M., Shaw, N. A., Nagashima, S., Venkiteswaran, J. J., Schiff, S. L., Watanabe, T., Fukui, M., Hanada, S., Tank, M., Neufeld, J. D.

Issue&Volume: 2024-03-13

Abstract: Scientific exploration of phototrophic bacteria over nearly 200 years has revealed large phylogenetic gaps between known phototrophic groups that limit understanding of how phototrophy evolved and diversified1,2. Here, through Boreal Shield lake water incubations, we cultivated an anoxygenic phototrophic bacterium from a previously unknown order within the Chloroflexota phylum that represents a highly novel transition form in the evolution of photosynthesis. Unlike all other known phototrophs, this bacterium uses a type I reaction centre (RCI) for light energy conversion yet belongs to the same bacterial phylum as organisms that use a type II reaction centre (RCII) for phototrophy. Using physiological, phylogenomic and environmental metatranscriptomic data, we demonstrate active RCI-utilizing metabolism by the strain alongside usage of chlorosomes3 and bacteriochlorophylls4 related to those of RCII-utilizing Chloroflexota members. Despite using different reaction centres, our phylogenomic data provide strong evidence that RCI-utilizing and RCII-utilizing Chloroflexia members inherited phototrophy from a most recent common phototrophic ancestor. The Chloroflexota phylum preserves an evolutionary record of the use of contrasting phototrophic modes among genetically related bacteria, giving new context for exploring the diversification of phototrophy on Earth.

DOI: 10.1038/s41586-024-07180-y

Source: https://www.nature.com/articles/s41586-024-07180-y