Institute of Biopharmaceuticals, Taizhou University, 1139 Shifu Avenue, Taizhou, 318000, China.
School of Pharmaceutical Sciences, Taizhou University, 1139 Shifu Avenue, Taizhou, 318000, China.
Arch Microbiol. 2023 Aug 5;205(9):300. doi: 10.1007/s00203-023-03640-7.
Symbiotic nitrogen fixation (SNF) by rhizobium, a Gram-negative soil bacterium, is an essential component in the nitrogen cycle and is a sustainable green way to maintain soil fertility without chemical energy consumption. SNF, which results from the processes of nodulation, rhizobial infection, bacteroid differentiation and nitrogen-fixing reaction, requires the expression of various genes from both symbionts with adaptation to the changing environment. To achieve successful nitrogen fixation, rhizobia and their hosts cooperate closely for precise regulation of symbiotic genes, metabolic processes and internal environment homeostasis. Many researches have progressed to reveal the ample information about regulatory aspects of SNF during recent decades, but the major bottlenecks regarding improvement of nitrogen-fixing efficiency has proven to be complex. In this mini-review, we summarize recent advances that have contributed to understanding the rhizobial regulatory aspects that determine SNF efficiency, focusing on the coordinated regulatory mechanism of symbiotic genes, oxygen, carbon metabolism, amino acid metabolism, combined nitrogen, non-coding RNAs and internal environment homeostasis. Unraveling regulatory determinants of SNF in the nitrogen-fixing protagonist rhizobium is expected to promote an improvement of nitrogen-fixing efficiency in crop production.
根瘤菌共生固氮（SNF）是一种革兰氏阴性土壤细菌，它是氮循环的一个重要组成部分，是一种可持续的绿色方式，可以在不消耗化学能量的情况下维持土壤肥力。SNF 是由结瘤、根瘤菌感染、类菌体分化和固氮反应等过程产生的，需要共生体中各种基因的表达，以适应不断变化的环境。为了实现成功的固氮，根瘤菌与其宿主密切合作，对共生基因、代谢过程和内部环境稳态进行精确调节。在过去几十年中，许多研究已经取得了进展，揭示了大量关于 SNF 调控方面的信息，但提高固氮效率的主要瓶颈被证明是复杂的。在这篇小型综述中，我们总结了最近的进展，这些进展有助于理解决定 SNF 效率的根瘤菌调控方面，重点是共生基因、氧、碳代谢、氨基酸代谢、结合氮、非编码 RNA 和内部环境稳态的协调调控机制。揭示固氮主角根瘤菌中 SNF 的调控决定因素，有望促进作物生产中固氮效率的提高。
