碳源与氮源限制下细菌代谢调节研究进展

Metabolic regulation of bacteria with limited carbon and nitrogen sources

摘要:

营养限制是微生物最常面临的环境胁迫之一。除了在营养物质匮乏的海洋、冰川、沙漠、深层地表等自然环境中，越来越多的人工环境也出现了营养限制的特征，例如各类微污染水体、提标改造的废水生物处理系统等。基质浓度极大地影响着包括细菌在内的许多微生物的生长、代谢及群落结构，最终导致其功能的改变。为了在营养限制条件下维持生存，微生物首先需感知营养供给的减少，其后通过基因、蛋白质、信号分子、代谢产物等对各代谢过程进行全局调控，最后改变基质亲和力、生长速率、运动能力、形态等以适应营养不足。胞内各种信号物质及其触发的响应是微生物应对营养胁迫的关键。本文分别梳理了以细菌为代表的微生物应对碳源、氮源限制时的关键信号物质、受体蛋白/调控过程及响应结果，并分析了碳氮限制响应过程中的相互作用，以期为极端环境微生物的认识、营养限制条件下微生物的应用，尤其是低浓度污染物生物处理、生物监测等领域提供理论基础。

关键词:碳源限制;氮源限制;代谢调控;环腺苷酸(cAMP);严紧反应

Abstract:

Nutritional limitation is one of the common environmental stresses for microorganisms. In addition to natural environments such as oceans, glaciers, deserts, and deep surface severely deficient in nutrients, more and more artificial environments also present the characteristics of nutritional limitations, such as various micro-polluted water bodies and wastewater biological treatment systems with stricter discharge standards. Substrate concentration greatly affects the growth, metabolism, and community structure of microorganisms including bacteria, and eventually leads to changes in their functions. In order to survive with limited nutrients, microorganisms first need to perceive the reduction of nutrient supply, then regulate metabolic processes globally via genes, proteins, signal molecules, and metabolites, and finally change substrate affinity, growth rate, motility, and morphology to adapt to malnutrition. Intracellular signaling molecules and the responses triggered by them are the key for microorganisms to deal with nutritional stress. We sorted out the essential signal products, receptor proteins/regulation process and response results of microorganisms represented by bacteria when dealing with carbon and nitrogen source limitation, and then analyzed the interaction of carbon and nitrogen limitations in the response process. This review provides a theoretical basis for the cognition of microorganisms in extreme environments and the application of microorganisms under nutrient limitations, especially in the biological treatment of low-concentration pollutants and biological monitoring.

Key words:carbon limitation;nitrogen limitation;metabolic regulation;cyclic adenosine monophosphate (cAMP);stringent response