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.
