For ecosystems to remain stable, functional, and resilient, microbial reactions to changes in nutrient supply are crucial. A mix of ecological, evolutionary, and physiological variables influences these reactions. It is essential to comprehend these dynamics in order to manage ecosystems, particularly when considering pollution, land-use patterns, and environmental change. The proper propagation of microorganisms in the lab and their optimal growth in their natural habitats depend primarily on nutrients, which are essential for microbial growth. Nutrients that provide energy, carbon, and other essential components are needed. Depending on the cellular and metabolic processes of the organism, different nutrients are used to promote growth. All living organisms need the same nutrients, which comprise carbon, nitrogen, sulfur, phosphorus, potassium, magnesium, calcium, oxygen, iron, and other trace elements. Essential nutrients are those that an organism needs in order to function. The availability of specific nutrients dictates organismal growth by controlling and limiting activation of cellular and metabolic pathways necessary for progress. In industrial microbiology, this concept is critical, as microbial growth and production are dictated by proper cellular growth and metabolism. The production of vital components is typically restricted by the availability and concentration of a limiting nutrient. Hence, it is critical to identify the required nutrients and ensure these are given in the culturing of microorganisms. This chapter covers all the aspects referring to nutrient limitation and resource competition, adjustment in microbial metabolic pathways, physiological stress response, microbial community dynamics, microbial adaptation and evolution, and the impact of human activities and environmental changes, referring to pollution, eutrophication, and other agricultural practices.