The stress response is a metabolic program activated in response to unfavorable environmental factors. Various mechanisms are involved in its activation, depending on the type of stress factor and on the metabolic characteristics of the micro-organism. The stress response mechanisms occurring in bacteria are the general stress response, the stringent response, the oxidative stress response, the TA system, and QS, which is a mechanism of response to population cell density. The end result of the activation of this program, which is resistance to the same stress factor or cross-resistance (i.e. resistance to other types of stress factors), depends on the interaction at various levels between different stress response mechanisms. The phenomenon of resistance is particularly important in the case of soil bacteria, which is often exposed to both natural and anthropogenic stress factors. The stress response determines such diverse microbial functions as survival in periods of starvation, adaptation to the presence of antibiotics, synthesis of antibiotic substances, interactions with a eukaryotic symbiont, and atmospheric oxygen fixation. At the ecosystem level, it helps to maintain climax conditions, i.e. a quantitatively and qualitatively stabilized community of micro-organisms in a given environment, which affects the biological activity of the soil.