The bacterium Bacillus subtilis lives in the environmentally diverse soil habitat. Various environmental signals are sensed by the stressosome protein complex. Stimulation of the stressosome modifies its phosphorylation patterns and activates a signalling cascade that lead to protein expression changes. The thesis introduces models to study structural processes and signalling principles of the stressosome. Overall, the thesis enhances our understanding of the SigmaB-mediated general stress response and raises our awareness of the environmental integration of B. subtilis.