<p>This study investigated the influence of various treatments on the autofluorescence properties of <i>Bacillus subtilis</i>. Our results demonstrate that autofluorescence is not a static property but is significantly modulated by environmental and nutritional factors. Glucose limitation markedly reduced autofluorescence, highlighting its crucial role in maintaining cellular components involved in fluorescence. Environmental stressors exerted diverse effects: oxidative stress induced by hydrogen peroxide altered fluorescence patterns, while ethanol exposure enhanced fluorescence intensity. Heat and cold stress induced subtle changes, suggesting a degree of bacterial resilience. Lysis methods, such as autoclaving and sonication, significantly impacted fluorescence intensity and spectral profiles, revealing insights into the cellular localization and nature of fluorophores. Microscopy analysis confirmed the presence of wavelength-specific autofluorescence in <i>Bacillus subtilis</i>. These findings underscore the sensitivity of bacterial autofluorescence to cellular and environmental perturbations and highlight its potential as a valuable tool for monitoring bacterial health and stress responses.</p>