<p>Spontaneous biological oscillations are typically attributed to specific architectures within metabolic or gene regulatory networks. Here, we uncover a more general mechanism arising from the interplay between cellular growth, burdensome gene expression, and nutrient availability, which can generate oscillations in both growth and gene expression. Focusing on sporulation dynamics in <i>Bacillus subtilis</i>, we developed a minimal model that captures these coupled processes and analytically identified the range of continuous culture conditions that give rise to oscillatory behavior. These predictions were experimentally validated in chemostat cultures. Our results demonstrate that oscillations can emerge independently of specific genetic circuit architectures, and without external forcing. More broadly, they reveal that feedback between environmental conditions and cellular states is sufficient to drive oscillatory dynamics, suggesting that such behavior may be widespread in long-term cultivation systems where gene expression, growth, and resource availability are tightly coupled.</p>