The Bacillus subtilis circadian clock coordinates intricate spatiotemporal organisation

Many organisms have circadian clocks that anticipate the risks and benefits of the predictable 24 h solar cycle. However, the potential functions of circadian clocks in non-photosynthetic bacteria are poorly understood. Here, we show that the Bacillus subtilis circadian clock regulates colony expansion, in concert with key developmental and differentiation pathways that are central to its life cycle. The B. subtilis clock coordinates the spatiotemporal organisation of gene expression within expanding colonies by timing various processes to specific phases (times of day) within distinct colony regions. Our results support the idea that circadian clock-regulation over space, time and colony development in B. subtilis is analogous to circadian regulation of some processes in multicellular eukaryotes such as plants and mammals. The potential functions of circadian clocks in non-photosynthetic bacteria are poorly understood. Here, the authors show that the Bacillus subtilis circadian clock regulates the spatiotemporal organisation of gene expression within expanding colonies, by timing various processes to specific times of day within distinct colony regions.