The Bacillus subtilis circadian clock: from molecules to mutualism

Circadian clocks are biological timekeepers. They structure processes - from molecular pathways to behavioural attributes - over the 24h day. They are pervasive in eukaryotes yet remain almost completely unknown in bacteria. We propose to address this major knowledge gap by capitalising on our recent breakthrough discovery of a circadian clock in Bacillus subtilis. Our unpublished data reveal that robustness of the B. subtilis circadian clock increases when co-cultured with either the plant Arabidopsis, or the yeast Saccharomyces cerevisiae. We propose that the mutualistic interactions between microbes and other organisms in their environment utilise circadian clocks, allowing us to propose the new concept of “temporal mutualism”. Within this project, we will identify and understand the molecular structure and function of the B. subtilis circadian clock (WP1), which will be the first detailed characterisation of a circadian clock in a non-photosynthetic bacterium. We will exploit the interactions that occur between B. subtilis and plant circadian clocks to define this new concept of temporal mutualism (WP2 and 3). Co-culture of B. subtilis with S. cerevisiae will identify regulatory nodes that are common to plant/bacterium and fungus/bacterium temporal mutualism (WP3). We will probe the novel hypothesis that biofilm enables intra-species temporal mutualism via differentiated cell populations within the matrix-bound structure (WP3). We will use circadian formalisms (behaviour), molecular systems analysis and state of the art technological approaches (e.g., combinations of microfluidics, microscopy, reporter gene technology and optogenetics), which is only possible through our interdisciplinary collaboration. This work will drive a paradigm shift, to open a completely new field that will change current thinking by bridging chronobiology with microbiology and ecology.