Abstract

Co-authors: Hiroyuki Okano (UC San Diego), Rutger Hermsen (Utrecht University), Conghui You (UC San Diego)

When bacteria are cultured in medium with multiple carbon substrates, some substrate combinations are consumed simultaneously while other combinations are consumed sequentially. Understanding and manipulating the order of carbon utilization is crucial in characterizing trophism in complex ecosystems such as the gut microbiota, and in optimizing synthetic biology applications such as the breakdown of cellulose for biofuel production. Building on recent advances in the understanding of metabolic coordination exhibited by Escherichia coli cells through cAMP-Crp signaling, we show that this signaling system alone gives rise to simultaneous utilization, and derive an algebraic formula describing the resulting growth rate, based only on the growth rates on individual substrates. For substrate combinations that are utilized hierarchically, we reveal a simple regulatory strategy by which the hierarchy is ordered roughly by the rate of growth on single substrates.