Fitness Regulation by Timing Systems: Insight from Cyanobacteria and Purple Non-sulfur Bacteria

Abstract

Circadian clocks are the endogenous timing mechanisms that facilitate organisms to adapt to the daily cycles on the earth. Previous studies have demonstrated that cyanobacterial circadian clock enhances fitness under cyclic environment. In this dissertation, the adaptive value of circadian clocks were further confirmed in cyanobacteria under various culture conditions, and the potential mechanism of the clock-mediated fitness enhancement was explored. By establishing the global metabolic profiles of cyanobacterial strains, I found that the metabolism of cyanobacteria can be affected by the disruption of circadian clocks, which could be the potential mechanism of the clock-mediated fitness enhancement. In addition, a novel timing mechanism driven by kaiCRp, which is a homolog of cyanobacterial central clock gene kaiC, was discovered in a purple non-sulfur bacterium, and this timing mechanism also enhances fitness under light-dark cycles.