BackgroundDayight cycles regulate the circadian clock of organisms to program daily activities. Many species of microalgae have a synchronized cell division when grown under a dayight cycle, and synchronization might influence biomass yield and composition. Therefore, the aim of this study was to study the influence of dayight cycle on biomass yield and composition of the green microalgae Neochloris oleoabundans . Hence, we compared continuous turbidostat cultures grown under continuous light with cultures grown under simulated dayight cycles. ResultsUnder dayight cycles, cultures were synchronized as cell division was scheduled in the night, whereas under continuous light cell division occurred randomly synchronized cultures were able to use the light 10–15% more efficiently than non-synchronized cultures. Our results indicate that the efficiency of light use varies over the cell cycle and that synchronized cell division provides a fitness benefit to microalgae. Biomass composition under dayight cycles was similar to continuous light, with the exception of starch content. The starch content was higher in cultures under continuous light, most likely because the cells never had to respire starch to cover for maintenance during dark periods. Dayight cycles were provided in a ‘block’ (continuous light intensity during the light period) and in a ‘sine’ (using a sine function to simulate light intensities from sunrise to sunset). There were no differences in biomass yield or composition between these two ways of providing light (in a ‘block’ or in a ‘sine’). ConclusionsThe biomass yield and composition of N. oleoabundans were influenced by dayight cycles. These results are important to better understand the relations between research done under continuous light conditions and with dayight cycle conditions. Our findings also imply that more research should be done under dayight cycles.
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