The synchronized cell cycle of Neochloris oleoabundans and its influence on biomass composition under constant light conditions

The effect of cell cycle stage on biomass composition of the green microalgae Neochloris oleoabundans was investigated. N. oleoabundans was grown under constant light conditions in a flat panel photobioreactor operated as a turbidostat. Even though light conditions were constant, a synchronized cell division was observed with the cells dividing by multiple fission during the natural night. Presumably, the circadian clock was responsible for 'gating' cell division to this specific time frame. Oscillations in starch, protein and pigment content were observed during the cell cycle. These oscillations could be solely contributed to the cell cycle stage of the synchronized culture, since all experimental conditions were kept constant. A maximum in starch, protein and fatty acid content was obtained just before cell division. Biomass yield was also greatly influenced by the cell cycle and declined to a minimum during cell division. These findings highlight that knowledge of the cell cycle is of importance in microalgae process optimization.