The influence of day length on circadian rhythms of Neochloris oleoabundans

In this study the influence of day length on circadian rhythms of N. oleoabundans was investigated. N. oleoabundans was grown in a photobioreactor continuously operated (turbidostat), under various day/night (D/N) cycles; 20D4N, 16D8N and 12D12N. The following variables showed to be regulated by the circadian clock: maximum growth rate, start of starch synthesis and DNA replication to 4 and 8 copies. Timing of these processes was not influenced by day length. The length of the photoperiod caused changes in biomass composition, especially due to variations in starch content. In longer days, more starch was accumulated. Starch was used for cell division probably also when cell division occurred in the light. Therefore, also the timing of cell division should be considered in the production of microalgae biomass. This timing mechanism can be explored to produce biomass with a desired concentration of protein, lipids, carbohydrates or pigments.