A multiscale model approach for cell growth for lipids and pigments production by Haematococcus pluvialis under different environmental conditions.

The development of new technologies is essential to contrast the increasing global CO2 emissions. Microalgae-based biorefineries present a promising tool to reduce the presence of CO2 in our emissions (Bekirogullari et al 2018, Bekirogullari et al 2017). The development of processes for the simultaneous production of more than one product are essential to increase the possibility of making such biorefineries profitable (Garcia Prieto, Ramos, Estrada, Villar, & Diaz, 2017). Microalgae eukaryotic cells are able to produce pigments and lipids. The production of lipids and pigments could vary depending on the environmental stress conditions such as light intensity, nutrients concentration, medium salinity, and temperature (D'Alessandro & Antoniosi Filho, 2016). Haematococcus pluvialis produces lutein, beta-carotene, and lipids during growth, which makes it a potential candidate for the simultaneous production of high value products. H.pluvialis' division pattern ranges from the formation of two daughters up to 32 cells by multiple-fission (Shah, Liang, Cheng, & Daroch, 2016). New born cells achieve after a dimensional growth step a critical size point, where after that, they are able to keep growing and reproduce without any further input in the system, this point is called commitment point (CP). The achievement of an higher number of CP lead to a higher number of cells in the day/night cycle (Bisova & Zachleder, 2014). The above phenomena reaching one commitment point are described using a population balance model (PBM), in order to evaluate the influence of some environmental conditions on the cell growth. The model was fitted against synchronized experimental data, and then tested on a long duration experiment.