Light-limited microalgal growth: a comparison of modelling approaches

Microalgal growth models aim to predict growth rate as well as cellular composition, given the environmental conditions (such as temperature, nutrient availability, light, etc.). This generic purpose poses strong requirements to the structure of any model attempting to comply with it. First, cellular characteristics should be modelled, rather than taken as model input. Second, if one interprets ‘cellular composition’ as nutrient cell quota, rather than as nutrient ratios, models should be formulated at the level of the individual cell. Third, modelling should proceed by making assumptions about processes, rather than about states. This paper evaluates current modelling methodology in the light of these desiderata. The models examined mostly (but not exclusively) monospecific cultures in laboratory environments. Whereas the older models are inadequate in view of the generic purpose, recent models increasingly focus on cellular composition and on the processes that lead to changes in cellular composition. Models to be developed in the next few years thus have the potential to fulfil the generic purpose.