Abstract
Dissolved oxygen plays a key role in microalgal growth at high density. This effect was so far rarely quantified. Here we propose a new model to represent the combined effect of light, oxygen concentration and temperature (LOT-model) on microalgae growth. The LOT-model introduces oxygen concentration in order to represent the oxidative stress affecting the cultures, adding a toxicity term in the expression of the net growth rate. The model was validated with experimental data for several species such as Chlorella minutissima, Chlorella vulgaris, Dunaliella salina, Isochrysis galbana. It successfully predicted experimental records with an average error lower than 5.5%. The model was also validated using dynamical data where oxygen concentration varies. It highlights a strong impact of oxygen concentration on productivity, depending on temperature. The model quantifies the sensitivity to oxidative stress of different species and shows, for example, that Dunaliella salina is much less affected than Chlorella vulgaris by oxidative stress. The modeling approach can support an optimization strategy to improve productivity, especially for managing high oxygen levels.
Highlights
Dissolved oxygen plays a key role in microalgal growth at high density
For Chlorella minutissima and Isochrysis galbana the fit was carried out with Km = 0.203, reflecting the fact that experiments were performed at low oxygen concentrations and with limited oxygen stress
The LOT-model proves to accurately fit several experimental data sets at equilibrium or in dynamical conditions with an average error lower than 5.5%
Summary
Dissolved oxygen plays a key role in microalgal growth at high density This effect was so far rarely quantified. We propose a new model to represent the combined effect of light, oxygen concentration and temperature (LOT-model) on microalgae growth. The model was validated with experimental data for several species such as Chlorella minutissima, Chlorella vulgaris, Dunaliella salina, Isochrysis galbana. Microalgae are known for their capacity to produce long chain polyunsaturated fatty acids with positive effects on human health [3]. They can be a source of pigments and antioxidants for the cosmetic, pharmaceutical and food markets. When reaching a critical temperature some proteins start to denature, especially those involved in photosystems and electron transport chain, impacting cell metabolism [7] and eventually inducing cell mortality [8]
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