Production of β-carotene with CCAP19/18 at physically simulated outdoor conditions.

Batch growth and β-carotene production of CCAP19/18 was investigated in flat-plate gas-lift photobioreactors with a light path of 2 cm, operated in physically simulated outdoor conditions. CCAP19/18 showed robust growth with respect to pH 8.0-9.0 and 15-35°C at increasing salinity, simulating the evaporation of open photobioreactors. The highest β-carotene concentration of 25 mg L (3 mg g ) was observed in batch processes at pH 8.5, 15-30°C and increasing salinity up to 110 g L, simulating a typical Mediterranean summer climate. Intracellular β-carotene accumulation of CCAP19/18 was shown to be independent of light availability, although nutrient limitation (KHPO, MgSO, and/or ammonium ferric citrate) seems to enable stable β-carotene content in the algal cells despite increasing cell densities in the photobioreactor. Fully controlled, lab-scale photobioreactors simulating typical climate conditions of any region of interest are valuable tools for enabling a realistic characterization of microalgae on a laboratory scale, for production processes projected in open photobioreactor systems (e.g. thin-layer cascade photobioreactors).