Nannochloropsis sp. is a promising microalgal resource for production of food, feed and bio-based commodities, as it can grow relatively fast and combines high lipid content with high content of poly-unsaturated fatty acids.
High productivity with constant product quality can be achieved in fully controlled closed photobioreactors. In these closed photobioreactors, however, oxygen accumulation occurs and causes inhibition of the growth by photorespiration combined with photoinhibition.
Degassing crucial to achieve high algal productivity
The inhibitory effects of photorespiration and photoinhibition can be partly dealt with via the carbon concentration mechanism of the cells and by activation of the water-water cycle. At constant high oxygen concentration and high light intensity, however, the growth of the cells ceases. To our surprise, the accumulating oxygen did not affect the growth rate of the algae if the oxygen was removed regularly. In large scale production in closed photobioreactors, it is thus crucial apply degassing to achieve high algal productivity.