Assimilation of inorganic nitrogen for scaling up Desmodesmus communis (Scenedesmaceae) biomass production.

The feasibility of the green alga Desmodesmus communis for biomass production was investigated, firstly testing different nitrogen forms in the growth medium and the effect of CO2-enriched air supply, secondarily scaling up the cultivation system in 70 L photobioreactors (PBRs). Maximum nitrogen uptake rate obtained in the performed kinetic experiment was higher for ammonium than for nitrate (188.0 vs 11.7 μmol g−1 h−1); however, D. communis cultured in PBRs with only aeration grew faster with nitrate reaching a biomass yield (1.23 g L−1) and a productivity (0.036 g L−1 day−1) about twofold higher than with ammonium, which caused a pH decrease in the medium affecting the algal growth. CO2 supply allowed algal growth optimization, maintaining a high productivity with both nitrogen sources, slightly higher with nitrate (0.050 vs 0.038 g L−1 ay−1). Additionally, nitrate-supplied cells showed higher lipids (19.0 vs 9.4%) and proteins (33.0 vs 27.2%) values than those grown with ammonium. The semi-continuous scaled-up cultivation performed for 5 months attests the potential utilization of this species for valuable algal biomass production exploitable in various industrial applications.