Chlorella vulgaris as a lipid source: Cultivation on air and seawater-simulating medium in a helicoidal photobioreactor.

Abstract

The freshwater microalga Chlorella vulgaris was cultured batchwise on the seawater-simulating Schlösser medium either in a 1.1-L-working volume helicoidal photobioreactor (HeP) or Erlenmeyer flask (EF) as control and continuously supplying air as CO2 source. In these systems, maximum biomass concentration reached 1.65 ± 0.17 gL(-1) and 1.25 ± 0.06 gL(-1) , and maximum cell productivity 197.6 ± 20.4 mgL(-1) day(-1) and 160.8 ± 12.2 mgL(-1) day(-1) , respectively. Compared to the Bold's Basal medium, commonly employed to cultivate this microorganism on a bench-scale, the Schlösser medium ensured significant increases in all the growth parameters, namely maximum cell concentration (268% in EF and 126% in HeP), maximum biomass productivity (554% in EF and 72% in HeP), average specific growth rate (67% in EF and 42% in HeP), and maximum specific growth rate (233% in EF and 22% in HeP). The lipid fraction of biomass collected at the end of runs was analyzed in terms of both lipid content and fatty acid profile. It was found that the seawater-simulating medium, despite of a 56-63% reduction of the overall biomass lipid content compared to the Bold's Basal one, led in HeP to significant increases in both the glycerides-to-total lipid ratio and polyunsaturated fatty acid content compared to the other conditions taken as an average. These results as a whole suggest that the HeP configuration could be a successful alternative to the present means to cultivate C. vulgaris as a lipid source. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:279-284, 2016.