Process engineering strategy for high cell density-lipid rich cultivation of Chlorella sp FC2 IITG via model guided feeding recipe and substrate driven pH control

A novel process engineering strategy was demonstrated for high cell density lipid rich cultivation of Chlorella sp. FC2 IITG under heterotrophic condition. The strategy involves identification of growth promoting and/or lipid inducing substrates, model guided nutrient feeding recipe coupled with substrate driven pH control for high biomass titer and lipid enrichment via addition of selected lipid inducer. Strain characterization under various carbon sources resulted in glucose as growth promoter and sodium acetate as lipid inducer. Further, 49% improved biomass titer was achieved by media optimization as compared to the unoptimized media. Fed-batch with utilization profile based substrate feeding and HCl based pH control resulted in a biomass titer of 28.2 g L-1. Subsequent increase in biomass titer up to 48.3 g L-1 was achieved via model guided substrate feeding recipe and HCl based pH control. Finally, two phase fed-batch fermentation was demonstrated: (i) growth phase, where high cell density was achieved through model guided substrate feeding recipe coupled with substrate (nitric acid) driven pH control and (ii) lipid enrichment phase via addition of sodium acetate. This strategy resulted in biomass titer of 90.15 g L-1 with biomass and lipid productivity 19.75 g L-1 day(-1) and 7.7 g L-1 day(-1) respectively. (C) 2016 Elsevier B.V. All rights reserved.