High-density growth and crude protein productivity of a thermotolerant Chlorella vulgaris: production kinetics and thermodynamics

Abstract

Current study investigated the fermentative production of cell mass and crude protein using an axenic culture of the thermotolerant strain of Chlorella vulgaris grown mixotrophically in an illuminated 10-l glass bioreactor. The process was then upscaled to 1,000-l bioreactor. The organism supported maximum specific growth rate, crude protein volumetric productivity, and specific productivity of 1.2 day−1, 2.26 g l−1 day−1, and 0.76 g g−1 day−1, respectively, with urea as nitrogen source. Gibbs free energy, enthalpy, and entropy values for its formation were 74.3, 56. 2 kJ mol−1, and −59.1 J mol−1 K−1, respectively, in both reactors and corresponded to those of thermotolerant organisms. Algal biomass grown in 10-l bioreactor contained 0.52 ± 0.03, 12.6 ± 2.0, 60.0 ± 4.5, 0.4 ± 0.02, 4.5 ± 0.2, 12 ± 0.5, and 3.81 ± 0.5% carotenoids, carbohydrates, crude protein, DNA, RNA, lipids, and total chlorophyll, respectively. Dry biomass supported good growth of fish larvae comparable with that on commercial diet.