Comparison of growth, protein and carotenoid contents of some freshwater microalgae and the effects of urea and cultivation in a photobioreactor with reflective broth circulation guide on Desmodesmus subspicatus LC172266

Eze, Chijioke Nwoye; Ogbonna, Innocent Okonkwo; Aoyagi, Hideki; Ogbonna, James Chukwuma

This study assessed the potential of enhancing carotenoids and protein accumulation by Desmodesmus subspicatus LC172266 by urea supplementation and cultivation in a novel flat plate air-lift photobioreactor with broth circulation guides. Addition of 0.2 g L(−1) urea to BG11 medium significantly increased the cell growth in both flask and photobioreactor cultures. Carotenoid accumulation by D. subspicatus was about 5.7 times (15.5 ± 0.1 mgg cell(−1)) higher in the photobioreactor with reflective broth circulation guide than in the flask culture (2.3 ± 0.1 mgg(−1) cell) and about 46% higher than the carotenoid content obtained in the photobioreactor without broth circulation guide (control).The cell growth rate was about 2 times higher in the photobioreactor with reflective broth circulation guide (0.41 ± 0.005 day(−1)) than in flask culture (0.20 day(−1)), and in the control photobioreactor (0.28 day(−1)).Both the protein contents and biomass concentrations were significantly enhanced by cultivation in the novel photobioreactor. This research has demonstrated that the flat plate air-lift photobioreactor installed with reflective broth circulation guide substantially enhanced carotenoid production by D. subspicatus LC172266.