Use of FT-IR to Identify Enhanced Biomass Production and Biochemical Pool Shifts in the Marine Microalgae, Chlorella ovalis, Cultured in Media Composed of Different Ratios of Deep Seawater and Fermented Animal Wastewater

Abstract

Growth rates, photosystem II photosynthesis, and the levels of chlorophyll a and secondary metabolites of Chlorella ovalis were estimated to determine if they were enhanced by the addition of swine urine (BM) or cow compost water (EP) that had been fermented by soil bacteria to deep seawater (DSW) in an attempt to develop media that enabled batch mass culture at lower costs. Growth of C. ovalis in f/2, f/2-EDTA+BM60%, DSW+BM30%, and DSW+EP60% was enhanced and maintained in the log phase of growth for 16 days. The cell densities of C. ovalis in DSW+EP60% (4.1x10(6) Cells/ml) were higher than those of f/2 (2.9x10(6) Cells/ml), f/2-E+BM60% (3.7x10(6) Cells/ml), and DSW+BM30% (2.7x10(6) Cells/ml). The growth rate was also more favorable for C. ovalis cultured in DSW+EP60% (0.15 day(-1)) than that of C. ovalis cultured in the control medium (f/2) (0.12 day(-1)). Furthermore, the chlorophyll a concentration of C. ovalis cultured in DSW+EP60% (4.56 mg/l) was more than 2-fold greater than that of C. ovalis cultured in f/2 (2.35 mg/l). Moreover, the maximal quantum yields of photosystem II at 470 nm (Fv/Fm) were significantly higher in organisms cultured at f/2-E+BM60% (0.53) and DSW+EP60% (0.52) than in the other treatment groups. Finally, Fourier transformation infrared (FT-IR) spectroscopy revealed that C. ovalis grown in DSW+EP60% had more typical peaks and various biochemical pool shifts than those grown in other types of media. Taken together, the results of this study indicate that the use of DSW+EP60% to culture C. ovalis can reduce maintenance expenses and promote higher yields.