Effect of Inorganic Micronutrients on Cell Growth and Biochemical Components of Arthrospira maxima

Abstract

Underground seawater from Jeju Island, Korea (i.e. Jeju magma seawater, JMS) has high amounts of inorganic micronutrients as much as 7.5 to 55 times compared with the concentrations of zinc (Z, 0.019 mg/L), iron (F, 0.015 mg/L), manganese (M, 0.008 mg/L), vanadium (V, 0.015 mg/L), selenium (S, 0.013 mg/L) and germanium (G, 0.002 mg/L) in natural seawater. The micronutrients are the essential minerals for photosynthetic metabolism and growth of marine algae. However there is no information on the effect of micronutrients in JMS for marine algae, few studies of land plant cultivation using JMS have been conducted. The purpose of this study was to investigate the effect of inorganic micronutrients of JMS on growth effect of marine blue-green alga, Spirulina maxima. Screening of cell growth of S. maxima was carried out on 10 mL-flask for 14 days and measured by spectrophotometric measurement (λ=664 nm) cultured in 64 modified conventional media mixed with 6 mineral reagents under different concentration regimes referred by JMS concentration. After small scale culture, selected eight combinations of the minerals were then used for 20 L-scale to compare the biochemical differences and scale-up growth performance. In 10 mL-scale cultivation of screening experiment, the highest optical density was recorded in the medium containing combination of M and V (M+V), followed mixed M+Z+V and M+Z+F combinations. In scale-up cultivation, final biomass production and specific growth rate of S. maxima in the media containing single Z and mixed M+Z were significantly higher than other combinations. Protein levels were significantly increased in the experiment of mixed M+Z combination (p<0.05). Photosynthetic pigments of chlorophyll-a and C-phycocyanin were also significantly increased in the experiment of Z and mixed M+Z+V combinations, respectively (p<0.05). These results indicated that M and Z of JMS have significant effects on photosynthesis and cell growth of S. maxima.