Title: Effects of different light intensities on growth and biochemical composition of Nitzschia closterium f. minutissima and Isochrysis galbana Parke 8701
Abstract: Two marine microalgae Nitzschia closterium f. minutissima (MACC/B228) and Isochrysis galbana Parke 8701 (MACC/H060), both isolated from the sea area near Qingdao, were cultured at four irradiance levels( 20, 70, 140, and 260 μmol·s~(-1)·m~(-2)), and harvested in the exponential, late exponential and stationary growth phases. The effects of irradiance level on cell division rate (μ )and the influence of light intensity and growth phase on the gross biochemical composition, with emphasis on the total lipid and carbohydrate, were examined. N. closterium f. minutissima had the highest μ at the light intensity of 70 μmol·s~(-1)·m~(-2) and its optimum light intensity is 70-140 μmol·s~(-1)·m~(-2). At the intensity of 260 μmol·s~(-1)·m~(-2), the comparative slow cell division and shorter exponential growth phase were caused. I. galbana Parke 8701 had the highest μ at 140 μmol·s~(-1)·m~(-2), and it could reach a very high cell density even at 260 μmol·s~(-1)·m~(-2), though that was near its photoinhibiting light intensity when μ slightly decreased. Both of the microalgae had more lipid and less carbohydrate at lower irradiance, while contained less lipid and more carbohydrate at higher irradiance. Carbohydrate accumulated in the stationary growth phase and its content increased with the increasing light intensity regardless of the growth phase. The highest lipid contents of N. closterium f. minutissima and I. galbana Parke 8701 were found at the exponential phase at 70 μmol·s~(-1)·m~(-2) and at the late exponential phase at 20 μmol·s~(-1)·m~(-2), respectively. The highest carbohydrate contents of these two microalga were found at stationary phase at 140 μmol·s~(-1)·m~(-2). Both of them could reach a higher value of biomass at stationary phase at 140 μmol·s~(-1)·m~(-2). Under the same condition, their cellular lipid and carbohydrate were also in higher level.
Publication Year: 2004
Publication Date: 2004-01-01
Language: en
Type: article
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Cited By Count: 2
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