The photosynthetic performance and carbon fixation efficiency of thermophilic cyanobacteria Thermosynechococcus sp. under various carbon dioxide concentrations

碩士 === 國立彰化師範大學 === 生物學系 === 100 === Abstract Global warming is one of the most urgent problems that must be solved immediately by human society. Artificial carbon dioxide is regarded as the most primary greenhouse gases that cause climate change. However, the biological carbon sequestration must b...

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Bibliographic Details
Main Authors: Yi-Ming Chen, 陳以銘
Other Authors: Wei-Lung Wang
Format: Others
Language:en_US
Published: 2012
Online Access:http://ndltd.ncl.edu.tw/handle/49992922829555148777
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Summary:碩士 === 國立彰化師範大學 === 生物學系 === 100 === Abstract Global warming is one of the most urgent problems that must be solved immediately by human society. Artificial carbon dioxide is regarded as the most primary greenhouse gases that cause climate change. However, the biological carbon sequestration must be found out a species could tolerate of high CO2 level, high temperature and have high carbon mitigation ability. Therefore, the microalgae used in this study are thermophilic cyanobacteria Thermosynechococcus sp., isolated from hot spring. Determining its CO2 tolerance, growth rate, photosynthetic performance and carbon fixation efficiency under various CO2 levels. The results showed that the growth of Thermosynechococcus sp. cultured under initial pH 7.5 were increased from ambient air bubbling to 5% CO2. In contrast, a higher maximum biomass and productivity were 0.35 g DW L-1 and 0.036 g L-1d-1 could be obtained at 5% CO2, the growth was inhibited under 10% CO2 due to pH of the cultured medium was decreased to 5.6 by high CO2 level. However, the initial pH was raised to 11 to solve the low pH inhibition problems, the photosynthetic parameters Fv/Fm and rETRmax of Thermosynechococcus sp. cultured under 20% CO2 were 0.32 and 66 μmol electrons m−2s−1, respectively. In addition, Thermosynechococcus sp. exposed to a monochromatic LED source of red light resulted in a better growth than blue, green or mixed light, and which had the best biomass productivity of 0.017 g L-1d-1. Finally, the analysis of the efficiency of carbon sequestration found out a great performance of CO2 biofixation by Thermosynechococcus sp., there are highly CO2 fixation rate of 0.079 g CO2 L-1d-1 cultured under light intensity 100 μmol m-2s-1 with fluorescent lamps, photoperiod 12:12 h (light / dark), 55 °C, pH 11, 15% CO2, gas flow rate of 0.25 vvm and initial algal concentration of 0.1g / L, and also achieved optimal annual CO2 fixation rate of 28.79 kg CO2/ton/year.