Hsueh H T, Li W J, Chen H H, Chu H
Department of Environmental Engineering and Sustained Environmental Research Center, National Cheng Kung University, Tainan 701, Taiwan, ROC.
J Photochem Photobiol B. 2009 Apr 2;95(1):33-9. doi: 10.1016/j.jphotobiol.2008.11.010. Epub 2008 Dec 3.
There is a great potential to assimilate CO(2) and produce bio-energy from cellular component by utilizing carbon fixation of photosynthetic microorganisms. Two different types of photosynthetic microorganisms were used in the present study. The strain Thermosynechococcus sp. CL-1 (TCL-1) was previously isolated from a hot spring while Nannochloropsis sp.Oculta (NAO) from sea water. Two types of inorganic carbon were used (gaseous CO(2) and dissolved inorganic carbon, DIC) with nitrate as N source under different temperature conditions. The Monod model was used to relate its growth rate and DIC concentration. Additionally, lipid and carbohydrate of cell component, which can be used as bio-energy precursors, as function of CO(2) and DIC concentrations is quantified. The growth rate of TCL-1 decreased as CO(2) concentrations increased from 10% to 40% due to low pH inhibition with the maximum value 2.7 d(-1) at 10% CO(2). As for NAO, the maximum growth rate of about 1.6 d(-1) was obtained at 5% and 8% CO(2) (pH between 5.5 and 7 at 30 degrees C). Regarding the cultivation of TCL-1 under various DIC concentrations, the maximum growth rate of TCL-1 was 3.5 d(-1) at the initial DIC 94.3 mM, pH 9.5 and 50 degrees C. The carbohydrate content of TCL-1 increased from 2.1% to 33% as DIC concentration increased from 4.7 to 94.3 mM. However, the 33% carbohydrate content at 94.3 mM DIC was much less than 61% at 10% CO(2). That may be due to the fact that the cultivation at 94.3 mM DIC can not supply adequate amounts of DIC to produce carbohydrate under N-limiting conditions. Conversely, enough amounts of DIC supplied from washing flue gas for cultivating TCL-1 would provide a higher performance of carbon bio-fixation and carbohydrate production.
利用光合微生物的碳固定作用来同化二氧化碳并从细胞成分中生产生物能源具有巨大潜力。本研究使用了两种不同类型的光合微生物。嗜热栖热菌菌株CL-1（TCL-1）先前是从温泉中分离出来的，而隐甲藻（NAO）则是从海水中分离出来的。在不同温度条件下，使用了两种无机碳（气态二氧化碳和溶解无机碳，DIC）并以硝酸盐作为氮源。采用莫诺德模型来关联其生长速率和DIC浓度。此外，还对可作为生物能源前体的细胞成分中的脂质和碳水化合物作为二氧化碳和DIC浓度的函数进行了定量分析。由于低pH抑制作用，当二氧化碳浓度从10%增加到40%时，TCL-1的生长速率下降，在10%二氧化碳时最大值为2.7 d⁻¹。至于NAO，在5%和8%二氧化碳（30℃时pH在5.5至7之间）时获得了约1.6 d⁻¹的最大生长速率。关于在各种DIC浓度下培养TCL-1，在初始DIC为94.3 mM、pH为9.5和50℃时，TCL-1的最大生长速率为3.5 d⁻¹。随着DIC浓度从4.7 mM增加到94.3 mM，TCL-1的碳水化合物含量从2.1%增加到33%。然而，94.3 mM DIC时33%的碳水化合物含量远低于10%二氧化碳时的61%。这可能是因为在94.3 mM DIC下培养在氮限制条件下不能提供足够量的DIC来生产碳水化合物。相反，从洗涤烟道气中供应足够量的DIC用于培养TCL-1将提供更高的碳生物固定和碳水化合物生产性能。
