Liang Fang, Du Kui, Wen Xiaobin, Luo Liming, Geng Yahong, Li Yeguang
Institute of Bioengineering, Zhengzhou Normal University, Zhengzhou 450044, P.R. China.
Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, P.R. China.
J Microbiol Biotechnol. 2015 Dec 28;25(12):2116-24. doi: 10.4014/jmb.1505.05102.
To understand the effects of physicochemical factors on nitrite transformation by microalgae, a lipid-rich Chlorella with high nitrite tolerance was cultured with 8 mmol/l sodium nitrite as sole nitrogen source under different conditions. The results showed that nitrite transformation was mainly dependent on the metabolic activities of algal cells rather than oxidation of nitrite by dissolved oxygen. Light intensity, temperature, pH, NaHCO3 concentrations, and initial cell densities had significant effects on the rate of nitrite transformation. Single-factor experiments revealed that the optimum conditions for nitrite transformation were light intensity: 300 μmol/m(2); temperature: 30°C; pH: 7-8; NaHCO3 concentration: 2.0 g/l; and initial cell density: 0.15 g/l; and the highest nitrite transformation rate of 1.36 mmol/l/d was achieved. There was a positive correlation between nitrite transformation rate and the growth of Chlorella. The relationship between nitrite transformation rate (mg/l/d) and biomass productivity (g/l/d) could be described by the regression equation y = 61.3x (R(2) = 0.9665), meaning that 61.3 mg N element was assimilated by 1.0 g dry biomass on average, which indicated that the nitrite transformation is a process of consuming nitrite as nitrogen source by Chlorella. The results demonstrated that the Chlorella suspension was able to assimilate nitrite efficiently, which implied the feasibility of using flue gas for mass production of Chlorella without preliminary removal of NOX.
为了解理化因素对微藻亚硝酸盐转化的影响，以富含脂质且耐亚硝酸盐能力强的小球藻为研究对象，以8 mmol/L亚硝酸钠作为唯一氮源，在不同条件下进行培养。结果表明，亚硝酸盐的转化主要依赖于藻细胞的代谢活性，而非溶解氧对亚硝酸盐的氧化作用。光照强度、温度、pH值、NaHCO₃浓度和初始细胞密度对亚硝酸盐转化速率有显著影响。单因素实验表明，亚硝酸盐转化的最佳条件为：光照强度300 μmol/m²；温度30℃；pH值7 - 8；NaHCO₃浓度2.0 g/L；初始细胞密度0.15 g/L；此时实现了最高亚硝酸盐转化速率1.36 mmol/L/d。亚硝酸盐转化速率与小球藻生长呈正相关。亚硝酸盐转化速率（mg/L/d）与生物量生产率（g/L/d）之间的关系可用回归方程y = 61.3x（R² = 0.9665）描述，这意味着平均1.0 g干生物量可同化61.3 mg氮元素，表明亚硝酸盐转化是小球藻以亚硝酸盐为氮源的消耗过程。结果表明，小球藻悬浮液能够高效同化亚硝酸盐，这意味着在不预先去除氮氧化物的情况下，利用烟气大规模生产小球藻具有可行性。
