Abstract: Nostoc flagelliforme is a terrestrial filamentous nitrogen-fixing cyanobacterium that has been used as a health food and herbal medicine by Chinese and other Asian populations over centuries. The commercial source of N. flagelliforme biomss is harvesting from natural aquatic environments. Mass culture of N. flagelliforme in an engineered system is sought but has not been available, due in large to the lack of understanding the growth physiology of the organism under changing environments. In this study, the effect of temperature, nutrients and light intensity on growth and biochemical composition of Nostoc flagelliforme were investigated. The results indicated that growth rate and biochemical composition were influenced by temperature, nutrients and light intensity. Specific growth rates under 25℃ and 45 mmol/(m2×s) were the most rapid than under other conditions. Growth rates in the culture medium lacking N, P and Ca were of significant difference from the control BG11 medium (p<0.05). No obvious growth difference existed between Medium lacking K, lacking micronutrient As and the control medium. Content of exopolysaccharides (EPS) decreased accompanied with increasing of temperature. Low and high light intensities were helpful to EPS producing. Nutrients starvation was a great disadvantage for algae to produce EPS. Protein content at 25℃ was the highest among all temperature experiments. It increased accompanied with increasing of light intensity but decreased when cultured in the modified BG11 medium (one of nutriment ingredient was deficient). It could be concluded that 25℃ and 45 mmol/(m2×s) were optimal culture conditions and N, P and Ca were necessary for this algal growth.

Key words: culture conditions, specific growth rate, biochemical composition, Nostoc flagelliforme

摘要： 研究了温度、营养和光强对发状念珠藻(Nostoc flagelliforme Born. et Flah.)生长的影响. 结果表明，温度、营养和光强的变化影响其生长速率和细胞的生化组成. 藻细胞在25℃温度与45 μmol/(m2×s)光强下培养分别得到最大比生长速率；而N, P和Ca2+缺乏显著降低细胞的比生长速率，微量元素As和K缺乏对细胞生长速率没有明显影响. 随着培养温度的增加，胞外多糖含量逐渐下降；而不同光强对胞外多糖含量也具有显著影响，高光强和低光强下的多糖含量均高，而15~45 mmol/(m2×s)光强下的胞外多糖含量仅是高光强和低光强实验组的10%~20%左右；营养成份的缺失不利于多糖的合成，缺Ca等对胞外多糖的分泌影响较大. 适宜的生长温度(25℃)下蛋白质含量高于其它温度；高光强[90~180 μmol/(m2×s)]下的蛋白质含量显著高于其它光强；营养成份缺失的实验组蛋白质含量均比未缺失的对照组(BG11)低.

关键词: 培养条件, 比增长速率, 生化成份, 发状念珠藻