環境因子 對聚球藻RF-1光合作用的影響

Effect s of environmental factors on the photosynthesis of Synechococcus RF-1

林玫君(Mei-June Lin)

指導教授 ： 周雪美博士

國立臺灣師範大學/理學院/生物學系/碩士(2001年)

摘要

本研究是以台灣產的單細胞固氮藍綠菌-聚球藻RF-1(Synechococcus RF-1)為實驗材料，探討其光合作用的概日韻律、比較光合作用和膜蛋白COP23之概日韻律的差異性、及環境因子例如：溫度、光照強度和pH值等對聚球藻RF-1光合作用的影響。聚球藻RF-1之光合作用的釋氧速率具有概日韻律特性，經由12小時白光/12小時黑暗(12L/12D)或12小時紅光/12小時黑暗(12R/12D)馴化後，可建立其韻律，但12小時藍光/12小時黑暗(12B/12D)則否；紅光/黑暗馴化過程，若受遠紅光干擾，則會使韻律消失。除此之外，以12小時空氣/12小時含5% CO2之空氣交替通氣也可建立韻律。光合作用和COP23概日韻律具有以下兩點不同，第一是、光合作用和COP23概日韻律的高峰期分別是在光照期與黑暗期；第二是藍光、白光、紅光與黑暗的週期變化，皆可建立COP23之概日韻律。在含氮源培養環境，光合作用釋氧韻律會受到抑制，而且葉綠素a和類胡蘿蔔素的含量以及生長速率會增加。以5% CO2空氣通氣或50-70 mmol photons m-2 s-1光照強度培養時，光合作用速率、生長速率、以及葉綠素a含量均會下降。在pH8的培養環境，最適合光合作用進行和生長，若要在黑暗環境培養聚球藻RF-1，葡萄糖和果糖則是較佳選擇。

關鍵字

聚球藻RF-1 ； 概日韻律 ； 膜蛋白COP23 ； 釋氧速率 ； 馴化

並列摘要

The aim of this study was (1) to identify the circadian rhythm of photosynthesis, (2) to compare the circadian rhythm between photosynthesis and membrane protein COP23 (circadian oscillating polypeptide), and (3) to investigate the effect of environmental factors such as temperature, light intensity, pH value, on the photosynthesis of Synechococcus RF-1, which is an unicellular N2-fixing cyanobacterium isolated at Taiwan. The rate of oxygen evolution in Synechococcus RF-1 exhibited circadian rhythm, which could be established by 12h white light/12h dark (12L/12D) or 12h red light/12h dark (12R/12D) entrainment, but not by 12h blue light/12h dark (12B/12D). The rhythm disappeared if the entrainment of 12R/12D was disturbed by far-red light. In addition, the rhythm could be established by 12h air/12h 5 ﹪CO2 –enriched air conduction as well. There were two different characteristics between photosynthetic and COP23 rhythms. Firstly, the peaks of photosynthetic and COP23 rhythms were in the light and dark periods respectively. Secondly, the rhythm of COP23 could be established by 12B/12D as well as 12L/12D or 12R/12D photoperiods. When Synechococcus RF-1 was cultured in the presence of nitrate, the expression of photosynthetic rhythm established by 12L/12D was inhibited, the content of chlorophyll a and carotenoids and the rate of growth were increased; in the aeration of 5 ﹪CO2 and the irradiation of 50-70 mmol photons m-2 s-1, the rates of photosynthesis and growth, and the content of chlorophyll a declined. The optimal pH for the rates of photosynthesis and growth was pH8. The glucose and the fructose might be used as the carbon source if Synechococcus RF-1 was cultured in the dark.

並列關鍵字

Synechococcus RF-1 ； circadian rhythm ； membrane protein COP23 (circadian oscillating polypeptide) ； rate of oxygen evolution ； entrainment