溫度對棲狀褐茸藻生長與孢子囊生成之影響

Abstract

本研究藉由調控培養溫度來減少棲狀褐茸藻Hincksia mitchelliae的孢子囊生成，以避免採收藻體時，孢子及小苗被過濾掉的損失。基於棲狀褐茸藻於野外的生長季節，主要為冬、春兩季，因而設定三個溫度，18℃、23℃與28℃，進行棲狀褐茸藻的培養試驗。在溫度對棲狀褐茸藻孢子囊生成影響的實驗中，隨著培養溫度的上升，棲狀褐茸藻的孢子囊生成明顯地增加，並在第七天時，18℃, 23℃與28℃處理組的孢子囊生成量分別為0個/mL, 3個/mL與39個/mL。在溫度對其生物量影響的實驗中，發現經過一週的培養後，28℃處理組的生長速率低於18℃處理組，且於第三十八天收成時，兩者在每單位體積培養液中能採收到藻體的重量有顯著差異。而在藻褐素含量方面，28℃處理組則明顯低於18℃處理組，兩者分別為4.80±0.79mg/g與9.02±0.42mg/g。表示低溫培養有利於棲狀褐茸藻維持一定之生長速率與藻褐素含量。此結果顯示環境溫度上升，藻體生長會受到抑制，轉而刺激孢子囊的形成與孢子的釋出，推測溫度上升為一種逆境，使得藻類傾向有性繁殖。

Lab cultures of Hincksia mitchelliae were studied for the temperature effects on the sporangia formation in order to avoid spores and juveniles lost during algae harvest. The growth seasons of H. mitchelliae in field were reported from winter to spring. Thus, three different temperatures, 18℃, 23℃ and 28℃ were set to test the growth of H. mitchelliae. Formation of sporangia in H. mitchelliae culture was significantly enhanced by temperature raising . At 7th day, the sporangia formation observed at 18℃, 23℃ and 28℃ treatment was 0, 3 and 39 sporangia per mL, respectively. Comparing the growth between 28℃ and 18℃ treatment, it was observed lower temperature had higher growth rate, and thus there was significant difference in biomass between the two temperature treatments after 38 days. It was also noticed that the content of fucoxanthin was dramatically higher at 18℃ than that at 28℃, 9.02 mg/g and 4.80 mg/g, respectively. Accordingly all data pointed out lower temperature seemed to prefer for the growth and fucoxanthin content in H. mitchelliae culture. Sporangia formation and spore releasing are speculated to trigger by the stress of higher temperature for sexual reproduction.