小球藻品系繁多，生態類型多樣，其中有些種類可以在38°C生長，稱為耐熱性小球藻。在微藻應用開發上，耐熱性小球藻具有生長快、容易培養之優點。本文對五株品系之特性加以比較，其中SAG 211-31分離自德國，SAG 211-32與SAG 211-34來自日本，W-87 與T-89來自台灣。這些藻株的培養不需要生長素，能以尿素作為唯一氮源，可以利用葡萄糖或醋酸作為碳源在黑暗中行異營生長。在含有機碳源下以複分裂迅速繁殖，在適宜的條件下其細胞濃度大約每4小時增加一倍。在黑暗中經長期異營培養仍然含有葉綠素，只是其含量較低，大約為照光下之50%。由於這類小球藻在型態上不易區別，生理特性也很相似，造成鑑定上之困難，故探討以DNA進行鑑定之可行性，實驗結果證明random amplified polymorphic DNA (RAPD)可以作為鑑別不同藻株之方法。

The genus Chlorella comprises species which are wide1y diversified in their physio1ogica1 and eco1ogica1 properties. Among them the species which can grow at 38 °C has been grouped as the thermophi1ic Chlorella. The thermophi1ic green microa1gae have attained great importance not on1y in basic research but a1so in various fie1ds of biotechno1ogy. Properties of 5 thermophi1ic iso1ates, inc1uding SAG 211-31 from Germany, SAG 211-32 and SAG 211-34 from Japan, W-87 and T-89 from Taiwan, were examined. They are ab1e to use urea as so1e nitrogen source and no growth factor is needed for their cu1tivation. They grow rapid1y by mu1tip1e fission (the optica1 density of cu1ture was doub1e within 4 h.) in the presence of g1ucose or acetate. The ce11s contained ch1orophy11 even after 10 days (more than 30 generations) of dark heterotrophic growth. Random amp1ified po1ymorphic DNA (RAPD) reaction was proved to be a feasib1e method for identification or differentiation among thermophi1ic iso1ates.