变形虫Naegleria sp.TH8的分离鉴定及食藻特性

从太湖水样品中筛选分离到一株能吞噬水华鱼腥藻的原生动物TH8,经形态学及ITS rRNA序列分析鉴定为纳氏属变形虫(Naegleria sp.).显微观察显示变形虫TH8呈蛞蝓状,用透明半球形单伪足爆破前进,有运动滋养体、包囊和鞭毛体3个形态.变形虫TH8能在10~30℃生长并具有食藻活性,但在37℃或灭菌后的水华鱼腥藻中均不能生长.在新鲜水华鱼腥藻中25℃下指数期生长速率达到1.68 cell d-1.食藻特性研究表明,该变形虫在水华鱼腥藻生长的对数初期、对数后期和稳定期的吞食效果优于对数中期.水华鱼腥藻Chl a下降程度与变形虫初始浓度有关.

Identi fication and Herbivory Characteristics of Naegleria sp. TH8

A protozoan TH8,which can graze Anabaena flos-aquae,was isolated from the water samples of the Taihu Lake.It was identified as Naegleria sp.through morphology and ITS rRNA sequence analysis.Under microscopy,the amoeba TH8 was slug-like,burst forward with a transparent hemispherical single pseudopodia,and had three forms of active feeding,dormant cyst and transient flagellate.TH8 grew well under condition from 10 ℃ to 30 ℃ preying the fresh A.flos-aquae,but not at 37 ℃ or in autoclaved A.flos-aquae.The growth rate of TH8 in exponential phase could reach 1.68 cell d-1 at 25 ℃.Moreover,TH8 showed better prey effect in exponential initial stage,later stage and stationary phase of A.flos-aquae than in exponential medium-term.Initial concentration of the amoeba TH8 had significant influence on elimination of A.flos-aquae.