武汉东湖浮游病毒的丰度及多样性

STUDIES ON ABUNDANCE AND MORPHOLOGICAL DIVERSITY OF VIRIOPLANKTON IN THE DONGHU LAKE,WUHAN

运用透射电镜及荧光显微技术 ,对富营养化的武汉东湖中浮游病毒丰度及多样性进行了研究。电镜观察和计数结果显示 ,东湖中浮游病毒的丰度达到 10 8个 /mL。荧光显微镜计数结果约是电镜计数结果的 2 72倍 ,差异极显著 (P <0 0 1)。在东湖超富营养区的水样中观察到了多种与各种病毒形态类似的颗粒 ,其中大部分与噬菌体和噬藻体类似 ,具多种形态的尾部和六边形头部。还有一些线状、杆状、子弹形等形态的病毒粒子。研究结果显示东湖水环境中的浮游病毒不仅丰度极高 ,而且种类丰富。提示浮游病毒在东湖水环境和水生态系统中可能扮演重要角色。

Virioplankton,viruses in aquatic ecosystem,are now considered to be an abundant and dynamic component in the aquatic microbial communities that can regulate the biomass production and species composition of heterophic bacteria,cyanobacteria,and phytoplankton,influence biogeochemical cycling,and mediate gene transfer between microorganisms in aquatic ecosystems.Lake Donghu located in Wuhan city was a eutrophic shallow lake,which contains three trophic regions:hypereutrophic,eutrophic and mesophic region.To assess the ecological role of virioplankton in Lake Donghu,it is necessary to determine the abundance and the morphotype diversity of virioplankton.The virioplankton abundance was measured by transmission electron microscopy (TEM) direct counts and epifluorescence microscopy (EM) direct counts using SYBRGold stain in Lake Donghu.All data were analyzed by SAS8 1 (SATA) software packages (SAS Institute Inc.).Water column virioplankton abundances were revealed highest numbers (9 74×10 8mL -1 ) in eutrophic region and lowest numbers(7 68×10 8mL -1 ) in mesotrophic region by TEM.Virioplankton direct counts of hypereutrophic and eutrophic regions were significantly higher (P<0 05)than those of mesotrophic region.Virioplankton abundances counted by EM were significantly higher than those counted by TEM (P<0 01),up to 2 72 times on average.The analysis of morphological diversity of virioplankton by TEM showed that most virioplankters observed were similar to bacteriophages and cyanophages which had diverse tails and hexagonal heads.According to morphotype,most of them belong to Siphoviridae (Tail is noncontratile,long),Myoviridae (Tail is contractile,long and complex,consisting of a central tube and a contratile sheath separated from the head by a neck) and Podoviridae (Tail is short about 20 nm and noncontratile).In addition,filovirus,baculovirus,bullet shaped virus,rod shaped virus, and other viruses,were also detected.Some virus like particles observed with clear capsomer were similar to human and animal virus.In water samples,virioplankton abundance detected was much more than those of bacterioplankton,cyanobacteria and algae.The results suggest that virioplankton played vital roles in water environment and ecosystem of Lake Donghu.