In order to study the effects of the polycultured Hyriopsis cumingii, Hypophthalmichthys molitrix and Aristichthys nobilis on microbial community structure in aquaculture and to compare their different effects , three series of experiments which included M.rosenbergii-H.cumingii polyculture , Ctenopharyngodon idellus-H.cumingii polyculture and H.molitrix and A.nobilis-M.rosenbergii-H.cumingii polyculture were carried out in Haiyan County , Zhejiang Province , Jiujiang, Jiangxi province and Shanghai , separately.The 16S rDNA fingerprint was analyzed by DGGE technique .DGGE sketch map showed a total of 57 different bands for all samples , and the average number of bands from H.cumingii and /or H.molitrix and A.nobilis polyculture water samples higher than that from monoculture water samples .The analysis results of Shannon diversity index showed increased diversity indices when polycultured H.cumingii and/or H.molitrix and A.nobilis in aquaculture water .PCA analysis and DGGE clustering results showed that in the absence of H.molitrix and A.nobilis, the 16S rDNA map of H.cumingii and the main support species (M.rosenbergii, C.idellus) polyculture experi-mental groups clustered together, showing the impact of the H.cumingii on the microbial community structure in aquacul -ture water.When H.cumingii and H.molitrix and A.nobilis were polycultured together, the 16S rDNA map would clusteredinto two groups according to whether the H.molitrix and A.nobilis were introduced, suggesting that the impact of H.molitrix and A.nobilis on microbial was greater than that H.cumingii in aquaculture water in this study.20 significantbands were excised for sequencing and then constructed Phylogenetic tree .Results indicated that the main clones fromDGGE profile fell into 6 bacteria groups, including Actinobacteria (25%), Cyanobacteria(25%), Alphaproteobacteria(15%), Betaproteobacteria(15%), Gammaproteobacteria(10%), Epsilonproteobacteria(5%) and Euglenales(5%).%为了研究混养三角帆蚌（ Hyriopsis cumingii）和鲢（ Hypophthalmichthys molitrix）鳙（ Aristichthys nobilis）对池塘养殖水体微生物群落结构的影响，分别在浙江海盐、江西九江、上海浦东开展了罗氏沼虾－三角帆蚌混养、草鱼—三角帆蚌混养、罗氏沼虾－三角帆蚌－鲢鳙鱼混养三组系列实验。利用DGGE技术对养殖水体的16S rDNA进行指纹图谱分析。三组实验共鉴定出57条不同条带，每组实验中混养三角帆蚌或鲢鳙实验组的平均条带数均高于单养水体水样平均条带数。 Shannon多样性指数分析结果显示，各养殖水体混养三角帆蚌、鲢鳙后，多样性指数均有所增加。 PCA分析和DGGE聚类结果显示，在无鲢鳙的情况下，蚌与主养物种（罗氏沼虾、草鱼）混养实验组的16S rDNA图谱聚为一类，显示出蚌对于微生物群落结构影响的贡献；在同时引入鲢鳙和蚌的情况下，16S rD－NA指纹图谱则是按照有无鲢鳙聚为两类，提示在本实验中鲢鳙对于水体微生物的影响要大于蚌。对DGGE图谱其中20条显著条带进行回收、测序和系统发育分析，结果表明，所获序列主要分属于放线菌门（ Actinobacteria ，25％）、蓝藻门（ Cyanobacteria ，25％）、α－变形菌亚门（ Alphaproteobacteria ，15％）、β－变形菌亚门（ Betaproteobac－teria，15％）、γ－变形菌亚门（ Gammaproteobacteria ，10％）、ε－变形菌亚门（ Epsilonproteobacteria ，5％）、裸藻叶绿体（ Euglenales ，5％）。
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