Reconstruction of submerged vegetation is one of the key measures of eutrophication remediation.Using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and clone library analysis,we studied the impact of planting Potamogeton crispus and Vallisneria natans on bacterial diversity and community composition in West Lake,Hangzhou,China.Bacteroidetes (42.9%),Betaproteobacteria (30.8%) and Verrucomicrobia (14.3%) dominated in the water column from lake areas without submerged macrophytes.On the contrast,the proportion of Bacteroidetes reduced to 12.7% and 5.3%,respectively, after planting Potamogeton crispus and Vallisneria natans.Meanwhile,Betaproteobacteria increased to 52.4% and 59.5%,and Alphaproteobacteria increased from 4.4% to 19.0% and 12.8%,respectively.The proportion of Verrucomicrobia reduced substantially after planting Potamogeton crispus,but varied little after planting Vallisneria natans.This study indicates that submerged macrophytes can not only improve water quality,but also increase bacterial diversity,and shape bacterial community composition significantly.