Abstract: In this paper, the bacterioplankton diversity in the water body of Meiliang Bay in March, 2004 was studied by using the techniques of molecular biology, including the extraction of bacterial DNA, PCR amplification of bacterial 16S rDNA by universal primers, molecular clone, RFLP analysis, sequencing of 16S rDNA fragments, and sequence analysis. The clone library aimed at 16S rDNA and the phylogenetic tree were constructed. The analysis of sequencing results based on 16S rDNA indicated that the dominant bacterial groups were Cytophaga-Flavobacterium-Bacteroides (CFB) plylum (44.3%), β-Proteobacteria (25.3%), and γ-Proteobacteria (27.8%), and most of the bacteria were closely related to genera Flavobacterium, Pseudomona and Acidovorax. Compared with the eutrophicated lakes abroad, Tailu Lake, the heavily eutrophicated lake in China, had the unique characteristic of γ-Proteobacteria population dominated in winter.

Key words: Cinnamon soil, Returning straw into field, Promoted decay condition, Microbial biomass, Dynamic change