中文摘要：

分别于2011年6月和11月,在武汉东湖和南湖采集沉积物,作为夏季和冬季样品的代表,采用PCR-DGGE（Denaturing gradient gel electrophoresis,变性梯度凝胶电泳）和克隆测序方法研究沉积物中微生物多样性及其季节变化.结果显示,城市湖泊沉积物中微生物多样性十分丰富,冬季两个湖泊沉积物的DGGE条带总数为287条,夏季为317条.冬季和夏季,东湖的平均丰度分别为27.4和31.0,Shannon-Wiener指数分别为2.32和2.78;南湖的平均丰度分别为30.0和32.2,Shannon-Winner指数分别为2.83和2.86.两个湖泊的夏季微生物丰度和多样性指数均高于冬季;同一湖泊各样点之间的相似性更强,说明湖泊内部形成了自身特有的微生物群落结构.克隆测序的结果表明东湖、南湖微生物主要归属于3个细菌类群,其中,变形菌门占有优势地位,其次为拟杆菌门和厚壁菌门,分别占序列总数的77%、17%和6%.变形菌门中,β-变形菌纲和γ-变形菌纲为优势菌种,占序列总数的35%和31%.综上,东湖和南湖沉积物夏季微生物丰度和多样性指数均高于冬季,季节性变化影响了沉积物微生物群落的丰度和结构;本研究结果丰富了对城市富营养化湖泊沉积物微生物多样性的认识.

英文摘要：

Bacteria are very sensitive to environmental changes in the sediment. Little is known about the seasonal variations of bacterial community in sediments of the urban eutrophic lakes. This study aimed to reveal the seasonal variations of the abundance and structure of bacterial community in sediments of Donghu Lake and Nanhu Lake in Wuhan, China. PCRDGGE and cloning sequencing were used to measure the diversity and seasonal variations of bacterial communities in sediments of two eutrophic lakes. The results showed that urban lake sediments were abundant in bio-diversity of bacterial community with a total of 287 DGGE bands in winter and 317 DGGE bands in summer. For Donghu Lake, the average species richness values were 27.4 in winter and 31.0 in summer, respectively, and the Shannon-Wiener diversity indices were 2.32 in winter and 2.83 in summer. For Nanhu Lake, the average species richness values were 30.0 in winter and 32.2 in summer, and the Shannon-Wiener diversity indices were 2.83 in winter and 2.86 in summer. It was obviously that the Shannon-Wiener diversity indices and species richness values were higher in summer than in winter in both lakes. The reason might be that the higher temperature in summer could promote the growth of microorganisms in lakes and improve bio-diversity of bacterial community. The sediment samples in the same lake showed high similarity, suggesting that each lake formed its own unique internal structure of bacterial communities. The results of cloning sequencing showed that the main bacterial phyla in Donghu Lake and Nanhu Lake were Proteobacteria, Bacteroidetes and Firmicutes, with Proteobacteria being dominant, accounting for 77% of the total number of sequences, followed by Bacteroidetes（17%） and Firmicutes（6%）. In the Proteobacteria phylum, Alphaproteobacteria and Betaproteobacteria were predominant, accounting for 35% and 31%, respectively, of the total number of sequences. Our results suggested that the abundance and structure of bacterial community in sediments of the