太湖梅梁湾水域蓝藻水华前与水华末期细菌群落结构的变化

Changes in Bacterial Community Structure During Preceding and Degraded Period of Cyanobacterial Bloom in a Bay of the Taihu Lake

通过16S rRNA克隆文库研究了太湖梅梁湾2004年3月和9月表层水样中细菌组成的变化,发现在蓝藻水华前与水华末期的菌群结构存在差异,特别是最优势的细菌发生了很大变化.3月水样中的克隆子主要与Bacteroidetes(42.7%)、β-Proteobacteria(18.4%)、α-Proteobacteria(16.5%)和Actinobacteria(16.5%)相关,9月水样中的克隆子主要与Cyanobacteria(28.8%)、β-Proteobacteria(25.0%)、Actinobacteria(17.3%)和α-Proteobacteria(15.4%)相关.此外,在水华末期(9月)的细菌组成更为多样性,有11个类群;而未发生水华时(3月)的细菌组成只有7个类群.同相关研究比较发现,α、β-Proteobacteria,Actinobacteria均为太湖中的常见菌群,其分布较为广泛;而γ-Proteobacteria和Firmicutes多出现于太湖的沉积物中,在水体中较少出现;属于Bacteroidetes这一类群的浮游细菌在湖水中很丰富.所研究水域中发现的很多细菌的16SrRNA基因与出现在许多不同的淡水生境,包括国外贫营养湖、中营养湖和富营养湖中细菌的系统关系密切,还发现大量源于长江的克隆子,很少有与海洋中细菌相似的序列(除Bacteroidetes门的成员外).

Diversity of bacterioplankton in March and September （2004） in the eutrophic Meiliang Bay was determined by 16S rRNA gene sequences. Result showed that community composition, especially the most dominant bacteria during preceding and degraded period of Cyanobacterial bloom was different. Clones in the March clone library （M3） were mostly affiliated with Bacteroidetes （42. 7% ）, β-Proteobacteria （ 18.4% ） , α-Proteobacteria （ 16. 5% ） and Actinobacteria （ 16. 5% ）, while clones in the September clone library （M9） were mainly affiliated with cyanobacteria （28.8%）, β-Proteobacteria （25.0%）, Actinobacteria （17.3%） and α-Proteobacteria （15.4%）. Greater diversity in sequence composition was found in M9 （11 clusters） than that in M3 （7 clusters）. Compared with related study, α-Proteobacteria, β-Proteobacteria and Actinobacteria were widely found in the Taihu Lake, whereas γ-Proteobacteria and Firmicutes were more frequently detected in sediments, and Bacteroidetes were abundant in water. Most 16S rRNA gene sequences retrieved from the two libraries were closely related to freshwater bacteria in different aquatic ecosystems including oligo-, meso- and eu-trophic lakes. A large number of clones were originated from the Yangtze River. The sequences represented in marine habitats were rarely found except the members of Bacteroidetes. Fig 2, Tab 3, Ref 21.