链状亚历山大藻共附生细菌多样性

Phylogenetic diversity of bacteria associated with dinoflagellate Alexandrium catenella

采用非分离培养分析方法,直接提取链状亚历山大藻(Alexandrium catenella)共附生细菌总DNA,以之为模板进行PCR扩增获得细菌16S rDNA基因片段,并构建16S rDNA克隆文库。通过16S rDNA限制性酶切片段长度多态性(restriction fragment length polymorphism,RFLP)和测序方法对链状亚历山大藻共附生细菌的多样性进行了研究。84个16S rDNA克隆片段经限制性内切酶HaeⅢ酶切分析,得到30种不同的酶切指纹类型。挑选50个克隆子进行测序获得其16S rDNA部分序列,并对16S rDNA序列进行聚类分析构建了系统进化树。结果表明,链状亚历山大藻共附生的细菌多样性较强,优势细菌类群为变形菌α亚群(α-Proteobacteria)和拟杆菌(Bacteroidetes),其中玫瑰杆菌(Roseobacter sp.)在α-Proteobacteria中占绝对优势。

The phylogenetic diversity of bacteria associated with Alexandrium catenella was studied by 16S rDNA gene sequences, With culture-independent approach, the total bacterial DNA was extracted from A. catenella. 16S rDNA genes were amplified by PCR, and a 16S rDNA clone library was constructed. The phylogenetic diversity of the bacteria was determined by RFLP-16S rDNA sequencing of cloned DNA fragments. A total of 84 cloned 16S rDNA fragments were digested with restriction endonucleases HaeⅢ, and 30 different PFLP types were obtained. Fifty cloned partial sequences were acquired, most of which were related to Proteobacter, and mainly attributed to α- Proteobacteria and Bacteroidetes in the phylogenetic tree. In α-Proteobacteria, Roseobacter sp. was the dominant clade. This study demonstrated the prolific bacterial diversity of A. cateneUa.