Kojima Hisaya, Koizumi Yoshikazu, Fukui Manabu
Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, 192-0397 Tokyo, Japan.
Microb Ecol. 2006 Nov;52(4):765-73. doi: 10.1007/s00248-006-9127-8. Epub 2006 Aug 31.
Bacterial communities associated with sheaths of Thioploca spp. from two freshwater lakes (Lake Biwa, Japan, and Lake Constance, Germany) and one brackish lake (Lake Ogawara, Japan) were analyzed with denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments. The comparison between the DGGE band patterns of bulk sediment and Thioploca filaments of Lake Biwa suggested the presence of specific bacterial communities associated with Thioploca sheaths. As members of sheath-associated communities, bacteria belonging to Bacteroidetes were detected from the samples of both freshwater lakes. A DGGE band from Thioploca of Lake Biwa, belonging to candidate division OP8, was quite closely related to another DGGE band detected from that of Lake Constance. In contrast to the case of freshwater lakes, no bacterium of Bacteroidetes or OP8 was detected from Thioploca of Lake Ogawara. However, two DGGE bands from Lake Ogawara, belonging to Chloroflexi, were quite closely related to a DGGE band from Lake Constance. Two DGGE bands obtained from Lake Biwa were closely related to phylogenetically distant dissimilatory Fe(III)-reducing bacteria. Cloning analyses for a dissimilatory sulfite reductase gene were performed on the same samples used for DGGE analysis. The results of the analyses suggest that sheaths of freshwater/brackish Thioploca have little ecological significance for the majority of sulfate reducers.
利用16S rRNA基因片段的变性梯度凝胶电泳（DGGE）分析了来自两个淡水湖（日本琵琶湖和德国康斯坦茨湖）和一个咸水湖（日本小川原湖）的硫丝菌属菌鞘相关的细菌群落。琵琶湖沉积物和硫丝菌的DGGE条带模式比较表明，存在与硫丝菌菌鞘相关的特定细菌群落。作为菌鞘相关群落的成员，在两个淡水湖的样本中均检测到了属于拟杆菌门的细菌。琵琶湖硫丝菌的一个属于候选分类群OP8的DGGE条带与从康斯坦茨湖检测到的另一个DGGE条带密切相关。与淡水湖的情况相反，在小川原湖的硫丝菌中未检测到拟杆菌门或OP8的细菌。然而，小川原湖的两个属于绿弯菌门的DGGE条带与康斯坦茨湖的一个DGGE条带密切相关。从琵琶湖获得的两个DGGE条带与系统发育上距离较远的异化铁（III）还原菌密切相关。对用于DGGE分析的相同样本进行了异化亚硫酸盐还原酶基因的克隆分析。分析结果表明，淡水/咸水硫丝菌的菌鞘对大多数硫酸盐还原菌几乎没有生态意义。
