Zhou Jizhong, Davey Mary Ellen, Figueras Jordi B, Rivkina Elizaveta, Gilichinsky David, Tiedje James M
Center For Microbial Ecology, Michigan State University,East Lansing, MI 48824-1325,USA.
Institute of Soil Sciences and Photosynthesis, Russia Academy of Science,Pushchino,Russia.
Microbiology (Reading). 1997 Dec;143 ( Pt 12):3913-3919. doi: 10.1099/00221287-143-12-3913.
Genomic DNA was isolated from the active layer of tundra soil collected from the Kolyma lowland, Northeast Eurasia, near the Arctic Ocean coast. The SSU (small subunit) rRNA genes were amplified with eubacterial primers from the bulk genomic community DNA and cloned into plasmid vectors. Forty-three SSU rDNA clones were obtained, and all of them had different RFLP patterns. Phylogenetic analysis based on partial sequences (about 300 bp) established with the maximum likelihood method revealed the presence of three major and several minor groups that fell into 11 of the established lines of bacteria, and one sequence that could not be assigned to any of the described groups. Most of the clones belonged to the alpha (20.9%) and delta (25.6%) subdivisions of the Proteobacteria, with lesser proportions in the beta (9.3%) and gamma (4.7%) subdivisions, groups typically isolated from soil by culture methods. Fewer than 12% of the clones belonged to Gram-positive bacteria, and 16% of the clones were related to Fibrobacter. The majority of the clones (70%) had sequences that were 5-15% different from those in the current databases, and 7% of the clones had sequences that differed by more than 20% from those in the database. The results suggest that these tundra-derived clones are very diverse in phylogeny, and that many probably reflect new genera or families. Hence, most of the tundra soil bacterial community has never been isolated and thus the physiology and function of its dominant members appears to be unknown.
从欧亚大陆东北部、北冰洋海岸附近的科雷马低地采集的冻原土壤活性层中分离出基因组DNA。用真细菌引物从大量基因组群落DNA中扩增出小亚基(SSU)rRNA基因,并克隆到质粒载体中。获得了43个SSU rDNA克隆,它们都具有不同的限制性片段长度多态性(RFLP)模式。基于最大似然法建立的部分序列(约300 bp)的系统发育分析表明,存在三个主要类群和几个次要类群,它们属于已确定的11个细菌谱系,还有一个序列无法归入任何已描述的类群。大多数克隆属于变形菌门的α亚纲(20.9%)和δ亚纲(25.6%),β亚纲(9.3%)和γ亚纲(4.7%)中的比例较小,这些类群通常通过培养方法从土壤中分离得到。不到12%的克隆属于革兰氏阳性菌,16%的克隆与纤维杆菌有关。大多数克隆(70%)的序列与当前数据库中的序列有5%-15%的差异,7%的克隆序列与数据库中的序列差异超过20%。结果表明,这些源自冻原的克隆在系统发育上非常多样,许多可能代表新的属或科。因此,大多数冻原土壤细菌群落从未被分离出来,其优势成员的生理和功能似乎也未知。