Yan Shi, Fuchs Bernhard M, Lenk Sabine, Harder Jens, Wulf Jörg, Jiao Nian-Zhi, Amann Rudolf
Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen D-28359, Germany.
Syst Appl Microbiol. 2009 Apr;32(2):124-39. doi: 10.1016/j.syapm.2008.12.001.
The phylogeny, abundance, and biogeography of the NOR5/OM60 clade was investigated. This clade includes "Congregibacter litoralis" strain KT71, the first cultured representative of marine aerobic anoxygenic phototrophic Gammaproteobacteria. More than 500 16S rRNA sequences affiliated with this clade were retrieved from public databases. By comparative sequence analysis, 13 subclades could be identified, some of which are currently restricted to discrete habitat types. Almost all sequences in the largest subclade NOR5-1 and related subclade NOR5-4 originated from marine surface water samples. Overall, most of the NOR5/OM60 sequences were retrieved from marine coastal settings, whereas there were fewer from open-ocean surface waters, deep-sea sediment, freshwater, saline lakes and soil. The abundance of members of the NOR5/OM60 clade in various marine sites was determined by fluorescence in situ hybridization using a newly designed and optimized probe set. Relative abundances in coastal marine waters off Namibia and the Yangtze estuary were up to 3% of the total 4',6-diamidino-2-phenylindole (DAPI) counts, and in the German Bight off Helgoland the abundance was even up to 7%. In an open-ocean North Atlantic transect, between Iceland and the Azores, the NOR5/OM60 group was much less abundant (0.1-0.5%). Interestingly, the surface layer of North Sea intertidal sediments was very rich in NOR5/OM60, with absolute numbers >10(8) cells cm(-3) (or 4% of the total DAPI). An analysis of the frequencies of NOR5/OM60 16S rRNA genes in the Global Ocean Survey datasets provided further support for a marine cosmopolitan occurrence of NOR5/OM60, and a clear preference for coastal marine waters.
对NOR5/OM60进化枝的系统发育、丰度和生物地理学进行了研究。该进化枝包括“滨海聚集杆菌”KT71菌株，它是海洋需氧不产氧光合γ-变形菌的首个培养代表菌株。从公共数据库中检索到500多条与该进化枝相关的16S rRNA序列。通过比较序列分析，可识别出13个亚进化枝，其中一些目前仅限于离散的栖息地类型。最大的亚进化枝NOR5-1和相关亚进化枝NOR5-4中的几乎所有序列都源自海洋表层水样本。总体而言，大多数NOR5/OM60序列是从海洋沿岸环境中检索到的，而从开阔海洋表层水、深海沉积物、淡水、盐湖和土壤中检索到的较少。使用新设计和优化的探针组，通过荧光原位杂交确定了NOR5/OM60进化枝成员在各种海洋站点中的丰度。纳米比亚沿海海水和长江口的相对丰度高达总4',6-二脒基-2-苯基吲哚（DAPI）计数的3%，在黑尔戈兰岛附近的德国湾，丰度甚至高达7%。在冰岛和亚速尔群岛之间的北大西洋开阔海洋断面中，NOR5/OM60组的丰度要低得多（0.1-0.5%）。有趣的是，北海潮间带沉积物的表层富含NOR5/OM60，绝对数量>10(8) 个细胞/cm(-3)（或占总DAPI的4%）。对全球海洋调查数据集里NOR5/OM60 16S rRNA基因频率的分析，进一步支持了NOR5/OM60在海洋中广泛分布的情况，以及对沿海海水的明显偏好。
