Yergeau Etienne, Newsham Kevin K, Pearce David A, Kowalchuk George A
Netherlands Institute of Ecology (NIOO-KNAW), Centre for Terrestrial Ecology, Boterhoeksestraat 48, 6666GA, Heteren, The Netherlands.
Environ Microbiol. 2007 Nov;9(11):2670-82. doi: 10.1111/j.1462-2920.2007.01379.x.
Although soil-borne bacteria represent the world's greatest source of biological diversity, it is not well understood whether extreme environmental conditions, such as those found in Antarctic habitats, result in reduced soil-borne microbial diversity. To address this issue, patterns of bacterial diversity were studied in soils sampled along a > 3200 km southern polar transect spanning a gradient of increased climate severity over 27 degrees of latitude. Vegetated and fell-field plots were sampled at the Falkland (51 degrees S), South Georgia (54 degrees S), Signy (60 degrees S) and Anchorage Islands (67 degrees S), while bare frost-sorted soil polygons were examined at Fossil Bluff (71 degrees S), Mars Oasis (72 degrees S), Coal Nunatak (72 degrees S) and the Ellsworth Mountains (78 degrees S). Bacterial 16S rRNA gene sequences were recovered subsequent to direct DNA extraction from soil, polymerase chain reaction amplification and cloning. Although bacterial diversity was observed to decline with increased latitude, habitat-specific patterns appeared to also be important. Namely, a negative relationship was found between bacterial diversity and latitude for fell-field soils, but no such pattern was observed for vegetated sites. The Mars Oasis site, previously identified as a biodiversity hotspot within this region, proved exceptional within the study transect, with unusually high bacterial diversity. In independent analyses, geographical distance and vegetation cover were found to significantly influence bacterial community composition. These results provide insight into the factors shaping the composition of bacterial communities in Antarctic terrestrial habitats and support the notion that bacterial diversity declines with increased climatic severity.
尽管土壤传播细菌是世界上生物多样性的最大来源，但对于极端环境条件（如在南极栖息地发现的那些条件）是否会导致土壤传播微生物多样性降低，人们还了解得不够充分。为了解决这个问题，研究了沿着一条跨越超过3200公里的南极横断面采集的土壤中细菌多样性模式，该横断面跨越了27个纬度的气候严重程度增加的梯度。在福克兰群岛（南纬51度）、南乔治亚岛（南纬54度）、西格尼岛（南纬60度）和安克雷奇群岛（南纬67度）采集了植被覆盖和裸地的样地，同时在化石崖（南纬71度）、火星绿洲（南纬72度）、煤丘（南纬72度）和埃尔斯沃思山脉（南纬78度）检查了裸露的经霜冻分选的土壤多边形区域。从土壤中直接提取DNA、进行聚合酶链反应扩增和克隆后，回收了细菌16S rRNA基因序列。尽管观察到细菌多样性随着纬度增加而下降，但特定栖息地模式似乎也很重要。具体而言，在裸地土壤中发现细菌多样性与纬度呈负相关，但在植被覆盖地区未观察到这种模式。火星绿洲地点先前被确定为该区域内的一个生物多样性热点，在研究横断面中表现异常，具有异常高的细菌多样性。在独立分析中，发现地理距离和植被覆盖显著影响细菌群落组成。这些结果为塑造南极陆地栖息地细菌群落组成的因素提供了见解，并支持细菌多样性随着气候严重程度增加而下降的观点。
