Bioscience Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USA.
PLoS One. 2013 Aug 13;8(8):e71489. doi: 10.1371/journal.pone.0071489. eCollection 2013.
In this study we report the bacterial diversity of biological soil crusts (biocrusts) inhabiting polar desert soils at the northern land limit of the Arctic polar region (83° 05 N). Employing pyrosequencing of bacterial 16S rRNA genes this study demonstrated that these biocrusts harbor diverse bacterial communities, often as diverse as temperate latitude communities. The effect of wetting pulses on the composition of communities was also determined by collecting samples from soils outside and inside of permafrost water tracks, hill slope flow paths that drain permafrost-affected soils. The intermittent flow regime in the water tracks was correlated with altered relative abundance of phylum level taxonomic bins in the bacterial communities, but the alterations varied between individual sampling sites. Bacteria related to the Cyanobacteria and Acidobacteria demonstrated shifts in relative abundance based on their location either inside or outside of the water tracks. Among cyanobacterial sequences, the proportion of sequences belonging to the family Oscillatoriales consistently increased in relative abundance in the samples from inside the water tracks compared to those outside. Acidobacteria showed responses to wetting pulses in the water tracks, increasing in abundance at one site and decreasing at the other two sites. Subdivision 4 acidobacterial sequences tended to follow the trends in the total Acidobacteria relative abundance, suggesting these organisms were largely responsible for the changes observed in the Acidobacteria. Taken together, these data suggest that the bacterial communities of these high latitude polar biocrusts are diverse but do not show a consensus response to intermittent flow in water tracks over high Arctic permafrost.
在这项研究中，我们报告了栖息在北极极地区域（83°05'N）北部陆地极限的极地荒漠土壤生物土壤结皮（biocrusts）中的细菌多样性。本研究通过对细菌 16S rRNA 基因进行焦磷酸测序，证明了这些生物结皮拥有多样的细菌群落，其丰富度通常与温带地区的群落相当。通过收集来自永冻土水迹内外土壤的样本，还确定了水迹中湿润脉冲对群落组成的影响。水迹中间歇性的流动模式与细菌群落中门水平分类群的相对丰度的改变有关，但这些变化在不同的采样点之间有所不同。与蓝细菌和酸杆菌相关的细菌根据其在水迹内外的位置，表现出相对丰度的变化。在蓝细菌序列中，属于 Oscillatoriales 家族的序列比例在来自水迹内部的样本中相对于外部样本持续增加。酸杆菌在水迹中表现出对湿润脉冲的响应，在一个地点增加，而在另外两个地点减少。酸杆菌亚群 4 序列的趋势与总酸杆菌相对丰度的趋势一致，表明这些生物体在很大程度上对观察到的酸杆菌变化负责。总的来说，这些数据表明，这些高纬度极地生物结皮的细菌群落是多样的，但对高北极永冻土上水迹的间歇性流动没有一致的响应。
