Abstract
Investigating microbial response to environmental variables is of great importance for understanding of microbial acclimatization and evolution in natural environments. However, little is known about how microbial communities responded to environmental factors (e.g. salinity, geographic distance) in lake surface sediments of the Qinghai-Tibetan Plateau (QTP). In this study, microbial diversity and community structure in the surface sediments of nine lakes on the QTP were investigated by using the Illumina Miseq sequencing technique and the resulting microbial data were statistically analyzed in combination with environmental variables. The results showed total microbial community of the studied lakes was significantly correlated (r = 0.631, P < 0.001) with lake salinity instead of geographic distance. This suggests that lake salinity is more important than geographic distance in shaping the microbial diversity and community structure in the studied samples. In addition, the abundant and rare taxa (OTUs with relative abundance higher than 1% and lower than 0.01% within one sample, respectively) were significantly (P < 0.05) correlated (r = 0.427 and 0.783, respectively) with salinity, suggesting rare taxa might be more sensitive to salinity than their abundant counterparts, thus cautions should be taken in future when evaluating microbial response (abundant vs. rare sub-communities) to environmental conditions.
Highlights
Microbial community in natural environments could be classified into abundant and rare taxa with respect to their contribution to biomass and biodiversity[16]
Up to date no studies have reported on the distribution patterns of abundant and rare taxa in lake surface sediments
Salinity was an important factor influencing the microbial diversity and community structures in the surface sediments of the studied lakes. This finding was inconsistent with a recent study, in which geographic distance, rather than salinity, was shown to mostly influence sediment microbial community composition (MCC) of the QTP lakes[14]
Summary
Microbial community in natural environments could be classified into abundant and rare taxa with respect to their contribution to biomass and biodiversity[16]. It is necessary to reevaluate the effects of geographic distance and salinity on abundant and rare taxa in lakes with a large salinity range from freshwater to salt-saturation. Almost nothing is known about how geographic distance and/or salinity influence the distribution patterns of abundant and rare microbial communities in surface sediments of lakes with a large salinity range (up to salt saturation). The Qinghai-Tibetan Plateau (QTP) is the largest (2 × 106 km2) and highest (average ∼ 4500 meters above sea level) plateau on the Earth It contains thousands of saline/hypersaline lakes, which possess a broad range of environmental gradients such as salinity (from 0.1 to 426.3 g L−1) and pH (5.4–10.2)[18]. The QTP lakes represent the most pristine natural environments and receive minimal human influence, which avails to study the effects of natural environmental variables (e.g. geographic distance, salinity) on microbial communities (abundant vs rare taxa). The purposes of this study are 1) to investigate the salinity effect on MCC (including total, abundant and rare communities) in surface sediments of the QTP lakes, and 2) to discern which factor (geographic distance vs.salinity) significantly influences the distribution of total, abundant and rare MCCs, respectively
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