Spatial distribution of bacterial communities driven by multiple environmental factors in a beach wetland of the largest freshwater lake in China.

Xia Ding,Bo Li,Ming Nie,Chang-Ming Fang,Jia-Kuan Chen,Xiao-Jue Peng,Ming Xiao,Bin-Song Jin

doi:10.3389/fmicb.2015.00129

Abstract

The spatial distributions of bacterial communities may be driven by multiple environmental factors. Thus, understanding the relationships between bacterial distribution and environmental factors is critical for understanding wetland stability and the functioning of freshwater lakes. However, little research on the bacterial communities in deep sediment layers exists. In this study, thirty clone libraries of 16S rRNA were constructed from a beach wetland of the Poyang Lake along both horizontal (distance to the water-land junction) and vertical (sediment depth) gradients to assess the effects of sediment properties on bacterial community structure and diversity. Our results showed that bacterial diversity increased along the horizontal gradient and decreased along the vertical gradient. The heterogeneous sediment properties along gradients substantially affected the dominant bacterial groups at the phylum and species levels. For example, the NH+4 concentration decreased with increasing depth, which was positively correlated with the relative abundance of Alphaproteobacteria. The changes in bacterial diversity and dominant bacterial groups showed that the top layer had a different bacterial community structure than the deeper layers. Principal component analysis revealed that both gradients, not each gradient independently, contributed to the shift in the bacterial community structure. A multiple linear regression model explained the changes in bacterial diversity and richness along the depth and distance gradients. Overall, our results suggest that spatial gradients associated with sediment properties shaped the bacterial communities in the Poyang Lake beach wetland.

Highlights

Wetland ecosystems are considered the most biologically diverse ecosystems (Iasur-Kruh et al, 2009; Wang et al, 2012)
The results only provide a “snapshot” of how spatial gradients shaped the bacterial communities, they suggest that multiple environmental factors along spatial gradients can strongly mediate beach bacterial communities in a subtropical freshwater wetland region of China
Our study suggests that Proteobacteria, Acidobacteria, and Actinobacteria were dominant prokaryotes

Summary

Introduction

Wetland ecosystems are considered the most biologically diverse ecosystems (Iasur-Kruh et al, 2009; Wang et al, 2012). Systematic exploration of geographic bacterial patterns through the simultaneous consideration of contemporary environmental variations and stereoscopic spatial distribution (distance and depth) is largely lacking, resulting in a poor understanding of how environmental factors shape bacterial communities in beach wetlands of lake ecosystems (Yannarell and Triplett, 2005; Córdova-Kreylos et al, 2006; Zhou et al, 2008). Recent studies demonstrate that bacterial communities in lake wetland ecosystems are strongly correlated with a multitude of environmental factors over horizontal gradients ranging from hundreds of kilometers to centimeters (Terrados et al, 1999; Yannarell and Triplett, 2004; Crump et al, 2007). Expanding our knowledge of bacterial diversity and distribution from the surface to deeper sediment layers www.frontiersin.org

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