Impact of redox-stratification on the diversity and distribution of bacterial communities in sandy reef sediments in a microcosm |
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Authors: | Zheng Gao Xin Wang Angelos K Hannides Francis J Sansone Guangyi Wang |
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Institution: | (1) Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China;(2) Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao, 266555, China |
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Abstract: | Relationships between microbial communities and geochemical environments are important in marine microbial ecology and biogeochemistry.
Although biogeochemical redox stratification has been well documented in marine sediments, its impact on microbial communities
remains largely unknown. In this study, we applied denaturing gradient gel electrophoresis (DGGE) and clone library construction
to investigate the diversity and stratification of bacterial communities in redox-stratified sandy reef sediments in a microcosm.
A total of 88 Operational Taxonomic Units (OTU) were identified from 16S rRNA clone libraries constructed from sandy reef
sediments in a laboratory microcosm. They were members of nine phyla and three candidate divisions, including Proteobacteria (Alpha-, Beta-, Gamma-, Delta-, and Epsilonproteobacteria), Actinobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, Cyanobacteria, Firmicutes, Verrucomicrobia, Spirochaetes, and the candidate divisions WS3, SO31 and AO19. The vast majority of these phylotypes are related to clone sequences from
other marine sediments, but OTUs of Epsilonproteobacteria and WS3 are reported for the first time from permeable marine sediments. Several other OTUs are potential new bacterial phylotypes
because of their low similarity with reference sequences. Results from the 16S rRNA, gene clone sequence analyses suggested
that bacterial communities exhibit clear stratification across large redox gradients in these sediments, with the highest
diversity found in the anoxic layer (15–25 mm) and the least diversity in the suboxic layer (3–5 mm). Analysis of the nosZ, and amoA gene libraries also indicated the stratification of denitrifiers and nitrifiers, with their highest diversity being in the
anoxic and oxic sediment layers, respectively. These results indicated that redox-stratification can affect the distribution
of bacterial communities in sandy reef sediments. |
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