식생대와 비식생대 갯벌의 미생물 호흡과 관련된 delta-proteobacteria 군집구조

Abstract

The objectives of this study were to relate the major pathways of anaerobic microbial respiration to molecular phylogenetic evidence in the unvegetated (UMF) and vegetated mudflat (VMF) of the intertidal sediments. Depth integrated C oxidation rates were 5 times higher at VMF (351 mmol C m-2 d-1) in comparison to UMF (73 mmol C m-2 d-1). Dissimilatory sulfate- and Fe(III) reduction accounted for 49.3% and 35.6%, respectively, of the C oxidation at UMF site, but represented 19.9% and 37.3%, respectively at VMF site. The results indicated that both sulfate- and Fe(III) reduction were a significant C oxidation pathways in UMF site, whereas Fe(III) reduction was more significant at VMF site. Clones related to δ-Proteobacteria accounted for 25.2% of 539 clones sequenced for 16S rRNA genes, which was a good agreement with the results of T-RFLP analysis. Phylotypes affiliated with known Fe(III) or So reducing bacteria (Desulfuromonas/Pelobacter) were abundant in clone libraries from UMF (32.4%) and VMF (48.6%) sediments at deeper depths, whereas sequences close to sulfate reducers (Desulfobacterium & Desulfobulbus) were retrieved from all depths of the sediments sampled. Interestingly, the majority (56.2%) of the uncultured Desulfuromonas/Pelobacter group was observed in the rhizosphere of VMF (VMF-5 cm co). Therefore, the enhanced significance of Fe(III) reduction to C oxidation at the VMF site paralleled with the phylogenetic analysis of the δ-Proteobacteria.