DOI:10.1111/j.1574-6941.2009.00758.x

dsrAB gene; 16S rRNA gene; QC-PCR; phylogenetic analysis; phospholipid fatty acids; estuarine sediments. The vertical distribution and diversity of sulfate-reducing prokaryotes (SRPs) in a sediment core from the Pearl River Estuary was reported for the first time. The profiles of methane and sulfate concentrations along the sediment core indicated processes of methane production/oxidation and sulfate reduction. Phospholipid fatty acids analysis suggested that sulfur-oxidizing bacteria (SOB) might be abundant in the upper layers, while SRPs might be distributed throughout the sediment core. Quantitative competitive-PCR analysis indicated that the ratios of SRPs to total bacteria in the sediment core varied from around 2–20%. Four dissimilatory sulfite reductase (dsrAB) gene libraries were constructed and analyzed for the top layer (0–6 cm), middle layer (18–24 cm), bottom layer (44–50 cm) and the sulfate-methane transition zone (32–42 cm) sediments. Mos