The sulfate-reducing bacteria(SRB) community in the deep-sea sediments of the west Pacific Warm Pool(WP) was surveyed by molecular phylogenetic analyses using primers targeting the 16S rRNA gene fragments of SRB. Specific 16S rRNA gene libraries from five sediment layers(1-cm,3-cm,6-cm,10-cm and 12-cm layer) of the 12-cm core of WP-0 were constructed. The clones in the five libraries were differentiated by restriction fragment length polymorphism(RFLP) and representative clones were selected to sequence. It was found that the clones fell into four groups,which were closest related to Desulfotomaculum,Desul-facinum,Desulfomonile and Desulfanuticus. Desulfacinum-like clones were only detected in the upper layers of the sediment core,whereas Desulfomonile-like clones were only present in the deeper layers. Fluorescence in situ hybridization(FISH) was further carried out to visualize and count the SRB and bacteria in the five sediment layers. It was found that SRB constituted only a small proportion of the bacteria community(0.34%-1.95%) ,it had the highest content in the 3-cm layer(1.95%) and had a depth-related decreasing tendency along the 12-cm core.
