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Marine sponges harbour dense and diverse micro-organisms which includes sulphate-reducing bacteria (SRB). SRB are known to play a key role in the cycling of marine elements. However, in contrast to carbon and nitrogen cycling bacteria, SRB associated with marine sponges are largely unexplored. In this study, we explored the phylogenetic diversity of the SRB associated with three shallow-water sponges Arenosclera heroni, Dysidea arenaria and Astrosclera willeyana from the South China Sea by cloning-and-sequencing approach of SRB 16S rRNA gene with specific primers. The results showed that SRB associated with sponges mainly belonged to the genus Desulfovibrio in the class Deltaproteobacteria, i.e. a total of 14 Desulfovibrio-related OTUs were obtained from three sponges. The exception is identical OTUs from different sponges. Each sponge species harboured a unique set of Desulfovibrio OTUs, with only a few shared OTUs observed between species, suggesting different species of Desulfovibrio in different species of sponges. Meanwhile, some Desulfovibrio OTUs had a low similarity (<97%) with related sequences in GenBank and phylogenetic analysis indicating novel Desulfovibrio symbionts in sponges. The results contribute to the overall understanding of the phylogenetic diversity of SRB associated with sponges.