Enrichment of microbial consortia provides an approach to simulate and investigate microbial communities in natural environments.In this study,a cellulolytic microbial consortium SQD-1.1 was enriched from mangrove soil of Qinglan port (Hainan,China) by 27-times continuous subcultivation under anaerobic static conditions.The consortium could completely degrade0.2%(w/v) filter paper within three days and utilized it as the sole carbon source.PCR-denaturing gradient gel electrophoresis (DGGE) analysis revealed a stable microbial community structure in the incubation process of 10days and in the procedure of subcultivation.24 OTUs belonging to seven phyla were obtained from the full-length 16S rRNA gene library.Five clones,closest related to the genera Alkaliflexus,Clostridium,Alistipes,Spirochaeta and Trichococcus,were the predominant ones.Among them,M117,phylogeneticly showing high similarity (16S rRNA gene identity,95.3%) with the cellulolytic anaerobic bacterium Clostridium straminisolvens CSK1T,was the potential key cellulolytic bacterium.Using the plate cultivation method,twelve strains,including one potential new species and four potential new species of new genera,were isolated.The strainP2,corresponding to the most frequently detected clone (M05) in the 16S rRNA gene library,showed both CMCase and xylanase activity and may be another important cellulolytic bacterium.The findings of cellulase activity in cell pellet and cohesion and dockerin domains in metagenome data further suggested the potential of utilization of cellulosome by the consortium to degrade cellulose.Consortium SQD-1.1 provides a candidate for investigating the mechanism of cellulose degradation under anoxic conditions in natural environments.