In the context of biofuel production from marine microalgae species, the anaerobic digestion could have the potential to make the system more sustainable and energetically viable. However, the presence of salts will involve inhibition of methanogenesis. In order to evaluate the ability of halophilic microorganisms from anaerobic sediments to acclimate to process conditions and to high ionic concentration, two reactors were carried out continuously for 120 d with a hydraulic retention time (HRT) of 20 d. At an ionic concentration of 45 g.L-1, an organic matter conversion into valuable compounds as acetate and methane can be obtained. An acetate production of around 0.23 gCOD-C2.gCODintroduced -1 and a specific methane production of 36 mLCH4.gCODintroduced -1 were obtained during the steady state. However, some factors as the presence of sulphate-reducing bacteria (SRB) limit the acetate conversion into methane by the competition and essential metal precipitation phenomena. Quantitative PCR showed that the ratio Archaea/SRB was superior to 1 in bioreactors indicating that archaeal community became dominant and so an abundance shift was obtained compared to the microbial composition in sediments. Therefore the methane production can be promoted in bioreactors from halophilic microbial communities.