Sodium oxalate is an organic impurity produced during the Bayer refining of bauxite as a result of the degradation of humic materials associated with the ore. Physico-chemical oxalate destruction techniques, such as combustion, are often expensive and often pose greater environmental risk than the storage of solid oxalate waste. Biodegradation is a more economical and environmentally friendly way to degrade oxalate, but the microbial communities responsible for oxalate degradation have remained largely uncharacterised. In the present work, the microbial community of a full-scale bioreactor achieving complete degradation of oxalate was characterised using 16S rRNA gene clone libraries followed by phylogenetic analysis of the cloned near full-length 165 rRNA sequences. The community was dominated by species belonging to the alpha-, beta- and gamma-Proteobacteria groups. Novel oxalate-degrading bacteria belonging to the genus Halomonas and the beta-Proteobacteria group were isolated from the microbial community and are currently being characterised. (C) 2011 Elsevier Ltd. All rights reserved.