Characterisation of a Novel Genus of Oxalate-Degrading Beta-<i>Proteobacteria</i> Isolated from a Full-Scale Bioreactor Treating Bayer Liquor Organic Wastes

Abstract

A novel industrial-scale bioreactor was implemented by Alcoa of Australia (Alcoa) at its Kwinana alumina refinery (Western Australia) for the degradation of oxalate, an organic byproduct of the Bayer alumina refining process. At the Kwinana refinery oxalate is removed from the Bayer Liquor via a separate side-stream as it increases the operating costs associated with the process and, at sufficiently high levels, may adversely affect the quality and yield of the final alumina product. The bioreactor process provides a more economic and environmentally friendly method for the treatment of removed oxalate compared with chemical conversion or storage of the solid by-product. In previous studies, the microbial community composition of the bioreactor was investigated and was found to be largely dominated by microorganisms of the α-, β- and γ-Proteobacteriasubgroups. During the present study, two bacteria that had the ability to use oxalate as a sole source of carbon and energy were isolated from samples obtained from the bioreactor. Phylogenetic and physiological analyses indicated that the two isolates were probably strains of a novel species of a novel genus within the β-Proteobacteriasubgroup. Isolation and characterisation of the microbial communities within the bioreactor system has the potential to improve process operation, which may have a positive impact on the biological oxalate destruction process and the footprint of alumina production.