The ASTER™ process is commercially used to bioremediate cyanide- (CN-) and thiocyanate- (SCN-) containing waste water, typically, from cyanidation of refractory gold ores. There are currently three industrial-scale ASTER™ processes in operation worldwide. This aerobic bioprocess reduces the CN- and SCN- concentrations to below 1 mg/L in a continuous system, facilitating reuse or safe discharge of process water. To date, the microbial consortia associated with this bioprocess have been poorly characterized and, as a result, the relative abundance and diversity of the community has been significantly under-represented. Researchers within the Centre for Bioprocess Engineering Research (CeBER) at the University of Cape Town, together with those at the University of California, Berkeley are employing a molecular approach, including 16S rRNA gene surveys and metagenomic analysis, to study CN- and SCN- biodegradation within laboratory-scale reactors.
On-going investigations focus on identification of key microbial community members associated with, in particular, SCN- biodegradation. The metagenomic approach has demonstrated a much greater diversity than previously expected from culture-based and 16S rRNA approaches, with over 100 species proposed to be presented, including a new genus, termed Kapabacterium. The culture-based and 16S rRNA approaches remain critically important for characterization of key players in terms of physicochemical operation and in developing quick monitoring methods for culture dynamics and visualization. These are important in studying the dynamic response of this complex microbial community to shifts in the operating window of the process. Both metagenomic studies and culture-based studies are enabling us to identify the metabolic potential of the community. Ultimately, industrial process design and operation will benefit from a detailed understanding of the microorganisms involved in the destruction of CN- and SCN- compounds.
Authors:
 Dr Rob Huddy, Research Officer at the Centre for Bioprocess Engineering Research (CeBER), UCT |
 Prof Sue Harrison, Director for the Centre for Bioprocess Engineering Research (CeBER), UCT |
Source articles:
- Huddy R.J., van Zyl A.W., van Hille R.P. and Harrison S.T.L. (2015). Characterisation of the complex microbial community associated with the ASTER™ thiocyanate biodegradation system. Minerals Engineering 76, 65-71
- Kantor R.S., van Zyl A.W., van Hille R.P., Thomas B.C., Harrison S.T.L. and Banfield J. (2015). Bioreactor microbial ecosystems for thiocyanate and cyanide degradation unravelled with genome-resolved metagenomics. Environmental Microbiology. (in press). Doi: 10.1111/1462.2920.12936
