Characterisation of the Complex Microbial Community Associated with the ASTER™ Thiocyanate Biodegradation System

The ASTER™ process is used to bioremediate cyanide- (CN-) and thiocyanate- (SCN-) 13 containing waste water. This aerobic process is able to reduce the CN- and SCN14 concentrations to below 1 mg/L efficiently in a continuous system, facilitating reuse of 15 process water or safe discharge. Such remediation systems, which completely eliminate risk 16 associated with the pollutants, are essential for sustainable mineral processing and the long 17 term minimisation of environmental burden through both pollutant destruction and exploiting 18 opportunities for nutrient recycle. Process robustness of these bioremediation options can be 19 enhanced by good understanding of the microbial community involved in the process. To 20 date, the microbial consortia associated with the ASTER™ bioprocess have been poorly 21 characterised using isolation approaches only. As a result, the relative abundance and 22 diversity of the community has been significantly under-represented. In this study, both planktonic and biofilm-associated biomass have been observed. 23 Microscopy has revealed the 24 diversity of these communities, including bacteria, motile eukaryotes, filamentous fungi and 25 algae, with the biofilm densely packed with microorganisms. The results of the molecular 26 characterisation study reported here, using a clone library approach, demonstrate that the 27 microbial community associated with the ASTER™ bioprocess system is far more complex 28 than previously suggested, with over 30 bacterial species identified thus far. On-going 29 investigations focus on identification of key microbial community members associated with 30 SCN- biodegradation and other critical metabolic functions, as well as the expected dynamic 31 response of this complex microbial community to shifts in the operating window of the 32 process