EVALUATING THE METAL TOLERANCE CAPACITY OF MICROBIAL COMMUNITIES ISOLATED FROM THE ALBERTA OILSANDS PROCESS WATER

Water treatment and management is a growing concern for Alberta oilsands operators, as surface mining of bitumen has accumulated large volumes of wastewater stored in tailings ponds. Oil sands process affected water (OSPW) contains many contaminants of environmental concern, including polyaromatic hydrocarbons, residual bitumen, naphthenic acids, diluents, and heavy metals. The acutely toxic organic compounds are metabolized by naturally occurring OSPW bacteria to varying degrees. However, metals can inhibit the natural degradation of the organic portion of concern, as well as having an inherent toxicity themselves. Thus, our aim is to evaluate the inhibitory concentrations of various metal toxicants on the microbiota to assess their potential for bioremediation. We cultured a mixed species microbial community from an OSPW inoculant to evaluate their susceptibility to metal toxicity over a wide range of metals and concentrations, using a minimal media amended different carbon sources. Cupriavidus metallidurans, known to have a high number of metal resistance genes, was used as a model for a metal-resistant bacterium as a basis for comparison. Both biofilm and planktonic cultures were grown using the Calgary Biofilm Device (CBD) and in a 96-well microtiter plate, respectively, in order to screen planktonic minimum inhibitory concentrations (MICs) and minimum biofilm inhibitory concentrations (MBICs). This information was correlated with physiochemical parameters of the metals tested. While similar metal tolerances were observed with the OSPW community and our metal resistant model organism, differences were seen in correlations with the specific physiochemical characteristics of the metal-ions. These differences were seen in parameters reflecting metal-ligand affinities, suggesting that the OSPW consortia may have developed adaptations to mediate the toxicological effects of metal ions found endogenously in their environment.