Sulphate-Reducing Bacteria in Ground Water Samples from Olkiluoto:Analyzed by Quantitative PCR

The GEOFUNC Project is connected to safety and risk assessment research on the final disposal site of nuclear waste disposal. Sulphate-reducing micro-organisms, which are the major group of micro-organisms of concern, are able to cause copper corrosion by converting sulphate to sulphide, which is a very corrosive agent. The quantitative assessment of sulphate reducers by the qPCR method, which is based on sulphite reductase gene quantification, is related to the transformation of sulphate to sulphide. In this project we developed external and internal standard methods for our qPCR method in order to evaluate the quantitative amount and efficiency of DNA extractions and PCR inhibition possibly caused by high salt or iron concentrations. These standards are needed in quantifying and estimating the real quantity of sulphate reducers on the basis of their functional genes. Sulphate reducers were detected in all the samples studied. Based on this small dataset, no clear relationships were found between the geochemistry and the numbers of sulphate reducers, and the phenomena should be studied in more detail with more variable drillhole waters in the future