Basic statistical analysis of abiotic and microbial variables was performed by using XLSTAT as follows: linear relationships among measured abiotic variables of groundwater were investigated by Pearson correlation, where the P-value of 0.05 was used as a significance threshold, while relationships between abiotic and microbial variables were revealed by canonical correspondence
analysis. Clustering of T-RFLP and SNuPE profiles was performed by the Jaccard similarity coefficient using the PAST software package [14].