The methanogen community composition was examined by utilising DGGE and direct clone library analysis on PCR products
obtained with mcrA-GC and mcrA primers. The PCR products with a GC-clamp (20-25 ml) were separated using DGGE with modifications in the denaturant gradient (30-60%) and acrylamide-bisacrylamide concentration (9%). The gels were run for 17.5 h at 80 V. After electrophoresis, the gels were stained with SYBR Gold nucleic acid gel stain and photographed . The PCR fragments without a GCclamp were cloned into commercial plasmid vectors