the DGGE analysis of the PCR products was performed by electrophoresis
for 20 min at 20 V and 15 h at 70 V through 8% polyacrylamide
gel containing a linear gradient of denaturant ranging
from 40% to 70% in 0.5 TAE buffer at a constant temperature of
60 C. DGGE gels were stained with Sybr-Gold for 60 min and photographed
on Gel DocXR system (Bio-Rad Laboratories) and the
bands in the gel were excised (Boon et al., 2002).