Selected DGGE bands were excised in triplicates to ensure that each
band represented only one type of bacterium. These bandswere excised
using sterile wide-pore pipette tips and transferred into tubes containing
50 μl of sterile water and eluted at 4 °C overnight. From the eluate,
2 μl were used as DNA template and re-amplified using the PCR conditions
describe above,with the following modifications: 16 cycles of regular
PCR, primer 357F without the GC clamp, and the total reaction
volume was 25 μl. Following re-amplification, 8 μl of each PCR product
were analyzed and imaged as described previously to confirm successful
amplification of the V3 region. The re-amplified DNA fragments
were purified using the MultiScreen PCRμ96 Filter Plate (Millipore Corporation,
Billerica, MA, USA). Sequencing was then performed using