The PCR amplification protocol was as follows: 94 C initial
denaturing for 3 min; 94 C denaturing for 30 s, 55 C annealing
for 40 s, 72 C extending for 1 min, 30 cycles; 72 C extending for
5 min. The 25 ul of PCR contained: 2*Master Mix (TianGen, contained
0.1 U Taq polymerase, 500 mM dNTPs, 20 mM Tris–HCl
(pH 8.3), 100 mM KCl, 3 mM MgCl) 12.5 ul and 10 uM in each forward
and reverse primers. The regions corresponding to positions
357 and 518 in the 16S rDNA of Escherichia coli were PCR-amplified
by EUB357f (50
-CCTACGGGAGGCAG CAG-30
) with a GC clamp
(50
-CGCCCGCCGCGCCCCGCGCCCGGCCCGCCGCCC CCGCCCC-30
) at
the 50 end to stabilize the melting behavior of the DNA fragments
and the reverse primer UNIV518r (50
-ATTACCGCGGCTGCTGG-30
)
(Ki