DGGE of PCR-amplified 16S rDNA fragments was
first used to profile community complexity of a micro-
bial mat and bacterial biofilms (Muyzer et al., 1993).
For this purpose bacterial genomic DNA was extracted
from natural samples, and segments of the 16S rRNA
genes were amplified in the polymerase chain reaction
(PCR; Saiki et al., 1988).