Normalization is a procedure classically employed to detect rare sequences in cellular
expression profiles (i.e. cDNA libraries). Here, we present a normalization protocol involving
the direct treatment of extracted environmental metagenomic DNA with S1 nuclease; referred
to as Normalization of metagenomic DNA: NmDNA. We demonstrate that NmDNA, prior to
post hoc PCR based experiments (16S rRNA gene T-RFLP fingerprinting and clone library),
increased the diversity of sequences retrieved from environmental microbial communities by
detection of rarer sequences. This approach could be used to enhance the resolution of
detection of ecologically relevant rare members in environmental microbial assemblages.