Normalization of environmental metagenomic DNA enhances the discovery of under-represented microbial community members

Abstract

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.