Recent advances in culture-independent studies of microbes had proved to be more reliable and efficient than the conventional ones. The isolation of good quality and quantity of total community DNA are one of the major hurdles in this endeavour. Shearing of DNA during the extraction process and the co-extraction of inhibitory compounds reduce the quality of the isolated nucleic acids making it unsuitable for the construction of large insert metagenomic libraries. In the present study, a multi-level filtration step was brought in which efficiently isolated total bacterial DNA from three different environment samples. The preprocessing method could efficiently improve the 260/230 ratio of the isolated DNA by 2.3-45 % and decreased the protein contamination by 22.5-34.5 % on saltpan and arctic sediment samples, respectively. The more significant part of the experiment was that the DNA obtained was of high quality with minimal shearing making it most suitable for the construction of large insert genomic libraries. PCR amplification of 16S rRNA gene confirmed that the filtration method was effective in the isolation of high-quality DNA.
Keywords: DNA isolation; High molecular weight DNA; Metagenomic DNA; Preprocessing.