ABSTRACT
There are a range of methods that are available for extraction of metagenomic deoxyribonucleic acid (DNA) from environmental samples. However, none of the methods reported hitherto is universally applicable and every type of soil sample requires optimization of DNA extraction methods. Metagenomic DNA isolation from soil and sediment samples can be broadly classified into direct and indirect extraction procedures. Direct DNA isolation is based on cell lysis within the sample matrix and subsequent separation of DNA from the matrix and cell debris or separation of the cells from the soil matrix followed by cell lysis. The indirect approach involves the separation of cells from the soil matrix followed by cell lysis and DNA extraction. The expression vector varies with the range of target insert DNA and size of gene required for cloning. Functional screening of metagenomic libraries can be done by chemical dyes and insoluble or chromophore-containing derivative medium.
