SDS based cell lysis is the most widely used DNA extraction method, whereby DNA yield is more

compared to freeze thawing and use of other detergents [21]. Physical treatments such as grinding, sonication and bead beating homogenises soil particles and can access individual microbial cells Olaparib datasheet within a sample but with greater possibility of DNA shearing. Previous studies revealed that a combination of chemical and mechanical lysis can yield twice the amount of DNA than by any single method alone [20]. In the present study mechanical disruption of cell wall by grinding with liquid nitrogen and bead beating (method 2 and 3) resulted in increased DNA shearing, when compared to the gentle freeze-thawing Bleomycin method 4. Although

the liquid nitrogen method yielded the shortest DNA fragments, it also has reduced amounts of contaminants. Consequently a combination of chemical lysis along with mild physical methods can greatly influence the total DNA content in terms of quantity and quality. Despite the shearing of DNA in all 3 soil samples employing liquid nitrogen extraction technique, they yielded 16S rRNA gene amplification using a single set of primer without the addition of any PCR enhancers or additives, thereby suggesting the suitability of the method in diverse soils and Acyl CoA dehydrogenase also in diversity studies. Commercial DNA extraction kits are now commonly used for extraction of high molecular weight DNA from complex habitats. Studies evaluating various commercial kits to other methods have shown that DNA yield and purity vary based on methodology and soil type. The mechanism of purification of these kits is based on the adsorption

and desorption of the nucleic acids in presence of chaotropic salts [22] which results in contaminants free DNA but the quantity of DNA obtained will be less compared to classical method of DNA extraction. Previous studies recommended that slight modification of protocols employing commercial kits or a combination of classical isolation methods followed by purification of DNA using commercial kits can greatly affect the quantity and quality of the isolated DNA [23], [24] and [25]. In the present study maximum DNA yield was obtained in lysozyme-freeze-thawing protocol (method 4), although the presence of residual amounts of humic and protein contaminants hindered PCR reaction. In conclusion all methods yielded an acceptable amount of DNA, but were not suitable for further downstream processing, except that obtained by method 2.