Optimization of DNA Extraction from Blood Samples Contaminated with Clay Using Additive Reagents
Keywords:
DNA extraction, clay soil, additive reagent, forensic geneticsAbstract
Background : Clay-contaminated blood samples present a significant challenge for forensic DNA analysis. The composition and chemical properties of clay soil, which is abundant in minerals and possess a high DNA adsorption capacity, often lead to a reduction in the efficiency of DNA extraction and PCR amplification. These issues pose a major obstacle in forensic genetic identification.
Objective : To compare the efficiency of additive reagents used in combination with a commercial DNA extraction kit in extracting human DNA from clay-contaminated blood samples.
Material and methods : DNA was extracted from blood samples contaminated with clay using a commercial DNA extraction kit with the addition of one of the following additive reagents, including Sodium dodecyl sulfate (SDS), Potassium dihydrogen orthophosphate (KH2PO4), Skim milk, and Nuclease free water, during the cell lysis step. The efficiency of each additive was subsequently compared with the control group based on the quantity of DNA extracted, which was measured using Real-time PCR.
Results : The additive KH2PO4 yielded the highest amount of extracted DNA with statistical significance (p < 0.05) compared to the other additives and the control group, followed by SDS and Skim milk, respectively. Furthermore, assessment of DNA samples quality, using the Internal PCR control (IPC), indicated that KH2PO4, SDS, and Skim milk could reduce the effects of soil-derived inhibitors that may be co-extracted with DNA during the extraction process, such inhibitors can negatively impact the efficiency of the PCR reaction.
Conclusion : KH2PO4is the most effective additive for increasing the yield of extracted DNA and mitigating the inhibitory effects of soil-derived substances in DNA samples. Therefore, it is a suitable choice for the extraction of DNA from blood samples contaminated with clay soil.
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