Extraction of Human DNA from Soil: Protocol Adaptations

TL;DR

This study adapts and evaluates three existing DNA extraction protocols to improve recovery of human DNA from soil samples, addressing challenges like humic acid interference in forensic and archaeological contexts.

Contribution

It introduces modified protocols specifically optimized for extracting human DNA from soil, filling a gap in forensic and archaeological DNA analysis methods.

Findings

Protocols successfully extract human DNA from soil samples.

Humic acids inhibit PCR but can be mitigated with protocol adjustments.

Enhanced extraction methods improve DNA yield and purity.

Abstract

PCR-based analysis of DNA is utilized in a wide variety of fields, including Forensic Science. Aside from the more common ample sources, material analyzed here can refer to specimen excavated from a soil environment, or a sampling of the soil itself to recover DNA leached into the soil from decomposing human remains or from body fluids intermingled with the soil in an outdoor crime scene. The common problematic of these types of sample is the presence of humic acids, which are a component of any soil environment, and when the co-extracted with the DNA, lead to inhibition of enzyme-based procedures including PCR. While a variety of methods exist for the extraction of DNA from excavated skeletal remains, protocols for extraction of DNA from the soil directly are usually targeting soil microorganism. To address the need for methodology suitable for extraction of human DNA from soil, a selection of three published protocols were adapted for this purpose, to be tested and evaluated using standardized samples. The resulting protocols are presented here.