Mitochondrial DNA Extraction from Burial Soil Samples at Incremental Distances: A Preliminary Study

Area of Science:

• Forensic Science
• Molecular Biology
• Environmental DNA (eDNA)

Background:

• Soil DNA preservation and degradation rates are understudied.
• Previous research may overestimate the persistence of DNA in environmental samples.

Purpose of the Study:

• To investigate the persistence of Sus scrofa domesticus (domestic pig) DNA in soil.
• To determine the timeframe for detectable mitochondrial DNA fragments in open-air decomposition scenarios.

Main Methods:

• Amplification of a 212 bp mitochondrial fragment from soil samples around decomposing pig remains.
• Sampling at 145 days and again at 768 days post-burial.
• Conducting inhibition tests to assess DNA presence and quality.

Main Results:

• Pig DNA was detected in soil samples collected 145 days after decomposition began.
• No pig DNA was detectable 768 days after burial, indicating significant degradation.
• Inhibition tests confirmed the absence of amplifiable pig DNA at the later time point.

Conclusions:

• Genetic material leaches radially from the source in soil.
• DNA fragments exceeding 200 bp have a limited persistence in soil, particularly in western Montana.
• Soil DNA analysis for forensic purposes should prioritize samples collected within the initial months of decomposition.