Bacterial Profiling of Soil For Forensic Investigations: Consideration of Ex Situ Changes in Questioned and Known Soil Samples |
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Authors: | David R Foran PhD Alyssa J Badgley MS |
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Institution: | 1. Forensic Science Program, School of Criminal Justice and Department of Integrative Biology, Michigan State University, 655 Auditorium Road, 560 Baker Hall, East Lansing, MI, 48824;2. Forensic Science Program, School of Criminal Justice, Michigan State University, 655 Auditorium Road, 560 Baker Hall, East Lansing, MI, 48824 |
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Abstract: | Soil, being diverse and ubiquitous, can potentially link a suspect or victim to a crime scene. Recently scientists have examined the microbial makeup of soil for determining its origin, and differentiating soil samples is well-established. However, when soil is transferred to evidence its microbial makeup may change over time, leading to false exclusions. In this research, “known” soils from diverse habitats were stored under controlled conditions, while evidence soils were aged on mock evidence. Limited quantities of soil were also assayed. Bacterial profiles were produced using next-generation sequencing of the 16S rRNA gene. Overall, known soils stored open at room temperature were more similar to evidence soils over time than were known soils stored bagged and/or frozen. Evidence soils, even as little as 1 mg, associated with the correct habitat 99% of the time, accentuating the importance of considering ex situ microbial changes in soil for its successful use as forensic evidence. |
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Keywords: | forensic science forensic soil analysis bacterial profiling soil microbial profiling taxonomic abundance chart nonmetric multidimensional scaling bagged trees random forest |
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