Microbial DNA in Human DNA Extracts: Recoverability of the Microbiome in DNA Extracts Stored Frozen Long-Term and its Potential and Ethical Implications for Forensic Investigation

Sguazzi, Giulia, Mickleburgh, Hayley L., Ghignone, Stefano, Voyron, Samuele, Renò, Filippo, Migliario, Mario, Sellitto, Federica, Lovisolo, Flavia, Camurani, Giulia, Ogbanga, Onengiye, Gino, Sarah and Procopio, Noemi (2022) Microbial DNA in Human DNA Extracts: Recoverability of the Microbiome in DNA Extracts Stored Frozen Long-Term and its Potential and Ethical Implications for Forensic Investigation. Forensic Science International: Genetics, 59. p. 102686. ISSN 1872-4973

1-s2.0-S1872497322000278-main.pdf - Published Version
Available under License Creative Commons Attribution 4.0.

Download (2MB) | Preview
Official URL: https://doi.org/10.1016/j.fsigen.2022.102686


Human DNA samples can remain unaltered for years and preserve important genetic information for forensic investigations. In fact, besides human genetic information, these extracts potentially contain additional valuable information: microbiome signatures. Forensic microbiology is rapidly becoming a significant tool for estimating post-mortem interval (PMI), and establishing cause of death and personal identity. To date, the possibility to recover unaltered microbiome signatures from human DNA extracts has not been proven. This study examines the microbiome signatures within human DNA extracts obtained from six cadavers with different PMIs, which were stored frozen for 5 – 16 years. Results demonstrated that the microbiome can be co-extracted with human DNA using forensic kits designed to extract the human host’s DNA from different tissues and fluids during decomposition. We compared the microbial communities identified in these samples with microbial DNA recovered from two human cadavers donated to the Forensic Anthropology Center at Texas State University (FACTS) during multiple decomposition stages, to examine whether the microbial signatures recovered from “old” (up to 16 years) extracts are consistent with those identified in recently extracted microbial DNA samples. The V4 region of 16S rRNA gene was amplified and sequenced using Illumina MiSeq for all DNA extracts. The results obtained from the human DNA extracts were compared with each other and with the microbial DNA from the FACTS samples. Overall, we found that the presence of specific microbial taxa depends on the decomposition stage, the type of tissue, and the depositional environment. We found no indications of contamination in the microbial signatures, or any alterations attributable to the long-term frozen storage of the extracts, demonstrating that older human DNA extracts are a reliable source of such microbial signatures. No shared Core Microbiome (CM) was identified amongst the total 18 samples, but we identified certain species in association with the different decomposition stages, offering potential for the use of microbial signatures co-extracted with human DNA samples for PMI estimation in future. Unveiling the new significance of older human DNA extracts brings with it important ethical-legal considerations. Currently, there are no shared legal frameworks governing the long-term storage and use of human DNA extracts obtained from crime scene evidence for additional research purposes. It is therefore important to create common protocols on the storage of biological material collected at crime scenes. We review existing legislation and guidelines, and identify some important limitations for the further development and application of forensic microbiomics.

Item Type: Article
Additional Information: Funding information: This work was supported by UKRI through a Future Leaders Fellowship [MR/S032878/1] awarded to Noemi Procopio; and partially by the Universit`a del Piemonte Orientale [FAR 2017] to Filippo Ren`o, Mario Migliario and Sarah Gino. The taphonomic experiments at FARF were supported by the European Research Council under the European Union’s Seventh Framework Program (FP7/2007-2013)/ERC Synergy grant agreement no. 319209, the Leiden University Fund Byvanck grant number 5604/30-4-2015/Byvanck, and the 2017 Royal Netherlands Academy of Arts and Sciences (KNAW) “National Postdoc Prize” awar- ded to Hayley Mickleburgh.
Uncontrolled Keywords: Microbiome, Forensic genetics, Cold cases, Metabarcoding, Cadaveric decomposition, Storage guidelines
Subjects: C400 Genetics
C700 Molecular Biology, Biophysics and Biochemistry
Department: Faculties > Health and Life Sciences > Applied Sciences
Depositing User: Elena Carlaw
Date Deposited: 16 Mar 2022 11:47
Last Modified: 05 Apr 2022 09:00
URI: http://nrl.northumbria.ac.uk/id/eprint/48682

Actions (login required)

View Item View Item


Downloads per month over past year

View more statistics