Application of Microbiome in Forensics

Recent advances in next-generation sequencing technologies and improvements in bioinformatics have expanded the scope of microbiome analysis as a forensic tool.Microbiome research is concerned with the study of the compositional profile and diversity of microbial flora as well as the interactions between microbes,hosts,and the environment.It has opened up many new possibilities for forensic analysis.In this review,we discuss various applications of microbiome in forensics,including identification of individuals,geolocation inference,and post-mortem interval(PMI)estimation.

Inferring the Postmortem Interval of Rat Cadaver after Boiling Water Treatment Based on Microbial Community Succession

Background:In forensic investigations,accurate estimation of the postmortem interval(PMI)is an important task,but also an ongoing challenge.Especially in cases where the cadaver has been specially treated,for example,by boiling,the determination of PMI becomes extremely difficult.Previous studies have shown that the succession of the microbial community after decomposition of the cadaver can be used to infer PMI.However,the feasibility of determining the PMI of boiled cadavers has not yet been demonstrated.Aims and Objectives:The main objective of this study was to test whether we can infer PMI of boiled cadavers based on the succession of microbial communities.Materials and Methods:SD rats were killed by cervical dislocation.Subsequently,the rat cadavers were divided into the case(boiled cadavers)and control(unboiled cadavers)groups.Rectal samples were collected from the rats for 45 days and at nine time points.High-throughput sequencing of the 16S rRNA gene was performed to characterize the microbial community in the rectum.Results:The results showed that the composition and relative abundance of bacterial communities at the phylum level were significantly different between the case and control groups.The alpha diversity of the microbial community showed a decreasing trend with the decomposition process.Principal coordinate analysis showed that the case and control groups had obvious patterns along the succession of microbial communities.The rectal microbial communities showed a significant linear trend in the time course of decomposition.A random forest model was used to infer PMI.The goodness-of-fit(R2)of the model was 68.00%and 84.00%,and the mean absolute errors were 2.05 and 1.48 days within 45 days of decomposition for the case and control groups,respectively.Conclusions:Our results suggest that microbial community succession could be a potential method to infer PMI of boiled cadavers.

Sequencing of human identification markers in an Uyghur population using the MiSeq FGx^(TM) Forensic Genomics System

Massively parallel sequencing(MPS)offers a useful alternative to capillary electrophoresis(CE)based analysis of human identification markers in forensic genetics.By sequencing short tandem repeats(STRs)instead of determining the fragment lengths by CE,the sequence variation within the repeat region and the flanking regions may be identified.In this study,we typed 264 Uyghur individuals using the MiSeq FGx^(^(TM)) Forensic Genomics System and Primer Mix A of the ForenSeq^(^(TM)) DNA Signature Prep Kit that amplifies 27 autosomal STRs,25 Y-STRs,seven X-STRs,and 94 HID-SNPs.STRinNGS v.1.0 and GATK 3.6 were used to analyse the STR regions and HID-SNPs,respectively.Increased allelic diversity was observed for 33 STRs with the PCR-MPS assay.The largest increases were found in DYS389II and D12S391,where the numbers of sequenced alleles were 3–4 times larger than those of alleles determined by repeat length alone.A relatively large number of flanking region variants(28 SNPs and three InDels)were observed in the Uyghur population.Seventeen of the flanking region SNPs were rare,and 12 of these SNPs had no accession number in dbSNP.The combined mean match probability and typical paternity index based on 26 sequenced autosomal STRs were 3.85E36 and 1.49Eþ16,respectively.This was 10000 times lower and 1000 times higher,respectively,than the same parameters calculated from STR repeat lengths.

Recent Developments in Forensic DNA Typing

The field of forensic DNA typing,often referred to as“DNA fingerprinting,”has evolved and expanded considerably since its beginnings in the mid-1980s.Originally,forensic DNA typing was primarily used for individual identification and criminal investigations,but it has evolved into a versatile discipline with a wide range of applications.This article addresses the growing scope of forensic genetics,which includes advances in DNA sequencing technologies,mixture analysis,body fluid identification,phenotypic profiling,forensic genealogy,microbiological analysis,exploration of novel markers,and ethical and legal considerations.These developments have enabled the analysis of difficult samples and provided comprehensive insights into the origins of biological evidence.In an ever-evolving landscape,forensic genetics continues to shape the future of forensic science by providing new tools and techniques that help deliver justice in an increasingly complex world.