Highlights
- •Individual pubic hair microbiomes are gender-biased but can be repeatedly identified from independent samples taken at the same time.
- •The level of intra-individual variation differs between individuals and affects the ability to predict some individuals.
- •Short term storage of pubic hair at various temperatures does not significantly affect the recovered bacterial microbiome.
Abstract
A potential application of microbial genetics in forensic science is detection of
transfer of the pubic hair microbiome between individuals during sexual intercourse
using high-throughput sequencing. In addition to the primary need to show whether
the pubic hair microbiome is individualizing, one aspect that must be addressed before
using the microbiome in criminal casework involves the impact of storage on the microbiome
of samples recovered for forensic testing. To test the effects of short-term storage,
pubic hair samples were collected from volunteers and stored at room temperature (∼20 °C), refrigerated (4 °C), and frozen (–20 °C) for 1 week, 2 weeks, 4 weeks, and 6 weeks along with a baseline sample. Individual
microbial profiles (R2 = 0.69) and gender (R2 = 0.17) were the greatest sources of variation between samples. Because of this variation,
individual and gender could be predicted using Random Forests supervised classification
in this sample set with an overall error rate of 2.7% ± 5.8% and 1.7% ± 5.2%, respectively. There was no statistically significant difference attributable
to time of sampling or temperature of storage within individuals. Further work on
larger sample sets will quantify the temporal consistency of individual profiles and
define whether it is plausible to detect transfer between sexual partners. For short-term
storage (≤6 weeks), recovery of the microbiome was not affected significantly by either
storage time or temperature, suggesting that investigators and crime laboratories
can use existing evidence storage methods.
Keywords
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Article info
Publication history
Published online: October 07, 2016
Accepted:
September 26,
2016
Received in revised form:
September 12,
2016
Received:
July 26,
2016
Identification
Copyright
Published by Elsevier Ireland Ltd.
