The skin is the largest human organ, and it plays host to a diverse collection of microorganisms, collectively known as the skin microbiome. Multiple factors affect the composition of the skin microbiome, but a core group of microorganisms tend to remain fairly stable. Understanding the interaction between the skin microbiome and skin cells has guided key discoveries in fields from cosmetology to dermatology.
Now, the skin microbiome is showing promise in yet another field—that of human identification, especially in situations when human DNA is of low quantity.
In this interview, Allison Sherier summarizes previous studies that have shown the skin microbiome composition remains relatively stable for up to 3 years. It is also an abundant source of DNA: a skin swab typically contains DNA equivalent to only four human diploid cells but enough microbial DNA to allow accurate identification. For casework samples, microbial DNA profiling can provide valuable information that complements human DNA profiling.
For Sherier’s project, the research team collected skin swabs from the non-dominant hand of 51 individuals in triplicate, extracted DNA, enriched the samples prior to library preparation, and sequenced the libraries. The data were analyzed to classify unknown samples to the individual that they most resembled. The accuracy of classification ranged from 88% to 95%, suggesting that AIMs in targeted microorganisms can improve the accuracy of human identification.
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