Microbiome
Definition
The total community of microorganisms (bacteria, archaea, fungi, viruses) inhabiting a body site, along with their collective genetic material. Each body site has a characteristic microbiome shaped by local pH, moisture, nutrients, and immune factors.
- Community members
- Bacteria, archaea, fungi, viruses
- Variation
- Characteristic composition per body site
- Shaping factors
- pH, moisture, nutrients, immune factors
- Forensic use
- Body fluid source identification
Common questions
Why is microbiome composition useful for identifying a body fluid?+
Because saliva, vaginal secretions, skin, and gut each host a distinct and reproducible mix of dominant bacterial taxa, a stain's microbial profile can be matched against reference community signatures to infer which fluid deposited it.
What limits microbiome-based identification in casework?+
Individual diet, health, and environment cause real variation between people at the same body site, and degradation or contamination of a stain can shift the detectable community, so results are interpreted as probabilistic rather than absolute.
Related terms
- 16S rRNA Gene
- The gene encoding the 16S ribosomal RNA subunit present in all bacteria and archaea. Conserved regions allow universal amplification; hypervariable regions (V1-V9)...
- Amplicon Sequencing
- A sequencing approach where a specific locus (here the 16S hypervariable region) is amplified from all members of a microbial community and...
- Community State Type (CST)
- A classification of vaginal microbiome profiles into distinct clusters. Most CSTs are dominated by a single Lactobacillus species; one CST (often called...
- OTU / ASV
- Operational Taxonomic Unit (OTU) and Amplicon Sequence Variant (ASV) are the units of microbial diversity in 16S data. OTUs cluster reads at...
- Shotgun Metagenomics
- Sequencing all DNA in a sample rather than just the 16S amplicon. Provides taxonomic resolution beyond 16S and can characterise viruses and...