Did you know that humans contaminate a house, more than the other way round?
US scientists compared bacteria from home surfaces with the families that lived there using genomic sequencing.
They found bacteria from home surfaces matched the family living there, with most of the bacteria coming from human skin.
In blinded tests, floor samples easily predicted the family living there.
When people moved house, the bacteria went with them, indicating that household bacteria come from its human inhabitants.
Also, if a family member was absent for a few days, the microbial communities in the house rapidly changed to reflect that.
This study shows that humans influence (contaminate) the microbiome of a house more than the other way round.
Forensics might soon be able to match bacteria from a crime scene to a suspect.
Do you want more information?
Background
There are 10 times as many bacteria on a human body than human cells. – Bacteria (prokaryotes) are much smaller than human cells (eukaryotes).
They line all body surfaces, including skin, digestive tract and genitals.
Bacteria also make up about half the mass of poo.
There are up to 10,000 different species of bacteria on humans and these populations are different for each human (‘microbial fingerprint’).
Skin-to-surface contact can transfer millions of bacteria per event.
Materials and Methods
US researchers measured bacteria associated with seven families and their homes. 1625 samples were taken from hands, noses, feet, floors, door knobs, light switches, kitchen benches and pets. The amount and type of bacteria was identified by genomic sequencing.
Results
Microbial samples from home surfaces matched the family living there.
Most of the bacteria come from human skin.
In blinded tests, floor samples easily predicted the family living there.
Three families moved house during the test period and the microbial communities in both houses were similar, indicating that household bacteria come from its human inhabitants.
If a family member was absent for a few days, the microbial communities changed to reflect this. This indicates the microbiome changes rapidly.
In one house, a couple in a relationship shared with a housemate. The couple had a more similar microbial signature with each other than with the housemate, indicating frequent sharing of bacteria (e.g. kissing).
The hand has a particularly high microbiome turnover rate, probably due to hand washing that resets the communities frequently.
Discussion
This study shows humans influence (contaminate) the microbiome of a house more than the other way round.
Forensics might soon be able to match bacteria from a crime scene to a suspect.
Article
Longitudinal analysis of microbial interactions between humans and the indoor environment
Lax et al., 2014 Science 345:1048-52
Keywords
Bacteria, germs, microbiome, microbial, prokaryote, eukaryote, skin, contaminate, forensic, human, family, house, home
Subject
Science, Biology, Microbiology, ST1-11LW, ACSSU211, SC4-15LW, ACSSU112