Do you think of your body as a habitat? Have you ever considered the multitudes of microscopic organisms that colonize your skin? Most of us don’t, but the truth is that you are a teeming ecosystem of bacteria and other microbes. Even more, each person has a distinctive ‘fingerprint’ associated with their own unique microbiome, or the ecosystem found on their person.
However, you also impact the environment you occupy; your house is covered in your own microbes, and so is anyone else who lives with you- even your pets. In fact, you’re also covered in their bacteria. Entire families can be linked by the microbial communities found on their skin, and their houses associated by finding the same communities on inanimate objects. About 77% of the time, a person’s bacterial signature can be matched to their house accurately!
A person’s individual microbial signature is most distinct within the nose and least on the hands. On average, about a third of a person’s skin microbiome is the same as that of surfaces within their house, though this can rise or fall depending on the individuals and areas sampled. Merely by existing in a space, you spread your own microbial fingerprint. Conversely, the longer you are away from an area, the weaker this fingerprint is on an area.
Of course, the big question- can any of the bacteria in my house hurt me? This study found that your hands actually have the highest chance of carrying microbes that can make you sick, and that’s because your hands touch the most surfaces in your house. Countertops were found to have more potentially harmful types of bacteria than any other surface in a house.
Knowing this, scientists can apply knowledge of microbes to assess the spread of disease, individual health, and the impact of humans on bacterial diversity. Since an increasing number of people are spending time indoors and at home, understanding the spread of bacteria in the context of health in our homes and how our actions serve to spread our signature to our environment and to others.
Recent investigations into the microbial communities in human-made environments have revealed the composition of such environments to be directly linked to the occupants of each space, human and animal alike. Utilizing 16S rRNA amplicon sequencing, the microbial communities from numerous surfaces within homes and on human occupants were characterized and compared to identify patterns.
In this study, 1625 samples yielded 21,997 OTUs over a 4-6 week period. Several of the families moved during the period of the study; when this occurred, samples were obtained from both the old and new spaces. Analysis of similarities (ANOSIM) differentiation was used to compare differences between surfaces, humans, and pets within and between the homes studied.
Within each study area, humans were the greatest contributors to bacteria found on surfaces. Actinobacteria and Proteobacteria, two major components of human skin flora, dominated such samples. Between humans, the soles of the feet were found to contain the most unique OTUs, while the palms of the hands were least distinct.
It was found that a person’s skin sample could be matched to commonly accessed surfaces within their house 76.7% of the time, demonstrating not only that microbial communities in homes are significantly more similar to those of their occupants, but that colonization can occur rapidly. Additionally, the longer an occupant was not within the area, the less their own microbial signature could be detected in samples. This may indicate rapid turnover of bacteria or demonstrate how significant the contribution of microbial transfer from skin to surfaces is within a space.
The study also looked briefly into microbes with pathogen potential by utilizing shallow shotgun metagenomic sequencing. Corynebacterium was found on all humans, with Enhydrobacter-, Streptococcus-, and Enterobacter-like bacteria found on surfaces around the house, especially on countertops. Close matches for Pantoea agglomerans and Acinetobacter baumannii were also observed in kitchen samples. Hand samples were found to have the greatest potential for pathogenic bacteria, sharing the greatest similarity with countertops.
Better understanding the impact of humans upon the microbiome in environment they occupy and how these microbes are distributed and spread is a crucial and understudied facet of human health. This study works to look into the origins and patterns of such communities, with intriguing discoveries with applications in healthcare and microbial analysis.
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