Vacuuming may affect our microbiomes

The westernized lifestyle includes something that we often do not realize is a more important part of our life than it was to people hundreds of years ago: cleaning. With newly developed technology, like vacuuming, we are able to maintain cleaner homes, but this has also increased exposure to allergens such as dust mites. Allergens have a proven impact on the immune system of exposed persons, and as we have seen, the microbiome and the immune system are closely linked. The work of certain Norwegian scientists, published by Microbiome, explores the significance of washing and vacuum cleaning on the gut microbiome of mothers and their children.

The study group included 358 mother-child pairs that were included in a controlled non-randomized longitudinal study called IMPACT (Immunology and Microbiology in Prevention of Allergy among Children in Trondheim). Data was tested for the pregnant woman and then their two-year-old children (two years later). Average cleaning frequencies were 2.9 washings and 6.6 vacuum cleanings per month. For pregnant women, increase in Faecalibacterium prausnitzii showed the strongest association with increased vacuum cleaning frequency in once statistical model, while Roseburia faecis was found to have the strongest association in another statistical model. For the 2-year-old children, the Blautia species in one model, and the Oscillospria species in a second model, were identified as significant.

While the results of this study are a bit confusing, the main point is that the indoor household environment, including hygienic behavior, could have a potentially significant influence on the adult gut microbiome. High frequency of vacuuming could increase allergen presence in the air, which, when breathed in, could go on to influence the immune system – and therefore the microbiome. While many other environmental factors could not be controlled for in this study, the results do bring up the possibility of allergen and microbiota association.       

The microbiome of the international space station

Characterization of the microbial composition of the International Space Station (ISS) is a topic that currently interests the National Aeronautics and Space Administration (NASA). The ISS is an interesting environment because it is a built environment that experiences constant human contact, microgravity and space radiation. Understanding the ISS microbial community would help with help and safety concerns as well as proper maintenance of the ISS. Scientists across the United States combined their efforts to properly characterize the microbial community of the ISS, and compared it to cleanrooms on Earth. The results were published by Microbiome.

         Samples were collected from ISS high-efficiently particulate arrestance (HEPA, vacuum cleaner bag components from the ISS, and two cleanrooms at the Jet Propulsion Laboratory (JPL) in Pasadena, CA. Cleanrooms are closed rooms with little human traffic and filtered air. Bacterial and fungal samples were cultured and sequenced using next generation sequencing techniques in order to determine identities. Sixteen fungal strains were isolated from the ISS samples compared to the three strains from JPL samples, with most strains being associated with the phylum Ascomycota. Bacterial samples from the ISS were dominated by Actinobacteria, Bacilli, and Clostridia, while samples from the JPL were dominated by Alphaproteobacteria and Gammaproteobacteria. On a genus level, the two sample environments were completely distinct as well.

         This study shows that the International Space Station has a very distinct microbial community that must be monitored. As we know that the microbiome is so influential on health, it is important that the ISS bacteria are characterized in order to ensure the health and safety of those on board. This is just another important example that the microbiome has a great influence on humans, even from out in space.         

What bacteria live in the gym?

A lot of research goes into understanding the complexity and dynamics of the human microbiome in the GI tract or the mouth, to name a few locations. In an article published by Microbiome, researchers at Northwestern University took a different perspective in that they looked at how the human microbiome affects the environments around us. A very interesting point raised by the article is that Americans spend most of their time in so-called “built environments,” which are indoors. The microbes of these indoor environments are mainly affected by the humans that interact with them, so the scientists at Northwestern University took to studying how the bacterial composition of indoor athletic equipment and facilities are affected. This specific environment was chosen mainly because of the numerous different human encounters it experiences.

For 2 days, the researchers collected swab samples in 3 athletic facilities. Samples were collected every 2 hours from the floor, mats, elliptical handles, free weights, and benches from 8 am to 6 pm, and a total of 356 samples were collected.  After sequencing and analysis, the researchers concluded that, consistent with all three facilities, the bacteria found on the equipment was most likely to be from the human skin, with Pseudomonas and Acinetobacter showing up in the most samples. Besides microbiota from the skin, other bacteria were found to be abundant such as Bacteroides from the human intestinal tract on elliptical handles and Finegoldia, also from the GI tract, on benches.

As for which sampled location had the most stable bacterial community, it was found that the floor and mats showed the least change in structure. This is most likely because elliptical handles, free weights, and benches come in more direct contact with human skin. Across the board, the only genera which were found in all samples from every surface type were Staphylococcus and Pseudomonas. It is important to remember that none of this means athletic facilities are blooming with harmful bacteria, and we should stay far away. In fact, the environment is not very conducive to the thriving of bacteria, because it lacks a lot of resources. What we should take away from this study is that any surface that comes in contact with human skin is likely to reflect the microbiome of that person. 

Home is where the heart...and microbiome is.

A fascinating study was published today in the journal Science that discusses the results of the home microbiome project.   The study tracked 7 families over the course of 6 weeks and sampled the microbiome of their homes, hotel rooms, and everywhere else they resided (3 of the families moved homes in the 6 week period).  They then linked these microbiomes with the hand, nose and feet microbiomes of the people who lived in each space.  The results showed that wherever we go, we take our microbiomes with us.  Basically, when moving to a new home, within days the microbiome of that family is established in the new abode (very rapid!), and was stable thereafter.  These bacteria are not random; they come directly from our hands, feet, and other areas of contact between our bodies and our environment.  Furthermore, there is variation between the microbiomes of each family and their home, meaning that a home microbiome could act as an identifying characteristic (fingerprint) as to who lives there.

Some other notes from the study, the floor microbiomes of our homes vary the most.  If you share a home you have similar hand microbiomes as those you share with.  Couples share more of a microbiome than individuals who are merely living together, but cohabitating does increase similarity in microbiome.

This work, along with many other studies, is happening because of the microbiome of the built environment project (MoBE) created and funded by the Alfred P. Sloan Foundation.   As the United States and world continue the trend towards urbanization it is vital to learn about the microbiome of the environment we create and interact with, and how this can affect our health.  So far the major findings from the MoBE project have demonstrated that the microbiome where we live looks an awful lot like our microbiome!

Editors note: I wonder if this home microbiome contributes to the fact that homes smell differently depending on who lives there?