Toothbrushes and showerheads are full of viruses? The hidden "ecosystem" in the bathroom

When we think of biodiversity, we may picture lush rainforests, vast oceans, or colorful coral reefs. However, surprisingly, there is also an "ecosystem" rich in biodiversity right in our bathrooms!

Today, I would like to share with you a latest study published in Frontiers on October 9, 2024, revealing the world of microorganisms hidden in the bathroom.

This new research started with a simple curiosity: What microorganisms live in our home environment? In our homes, dry surfaces such as tables and walls are not suitable for the survival of microorganisms. So, where do microorganisms like to settle down? The answer is - humid places. Yes, showerheads and toothbrushes are paradise for microorganisms.

Previous studies have found that shower heads and toothbrushes are home to a variety of bacteria. So, in addition to these bacteria, are there other microorganisms? With this question in mind, scientists have begun further exploration.

To answer this question, the researchers conducted metagenomic sequencing on samples of 34 toothbrushes and 92 showerheads from multiple households. So, what is metagenomic sequencing?

Simply put, metagenomic sequencing is an advanced genomics technology that allows scientists to directly extract and analyze the genetic material of all microorganisms from environmental samples without culturing each microorganism. It is like taking a "family portrait" of the entire microbial community, which not only shows the types of microorganisms ("who is present"), but also reveals their functional potential ("what are they doing"), helping us to fully understand the microbial community in the environment.

If traditional sequencing is like reading a specific chapter in a book, then metagenomic sequencing is more like scanning all the books in the entire library at once without a catalog and trying to organize the information. This not only saves time, but also gives us the opportunity to discover "rare books" that we have never known before.

The results were astounding: a total of more than 600 bacteriophages were found in these samples! So, what are bacteriophages?

In simple terms, bacteriophages are viruses that specifically infect and kill bacteria, and are the "natural enemies" of bacteria. They can attach to the surface of bacteria, inject their own genetic material into the cells, hijack the bacterial cell machinery to replicate themselves, and eventually cause the bacterial cells to lyse and die.

What's even more interesting is that the types of phages on each showerhead and toothbrush are almost unique. In other words, the microorganisms on your showerhead may be completely different from those on my showerhead. There is very little overlap between any two samples, which means that each family's bathroom is like an isolated microbial "island" with its own unique microbial ecosystem.

This high diversity makes scientists realize that there may be more phages that have not yet been discovered. This is of great significance for our understanding of microbial ecosystems and the development of new biotechnologies.

Among the many phages found, the researchers were particularly interested in a type that infects mycobacteria. This type of phage was found in higher numbers in the samples. The mycobacterium genus includes a variety of bacteria, some of which are pathogenic bacteria that cause tuberculosis, leprosy, and other chronic lung infections. If we can gain a deeper understanding of the functions of these mycobacterial phages, it may help develop new ways to fight these pathogens.

For example, in recent years, phage therapy has received increasing attention as an alternative method for treating bacterial infections. Phages may become an effective "weapon" for bacteria that are resistant to antibiotics. If we can use these phages to specifically eliminate pathogenic bacteria, it will have a profound impact on the medical field.

Hearing this, you may ask, will there be any harm to our health if there are so many viruses on the shower heads and toothbrushes at home?

In fact, there is no need to worry. First of all, these bacteriophages are specifically designed to infect bacteria and are not a threat to human cells. They do not cause disease in the human body. Secondly, microorganisms are everywhere. There are a large number of microorganisms living on our skin, in our mouths, and in our intestines. They live in harmony with us and are even essential to our health.

Although microbes coexist with us, good hygiene habits are still important. Here are some simple tips:
First, if you want to clean your shower head, you can soak it in vinegar to help remove scale and some microorganisms, or just wash it with ordinary soap and water;
Second, it is recommended to replace the toothbrush every three months, or when the bristles are worn;
Third, there is no need to use strong disinfectants or "antibacterial toothbrushes". Excessive disinfection may disrupt the balance of microorganisms and may promote the emergence of antibiotic-resistant bacteria.

Through this study, we know that there is such a rich microbial world hidden in our seemingly ordinary daily environment. Perhaps it is these tiny lives that constitute an indispensable part of our lives. Next time you walk into the bathroom, think about it: how many unknown stories are hidden in the corners we can't see, waiting for us to discover?

Paper link:
https://www.frontiersin.org/journals/microbiomes/articles/10.3389/frmbi.2024.1396560/full

This article is a work supported by the Science Popularization China • Creation Cultivation Program

Author: Lv Tongzhou

Reviewer: Liang Qianjin, Professor of School of Life Sciences, Beijing Normal University

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.