Household microbiomes are communities of microorganisms that inhabit the surfaces and environments within your home. According to recent research published in the Frontiers in Microbiology journal,1 certain surfaces and environments in your household harbor diverse communities of bacteriophages.
Showerheads and toothbrushes are particularly significant as they serve as constant habitats for these microbes, creating glue-like communities — called “biofilms” — where these tiny organisms thrive.2 The microbes found in these surfaces play a crucial role in shaping the balance between beneficial and harmful bacteria in your home, and could have direct implications for your health and well-being.
The interactions between bacteriophages and bacteria in your household items could suppress pathogenic bacteria and promote a healthier living environment. Moreover, these findings challenge the conventional perception of microbes as solely harmful invaders, highlighting their life-saving advantages.
How Indoor Microbiomes Shape Our Health
Indoor environments play a significant role in influencing human health through the complex communities of microorganisms they harbor. Research has consistently shown that your home, workplace and public spaces are teeming with bacteria and viruses that impact your well-being.3 However, most studies have primarily concentrated on bacterial populations, often overlooking the viral counterparts that coexist with them.
Bacteriophages, or phages, are the natural enemy of bacteria; they are tiny, tripod-looking viruses that specifically infect bacteria. These phages act by hunting, attacking and gobbling up bacterial species, making them essential in regulating pathogenic bacteria populations.4
Phages contribute to microbial diversity by controlling which bacteria thrive and which die off.5 The dynamics between phages and their bacterial hosts reveals how microbial communities maintain balance and resist the overgrowth of harmful bacteria, and advancing our knowledge of phage interactions within household biofilms allows for the creation of new, innovative approaches in health and sanitation.
By exploring these viral communities, scientists aim to uncover new ways to promote beneficial microbes and suppress pathogens, ultimately enhancing the cleanliness and safety of our daily environments.6 This research fills a crucial gap, providing insights that could transform how we manage indoor microbial ecosystems for better health outcomes.
Uncovering Hidden Guardians in Your Bathroom
To explore their hypothesis, the researchers used metagenomic sequencing, a powerful technique that deciphers genetic material from environmental samples. By analyzing 34 toothbrush and 92 showerhead samples, they aimed to identify and characterize the viral populations present.
The results were striking — a vast diversity of novel phages emerged, many of which had never been documented before. The researchers identified a total of 616 high-quality viral operational taxonomic units (vOTUs), within biofilms from showerhead and toothbrush samples. These vOTUs represent distinct groups of bacteriophages, each interacting with specific bacterial hosts.
The sheer number of unique viral sequences highlights the complexity and richness of the viral communities in everyday household items. Erica M. Hartmann, an indoor microbiologist and the study’s lead author said:7
“The number of viruses that we found is absolutely wild. We found many viruses that we know very little about and many others that we have never seen before. It’s amazing how much untapped biodiversity is all around us. And you don’t even have to go far to find it; it’s right under our noses.”
These initial findings not only highlighted the complexity of indoor microbiomes but also set the stage for deeper investigations into how these phages influence bacterial populations.
Showerheads and Toothbrushes Have Distinct Types of Phages
The featured study stems from previous research,8 also led by Hartmann, along with her colleagues from the University of Colorado, that was published in the Microbiome journal in 2021. Dubbed “Operation Pottymouth,” the researchers identified how flushing a toilet spreads bacteria to toothbrushes and showerheads.
“This project started as a curiosity. We wanted to know what microbes are living in our homes. If you think about indoor environments, surfaces like tables and walls are really difficult for microbes to live on. Microbes prefer environments with water. And where is there water? Inside our showerheads and on our toothbrushes.”9
In the latest study, Hartmann and her team found that viral communities in showerheads and toothbrushes are distinct from one another. No single vOTU was found across all samples, and the most abundant phages differed between the two household items.10 This distinction reflects the specialized environments each item provides.
Showerheads, which are less frequently in direct contact with humans, harbor phages linked to environmental bacteria, such as those from water sources.11 In contrast, toothbrushes, constantly exposed to the human oral microbiome, contain phages associated with oral bacteria, like Streptococcus and Veillonella.12 These phages are likely involved in maintaining a balanced microbiome that prevents the overgrowth of pathogenic species.
This means that even within the same household, different items cultivate unique viral ecosystems. The lack of shared vOTUs between showerheads and toothbrushes emphasizes the role of specific environmental conditions and microbial sources in shaping viral communities.
Another significant finding of the study is the positive correlation between viral richness and bacterial richness in household biofilms. This means that areas with a higher variety of bacterial species also tend to have a greater diversity of bacteriophages.13
Interestingly, while viral richness aligns with bacterial richness, the distribution of phage abundance across these species does not follow the same pattern. Basically, having more types of bacteria leads to more types of phages, but it doesn’t necessarily mean that the phages are evenly spread among all bacterial hosts.
These findings highlight the uniqueness of each microbial habitat within your home, driven by factors like how they’re used and exposed to different bacterial sources.
“There’s just an enormous amount of microbial diversity. And for every bacterium, there’s potentially tens or hundreds or even thousands of viruses that infect it,” Hartmann said.14
Novel Phages Discovered in Household Microbiomes
Another notable discovery from this research is the identification of numerous novel phages, which could possess unique functions and interactions that are not yet understood. The presence of these novel phages suggests that household microbiomes are more complex and diverse than previously thought.
A third intriguing finding was the presence of Mycobacteriophages in showerhead samples.15 These viruses specifically target Mycobacterium species, some of which are pathogenic to humans, indicating a natural mechanism for controlling harmful bacteria in these environments.
This could mean phages are able to act as biological agents that manage and reduce the presence of pathogenic bacteria, thereby enhancing household hygiene and reducing the risk of infections.
The researchers also found no evidence of harmful antibiotic resistance or virulence genes within the identified phages.16 This finding is reassuring, because that means these household phages are not spreading harmful traits to bacteria. They merely control bacterial populations, without introducing additional threats.
These phages could also be used for future biotechnological applications, like phage therapy, helping target and eliminate specific harmful bacteria without the risk of exacerbating antibiotic resistance.
“There’s interest in designing maybe more sophisticated drugs, so that instead of taking a broad-spectrum antibiotic and wiping out your entire microbiome, you would be able to take this drug that would only affect the pathogen and leave the rest of your microbiome intact,” Hartmann said.17
How Do These Findings Impact Today’s Society?
The presence of life-saving bacteriophages in everyday household items like showerheads and toothbrushes holds significant implications for public health. By naturally regulating bacterial populations, these phages help reduce the prevalence of harmful bacteria, lowering the risk of infections and illnesses inside your home.
Another advantage is the development of new sanitation strategies that maximize phages. It could help identify methods that eliminate the need for chemical disinfectants that disrupt beneficial microbes, for example.18
Understanding the intricate relationships between phages and bacteria also helps foster environments that support beneficial microbial communities. For instance, materials and surfaces that encourage the growth of health-promoting phages could be integrated into home designs, providing natural defense mechanisms against harmful pathogens without chemical solutions.19
The biotechnology sector also takes advantage of these findings, paving the way for phage-based therapies and products, such as targeted cleaning and sanitation agents, as well as medical treatments.20,21 Importantly, phage-based solutions could be implemented in healthcare facilities to minimize the risk of hospital-acquired infections and reduce antibiotic use.22,23
How to Utilize the Life-Saving Microbiomes in Your Home
The discovery of life-saving microbes in everyday household items like showerheads and toothbrushes marks a significant shift in our understanding of indoor environments. This research reveals the complex and vital role that bacteriophages play in maintaining healthy microbial ecosystems within our homes.
By incorporating microbiome-friendly practices into your daily cleaning routine, you will help beneficial microbes to thrive. Simple changes, such as using natural, nontoxic cleaning products and ensuring thorough drying of showerheads and toothbrushes, help maintain a healthier balance of phages and bacteria.24
The use of household air and water filters significantly influences indoor microbiomes. Installing a high-quality water filter limits environmental bacteria in showerheads, allowing beneficial phages to manage bacterial populations effectively.25 Similarly, air purifiers with microbial filters reduce airborne bacteria, promoting a stable indoor microbiome.26
“Microbes are everywhere all the time … We wouldn’t be able to digest our food or fend off infection if we didn’t have our microbes.” Hartmann said.
“As much as we might initially react with a little ick factor, I think it’s really important to approach the microbial world with a sense of wonder and curiosity that these are actually things that do an enormous amount of good and potentially harbor an enormous potential for biotechnology.”27
