Meet The Microbes of Your Home

Written by Emma Loewe: Writer, author, and editor of Cultured. Her writing explores the intersection of nature, climate, and human health. Emma is the author of “Return to Nature” and “The Spirit Almanac.”
Reviewed by Jennie O’Grady: Senior SciComms Specialist at Seed Health

Exiguobacterium, a genus of rod-shaped, yellow-orange bacteria, is a microbial nomad. It’s been discovered in the hot springs of Yellowstone National Park, the frozen ancient vaults of Siberian permafrost—and in the steamy depths of a residential dishwasher.¹ Its species offer a case study in resilience as it’s able to survive pressure, radiation, and salinity that send all other living organisms packing.

Every time you walk in your front door, you’re greeted by remarkable roommates like these—a vast microscopic web that unites your space to some of the most extreme environments on our planet. Let’s get to know these cohabitants, and learn how their adaptations may help us combat issues as huge as climate change and biodiversity loss (yes, really). 

The Microbial World in Your Home

Many fixtures of the average kitchen and bathroom—dishwashers, refrigerators, microwaves—have conditions that mimic the least hospitable environments on Earth. They teeter between humidity and aridness, high heat and freezing temps. As such, they attract microbes that can withstand such extremes, fittingly known as “extremophiles.” 

Where you live, who you live with, your pets, your airflow, and your cleaning habits all shape the exact microbial ambiance of your home.¹⁸ But even if you’re a neat freak, you’re still likely surrounded by thousands of bacterial species at any given time—and that’s a good thing! While a small fraction of bacteria can be pathogenic and lead to infection, the vast majority are harmless. Some even help protect us from autoimmune disorders and allergies—hence why completely sanitizing and disinfecting your home actually isn’t such a great idea. 

As a team of biologists wrote in a 2013 research paper, “No home is without life, the question is simply which life occurs in a given home.”¹⁸

Let’s explore a sampling of the extremophiles that have been found in residential environments, and how their adaptations could help transform our approach to climate, health, sustainability, and beyond.

Coffee Machines: Enterococcus and Pseudomonas

Pop the pods of your Nespresso machine under a microscope after brewing, and you’ll likely spot Enterococcus and Pseudomonas bacteria that are naturally associated with coffee beans and hulls.¹⁹ These hearty microbes survived the journey from the coffee farm to your kitchen, and then somehow managed to withstand the boiling-hot temperatures of the brewing process. Along the way, these resilient java-dwelling organisms also dodged the antibacterial properties of coffee beans themselves.

Outside the home: Away from the home environment, certain types of Pseudomonas bacteria have been proposed for bioremediation projects (which use plants and microbes to reduce environmental pollution).²⁰ Caffeine is a common contaminant in water (detected in over 50% of freshwater samples in some surveys), and it can induce oxidative stress and neurotoxicity in fish and coral.^21,22 In the future, some species of Pseudomonas may prove useful in gobbling it up in the wild and converting it to energy.

Microwaves: Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes

It’s easy to assume that microwaves are sterile but in reality, many types of bacteria have managed to survive their electromagnetic radiation. After collecting samples from the inside of domestic microwaves, microwaves used in shared large spaces (such as in office spaces and cafeterias), and laboratory microwaves, researchers found an assortment of over 100 bacterial isolates—mostly dominated by Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes. Many of these microbial types are also found on human hands, so we likely transfer them to our machines during the food prep process.²³ 

Outside the home: Some thermophiles (bacteria that can survive high heat), like those found in microwaves, may be leveraged to help us study and adapt to climate change-induced temperature increases. They may also prove helpful for the industrial creation of clean energy sources like hydrogen, which require very high temps.²⁴

Dishwashers: Gordonia, Micrococcus, Chryseobacterium, and Exiguobacterium

Like the bacteria in microwaves, those in dishwashers must survive high temperatures. But they also need to evade alternating wet and dry periods, and the presence of detergents. If you add sodium chloride to your dishwasher as a water softener, you’re throwing another hurdle at these microbes: high salt concentrations. Gordonia, Micrococcus, Chryseobacterium, and Exiguobacterium are a few bacterial genera that have been found to withstand all of these harsh conditions.²⁵ 

Outside the home: Certain strains of Gordonia and Chryseobacterium can be harnessed to clean pollutants like petroleum and heavy metals out of the soil in extreme environments like nuclear waste sites.^26,27 

Hot Water Heaters: Thermus scotoductus

One bacterial species, Thermus scotoductus, seems to dominate domestic water heaters.³ These thermophiles can live at temperatures from 112 to 176 degrees Fahrenheit (50 to 80 degrees Celsius) and species of this genus are also known to frequent hot springs.^28,29 Interestingly enough, members of this microbial family don’t die when temperatures dip too low for their liking. Instead, they “freeze” and go dormant in a process called natural cryopreservation.³⁰

Outside the home: The ability of thermophiles to withstand extremely hot (and cold) temperatures is of special interest to astrobiologists who are searching for life on other planets like Mars. (They’re even referred to as microbial “space travelers” in some circles.)³⁰ So, your hot water heater could provide clues about the Martian biosphere. How’s that for a fun fact of the day?

What We Can Learn From This Ecosystem

Clearly, our home is an ecosystem of its own: an arena of ceaseless competition, resilience, and adaptation. This unseen world of the home is not only extraordinary—it’s a frontier for groundbreaking research. 

For example, scientists in our SeedLabs network are investigating how a bacteria that was first identified in soil (a strain of Pseudomonas putida) can help combat the plastic pollution crisis. After finding that the bacteria contained enzymes and catabolic pathways that were capable of degrading polyethylene terephthalate (PET) plastic, researchers studied how to use it in a reaction that converts landfill-bound single-use plastic into a material that can be repurposed for various goods like sneakers or chairs. As proof that the microbes under our feet can be leveraged for world-changing science, this humble soil bacteria was put to work aboard the International Space Station, where a team studied its capacity for biological upcycling of on-board plastic. 

The extremophiles in our homes hold similarly boundless potential. They could catalyze biological and chemical processes that absorb greenhouse gasses from the environment, remediate toxic pollutants, or help solve any number of climate-related threats to our collective future.

Scientists won’t know what these bacteria are capable of until they collect, sample, and analyze them. And to do that, they’ll need your help.

A Call for Community Science

In an effort to collect an array of new extremophiles (and bring cutting-edge science closer to home), Seed is proud to announce The Extremophiles Campaign: In Your Home. This participatory science project is an initiative of our partners The Two Frontiers Project—a research organization specializing in exploring extremophile microbes for the good of people and the planet—and their collaborators at CitSci, a global community science support platform.

The premise is simple: We want our community to participate in exploring the microbial life in extreme environments of their homes by submitting observations of interesting signs of microbial growth. From there, a group will be selected to collect samples of these bacteria to be analyzed by The Two Frontiers Project.

If you’re interested in getting involved, follow this link to sign up for The Extremophile Campaign: In Your Home on the CitSci platform and share information about interesting signs of microbial growth you may have in your home. From there, hang tight: scientists from The Two Frontiers Project will review the submissions and select 100 that are of interest for sampling—based on uniqueness, location, and sample features. 

If your home is chosen, you’ll be shipped a specialized sampling kit and instructed on how to collect and send in your microbes for metagenomic sequencing, to determine their identity and genetic features. Along the way, you’ll get to learn more about the progress of the project and interact with other participants on CitSci’s project dashboard and through regular update emails. In the end, the results will be part of an open-sourced global scientific database of extremophile microbes—your personal contribution to potentially limitless innovation.

The Key Insight

Mary Oliver once asked, “Do you think there is anything not attached by its unbreakable cord to everything else?”³¹ This unbreakable cord also unites the unseen world—connecting the microbes in our home to some of the biggest threats of our lifetimes including the climate crisis. It’s high time to wrangle them out of coffee machines and dishwashers to learn what they can teach us about ecosystems near and far.

The Extremophiles Campaign will allow individuals from across the nation to play a part in this microbiological discovery, proving that science can and should happen anywhere—not just in the lab. Learn more and join in here.

Explore More From The Two Frontiers Project Here:

• A Volcanic Microbe to Capture Carbon
• Can We Combat Climate Change With Microbes?
• The Bacteria That Could Help the World Curb Emissions