A bottle of bacterial spores is not what you’d expect to find in the home care aisle of your local supermarket. But live microbes are the hot ingredient in the cleaning product industry right now.
Of course, microbes are in us, on us, and around us—our constant microscopic companions. Without them we become malnourished and sickly.
Outside our bodies, they do all sorts of useful chemical work. Lactic acid bacteria turn milk into yogurt, complex microbial consortia in wastewater treatment plants clean up humanity’s most repulsive messes, and precision fermentation is often cited as the next frontier in specialty chemical production.
Home care, though, is a new place for microbes to bloom. A wave of products hitting the market say they will deliver a deeper clean and a healthier domestic microbiome—if consumers can be persuaded to intentionally seed their homes with beneficial bacteria.
These aren’t just any old bugs. According to John Harp, deployment team lead for microbial cleaners at the microbe and enzyme maker Novozymes, the species being rolled out in cleaning products are Bacillus and Lactobacillus bacteria isolated from natural environments including soil, waterways, and animal microbiomes.
A good microbial janitor has two main characteristics, Harp says. First, it needs to excrete enzymes in large quantities. The enzymes do the heavy cleaning, catalytically breaking down recalcitrant soil materials such as grease, starch, and protein into small chunks that the bacteria can absorb and eat.
The other feature Harp looks for is the ability to form spores. In response to stresses such as starvation or exposure to certain chemicals, some bacteria grow one or more protective outer layers and go dormant. When such bacteria are blended into a cleaning product, the spores are able to survive rough handling, long storage, formulation with surfactants and preservatives, and other conditions that would kill them in their active form.
“Once the right signals are in place—and usually those signals are nutrients, some water, and a good temperature—they will transition from that spore form into the vegetative form, which is where they’re active and where they can secrete enzymes,” Harp says. With a hard-surface cleaner, that transition happens when the spores get lodged in microscopic nooks and crannies alongside dirt and grime that conventional cleaning ingredients leave behind.
The art for microbe providers is in finding the species and strains that form robust spores but then crank out enzymes in their active form, Harp says. The right ones are usually Bacillus bacteria. The species being used are classified by the US Centers for Disease Control and Prevention (CDC) as biosafety level 1. That designation means they pose low risk to personnel and the environment and are highly unlikely to cause disease in healthy laboratory workers, animals, or plants, according to the CDC. For example, bread yeast is biosafety level 1.
The microbial cleaner category is maturing quickly, but one of the most unsettled things about the segment is what to call the microbes. They can be called probiotics, a consumer-friendly term for beneficial microbes, but most probiotics today are in food products such as yogurt and kombucha. The cleaning industry is anxious about anything that could conflate food and floor cleaner in the public mind.
The American Cleaning Institute (ACI), an industry group, strongly urges its members to use the word microbial. “We’re not a fan of using the term probiotic to label the organisms that we use in cleaning products, because the product is not meant for ingestion,” explains James Kim, ACI’s vice president for science and regulatory affairs. “I think there’s a danger in conveying a message to consumers that these are in some ways similar to any sort of nutritional supplement.”
Despite the ACI’s urging, probiotic has a narrow lead among products on the shelf now. That may be because edible probiotics have paved the way to consumers’ increasing comfort with the idea of beneficial microbes, says Brandon Beyer, global manager for cleaning application development at the chemical distributor Univar Solutions.
Paired with a strong sustainability story—replacing petrochemicals with naturally derived microbes—that comfort is a big part of why microbials are claiming a growing share of the market for green home care products. In the next 5–10 years, “I think it’s gonna be a hockey stick in terms of growth,” Beyer says.
In fact, the growth is already strong, according to Annie Morris, editor in chief of Made in CA, a Canadian consumer product magazine and economic data group. “With consumers increasingly looking for natural, nontoxic cleaning solutions, microbial probiotics have become a popular choice,” she says. “This trend is likely to continue growing rapidly in the coming years.”
The consumer interest has been tempered so far by high prices and limited availability, Morris says. A 650 ml spray bottle of Reckitt Benckiser’s Veo brand all-purpose microbial cleaner sells for $20 in Walmart’s online store, for example, while garden-variety all-purpose cleaners generally run about $5. “As with any new technology, it can often be difficult to scale production and bring down materials and production costs,” Morris says.
Another challenge is the pace of microbial cleaning. Bacteria do their work on the order of hours, days, or even weeks. That speed wouldn’t satisfy the average consumer, so formulators are creating products that combine bacteria with conventional cleaning surfactants.
Bona, a historically cautious producer of premium floor cleaners, is launching its first microbial product—and the consumer education piece is a work in progress, according to John Schierlmann, the firm’s R&D director. As he’s focusing on production and on setting up the first orders from national retailers, Bona’s marketing team is working with Novozymes on side-by-side patch tests and other ways to demonstrate the deeper clean that microbes offer. “It’s really hard to get that across to people,” Schierlmann says.
Designed to eliminate pet urine, Bona’s microbial formulation pairs biobased surfactants that accomplish the basic mess removal with bacteria that feast on the stinky nitrogenous molecules that often dodge mops and rags.
Beyer at Univar says microbes are especially good at dealing with grease and odors. The two are related, he says, because fats can degrade into butyric acid, which smells like vomit. Fatty alcohols are another common source of stink. The bacterial cleaners both eat many such bad-smelling molecules and outcompete malodorous bacteria that may also be around. Shoes and athletic pads, often referred to as soft nonlaundered goods, are an application for microbial cleaners that Beyer expects to see develop soon.
The cleaning partnership of chemistry and biology that Schierlmann describes is likely to be a dominant approach. Harp says formulators have to choose their surfactants, preservatives, and fragrances carefully. Most conventional nonionic surfactants work well combined with microbes; cationic quaternary ammonium surfactants are antimicrobials and definitely don’t. Companies making rhamnolipids and sophorolipids, emerging classes of biobased surfactants, say that early microbial compatibility tests are promising.
Phenoxyethanol is the preferred preservative, Beyer says. Scent can be tricky. Natural-focused brands like to use essential oils for fragrance, but many of those oils have strong antimicrobial effects.
While the microbial cleaner business is growing, the products are still niche. The market for cleaning microbes themselves is around $10 million per year, according to Hossein Mahmoud, global business development director for biotechnology at the chemical maker Croda. The firm has separate microbials for reducing odors and for cleaning hard surfaces, and a newer formulation that does both.
Independent and direct-to-consumer brands are the most likely to offer microbial cleaners currently, Mahmoud says, but multinational firms such as Bona, Unilever, and Reckitt are dipping their toes in. The US and Europe are leading the way, and he’s seeing strong interest in parts of Asia.
Both Mahmoud and Beyer also expect growth from institutional customers. Live microbes have a longer history in that part of the cleaning market, and their potential to reduce the labor required to clean public spaces such as airport bathrooms has janitorial service providers intrigued.
If suppliers can prove efficacy, ramp up production, and bring costs down, microbial cleaning products have the potential to change the way people clean their homes for the better, Mahmoud says. “Using antimicrobials is, in some places, still necessary, sure. But actually, in most cases, you don’t need them. And then at the end, they will harm more than they will benefit the consumers because you can cause microbial resistance and introduce toxic chemicals unnecessarily.”
Novozymes’ Harp adds that consumer acceptance of microbial cleaners is growing as the science of producing and formulating with microbes is maturing. “People are recognizing that microbes are not the enemy and that they’re, in fact, a supercritical part of human health and the environment,” he says. During the pandemic, disinfection became a priority for most consumers, but that was just a pause in a long trend toward a microbiome-friendly mindset.
“We probably shouldn’t use disinfectants to clean up spaghetti sauce,” Harp says. “Let’s be a little bit more aware of who’s there and why we’re using these products.”