Are There Bacteria in Your Buick, Microbes in Your Mazda?

Buckle up for an auto-microbiome road trip

Scrambling the letters of the word “bacteria” produces the anagram “a car bite,” which seems a suitable way to introduce this week’s exploration of some eye-opening automobile/bacteria connections.

And as we’ll see, some do indeed relate to food.

In 2014, the American Automobile Association estimated that the average US driver spends 46 minutes a day in their car.

It may not be surprising to learn, therefore, that it’s not just candy wrappers and apple cores that we leave behind when we close the car door.

For it seems we also deposit a fair amount of bacteria.

In fact, over the years, researchers have shown that our cars can become mobile microbial menageries.

Let’s start with a 2014 study performed by researchers from the University of Michigan, in association with engineers from the Ford Motor Company, and reported in a scientific journal with the, uh, delightful title Biofouling.

They examined 18 vehicles, some of which were shared between different drivers, swabbing a range of surfaces for bacteria.

They discovered the greatest abundances were: 1) around cupholders between the front seats, 2) on the steering wheel, and 3) on the door latch.

The dominant phyla were Staphylococcus and Propionibacterium, with the former’s strains being mainly S. epidermis, S. aureus, and S. warnerii.

Rather disturbingly, nearly a quarter of the S. aureus strains that were found in shared community vehicles were resistant to methicillin.

Yup, bad old MRSA – or Methicillin-resistant Staphylococcus aureus – the bacterium responsible for several difficult-to-treat infections in animals and humans. Yikes.

Fascinatingly, the researchers studied the effects of covering surfaces in the car’s interior with a coating containing 5% silver ion additives, which would be incorporated during manufacturing.

This eliminated culturable pathogenic bacteria for as long as five months.

In a second study, led by microbiologist Dr Charles Gerba, 100 vehicles were checked for bacteria lurking around on 11 different surfaces.

The cars were in either Tucson, Oakland/Pleasanton, Chicago, Washington D.C., or Tampa.

Dr. Gerba’s research showed that it’s food spills in cars that lead to the most bacteria (hence the aptness of “a car bite”).

His team also found more bacteria in vans and SUVs than in cars, perhaps because these larger vehicles carried a greater number of people, probably including children, whose food spills may well encourage bacteria.

Another pretty intriguing finding was that the number of bacteria the researchers found (measured by colony-forming units per square inch) was related to the mean average monthly rainfall for each city studied.

The experimenters’ conclusion was that this could be a reflection of the longer survival of bacteria in moist environments.

A third study on bacteria in cars was carried out by a team from Aston University in the UK, who surveyed almost 1,400 vehicles.

This time they discovered surprising amounts of bacteria on the cars’ dashboards.

By the way, the part of a car in front of the driver is called a dashboard for reasons dating back to horse-drawn carriages, which often featured a small screen designed to protect passengers from mud and other debris “dashed up” by the horse’s hooves.

Back, though, to those Aston University scientists, who suggested that dashboards may receive a liberal dose of bacteria via the air circulated through their vents, while they also noted that dashboards can get heated by the sun, creating warm, bacteria-friendly conditions.

The team leader said: “People would be horrified at the thought of eating off their toilet seat, but few people realize eating off their dashboard is just as likely to make them sick.”


Finally, though, lest we conclude that all car/bacteria connections are negative, let’s express admiration for the scientists in Korea who have developed a way of making gasoline from E. coli bacteria.

Biofuels involving bacteria aren’t new, but before 2013 they were generally replacements for diesel rather than gas.

The Korean researchers took modified E. coli and fed it glucose, causing the bacteria to produce enzymes that could convert sugar into fatty acids, which were then transformed into short-chained alkane hydrocarbons with the same structural and chemical integrity as gasoline.

They’ve still some way to go, as it takes 6 liters of glucose culture to make just a teaspoon of gasoline, enough to power an average American car for, well, 165 feet.

But it’s a start.

And perhaps it’s no coincidence that an anagram of E. coli is “oleic” – another type of fatty acid.

Further reading

American Driving Survey

Germs in Your Car Driving You Crazy

Bacteria in Fuel

E. Coli Bacteria Used to Create Gasoline

Elucidation of bacteria found in car interiors and strategies to reduce the presence of potential pathogens

How dangerous are the bugs in my dirty car?

Microbial production of short-chain alkanes

Car Interiors Are Laden with Bacteria

Researchers Bioengineer Bacteria That Poops Out Gasoline