if you hear "fuel spill," your first response these days might be a sharp intake of breath as you calculate how much of your $6-per-gallon fill-up just dripped down your quarter-panel. a tragic loss, to be sure, but nothing compared to the damage done by large-scale industrial accidents. wait for it to evaporate off your shoe. and don't light a match for a while. cleaning up after an oil tanker or refinery has a leak is a more major undertaking, and the environmental effects can last decades. there are many methods for removing chemical contaminants from the ocean or soil, including the use of fungus or bacteria that can break down oils and fuels. this is known as bioremediation.
scientists are always on the lookout for new chemical-eating microscopic critters, both for use in biological cleanup and for the pure joy of scientific discovery. most research on new species has been done in the vicinity of fuel spills, with the logical assumption that anything living there is possibly munching on the contamination. recently, biologists from the institute of integrative biology (i²sysbio) and the darwin bioprospecting excellence team, both based in valencia, spain, decided to look somewhere new for their new organisms, right in the parking lot outside their research labs. the team took samples from their own cars, just under the fuel filler lid, and discovered several kinds of bacteria happily hitching a ride, including a never-before-catalogued species. when bred in their lab, the new "bugs" proved capable of living in highly concentrated fuel samples. they were also capable of degrading those samples over time, which might make them valuable in future bioremediation efforts.
we spoke with manuel porcar, who kindly answered our questions about the paper, about hungry bacteria, and about how he, àngela vidal-verdú, daniela gómez-martínez, juli peretó, and adriel latorre-pérez owe their research success to a toyota.
c/d: why is fuel so hard to clean up?
manuel porcar: even though it is an organic compound, like proteins, sugars, or lipids, this kind of chemical is difficult to metabolize. this means that there are a moderate number of bacteria able to feed on fuel, and those who do, do it slowly.
what do bacteria do to break down fuel? do they eat it? evaporate it? chop it into less harmful components?
they use it as a carbon source, which is a sophisticated way to say that they eat it. they use it as food and grow (multiply) by eating fuel with no other carbon source.
what gave your team the idea to look at cars?
we have quite exotic ideas. we recently won an ignobel prize [an award given out for research that is both silly and thought-provoking] for our study on bacteria living on wasted chewing gums. the compartment behind the metallic tank lid is interesting because it collects bacteria from wherever the car is driving and has fuel as the almost unique carbon source. it hadn't been studied yet, so, a good choice, i guess.
you ended up testing at the inside of the fuel filler cap. what other areas did you consider looking at on the cars?
just that one for the reasons above. but other parts could bear a very different microbiome. inside the engine, for example, where high temperatures are reached, thermophilic bacteria could (maybe) be found.
there are already known bacteria that can speed the breakdown of oil or fuels that are found in the ocean and in the dirt. are all the samples you got new discoveries?
we did identify a new species (in the sense of one unknown to science, belonging to the genus isoptericola). the rest of the strains ("races") we found belonged to known species.
what makes and models of cars did you use in the study?
we used our own cars, we had many different brands. mine was a peugeot 206 and the one hosting the new isoptericola species was a toyota yaris hybrid.
in the paper, you wrote there were 20 samples, but one didn't return enough dna. was that car too clean? too new? why was nothing living on just one car?
maybe it was too clean, but certainly there was something alive there, because microorganisms are basically everywhere. but the concentration was maybe too low for us to retrieve dna.
your study found dna in both gasoline and diesel, but focused on diesel in the testing of the fuel degradation. why?
we only quantified diesel. among other reasons, gasoline evaporates faster, which makes quantification of gasoline difficult.
our readers are probably wondering if they need to go spray their gas caps with hand sanitizer. if the bacteria on the caps are breaking down fuel, does that affect the fuel in our tanks?
very likely not, because the speed at which they can consume fuel is very low compared to the car's consumption. but in some environments like gas stations in summer, boats at dock, and diesel storage tanks, bacterial degradation of fuel can indeed be a problem.
if we breed cleanup bacteria, will they cause unforeseen problems after they complete their cleanup tasks, or do they die off, or eat other things?
they are already there and bacteria can be transported by the wind, so it is almost impossible that they would act like gremlins on other materials. the use of microorganisms to remove pollutants is called bioremediation and it is a very exciting and promising biotech application.