Your car holds more life than you think

We all sleep, live, work, love, dream and die within an invisible ocean of -almost fully unknown - microbial life.

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Some microbiologists focus on the fundamental principles of tiny life, from biofilm formation to gene regulation; some go for tools, CRISP-R being the most noticeable example of a game-changing molecular biology technology; finally, others prefer to focus on applications, from clinic essays to legal aspects. But biotechnology takes time, and well before a pill containing a life-saving biomolecule is given to a patient, or a bioremediation strategy is set in place on a polluted site, a bioprospecting effort has been carried out. This is what some microbiologists do, and certainly this is what we do: hunting bacteria from the wild that might hold potential in any biotechnological application.

In my academic lab at the @I2Sysbio and at the bioprospecting company I cofounded, @DarwinBioprosp, we look for bacteria or fungi in natural and artificial environments. The goal being Darwinian (selection), we start by identifying environments that are both poorly explored, and yet display high biodiversity. We have studied solar panels, deserts, coffee machines or wasted chewing gums (a work that made us the proud winners of last year’s IgNobel prize in Ecology!). And from all that, we have learnt that exotism, in microbiology, does not necessarily mean distant. Unknown, potentially useful microorganisms can be found -literally- on you, or very close to you. They are there, have been there for a long time, just waiting to be discovered. In places such as the fuel-soaked dirt that accumulates around the tank lid of your car.

Why the car tank lid? Well…why not? It is a particular habitat, with plenty of hydrocarbons, subjected to large temperature fluctuations and with a continuous flow of nutrients (and genomes) from the circulating air. Think about this: when you drive your car, you are forcing an airborne flow of dust, pollen, plant debris and also microorganisms into that small world behind the metal lid of the fuel tank. From that starting point, we get an exciting combination of microbial biodiversity (constant input of what the wind brings), an extremophilic environment (heat shocks, low water activity) and a recalcitrant (but yet edible) carbon source. With all these ingredients…Darwin, make your magic!

First, there were two questions we wanted to answer: what is the microbiome of that previously unreported micro-niche, polluted with (or blessed with, from a microbial perspective) diesel and gasoline? Does it bear microorganisms with potential in hydrocarbon bioremediation?

Second, the strategy. I set a very simple experimental design: let’s get samples from automobiles, ours or from our family and friends: ten diesel and ten gasoline cars. First Daniela (the person photoshopped in the picture) and then Àngela collected the biomass accumulated around the plastic car tank lid (not the metal lid) of the cars and carried out a culturomics approach (we set a collection). Adriel was in charge of the NGS characterization (we described the microbial taxonomic profiles of the microbial communities) and Àngela and Daniela carried out a Lab Adaptive Evolution with diesel or gasoline as the sole carbon sources. Finally, Àngela, with the help of Juli, analyzed and quantified the degradation of diesel by a set of selected bacteria.

Now, the results. We found that the car tank lid was home of a community of Pseudomonas, Achromobacter and other bacteria with diesel-degrading ability, and which proved able degrade roughly half of the diesel we fed them in a matter of weeks. All the data are in the article, just published in NPJ Biofilms and Microbiomes, and available here: https://www.nature.com/articles/s41522-022-00299-8

 

One last thing. We were delighted to learn that, among the selected diesel-degrading strains, there was at least one, Isoptericola spp., which is very likely a new species. I have to admit that I would have been thrilled to learn that my old Peugeout was the home of that taxonomic newcome. But it was not my car, but Juli’s, the one from which the strain was isolated: a hybrid Toyota Yaris. Notice that this is a gasoline car, not a diesel one, and yet Isoptericola spp. proved able to efficiently biodegrade diesel (we have no data yet with gasoline, for technical difficulties we hope to solve shortly). This is a very nice example of exaptation: a “preadaptation” to diesel degradation found in an environment with a (relatively) similar selection pressure: a gasoline tank lid.

The characterization of the new species is already under way in our lab, and I just hope that I will be able to convince the team to name our small friend Isoptericola toyotensis!

Manuel Porcar

PhD, University of Valencia/Darwin Bioprospecting Excellence