For the sense of smell, almost more than any other, has the power to recall memories and it’s a pity we use it so little.
— Rachel Carson

I am intrigued by the how microbes interact and communicate with each other via volatiles. From studying fungal-bacterial interactions on a molecular level, I moved to studying microbial volatile interactions in the plant holobiont (the inseparable unit of the plant and its microbiome) to uncover mechanisms by which microbes help plants adapt to climate change induced drought. This will set the basis to engineer the microbiota to create climate change resilient crops for agriculture.

Why are volatiles so important for life on earth?

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As Rachel Carson states, the sense of smell evokes the strongest memory of all the senses. You may wonder how this relates to microorganisms? Most odors we perceive as humans are in fact produced by microorganisms. Remember that the sweet, fresh, powerfully evocative smell of fresh rain when taking a walk in a forest after the first rainfall after a dry spell? This earthy-smelling substance is geosmin, a chemical released into the air by soil-dwelling bacteria when rain falls onto dry soil.

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Or think of the characteristic seashore aroma, which is due to dimethyl sulfide, a rather stinky sulfur compound that puts the funk in everything from nori, to truffles, and beer. But not all bacterial odors are necessarily good in the perspective of the receiver; especially sulfur compounds can be repelling, just think of the smell of rotten eggs or potatoes. 

Odors, good and bad, are due to volatile organic compounds (VOCs), and can be a form of information signals between different organisms. Chemically speaking, VOCs are small carbon-containing molecules with low molecular weight, high vapor pressure, and low boiling point. In environments, where microbes are physically separated and rely on communicating with each other, one could think of VOCs as “words” that build the “language” of microorganisms. 

Check out the video below to see how microbes emit volatiles in the root surrounding of plants.