Ruth Schmidt gives voice to fungi and bacteria

Microbial ecologist Ruth Schmidt (NIOO-KNAW) has successfully defended her PhD thesis on volatile communication between fungi and bacteria. Their shared 'language of fragrances' may well be the world's most frequently used form of communication. For her defence, Schmidt offered a unique insight into what a 'conversation' might look like.

"The sense of smell is the first sense we use when we are born", Ruth Schmidt pointed out in her introduction. It's even powerful enough to recall memories. "So when you imagine walking on the beach, you will recall the aroma of the shore."

"Many of you will not know this", "continued Schmidt, but this typical aroma "is in fact produced by micro-organisms feeding on phytoplankton".

Another typical example is when you walk in the forest in summer after a rainfall. Again, it's micro-organisms that produce this unmistakable smell: "the aroma of the earth".

Terpenes

If you were to go belowground, you'd see that fungi and bacteria growing around the roots of plants release these aromas - or rather the volatile organic compounds (VOCs) that they're made up of, also known as Terpenes - as communication signals.

Not only do these Terpenes work across relatively long distances, they also work between groups of micro-organisms with a very different cellular make-up: fungi and bacteria.

Considering the fact that there are billions of micro-organisms in a single handful of soil, it almost automatically makes 'Terpene' the world's most frequently used language.

War of words?

Schmidt invited her two assistants to demonstrate the kind of exchanges - words - that fungi and bacteria might have using Terpenes to communicate.

In this way, she managed to give voice to the two groups of micro-organisms. But what would they actually be telling each other?

"What I found out during my PhD", said Schmidt, "was that those kind of words cause the bacterium to move. Either away from or towards the fungus.

Multilingual

At the same time, the bacterium realises that it can also speak the same language, although they may not know exactly what the other one means.

"We don't know yet what kind of role this volatile has in the actual conversation", Schmidt conceded. "But we do know that Terpene is a language that can be used between micro-organisms as the most common language used belowground. Many of us are multilingual, we speak different languages. Microbes can also be multilingual!"
 

• Volatile communication between fungi and bacteria, R.L. (Ruth) Schmidt. Thesis defence: Wageningen UR, 20 October 2017, promotor: Wietse de Boer (NIOO-KNAW), co-promotor Paolina Garbeva (NIOO-KNAW)