What are the most promising applications of living materials? Interview with scientific director at the Leibniz Institute for New Materials and professor at Saarland University in Germany, Prof. Dr Wilfried Weber. He is also involved in the European projects STEADY (funded by the European Research Council) and LoopOfFun (funded by the European Innovation Council).

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What biological systems — bacteria, fungi, etc. — are most promising as building blocks of ELMs, and why?

Wilfried Weber: The answer depends on the application area. In medicine, for example, probiotic bacteria are very promising because these are organisms that already live in or on our body. If we can use them and program them for specific purposes, such as aiding healing, that would of course be very beneficial. A lot of existing drugs are produced by living cells, so why not produce them directly where needed? We can transfer the genetic information of how to make a drug – such as growth factors or antibiotics – into bacteria. If we then integrate the bacteria into an ELM which we place in the body, it provides continuous supply of the therapeutic properties. Potentially, it can even be proactive and self-regulate, meaning it adjusts to changes in the body and the patient doesn’t even notice anything is wrong.

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Which application(s) do you see as the most promising and why?

Wilfried Weber: On top of medicine, another sector where ELMs hold a big promise is construction. Construction is one of the most polluting sectors on the planet, which is why biological solutions would be helpful. In this sector, mycelium-based materials are showing to be the most promising because mycelium can form fibers and glue structures together, in a sense. A product that is already on the market is living self-healing concrete. Concrete often cracks due to changes in temperature and roads then need to be repaired. The living concrete, however, can self-repair. It contains bacteria that are dormant and only become activated once they come into contact with water. When activated, they grow and therefore repair the crack. Afterwards, the bacteria can go back to the spore state and wake up again only once the conditions have changed. Cement production has a huge carbon footprint. Currently, 8% of the global CO2 emissions come from cement production. If we can use a biological solution, it’d therefore have a huge impact on the environment.

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Which applications do you focus on in your own research?

Wilfried Weber: We focus primarily on construction applications. For example, we are developing living wood composites. Current wood composites, such as particle or fiber boards, are made from petrol-based binders. We are developing bacteria- and fungal- based binders as fully bio-based, sustainable alternative that further provide additional smart functions such as self-coloration or damage sensing ability.

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What can ELMs do that conventional materials simply cannot? What's the most surprising capability that has been demonstrated so far?

Wilfried Weber: ELMs are adaptive, resilient and self-healing. In medicine, they can act as a self-replenishing depot. Instead of a patient taking pills every day, the bacteria can produce therapeutic properties for a long time. Using ELMs would also speed up the production of pharmaceuticals. ELMs give us the opportunity to treat untreatable diseases and to make treatments more effective, while making costs lower. For example, there is already one FDA-approved product using ELMs that treats the MacTel disease – which is a previously untreatable eye disease. Moreover, these materials are renewable. They only need energy from the environment. This makes ELMs more sustainable – especially in the construction industry. They decrease the carbon footprint and lead to better and longer-lasting products.

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What are the main challenges in the development and production of living materials?

Wilfried Weber: A challenge that will need to be overcome is regulations. Countries have different regulations on using genetically engineered organisms and these regulations are very strict in Europe. However, these regulations were created with food and feed in mind. There is no regulation focused on ELMs and their application in construction and medicine, for example.

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Where do you think ELMs will be in ten years - niche research curiosity or mainstream material?

Wilfried Weber: ELMs are now on the brink of getting into industries and the first products are already on the market. In ten years, we will see these materials on the market in different sectors. It’s a strongly growing area. Biobased materials are a big focus right now. Major entrepreneurs are noticing their potential and, in 2025, the World Economic Forum named engineered living therapeutics as one of the top ten emerging technologies. I’d also like to note that the EU is really taking a leading role in this sector. Europe is well positioned and has an advantage in this field. We should ensure that we maintain this advantage.

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