Disarm, don’t kill: protecting plants from bacterial disease without antibiotics

My name is Joana and I am, since September 2025, a happy PhD student working DTU Bioengineering. When I was in high shcool I could have never imagined that this is what I would be doing. I went to school in the south of Portugal, where I am from, and I was quite confused about what to do with my life. I chose to go to the University of Lisbon to study biology because I liked animals and wild-life documentaries. Lucky for me, this was a great choice. I had fun engaging in some wild-life monitoring activities, started a scuba diving club - but it was only when I discovered microbiology that I became set on the path I wanted to take. After completing the bachelors degree I moved to Copenhagen, never having set foot in Denmark before, to do a masters degree in microbiology. Life after defending the master thesis moved fast. I got offered a job as a research assistant at DTU, and after a year I got offered a research job at a start-up. This position was a big opportunity to develop a new microalgae biotechnology. I was out of my depth, but taking on this challenge was the most enriching experience I have had in my career so far. While the project progressed well, I was overworked and needed to stop. I quit my job and traveled for half-a-year before returning to Copenhagen ready to look for a new job. This was hard. It took many months but finally I landed a position in an office supporting biotechnological research. Although this was fine job, it made me miss doing research so much that I started looking for a PhD. The stars aligned, and here I am doing a PhD on a topic I am fascinated by. Microbiology still blows my mind every day, and I would love to share that with young people.

 

My project shows how diving into the rich world of microbial ecology can enlighten us to new strategies to protect plants from microbial diseases in a more sustainable way. Pseudomonas syringae is a bacterium that causes disease in a wide range of crops, resulting in major economic losses in agriculture worldwide. Current treatments, such as copper sprays and antibiotics, are not only harmful to the environment but are progressively less effective due to the development of resistance by the bacteria.

In this project, we test a different strategy: instead of killing the bacteria, we “disarm” them. The pathogen causes disease by releasing toxins that damage plant tissues. If we can break down these toxins, the bacteria could become much less harmful. In studying the plant and soil natural microbiomes, we have found that other bacteria can naturally break down similar toxins. We therefore want test whether these bacteria can also inactivate the toxins produced by P. syringae, and whether this reduces its ability to cause disease in plants. This approach would control P. syringae disease without killing the bacteria, placing less pressure on them to evolve resistance to the treatment.

We introduce a “disarm, don’t kill” approach for managing plant diseases caused by microbes, supporting the development of more environmentally friendly and durable ways to protect crops.