Montana State researchers aim to autonomously eliminate plant-killing bacteria from hydroponic farming systems

BOZEMAN - Three researchers from Montana State University recently received a nearly $600,000 grant from the U.S. Department of Agriculture to develop a system that can autonomously detect and remove crop-killing microbes from hydroponic farms before they cause damage to plants. Hydroponic farming is a method of growing plants without soil by supplying nutrients through water.

"This work is important to maintain food safety for our growing world," said Stephan Warnat, the project's principal investigator and an associate professor in the Department of Mechanical and Industrial Engineering in MSU's Norm Asbjornson College of Engineering. Co-project directors are the engineering college's interim Dean Christine Foreman, who is also a professor of chemical and biological engineering, and Stephanie McCalla, an associate professor of chemical and biological engineering.

Certain crops, especially lettuces, tomatoes, strawberries and herbs, grow extremely well indoors hydroponically. Other benefits of hydroponic farming, compared to traditional soil-based agriculture, include higher water efficiency, faster plant growth, greater crop yield per square foot, year-round production, and control over the growing conditions, including nutrient levels and light exposure. Plus, hydroponic farms can thrive in environments inhospitable to traditional agriculture methods, including deserts and infertile land.

"A hydroponic system allows you to grow fresh produce all year round, which can be beneficial in harsh environments with cold winters," Warnat said.

However, the challenges facing hydroponic farmers are substantial, including high startup costs and the fact that staple commodities such as wheat, corn and soybeans are considered far more economical to produce through traditional agriculture. The potential for toxic water-borne pathogens is another downside of hydroponic farming.

"The goal with this project is to keep pathogens out of the hydroponic system while allowing beneficial microbes to develop naturally," Warnat said. "The challenge is that when you have a circulating water system with a microbial community, potentially some pathogens are developing and soon the entire harvest is dead."

The team, Warnat said, plans to use electrochemical sensors to screen for harmful bacteria before they have a chance to harm the crops. The sensors are coated with aptamers, which are short, synthetic strands of DNA or RNA engineered to fold into a specific 3D shape. This unique shape allows it to act like a molecular "lock and key" to capture pathogens in the hydroponic systems. The electrochemical sensor changes its output based on the pathogen concentration. When they do, they trigger the release ofbiodegradable nanoparticles - made primarily from chitosan, a naturally occurring polymer - that have been engineered to capture bacteria, such as pathogenic Escherichia coli strains. When the chitosan binds to the harmful cells, it forms a larger agglomerate that can be removed by the hydroponic system's filtration equipment, protecting the harvest from pathogens.

The viability of the technologies involved in the three-step process - the detection, capture and removal of pathogens from a hydroponic farm - are each previously demonstrated to be effective. The system under development would combine the technologies in a way to automate the steps to protect hydroponic crops from harmful pathogens.

"The project addresses critical challenges faced by hydroponic farmers in Montana," said Dilpreet Bajwa, head of the Department of Mechanical and Industrial Engineering. "It will enhance productivity, profitability and resilience of hydroponic operations while supporting local food production and strengthening the state's agricultural economy."

Another benefit of early detection and eradication of harmful bacteria is it allows plant-nourishing microbes to develop into biofilms, which can be beneficial to the crops.

"Helpful biofilms can function as fertilizers," Warnat said. "These biofilms are healthy for plants. But you have to be careful which kind of biofilm is forming. If the pathogen is inside the biofilm, then that can lead to a catastrophic event - meaning total crop loss."

Examples of biofilms include plaque on teeth, the muck that sometimes grows inside plumbing fixtures, and the slippery coating commonly found on rocks in streams, rivers and lakes.

Foreman and Warnat are affiliated with MSU's Center for Biofilm Engineering, which is the world's first and largest biofilm research center.

The grant will fund two graduate students; one master's student and one doctoral student. The grant provides funding through April 30, 2029.