The Polish Patent Office has granted a patent to researchers from the Department of Plant Protection and Biotechnology and the Research and Implementation Laboratory of the Inter-University Faculty of Biotechnology at the University of Gdańsk and the Medical University of Gdańsk for a preparation designed to protect plants against diseases such as bacterial speck of tomato, bacterial wilt of solanaceous crops, or black rot of brassicas.

Bacterial plant diseases pose a significant problem for agriculture, horticulture and the production of plant material. Infection caused by bacteria can lead to a deterioration in crop quality or production losses. In the case of the most dangerous plant pathogens, regulations require their rapid detection and control in order to limit the risk of disease spread, which may lead, for example, to the destruction of the crop.

The options for directly controlling bacterial plant diseases are often limited. Therefore, new solutions are being sought that could effectively inhibit bacterial proliferation whilst being as simple as possible to produce and apply.

Researchers from the University of Gdańsk and Wrocław University of Technology have developed a preparation that protects plants against bacteria causing some of the most dangerous diseases in crops, which are subject to mandatory phytosanitary measures. The patented solution is based on a concept developed in earlier research and utilises aqueous solutions of relatively simple inorganic salts and cold atmospheric plasma.

A research team from the University of Gdańsk working on the invention comprised of dr hab. inż. Wojciech Śledź, head of the University of Gdańsk’s Research and Implementation Laboratory, who, together with his deputy dr Agata Motyka-Pomagruk, co-ordinated the research work of the University of Gdańsk team, dr Weronika Babińska-Wensierska and prof. dr hab. Ewa Łojkowska. The research team from the Wrocław University of Technology was led by dr hab. inż. Anna Dzimitrowicz, prof. PWr. The PWr research group comprised: dr hab. inż. Piotr Jamróz, prof. PWr, dr inż. Dominik Terefinko and prof. dr hab. inż. Paweł Pohl.

How the bactericidal preparation is made

A suitably prepared solution of water and mineral salts is exposed for a very short time to plasma generated under specific conditions. As a result of this process, the properties of the solution change, and it acquires the ability to inhibit, prevent the proliferation of, or destroy pathogenic bacteria. Importantly, this does not involve applying the plasma itself directly to the plant. The plasma is used to ‘activate’ the liquid, and the end product is a liquid preparation with antimicrobial properties.

Scientists have developed two methods for producing plasma-activated solutions: in the first, a specific volume of liquid is stored in a tank and exposed to plasma for a short period; in the second, the solution flows through a device where it comes into contact with plasma. Following this treatment, an antimicrobial preparation is obtained that is capable of effectively inhibiting bacterial growth or destroying bacterial cells. Importantly, the activation time required is short. Studies have confirmed that plasma-activated liquids effectively combat phytopathogenic bacterial cells.

The invention allows for the selection of both the type of salt, its concentration, and the method of activation, depending on the microorganism being targeted. The antibacterial properties of post-plasma solutions result from reactive oxygen and nitrogen species with antimicrobial properties, generated as a result of plasma-liquid contact. These agents are relatively unstable. Consequently, the use of post-plasma solutions will not lead to the accumulation of toxic residues in the environment, as is the case with chemical pesticides.

The formulation’s composition is suitable for use in combating common pathogens: Xanthomonas campestris, responsible for diseases in the Brassicaceae family, and Ralstonia solanacearum, a dangerous pathogen affecting many plant species.

The formulation is intended for manufacturers of plant protection products and technologies, agricultural and horticultural holdings, producers of propagating material, nursery stock and plants, and the agrobiotechnology sector.

‘Our aim was to develop a new and effective method of combating the bacteria responsible for serious plant diseases,’ explains dr hab. inż. Wojciech Śledź. ‘To this end, we utilised cold atmospheric plasma, which enables simple aqueous solutions of mineral salts to acquire antimicrobial properties. It is particularly important to us that the preparations obtained effectively curbed the proliferation of several significant plant-pathogenic bacteria, including pathogens subject to mandatory control.” These results open up the possibility of further developing the technology towards new solutions that support plant protection and reduce losses caused by bacterial diseases. We are currently seeking businesses interested in the further development of this technology and the formulations we have developed, with the aim of obtaining a plant protection product that has been field-tested and authorised for marketing.’

‘The patented invention is the result of fruitful collaboration between researchers from the University of Gdańsk and the Wrocław University of Technology, which began in 2015. The approaches we are developing concern the direct and indirect application of cold atmospheric plasma in agriculture, medicine, dentistry and environmental protection. We also strive to respond to the needs of the socio-economic environment that have been brought to our attention,’ emphasises dr Agata Motyka-Pomagruk.

‘Prof. Ewa Łojkowska’s team, together with researchers from the Wrocław University of Technology, has been conducting joint research for many years into solutions utilising cold plasma technology across a wide range of applications. This is now the ninth invention in the field of plant growth stimulation, seed protection, the elimination of pathogenic microorganisms and plant pathogens, the removal of endocrine-disrupting substances and antibiotics from water, and the control of microorganisms causing wound infections in farm animals and humans, which has been granted patent protection,’ comments Katarzyna Gronowska, director of the University of Gdańsk Technology Transfer Office, which coordinates the process of protecting inventions.

Effective protection of plants against bacterial diseases is of great importance to the agricultural sector and food safety. The patented invention lays the foundation for the development of a new group of antimicrobial preparations for agriculture, the composition and manufacturing process of which can be tailored to the specific pathogen being combated.