Combination of Nano and Biotechnology brings advances in biological control in agriculture

Research carried out by researchers from the Nanomedicine and Nanotoxicology Group at the São Carlos Physics Institute (GNano-IFSC/USP) is developing a biological control process against a gram-positive bacterium called Bacillus cereus, which is very present in green leafy vegetables, as well as in the dairy industry, a work that aims, above all, to reduce the use of antibiotics in agriculture.

Fernanda Coelho (in the photo), postdoctoral fellow at GNano-IFSC/USP and first author of the work recently published in the scientific journal “Biocatalysis and Agricultural Biotechnology”, under the supervision of researcher Valtencir Zucolotto, explains that all the work involved knowledge of so-called phage therapy (viruses that infect and destroy bacteria), and that it is nothing more than the use of bacteriophages - known as phages -, which are viruses that have the property of treating bacterial infections in humans, animals or plants.

These phages produce endolysin, an enzyme capable of recognizing and disrupting the cell wall of bacteria. The focus of the study was the use of a specific endolysin that was produced using biotechnology and subsequently associated with silver nanoparticles, which in themselves have an antimicrobial effect. This system showed activity against strains of Bacillus cereus, something that was verified both through antibacterial activity tests, as well as through transmission and scanning electron microscopy images.

Understanding the concept

Phage endolysins have a modular structure composed of enzymatically active domains (EADs) and a cell wall-binding domain (CWBD). CWBD recognizes and delivers endolysin to specific cell wall-associated ligand molecules with high specificity, while EADs provide the actual enzymatic activity that cleaves the peptidoglycan structure. “By working with endolysins, we have developed a highly targeted system to combat specific bacteria. In this study, the association with silver nanoparticles amplifies the effectiveness of the complex. In this way, we were able to propose a biological control system representing a viable, efficient and environmentally more appropriate alternative than the antibiotics used in agriculture. This approach is of particular importance to promote sustainable agriculture”, explains Fernanda.

Phage Therapy is already widely used in the United States and Europe, both in healthcare and agriculture. Despite the safe use of these phages, public opinion prefers the use of endolysin alone. According to the GNano researcher, there are several studies that prove that there are viruses that are highly selective for specific bacteria, precisely because of this protein called endolysin. “But why, during its production, does the virus use endolysin? It uses it to reproduce its viral cycle. Then, from there, it uses this endolysin to enter the bacteria, lysing the bacterial cell wall and causing its death”, he points out.

How the research was done

Fernanda Coelho's research is part of her post-doctorate, a project that was written in 2022, before the researcher had defended her doctorate and which began, in practice, in January 2023, with the award of a scholarship from Fapesp ( 2021/11081-8). “The project consisted of expressing a recombinant protein in bacterial systems and subsequently purifying it. In parallel, she was already working on the synthesis of silver nanoparticles. After obtaining the purified protein, it was combined with silver nanoparticles, creating a bioactive compound. Microscopy analyzes proved that the compound produced was efficient in causing the disruption of the cell wall, causing the elimination of the Bacillus cereus.

With the patent application already forwarded, Fernanda Coelho and her team believe that this is a system that can be used in agriculture, by rural producers, through a spraying process both on vegetables, to eliminate this bacteria, as well as to be added in milk samples during the pasteurization process, in order to reduce contamination by this bacteria. The pioneering research brings an important approach in the area of ​​sustainable agriculture.

For GNano Coordinator, Valtencir Zucolotto, responsible for the research, “the work shows the importance of this area of ​​interface between Nanotechnology and Biotechnology, which already brings and will certainly bring even more important advances to the medical and agribusiness areas”.

In addition to Fernanda Coelho and Valtencir Zucolotto, researchers Angelica Maria Mazuera Zapata and Thales Rafael Machado (all from GNano-IFSC/USP) and professor Fernanda Canduri (IQSC/USP) signed the scientific article. Access the full article at the link below: