Brazilian combination of nano and biotechnology creates biological control of Bacillus cereus

Researchers from the Nanomedicine and Nanotoxicology Group at the Institute of Physics of São Carlos (GNano-IFSC/USP) have developed the biological control of the bacterium Bacillus cereus. This gram-positive bacterium is present in leafy green vegetables, reducing the need for antibiotics in agriculture.

Fernanda Coelho, a postdoctoral researcher at GNano-IFSC/USP, explained that the entire project involved knowledge of phage therapy (viruses that infect and destroy bacteria). This technique used bacteriophages, or viruses capable of treating bacterial infections in humans, animals, or plants. These phages produced endolysin, an enzyme that recognized and broke down the bacterial cell wall.

The focus of the study was the use of a specific endolysin produced using biotechnology and subsequently associated with silver nanoparticles, which already have an antimicrobial effect. This system showed activity against strains of ″Bacillus cereus″, as verified through antibacterial activity assays and electron microscopy imaging.

Phage endolysins have a modular structure composed of enzymatically active domains (EADs) and a cell wall binding domain (CWBD). The CWBD recognized and directed the endolysin to the specific cell wall-associated ligand molecules with high specificity, while the EADs provided the enzymatic activity that cleaved the peptidoglycan structure.

"By working with endolysins, we developed a highly targeted system to combat a specific bacterium. In this study, the association with silver nanoparticles amplifies the complex's efficacy," Coelho stated. Thus, she explained, proposing a "viable, efficient, and environmentally more appropriate biological control system than the antibiotics used in agriculture is possible. This approach is of particular importance in promoting sustainable agriculture."

Coelho's research explained that her project involved expressing a recombinant protein in bacterial systems and purifying it. "In parallel, I was already working on synthesizing silver nanoparticles. After obtaining the purified protein, it was combined with silver nanoparticles, creating a bioactive compound," she added.

Microscopy analyses confirmed that the produced compound was effective in causing cell wall rupture, leading to the elimination of ″Bacillus cereus″.

With the patent application already underway, Coelho and her team believe agriculturists and rural producers can use this system by spraying vegetables to eliminate this bacterium and added to milk samples during the pasteurization process to reduce contamination.

For the GNano coordinator, Prof. Valtencir Zucolotto, who is responsible for the research, "the work highlighted the importance of this interface area between Nanotechnology and Biotechnology, which already brings and will certainly bring even more significant advances for the medical and agribusiness fields."

The scientific journal ″Biocatalysis and Agricultural Biotechnology″ recently published the scientific article on this discovery.

In addition to Coelho and Prof. Zucolotto, researchers Angelica Maria Mazuera Zapata and Thales Rafael Machado (both from GNano-IFSC/USP) and Prof. Fernanda Canduri (IQSC/USP) co-authored the article.

(Editing by Leonardo Gottems, reporter for AgroPages)

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