Characterization and evaluation of the antibiofilm activity of gold nanoparticles developed from green synthesis with Pediococcus acidulactici CE51

• Grant number: 24/15523-3
• Support Opportunities: Scholarships in Brazil - Master
• Start date: April 01, 2025
• End date: March 31, 2027
• Field of knowledge: Agronomical Sciences - Food Science and Technology
• Principal Investigator: Lizziane Kretli Winkelströter Eller
• Grantee: Kimberlly de Oliveira Silva
• Host Institution: Pró-Reitoria de Pesquisa e Pós-Graduação. Universidade do Oeste Paulista (UNOESTE). Presidente Prudente , SP, Brazil

Abstract

Microbial biofilms have a significant impact across various contexts. In healthcare, they are known for their antibiotic resistance, which complicates the eradication of infections and renders treatments less effective. In industrial settings, such as food processing plants, these biofilms can cause considerable damage, including pipeline blockages and reduced process efficiency, leading to additional costs and the need for constant maintenance. Therefore, proper management of biofilms is crucial for ensuring public health, operational efficiency, and environmental protection. In this context, nanotechnology has emerged as a promising alternative. Gold nanoparticles (AuNPs) are believed to have potential applications against biofilms due to their antibacterial properties. However, their synthesis through chemical and physical methods renders their application unviable due to the formation of toxic residues. To overcome these challenges, green synthesis (using natural substances like lactic acid bacteria) has become an attractive method for nanoparticle production due to its non-toxic nature, higher efficiency, easy availability, and cost-effectiveness. Therefore, the aim of this study is to characterize and evaluate the antibiofilm activity of gold nanoparticles developed through green synthesis with Pediococcus acidulactici CE51. Tetrachloroauric acid trihydrate (HAuCl4¿3H2O) will be used in the synthesis of gold nanoparticles from cell-free supernatant of P. acidulactici CE51 (SLC-AuNPs), with the color change from transparent to violet indicating the formation of SLC-AuNPs. The impact of temperature, pH, and supernatant concentration on the biosynthesis of SLC-AuNPs will be assessed. The formed nanoparticles will be characterized using various physicochemical techniques, such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Zeta potential, and dynamic light scattering to observe size, shape, and structure. The lethal concentration 50 (LC50) value of SLC-AuNPs will be determined in G. mellonella larvae. The antibacterial activity of purified bacteriocin, SLC-AuNPs, and AuNPs will be examined using the agar well diffusion assay. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) will also be evaluated. The XTT assay will be used to assess the metabolic viability of biofilms after exposure to the tested compounds. For confocal microscopy (CLSM) images, biofilms will be formed under the same conditions and concentrations in 24-well plates containing glass slides and stained with DAPI. Images will be recorded on a Nikon C2/C2si Confocal Microscope equipped with an advanced inverted microscope system (Eclipse Ti-E). Transcriptome analysis by RNA Seq will be performed under the tested conditions. The analyses will be conducted in triplicate with a significance level of 0.05. It is expected that the results will identify the antibiofilm properties of gold nanoparticles synthesized with P. acidulactici CE51 and demonstrate their effectiveness in inhibiting or removing microbial biofilms.