Biocontrole de Salmonella Heidelberg sob uma perspectiva nanotecnológica

Abstract

Salmonella spp and Escherichia coli are important etiological agents of foodborne diseases and their ineffective control in the industrial environment reflects in impacts on public health and the economy, which can spread bacterial resistance and spend more on treatments. This study was divided into two chapters. The first addresses general considerations that aim to elucidate particularities about Salmonella and E. coli, the sanitizers commonly used to control and contextualize the use of nanotechnology as an alternative to this problem. The second chapter aimed to verify the efficiency of the nanocontrol against Salmonella Heidelberg and E. coli. Two formulations of chitosan-based biopolymer nanoparticles were developed to encapsulate peracetic acid (APA) at a concentration of 0.8%, with or without the addition of biosurfactant. In parallel, two formulations of nanostructured lipid carriers (NCL) were developed containing Shea butter as a solid lipid and essential oils (EO) of cinnamon and oregano as liquid lipids, added with biosurfactant. The four formulations were characterized in terms of particle size, polydispersity index and Zeta potential, with analysis of the physicochemical stability at 25ºC for 120 (NLC) and 365 days (biopolymeric nanoparticles) and the morphology observed by transmission electron microscopy (TEM). The inhibition efficiency of the formulations against microorganisms was tested in a disk diffusion test and minimum inhibitory concentration (MIC). All formulations showed adequate physicochemical stability and ability to inhibit microorganisms. The TEM showed nanoparticles with morphology, contours and distribution suitable for this type of system. The formulation of chitosan encapsulating APA showed better results in the agar diffusion tests, with higher inhibition halos (32.33 - 33.7 mm) than the control group with only 0.8% APA (22.89 - 26.11 mm) in S. Heidelberg. Furthermore, the chitosan nanoparticles encapsulating APA with or without the addition of biosurfactant obtained MIC values of 0.63 and 1.25 mg. mL-1, for two strains of S. Heidelberg and 1.25 mg. mL-1 for E. coli strains. As for NLCs, admirable results were obtained with cinnamon EO, according to the MIC values (0.78 mg.mL-1) for E. coli strains. On the other hand, in S. Heidelberg strains, the best results were obtained with NLC containing oregano EO (0.65 mg.mL-1). The results suggest that the use of nanoparticles can be a promising alternative in the inhibition of microorganisms of importance to public health, especially in the current scenario of constant increase in resistance to conventional antimicrobials and the search for solutions that guarantee environmental sustainability.