Remoção de biofilmes de Pseudomonas aeruginosa em superfícies de aço inox 304L empregando agentes químicos

Abstract

Biofilms are formed by sessile communities cells adhered to a surface and to each other, embedded in a matrix of extracellular polymeric substances (EPS). These substances are produced by the microorganisms in order to increase their survival in a specific environment. The growth and unwanted adherence of biofilms affect a wide variety of microbial habitats, such as medical devices, heat exchangers and distribution of potable water systems. In a bottled water industry, for example, bacteria can form biofilms on any surface that is in contact with water and may contaminate it through production of metabolites, causing unpleasant taste and odor to the water. Serious public health problems can still be generated if the biofilm detachment of the pipe, especially if it is composed of pathogenic micro-organisms. When grown on metal surfaces, another problem occurs because these biofilms can accelerate corrosion process by altering the lifetime of metallic materials. This work aims to investigate the formation of biofilms of Pseudomonas aeruginosa on surfaces of stainless steel 304L, used in the mineral water industry, and how to remove them from the metal surface by treatment with mixtures of oxidizing and surfactants / neutralizing chemical agents. It also also aims to analyze, by using electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM), the electrochemical conditions and the morphology of the specimens before and after the application of chemical treatments. The contact times and concentrations of the chemical were arranged in the form order to obtain a response in terms of percentage removal of microorganism. The analysis were carried out by electrochemical impedance spectroscopy (EIS) in NaNO3 0.5 mol L-1 medium before and after the formation of biofilm, as well as after chemical treatment, in order to check the surface of the stainless steel under the mentioned conditons. There was a reduction in the number of viable cells of P. aeruginosa biofilm after applying the chemical treatment, under all conditions studied, with both tested mixtures (1 and 2), with significant influence of the studied parameters. The EIS results suggest that the interaction between the parameters and the components of the studied mixtures also influenced the electrochemical behavior of the surface. However, it was not possible to separately analyze the variables and find a direct relationship with the % removal of bacterial cells and the electrochemical results