| Congresso Brasileiro de Microbiologia 2023 | Resumo: 365-1 | ||||
Resumo:Acinetobacter baumannii is a Gram-negative coccobacilli, non-glucose fermenting, strictly aerobic, immobile, catalase-positive, oxidase-negative. Taxonomically, it belongs to the class Gamma-proteobacteria, to the order Pseudomonadales and to the family Moraxellaceae. Clinically it is characterized as an opportunistic pathogen. However, in recent years it has emerged as one of the main hospital pathogens, not only for its antimicrobial resistance profiles, but also for its ability to persist for a long time on surfaces. Many virulence factors have already been described for A. baumannii, but the literature is scarce with regard to the secretion of proteolytic enzymes. Thus, this study aimed to analyze the possible secretion of proteases by different strains of A. baumannii. Seventeen hospital strains of A. baumannii were obtained from previous isolation in two clinical analysis laboratories in Ponta Grossa, Paraná, Brazil. These strains were subcultured on Nutrient Agar or BHI Agar at 37°C for 24 hours and tested for their ability to oxidize glucose and lactose, in addition to their ability to grow at 42°C. Of these, three strains exhibited greater proteolytic activities, as observed by their areas of milk protein lysis after cultivation on two different types of Skim Milk Agar for 24 hours at 37°C. These three strains, named ABHU1, ABHU4 and ABHU9 were additionally cultured in 5% Nutrient Broth for 24 hours at 37°C. After centrifugation for sedimentation of bacterial cells, the supernatants were submitted to casein degradation assays (caseinolysis) and then revealed by the Bradford method, where in these assays the decrease in absorbance at 595nm is specifically evaluated. Strains ABHU1, ABHU 4 and ABHU9 showed, respectively, 27%, 25% and 18% of casein degradation under the tested conditions (0.05 mg/mL casein, PBS pH 7.4, 37°C, 24 hours) compared to the negative control. Although preliminary, these results demonstrate the production and protease secretion by 3 different strains of A. baumannii, which opens the opportunity for the research upon a possible new virulence factor for this pathogen. In this context, future perspectives for this study involve the biochemical characterization of these proteases by zymography assays and degradation kinetics with different substrates. Palavras-chave: Acinetobacter baumannii, Proteolytic activity, Caseinolysis Agência de fomento:Coodenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) | |||||