Formação de biofilme por Vibrio parahaemolyticus isolados de pescados e resistência a sanitizantes

Abstract

Vibrio parahaemolyticus is a pathogen can cause gastroenteritis by consumption of contaminated fish. Bacterial biofilm is a community of sessile microorganisms embedded in an extracellular matrix formed by exopolysaccharides, which may hinder the elimination of undesirable microorganisms in food. The objective this study was to verify the ability of V. parahaemolyticus isolated from fish from the estuary of Lagoa dos Patos-RS to form biofilm on different surfaces and after exposure to sublethal stress and test the effect of biofilm on resistance to sanitizing. To obtain the samples, 12 collections of arfantepenaeus paulensis (Pink shrimp) and of fish captured in the estuary of Lagoa dos Patos. Vibrio isolates were analyzed by polymerase chain reaction (PCR) to identification of the species. In addition to the isolates obtained in this study were also studied 15 other isolates of V. parahaemolyticus previously isolated in other works. The isolates were evaluated for biofilm production capacity in microtiter plates. The biofilm production capacity after the isolates had being subjected to different types of sublethal stress (42 °C, 20 °C, 4 °C and acid pH) was also tested. The isolates of V. parahaemolyticus able to form biofilm were tested for the capacity of forming biofilm on high density polyethylene, stainless steel, glass, exoskeleton of Farfantepenaeus paulensis and operculum of Micropogonias furnieri (Corvina). The sanitizer sodium hypochlorite efficiency was evaluated against the bacteria in the biofilms formed on the surface of the materials used. Among the 120 analyzed fish, V. parahaemolyticus were isolated from four (3.33%) fishes and two (16.66%) samples of F. paulensis. Among the 19 isolates analyzed, 89.5% were able to form biofilm and of these 25% increased the ability to form biofilm after some kind of stress. One of the two isolated was able to form biofilm, being classified as weak biofilm-forming; the other one was classified as nonbiofilm-forming. None of the isolates altered their ability to form biofilm when subjected to the stresses of 4 °C and 20 °C; however, regarding the stresses of 42 °C and pH acid, each strain responded differently. Eight isolates were tested for their ability to form biofilm on different surfaces, five were considered biofilm forming and more than one isolate formed biofilm on the surface of the M. furnieri operculum and high density polyethylene. One isolate formed biofilm in glass and one in stainless steel. None isolate formed biofilm in the shrimp shells. The sanitizer reduced biofilm formation on all surfaces. Based on the results, we concluded fishes of the species M. platanus and shrimp of the specie F. paulensis are hosts of V. parahaemolyticus usually a form biofilm. Exposure to sublethal stress conditions has distinct effect on different isolates, whose ability to form biofilm can be altered depending on the surface. The sodium hypochlorite at a concentration generally used in fish industries,reduces bacterial population of V. parahaemolyticus in biofilm, but does not eliminate the bacteria.