EFECTOS DE LA CONVERSIÓN LISOGÉNICA SOBRE LA FISIOLOGÍA Y VIRULENCIA DE Vibrio parahaemolyticus

Abstract

ABSTRACT Naturally, Vibrio parahaemolyticus occurs in the microbiota of marine invertebrates, and has been associated to outbreaks in aquaculture. In some members of the genus Vibrio, the virulence is increased by the infection of certain lysogenic phages (lysogenic state), however, it is unknown whether V. parahaemolyticus virulence can be modulated for the lysogenic conversion. In the present study the effect of lysogenic conversion on the physiology and virulence of V. parahaemolyticus was determined. Ten lysogenic phages (named α, 2, E2, S, ESE, 5c, 5s, 5+++, γ, W) isolated from clam and shrimp culture were used. The lysogenic states were induced experimentally by direct exposure of V. parahaemolyticus (strain ATCC 17802) to each phage and evaluated their effect on the hydrophobicity, enzyme production and use of different carbon sources through standard test. Also the changes in virulence were evaluated by challenge test in Artemia and shrimp larvae. And the production of toxins was assessed in a standard test of Artemia nauplii. The phages included in this study induced changes in the hydrophobicity of V. parahaemolyticus, from zero to moderate, and changes in the production of enzymes; including lipases and proteases. Simultaneously, changes in the metabolic profile of use of carbon sources were recorded. The phages named α, 2 and E2 significantly increased the virulence of V. parahaemolyticus for Artemia nauplii and the mixture V. parahaemolyticus/γ phage for shrimp larvae. The damages observed during the challenge test include lethargy and melanization of the body. The extracellular products produced by the 5+++ lysogen induces signs of damage and significant mortality in Artemia nauplii (p<0.05), indicating toxins production. Changes in the properties of V. parahaemolyticus by lysogenic conversion help to explain their variable effect during shrimp culture.