Characteristics of adherence of pathogenic Vibrio alginolyticus to the intestinal mucus of large yellow croaker (Pseudosciaena crocea)

Intestinal mucus (foregut mucus and hindgut mucus) extracted from large yellow croakers was used as a model of investigating the adhesion of pathogenic Vibrio alginolyticus by the method of isotope tracer. The results showed that pathogenic V. alginolyticus could adhere to the intestinal mucus of large yellow croaker strongly. The bacterial adhesion to foregut mucus and hindgut mucus reached equilibrium after incubated at 25 degrees C for 150 min and 180 min, respectively. The bacterial adhesion was influenced remarkably by environmental factors such as temperature, pH and salinity, and the maximal adhesion was achieved at 30 degrees C, acidic condition and the normal values of salinity of marine environment (3 5). Starved bacteria had no adhesive capacity. Lactic acid could inhibit the bacterial adhesion. In addition, the adhesion of V. alginolyticus depended on Na+ while Ca2+ or Mg2+ played an auxiliary role in bacterial adhesion. Results obtained from adhesion assaying under various conditions (heat treatment, protease and periodic acid treatment) indicated that the main components involved in the adherence process of V alginolyticus to the intestinal mucus might be glycoproteins. The results of adhesion assay after the mucus was roughly fractionated by gel filtration chromatography showed that the components with highest affinity might be the higher molecular mass. Our results indicated that the bacterial adhesion was governable, which might be useful for the epidemic control in fish culture. (C) 2007 Elsevier B.V. All rights reserved.