Alteration of structure and cellular protein profiles of Vibrio parahaemolyticus cells by high pressure treatment

Effects of high pressure processing on changes of cell morphology and cellular proteins were investigated using two Vibrio parahaemolyticus strains 10290 and 10292 subjected to pressure treatments (200 or 300 MPa for 5 min) at 20 °C. Cells with or without pressure treatments were studied for structural damage by leakage of internal cellular substances and scanning electron microscopy (SEM) and for cellular proteins profiles by total sulfhydryl contents and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Increase in leakage of cellular substances was observed as the pressure of a treatment increased. Scanning electron microscopy images revealed cell damage of both V. parahaemolyticus strains after the pressure treatments, particularly at 300 MPa for 5 min. Total protein and sulfhydryl contents in cellular protein extracts of both strains decreased as the pressure of a treatment increased. SDS-PAGE analysis of cellular proteins extracted from V. parahaemolyticus cells after the pressure treatments revealed changes of cellular protein profiles with a few protein fragments of 150–250 kDa being affected most. These data suggest that inactivation of V. parahaemolyticus cells by high pressure processing is associated with cell membrane damage and changes of cellular protein profiles, which appear to be dependent on the strain and pressure applied in a treatment.