Abstract: This research attempted to investigate the effect of high hydrostatic pressure (HHP) processing on the change
of intracellular soluble proteins in Vibrio parahaemolyticus isolated from aquatic products for the purpose of further
understanding the mechanisms of microorganism inactivation under HHP. Vibrio parahaemolyticus D, isolated from aquatic
products, and V. parahaemolyticus NYD, obtained by subjecting Vibrio parahaemolyticus D to high-pressure acclimatization,
were treated at different pressures (0, 100, 150, 200 and 250 MPa). Then viable cell counts were measured, intracellular
proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the leakage of
cellular contents as well as intracellular soluble proteins and total sulfhydryls were determined. The results showed that the
strains D and NYD were completely inactivated under 250 MPa treatments for 10 min, leaving the leakage of intracellular
substances including nucleic acids and proteins into the culture supernatant reaching the maximum level. Soluble protein and
total sulthydryl contents in intracellular protein extracts from both strains decreased with the pressure increasing. SDS-PAGE
analysis revealed the changes of intracellular proteins of 140–180 kD to be affected most by high pressure processing for
the two strains. These data suggest that the inactivation of V. parahaemolyticus by high pressure treatment is associated with
intracellular protein denaturation and the leakage of intracellular substances.

Key words: Vibrio parahaemolyticus, high hydrostatic pressure (HHP), protein profiles, sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE)