title: Na+-mediated piezoprotection in Rhodotorula rubra.
abstract: Sodium concentrations as low as 2 mM exerted a significant protective effect on the high-pressure inactivation (160-210 MPa) of Rhodotorula rubra at pH 6.5, but not on two other yeasts tested (Schizosaccharomyces pombe and Saccharomyces cerevisiae). A piezoprotective effect of similar magnitude was observed with Li+ (2 and 10 mM), and at elevated pH (8.0-9.0), but no effect was seen with K+, Ca2+, Mg2+, Mn2+, or NH4(+). Intracellular Na+ levels in cells exposed to low concentrations of Na+ or to pH 8.0-9.0 provided evidence for the involvement of a plasma membrane Na+/H+ antiporter and a correlation between intracellular Na+ levels and pressure resistance. The results support the hypothesis that moderate high pressure causes indirect cell death in R. rubra by inducing cytosolic acidification.
authors.affiliation: Laboratory of Food Microbiology, Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, 3001 Heverlee, Belgium.
authors.forename: Abram
authors.initials: A
authors.lastname: Aertsen
authors.forename: Barbara
authors.initials: B
authors.lastname: Masschalck
authors.forename: Elke Y
authors.initials: EY
authors.lastname: Wuytack
authors.forename: Chris W
authors.initials: CW
authors.lastname: Michiels
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D006863:Hydrogen-Ion Concentration; D008094:Lithium / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D015203:Reproducibility of Results; D012248:Rhodotorula / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D013045:Species Specificity
chemical_list: D017923:Sodium-Hydrogen Exchangers; D008094:Lithium; D012964:Sodium; D011188:Potassium