Lowering of cytoplasmic pH is essential for growth of Streptococcus faecalis at high pH

Lowering of cytoplasmic pH is essential for growth of Streptococcus faecalis at high pH.

The growth of Streptococcus faecalis at high pH was significantly stimulated by carbonate. In the absence of added carbonate the cells were unable to grow at a pH above 9.5, but in media containing 50 mM HCO3- they grew even at pH 10.5. Both rate and yield of growth at pH 9.5 were significantly stimulated by as little as 5 mM carbonate. The cytoplasmic pH in growing cells was maintained at abou...

Amplification of the Streptococcus faecalis proton-translocating ATPase by a decrease in cytoplasmic pH.

When Streptococcus faecalis was grown in the presence of protonophores , an ATPase activity of the membrane was increased at a pH below 8.0 but not at a pH above 8.0. Characteristics of this increased ATPase were identical to those of a proton-translocating ATPase (H+-ATPase) located on the membrane of normal cells. The cytoplasmic pH was regulated at 7.6 to 7.8 but was not regulated in the pre...

Prolonged Survival and Cytoplasmic pH Homeostasis of Helicobacter pylori at pH

Prolonged survival and cytoplasmic pH homeostasis of Helicobacter pylori at pH 1.

In the presence of urea, Helicobacter pylori survived for at least 3 h at pH 1. Under these conditions, the cells maintained their cytoplasmic pH at 5.8. De novo protein synthesis during acid shock was not essential for survival of H. pylori at pH 1.

PREDICTION OF HOT DEFORMATION BEHAVIOUR OF A PH STAINLESS STEEL AT HIGH STRAIN RATES

In this study the hot deformation behaviour of a precipitation hardened (PH) stainless steel at high strain rates has been predicted through hot compression testing. Stress-strain curves were obtained for a range of strain rates from 10-3 to 10+1 S-1 and temperatures from 850 to 1150°C. Results obtained by microstructure and stress-strain curves show that at low temperatures and high strain rat...