Appearance of a stress-response protein, phage-shock protein A, in Escherichia coli exposed to hydrophobic organic solvents.

A 28 kDa protein associated with the inner membrane was induced strongly in Escherichia coli K-12 cells grown in the presence of a hydrophobic organic solvent, n-hexane or cyclooctane. These organic solvents suppressed the growth (growth rate and yield) of E. coli. A partial amino acid sequence showed that this protein was the phage-shock protein PspA. PspA is known to be induced in E. coli cells under extreme stress conditions. The results suggest that E. coli cells are subject to strong stress in the presence of organic solvents. Introduction of a multi-copy plasmid vector carrying the psp operon into E. coli improved the survival frequency of cells exposed suddenly to n-hexane but not the growth rate of cells growing in the presence of n-hexane.