Over expression of inducible proteins in Escherichia coli by treatment with ethanol

It is reported that ethanol enhances DNA synthesis in E. coli cells [Basu, T and Poddar, R. K. (1994), Folia. Microbiol. 39, 3-6]. This communication reports that during growth of E. coli in the presence of 5% v/v ethanol, the derepressed expression of the cytoplasmic enzymes beta-galactosidase and D-serine deaminase per cell increased approximately three fold, while that of the periplasmic enzyme alkaline phosphatase decreased approximately 40% compared to control cell levels. However, in cells transformed with the plasmid pSM 456, bearing phoA-lacZ fusion, the level of induced synthesis of the hybrid protein PhoA-LacZ, controlled by the phoA promoter, was elevated by 25% in the presence of 5% v/v ethanol. This result suggests that the induction of the alkaline phosphatase precursor has also been enhanced by the ethanol treatment, but the inhibition in the export of the precursor across the cytoplasmic membrane, by the influence of ethanol, may represent the reason for the deficient expression of active alkaline phosphatase. It is proposed that there is an ethanol-mediated increase in DNA synthesis, resulting in gene amplification, which may enhance the synthesis of inducible proteins in ethanol-treated cells.