CHILLING CELLS ENHANCES BACTERICIDAL ACTION OF FATTY-ACIDS ON ESCHERICHIA-COLI

Preincubation at 0.degree. C considerably increased the bactericidal action of 0.4% nonanoic and decanoic acids on E. coli K-12 154. This lethal effect seemed to be dependent on the media used to grow the bacteria. Stationary-phase cells were more sensitive than those from exponential cultures. A mutant (FA31) resistant to the bactericidal action of cold shock and 0.4% decanoic acid was isolated from E. coli FA23 (an E. coli 154 derivative able to grow on 0.1% decanoic acid) by a recycling selection procedure. Other E. coli strains tested showed behavior similar to that of strain K-12 154. The chilling of cells as a tool to improve the bactericidal action of fatty acids in foods is discussed.