Influence of previous sub-lethal heat, cold and acid treatments on <i>Escherichia coli</i> BJ4 resistance to (+)-limonene.

a, b, c<p>: same letters indicate non-significant differences among mean values; <i>p</i>>0.05.</p><p>Log₁₀ of survival counts (CFU/mL) of <i>Escherichia coli</i> BJ4 (wild type) and BJ4L1 (Δ<i>rpoS</i>) (initial concentration: 3·10⁷ CFU/mL) by a treatment with 200 µL/L of (+)-limonene in citrate-phosphate buffer of pH 4.0. Table includes data from non-stressed cells (control) and cells exposed to different sub-lethal shocks before (+)-limonene treatments (mean ± standard error). Sub-lethal heat shock: 45 °C/2 h; sub-lethal cold shock: ice/4.5 h; sub-lethal acid shock: pH 4.5/1 h.