Figure 1.

Acid tolerance assays. Cells were grown to mid-exponential phase at 37°C under aerobic (□) or anaerobic (■) conditions and subjected to (A) citric acid, 2% (w/v); (B) lactic acid, 2% (v/v); (C) acetic acid, 2% (v/v); (D) 5 M HCl (volume sufficient for pH 3) in BHI broth. At intervals, samples were diluted in BPW and were plated by spiral plating, log reductions were calculated relative to time-point zero after 24–48 hours incubation at 37°C. Data presents the mean ± SEOM of three biological replicates conducted in duplicate.