Figure 4. Cold storage stability and pasteurization resistance of CHAPSH3b in milk.

A) 1.65 µM CHAPSH3b was stored in raw milk at 4°C for 3 days. Samples were taken every day, inoculated with 10³ CFU/ml of S. aureus Sa9 and incubated for 15 min at room temperature before plating. Non-cold storage protein was used as control. Cold storage stability was expressed as the percentage reduction of S. aureus Sa9 CFU/ml after CHAPSH3b addition. Values are the means ± standard deviations of two independent experiments. Bars having different letters are significantly different (P<0.05). B) 1.97 µM CHAPSH3b was pasteurized at 72°C for 15 s in raw milk (left) and commercial pasteurized milk (right). Samples were inoculated with 10³ CFU/ml and incubated for 0, 15, 30, 60 and 120 min at room temperature before plating. S. aureus inoculated cultures without lytic protein addition were used as control (dark grey bars). Light grey bars indicate S. aureus Sa9+ CHAPSH3b. Data from pasteurized samples with CHAPSH3b activity was expressed as log CFU/ml. Values are the means ± standard deviations of two independent experiments. Bars having asterisks are significantly different from the control (**P<0.01; ***P<0.001).