Fig. 2. HPLC analysis of C6-HSL degradation by JydB and restoration of C6-HSL by acidification of JydBhydrolysis product. (A) 1 mM C6-HSL substrate peak is shown as the control with an elution time of 9.5 min, which was monitored at 205 nm. (B) C6-HSL hydrolysis reaction was carried out with 4.6 μg JydB and 1 mM C6-HSL at 37°C for 15 min and terminated by boiling. The profile of the JydB-hydrolyzed C6-HSL product shows a new peak (5 min) of hydrolyzed product, whereas the C6-HSL substrate peak (9.5 min) is decreased. (C) C6-HSL was restored by acidification of JydBhydrolyzed C6-HSL product. The reaction mixture was acidified to pH 2 by adding 1N HCl and incubated at 4°C for 24 h.