Homogenates were prepared by placing each leaf into 1.5 L sterile filter stomacher bags (15 23 cm; Whirl-Pak,Nasco, Fort Atkinson, WI), and macerated in 50 mL of 0.1% (w/v) sterile peptone water (PW) with a stomacher blender (Seward Stomacher 400, London, UK) at room temperature for 2 min at 230 rpm.