Then, it was
gently collected and was put in a plastic basket. Each vegetable
sample was eluted by vigorous agitation followed by sonication
(INC. ultrasonic processor W-380, Japan) of each specimen
for 30 min in 1 L of sterile phosphate-buffered saline
(pH 7.4), to which 50 ml of 0.01% Tween 80 was added