grown in Kay's minimal medium at 37°C for 24 h. The flasks
were incubated with gyratory shaking (200 rpm) at 23°C.
Periodically, samples were taken from each flask for rhamnolipid
and protein determinations. For rhamnolipid analyses,
1-ml samples were filtered through a 0.22-p,m-pore-size
filter, and L-rhamnose was quantified. For protein analyses,
1-ml samples were heated for 10 min with 0.1 ml of 1 N
NaOH (to lyse cells), and the protein content was determined
by the method of Lowry et al.