Pure cultures of CB1190
were used to study gene abundance and expression during metabolic biodegradation
of dioxane. CB1190 was initially cultured in sterile 100-ml
bottles containing 20 ml of ammonia mineral salt (AMS) medium as
previously described (18, 32), with the exception that 20mMglucose was
used as the carbon source. After 5 days of growth on glucose, 60 ml of
CB1190 cells was filtered onto 0.2-m-pore cellulose filters (Nalgene,
Rochester, NY) and washed three times with phosphate-buffered saline
(PBS) solution to remove glucose. Cells were collected from the filter and
resuspended in 5ml ofAMSmedium to an average concentration of 3.2
108 cells/liter (standard deviation [SD], 4.8107 cells/liter). For dioxane
biodegradation experiments, 1 ml of concentrated CB1190 was used to
seed triplicate 100-ml screw-cap bottles containing a total volume of 20 ml
AMSmedium supplemented with 100 mg/liter dioxane. Bacterial cultures
were incubated at 30°C with 150 rpm of agitation.