*3.4. Cd2+ Adsorption Experiment*

The adsorption of ST11 cells for Cd2+ was examined. After culturing in an LB medium for 60 h, ST11 cells were harvested through centrifugation (H2050R, Xiangyi, China) at 6380× *g* and 4 ◦C for 10 min. The cells were then washed three times with Milli-Q deionized water to remove the residual medium. The obtained wet cells were used directly for Cd2+ adsorption without further treatment. An aqueous solution of Cd2+ with a concentration of 0–12 µmol/L was prepared, and 10 mL of the solution was added to a 15 mL glass test tube. Furthermore, the wet cells were added to the tube, and the cell concentration in the aqueous solution was set as OD<sup>600</sup> = 1.0. The above solutions were shaken at 25 ◦C and 150 rpm for 1 h. After centrifugation, the residual amount of Cd2+ in the supernatant was detected.

#### *3.5. Biodegradation of Crystalline Atrazine*

For experiments with crystalline atrazine, the bacterium was grown at 30 ◦C and 150 rpm in 150 mL-triangular flasks containing 30 mL of MSM supplied with different concentrations of atrazine as the sole source of carbon, nitrogen, and energy. A total of 1 mL of resuspended cells (OD600 1.0) was added into MSM. A certain volume of atrazine stock solution was evenly spread at the bottom of the pre-dried triangular flasks to avoid the influence of insoluble atrazine crystals on the absorbance detection of cells in the culture medium. A layer of homogeneous atrazine crystals was fixed at the bottom of the flask after the volatilization of dichloromethane for 12 h. In the process of cell culture, these crystals do not fall off from the bottom of the flask [47]. The regular interval for the biodegradation experiment was 48 h.

The biodegradation of atrazine was estimated indirectly as bacterial growth and atrazine content reduction. The bacteria were collected by centrifuging the culture medium at 6380× *g* and 4 ◦C for 10 min. The cells were washed three times with deionized water to remove the residual medium. The obtained wet cells were resuspended with MSM and the OD<sup>600</sup> was determined. The complete biodegradation of atrazine was confirmed microscopically by the disappearance of atrazine crystals at the bottom of triangular flasks and by ethyl acetate extraction of the crystals after biodegradation and analysis of the extracts with an Agilent high-performance liquid chromatography (HPLC) system.

#### *3.6. Biodegradation of Atrazine in NAPL*

DEHP was used as the NAPL for determining the ST11 biodegradability of NAPLdissolved atrazine. Experiments were performed in triangular flasks containing 24 mL of MSM and 6 mL of DEHP containing 9.25 mmol/L atrazine. The concentration of atrazine in the system was 1.85 mmol/L. For the inoculated sample, 1 mL of resuspended cells (OD600 1.0) was added to MSM. For the non-inoculated control experiment, no ST11 cells were added. The samples measured in triplicate were incubated at 30 ◦C on a rotary shaker at 150 rpm for 48 h.

The adherence of suspended bacteria to the liquid organic phase was tested. The method used was a modified assay of MATH [48]. DEHP (5 mL) and 20 mL of the cell suspension (OD<sup>600</sup> 0.6) in MSM were vigorously homogenized in a test tube for 1 min by a vortex agitator (SA8, Thomas Scientific, Swedesboro, NJ. USA). After 2 h of equilibration, the cells' adhesion to DEHP was estimated from the loss of aqueous phase absorbance at 600 nm. Furthermore, optical imaging of the droplets at the oil-water interface was carried out to detect the location of bacterial cells by phase-contrast microscopy (Eclipse E200, Nikon, Tokyo, Japan).
