The DGGE profiling was utilized to evaluate the effects of BTEX concentrations on structure of the microbial community in the ORICBs-column (Fig. 4a).
Sand was coated with microbial populations from petroleum wastewater sludge to simulate indigenous microbial communities in contaminated aquifers.
The DGGE profiles of BTEX degraders (i.e., CHXY119 and YATO411) were used as markers (Lane 1: bands k and m).
The bands k and m were detected at all sampling points (i.e., S1, S2, and S3) at BTEX concentrations of 20–120 mgL–1 (lanes 2–13).
This phenomenon indicates that CHXY119 and YATO411 can survive in high BTEX concentrations, and that the degraders can be distributed from the ORICBs to the column end (zone G).