Although different BTEX pollutants showed different removal dynamics, the doses of the immobilized Mycobacterium sp. CHXY119 had almost no effect on removal efficiency (Fig. 2), suggesting the treatment characteristic of the immobilized bead. The immobilized bead removed BTEX in two separate steps, i.e., transport from the outside of the bead to the inside and then biodegradation by the immobilized cells.