Study on the Mechanism by Which Fe³⁺ Promotes Toluene Degradation by Rhodococcus sp. TG-1

Volatile organic compound pollution caused by toluene has become a global issue. In order to solve this problem, biodegradation of toluene has been applied all over the world. This study investigated the effects of Fe³⁺ on toluene degradation by the Rhodococcus sp. TG-1. The results show that 1 mg L^-1 Fe³⁺ increased the degradation rate of 600 mg L^-1 toluene from 61.9% to 87.2% at 16 h. The acceleration mechanism of Fe³⁺ was explicated using transmission electron microscope (TEM) and energy-dispersive X-ray spectroscopy (EDX) analyses, coupled plasma optical emission spectroscopy, an enzyme activity assay, and transcriptome analysis. Four genes were detected to be significantly up-regulated under Fe³⁺ induction, suggesting that Fe³⁺ might be implicated in toluene degradation. Meanwhile, Fe³⁺ was a component of the active center of catechol 1,2-dioxygenase (C12O) and significantly improved the enzyme activity of C12O. The mechanism by which Fe³⁺ accelerates toluene degradation was proposed based on the transcription levels of degradation genes and the enzyme activity of C12O. This study provided an improved method for enhancing the degradation effect of toluene and furthered our comprehension of the mechanism of toluene degradation.