Individual or synchronous biodegradation of di-n-butyl phthalate and phenol by Rhodococcus ruber strain DP-2

•A Rhodococcus ruber strain degraded DBP and phenol.•Degradation kinetics of DBP or phenol fit modified first-order models.•Degradation interaction between DBP and phenol was studied by strain DP-2.•The degradation genes transcriptional were quantified by RT-qPCR. The bacterial strain DP-2, identified as Rhodococcus ruber, is able to effectively degrade di-n-butyl phthalate (DBP) and phenol. Degradation kinetics of DBP and phenol at different initial concentrations revealed DBP and phenol degradation to fit modified first-order models. The half-life of DBP degradation ranged from 15.81 to 27.75h and phenol degradation from 14.52 to 45.52h under the initial concentrations of 600–1200mg/L. When strain DP-2 was cultured with a mixture of DBP (800mg/L) and phenol (700mg/L), DBP degradation rate was found to be only slightly influenced; however, phthalic acid (PA) accumulated, and phenol degradation was clearly inhibited during synchronous degradation. Transcriptional levels of degradation genes, phenol hydroxylase (pheu) and phthalate 3,4-dioxygenase (pht), decreased significantly more during synchronous degradation than during individual degradation. Quantitative estimation of individual or synchronous degradation kinetics is essential to manage mixed hazardous compounds through biodegradation in industrial waste disposal.