Ricinus communis as an Element Biomonitor of Atmospheric Pollution in Urban Areas

Iopromide has been frequently detected in different environmental compartments. However, the biodegradation of iopromide was limited, and significantly different removal efficiencies by various methods were reported. In this study, a Pseudomonas sp. I-24 isolated from activated sludge in a sewage treatment plant was used to degrade iopromide. Four different cosubstrates were selected as the cometabolic carbon and energy sources. The results showed that cosubstrate starch was able to increase catabolic enzymatic activity and enhance iopromide degradation. The degradation efficiency of iopromide was as high as 88.24 %, which was much higher as compared with other cosubstrates (38.58–51.44 %) and blank sample (2.81 %). Additionally, the highest enzymatic activity of 0.182 mU for iopromide degradation was also obtained when adding starch as a cosubstrate, somehow supporting that higher enzymatic activity resulted in higher degradation efficiency for iopromide. Although little was illuminated about the molecular mechanism during the degradation process of iopromide with starch addition, the two-dimensional gel electrophoresis results indicated that the iopromide-degrading cells growing with cosubstrate starch underwent significant physiological changes.