Efficient biodegradation

of chlorophenols in aqueous phase by magnetically immobilized aniline-degrading Rhodococcus rhodochrous strain Jianfeng Hou1, Feixia Liu1,3, Nan Wu1,2, Jiansong Ju2 and Bo Yu1* Background: Chlorophenols are environmental contaminants, which are highly toxic to living beings due to their carcinogenic, mutagenic and cytotoxic properties. Bacterial degradation has been considered a cost-effective and eco-friendly method of removing chlorophenols, compared to the traditional physical–chemical processes. Results: In this study, we first developed an efficient process for the biodegradation of chlorophenols by magneti-cally immobilized Rhodococcus rhodochrous cells. R. rhodochrous DSM6263 degrades chlorophenols following the first step of hydroxylation at the ortho-positions of chlorophenolic rings. The cells immobilized by k-carrageenan with 9 g/L Fe3O4 nanoparticles could efficiently degrade 2-chlorophenol, 4-chlorophenol, 2,3-dichlorophenol and their mixture, which were even higher than those by free cells. The magnetically nanoparticle-immobilized cells could be used at least for six cycles. Conclusion: Given the much easier separation by an external magnetic field and high degradation efficiency, this study provides a promising technique for improving biocatalysts used in the bioremediation process for chlorophe-nols in wastewater