Phenanthrene

Chemicals were purchased from the following sources:
Dichloromethane (DCM), analytical reagent grade 99.99 %, hexane, laboratory reagent grade, and acetone, analytical reagent grade 99.99 %, were all from Fisher Scientific, Loughborough, UK. Dimethylsulphoxide (DMSO), molecular biology grade ≥99.9 %, benzo[a]pyrene (>96 % purity; CAS: 50-32-8 601-032-00-3), pyrene (99 % purity, CAS 129-00-0) and Pronase E (from Streptomyces griseus) were from Sigma-Aldrich, Gillingham, Dorset, UK. Naphthalene (99 % purity, CAS 91-20-3) and phenanthrene (98 % purity, CAS 85-01-8) were from Alfa Aesar, Ward Hill, MA, USA. FPG was kindly provided by Professor Andrew Collins from Oslo University, Norway. Ultrapure low melting point agarose (LMPA) and foetal bovine serum (FBS) were both from Life Technologies, Paisley, UK.

Phenanthrene was purchased from Alfa Aesar (England) and antibiotics used in this study were obtained from Sigma-Aldrich (United States). E. coli Top 10 and E. coli BL21 (DE3) strains were used for propagation of plasmids and overexpression. Restriction endonucleases, Taq DNA polymerase, DNAiso reagent, RNAiso Plus, DNase I, cDNA Synthesis Kit, SYBR^® Premix DimerEraser™ and T4 DNA ligase were obtained from Takara (Takara, Dalian, China) and used according to manufacturer’s instructions. The expression vector pET-28a (+) and pMAL-c5X were purchased from Invitrogen (Shanghai, China) and New England Biolabs (USA) respectively.

The natural sediment was collected from the top 0–20 cm of the sediment in Lanzhou Reach of the Yellow River. It was washed using double distilled water, air-dried, and sieved to obtain the size fraction of 38–75 μm. H₂O₂ treatment was performed to obtain the organic-free sediment according to Kunze and Dixon [13 ], followed by the steps of washing, drying, and sieving. The same size fraction as the natural sediment was used for the experiment. Kaolinite (a product of inorganic clay) was purchased from Fuchen Chemical Reagent Co., Inc. (Tianjin, China) and was used without further treatment.
Phenanthrene and pyrene were purchased from Acros Organics (New Jersey, USA). NP was purchased from Tokyo Chemical Synthesis Ind. Co. Ltd (Tokyo, Japan). They were dissolved in methanol to make their respective stock solution. Humic acid (HA) was purchased from Tianjin Guangfu Fine Chemical Research Institute in China, which was dissolved in 0.1 mM NaOH solution and filtrated through a 0.45 μm membrane to obtain a stock solution (0.89 g/L).