Hejun Ren

Cloning and characterisation of a novel 2,4-dichlorophenol hydroxylase from a metagenomic library derived from polychlorinated biphenyl-contaminated soil

A novel 2,4-dichlorophenol hydroxylase (TfdB, EC 1.14.13.20) gene, designated as tfdB-JLU, was identified from a metagenome constructed from polychlorinated biphenyl-contaminated soil by functional screening and heterologously expressed in Escherichia coli. The deduced amino acid sequence of tfdB-JLU exhibited less than 48% homology with other known TfdBs. The enzyme exhibited a wider substrate spectrum than the previously reported TfdBs and higher relative activity towards ortho-substituted dichlorophenols, 2-chlorophenol, and 3-chlorophenol than towards 2,4-dichlorophenol, the preferred substrate of other known TfdBs. The enzyme had a Km of 5xa0μM for 2,4-dichlorophenol and 6xa0μM for NADPH. The optimal temperature and pH of the enzyme were 25°C and 7.5, respectively. Activity of the purified TfdB-JLU was slightly enhanced by Ca2+, Mn2+, Co2+, and Fe2+, and completely inhibited by Cu2+, Hg2+, and Zn2+. This study is the first report to identify a novel TfdB from a metagenome.

Recombinant protein, AlnA, combined with transgenic alfalfa remediates polychlorinated biphenyl-contaminated soils: efficiency and rhizosphere microbial community response.

ObjectiveTo investigate the remediation efficiency of polychlorinated biphenyl (PCB)-contaminated soils by the combination of a bioemulsifying protein, AlnA, and alfalfa expressing bphC.ResultThe combination of AlnA and transgenic alfalfa promoted PCB soil remediation through the pot experiments. The removal rates of tri-PCBs (PCB 16/PCB 32 and PCB 31/PCB 28) and tetra-PCB (PCB 49) in transgenic alfalfa/AlnA treatment were 3.6-, 1.1-, and 2-fold higher than in transgenic alfalfa treatment alone. Analysis of gene copy number revealed that the PCB-degrading gene, bphC, of Pseudomonas-like bacterial populations in transgenic alfalfa/AlnA treatment increased 1.5-fold compared with that of unplanted soils. Bacterial community Illumina sequencing showed Pseudomonas, Arthrobacter, and Sphingomonas positively correlated with the removal rates of PCBs.ConclusionsPCB removal was unrelated to bacterial community diversity but positively correlated with their specific degraders and bphC gene expression.

Garlic root biomass as novel biosorbents for malachite green removal: Parameter optimization, process kinetics and toxicity test

The potential of the agricultural waste garlic root to remove malachite green(MG) from aqueous solutions was evaluated. The adsorption of this dye onto garlic root was confirmed by means of Fourier transform infrared analysis(FTIR) and scanning electron microscopy(SEM). The equilibrium data fitted well into the Langmuir model(R2>0.99), and the adsorption kinetics followed the pseudo-second-order equation(R2>0.99). The maximum adsorption capacities of MG onto the adsorbent were 172.41 and 232.56 mg/g with the addition of 1 and 2 g/L garlic root, respectively. The optimal conditions for MG removal were established on the basis of orthogonal experiments(OA16 matrix). The concentrations of both MG and garlic root significantly affected the removal efficiency. The acute toxicity test indicated that the treated MG solutions were less toxic than the parent solutions. These results suggest that garlic root is a potential low-cost adsorbent for removing dye from industrial wastewater.

Oxidative removal of metronidazole from aqueous solution by thermally activated persulfate process: kinetics and mechanisms

Metronidazole (MNZ) is widely used in clinical applications and animal feed as an antibiotic agent and additive, respectively. Widespread occurrence of MNZ in wastewater treatment and hospital effluents has been reported. In this study, the mechanism of MNZ degradation in aqueous solutions via thermally activated persulfate (TAP) process was established under different conditions. The kinetic model was derived for MNZ degradation and followed pseudo-first-order reaction kinetics and was consistent with the model fitted by experimental data (R2xa0>xa098.8%). The rate constant increased with the initial dosage of persulfate, as well as the temperature, and the yielding apparent activation energy was 23.9xa0kcalxa0mol−1. The pH of the solutions did not have significant effect on MNZ degradation. The degradation efficiency of MNZ reached 96.6% within 180xa0min for an initial MNZ concentration of 100xa0mgxa0L−1 under the optional condition of [PS]0xa0=xa020xa0mM, Txa0=xa060xa0°C, and unadjusted pH. SO4·−

Enhancing bacterial transport with saponins in saturated porous media for the bioaugmentation of groundwater: visual investigation and surface interactions

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Chemical–biological hybrid reactive zones and their impact on biodiversity of remediation of the nitrobenzene and aniline contaminated groundwater

and HO· were confirmed using electron paramagnetic resonance (EPR) spectra during TAP process. Radical quenching study revealed that SO4·−

Synthesis and characterization of saponin‐modified Fe3O4 nanoparticles as heterogeneous Fenton‐catalyst with enhanced degradation of p‐nitrophenol

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