The Preparation Of Novel Quinone Modified Materials And Their Enhancement Effects On N-substituted Aromatics And Cr(?) Bioreduction

At present, the release of refractory organic pollutants and toxic heavy metals results in serious water pollution. Bioremediation is an efficient method for controlling these pollutants. However, anaerobic bio-reduction rates of these polutants are low due to the slow metabiolism rates and electron transfer limitations of microorganisms. Quinone compounds (QCs) can accelerate the electron transfer from electron donor to electron acceptor during pollutants reduction, which improves pollutant reduction rate by one or several orders of magnitude. Thus, the usage of QCs in pollutants chemical reduction or bio-reduction has attracted much attention. Soluble QCs would result in the secondary contamination, one promising strategy for the application of QCs is their immobilization. On the basis of above background, this dissertation aims to develop new quinone-modified materials, study their catalytic performance on N-substituted aromatics and Cr(VI) reduction, and explore the response of E. coli facing quinone-modified materials at gene level.AQS-PETFC was prepared using Poly (ethylene terephthalate) fiber cloth (PETFC) as a carrier through a two-step covalent chemical method and the enhancement effect of AQS-PETFC on N-substituted aromatics bioreduction was investigated. The results showed that (i) the concentration of AQS immobilized on PETFC was 0.012 mmol g-1 cloth and AQS-PETFC presents better hydrophilicity and biocompatibility than unmodified PETFC; (ii) the addition of AQS-PETFC resulted in the increased anaerobic biotransformation rates of various azo dyes and nitroaromatics (The removal rates were about 1.6-3.7-fold higher than those in the absence of AQS); (iii) AQS-PETFC could be used as a biocarrier, although cells and EPSprotein attachment on the AQS-PETFC resulted in the decrease of its catalytic performance, this negative effect could be eliminated using the periodic cleaning.AQS-RGO was prepared using reduced graphene oxide (RGO) as a carrier through a two-step covalent chemical method and the enhancement effect of AQS-RGO on Acid Yellow 36 (AY 36) chemical reduction or bio-reduction was investigated. The results showed that (i) the concentration of AQS immobilized on RGO was 0.016 mmol AQS g-1 RGO; (ii) both AY 36 chemical reduction rate and AY 36 bioreduction rate could be enhanced by AQS-RGO; (iii) the optimal pH was 6 in AQS-RGO mediated AY 36 chemical reduction and the effect of temperature on AQS-RGO mediated AY 36 chemical reduction followed Arrhenius trend; (iv) AY 36 bioreduction could be enhanced in a dose-dependent manner of AQS-RGO and the optimal dosage of AQS-RGO in this study was 100 mg·L-1.Q-GOs were prepared using graphene oxide (GO) as a carrier through a one-step covalent chemical method and the enhancement effects of Q-GOs on Cr(VI) bio-reduction by HK-1 was investigated. The results showed that (i) the concentration of AQ and NQ immobilized on GO was 2.69 mmol AQ g-1 GO and 1.93 mmol NQ g-1 GO, respectively; (ii) A facultative anaerobic strain capable of removing total Cr was isolated from activated sludge and named Acinetobacter sp. HK-1 on the basis of the sequencing of the 16S rDNA gene, and the optimal conditions for HK-1 reducing Cr(VI) were 1 g·L-1 glucose, pH 7, T 35?, and the Cr(VI) reduction rate could reach 3.82 mg h-1·g-1 cell under optimal conditions; (iii) the Cr(VI) reduction rate could reach 190 mg h-1·g-1 cell in the presence of 50 mg·L-1 NQ-GO, and the catalytic performance of NQ-GO was better than AQ-GO; (iv) the Cr(VI) reduction activity of cell membrane proteins and cytoplasmic and periplasmic proteins could be increased by 18.1-fold and 7.3-fold, respectively, in the presence of NQ-GO.Whole-genome DNA microarrays were used to investigate a quinone-reducing bacterium Escherichia coli K-12 (E. coli K-12) transcription response AQSim reduction and azo dye acid red 18 (AR 18) reduction. Morover, RT-PCR analysis and gene-knockout experiment were performed to verify the reliability of the data from the microarray experiment. The results showed that (i) AQSim was more accessible for the cells of E. coli K-12 than AR 18; (ii) despite there being some differences between AQSim reduction and AR 18 decolorization, more similarity could be observed in the two processes; (iii) there were likely multiple pathways for AQSim reduction and AR 18 reduction and a major candidate for such an alternate pathway is the significantly upregulated nrfABCD genes, annotated as nitrite reductase; (iv) genes encoding dehydrogenases (fdhF and yqhD) and reductases(dmsABC, frdBCD and nrfABCD) were likely key parts of the gene network responsible for transferring electrons from an electron donor to AQS-PETFC and AR 18.