| Bisphenol F?BPF?is a monomer used in the synthesis of industrial products.The wide usage of these products has resulted in the detection of BPF in anaerobic environment including groundwater,sediment and soil.BPF has endocrine disruption toxicity,genotoxicity,neurotoxicity and cytotoxicity,and has great potential harm to the ecological environment and human health.Therefore,BPF released into the environment needs to be effectively treated.Meanwhile,the anaerobic biotransformation rate of BPF in the environment is very slow.In order to reveal the anaerobic fate of BPF and improve the anaerobic biotransformation rate of BPF,the characteristics of anaerobic biotransformation of BPF were studied by Pseudomonas sp.HS-2 with nitrate as an electron acceptor,and the RNA-seq analysis was carried out.Based on this,the enhanced effect of quinone modified graphene oxide on anaerobic biotransformation of BPF was studied.Strain HS-2 could anaerobically transform BPF to 4,4-dihydroxydiphenylketone using nitrate as an electron acceptor.When the initial concentration of BPF was 20 mg/L,the optimal conditions for anaerobic transformation of BPF were:5 mM nitrate,pH=7 and a temperature of 35°C.Transcriptome sequencing revealed that 493 differentially expressed genes were up-regulated and 71 differentially expressed genes were down-regulated during the anaerobic transformation of BPF.Among these up-regulated genes,the genes encoding ethanol dehydrogenase,acyl coenzyme A transfer and synthesis,cytochrome b and NAD?P?H dehydrogenase were assumed to participate in the anaerobic transformation of BPF.Meanwhile,some substance transport genes encoding ABC transporter,porin and outer membrane protein,etc,and stress-related genes encoding chemotaxis protein,general stress,superoxide dismutase and thioredoxin,etc were up-regulated.Moreover,the genes related to energy-producing were also up-regulated in the process of anaerobic biotransformation of BPF.Under the optimal conditions,four hydrophobic anthraquinone compounds including anthraquinone,1-aminanthraquinone,2-aminanthanthraquinone?AQ?and 2-hydroxy-anthanthraquinone could promote anaerobic biotransformation of BPF,and the accelerating effect of 2-aminanthanthraquinone was the most obvious.When the concentration of AQ was20 mg/L,the pseudo-first-order reaction rate constant(k-1)was 2.9×10-22 h-1,which increased37.1%compared with that without AQ.Strain HS-2 could not transform BPF in the addition of AQ without nitrate.Under the above conditions,graphene oxide?GO?could also promote BPF biotransformation.In the presence of 20 mg/L GO,the k was 3.2×10-2h-1,which was58.8%higher than that without GO.When the mass ratio of AQ to GO in2-aminoanthraquinone modified graphene oxide?AQ-GO?composite was 1:4,the anaerobic biotransformation rate of BPF was the highest among the tested ratios.With the concentration of AQ-GO?1:4?of 30 mg/L,its accelerating effect on BPF biotansformation was the most obvious among the tested concentrations.The k reached 8.5×10-22 h-1,which is 3.1-fold higher than that without AQ-GO(2.1×10-2).Further study showed that when the concentration of AQ-GO was 15 mg/L,its accelerating effect was higher than the sum of AQ and GO alone,indicating that a synergistic effect ocurred. |
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