Effects Of Graphene Oxide On The Anaerobic Biotransformation Of Bisphenol F

Bisphenol F(BPF)is a starting monomer for the production of polycarbonate plastic and epoxy resin.As an endocrine disruptor,it is of carcinogenicity,teratogenicity and mutagenicity,thereby it has great potential threat to the ecological environment and human health.With the prohibited use of bisphenol A,BPF as a substitute has been detected in anaerobic environment,e.g.,groundwater,soil and sediment.Its fate and transport in the environment have also been concerned by scholars.Recent studies showed that graphene oxide(GO)as an electron mediator can increase the anaerobic transformation rate of pollutants due to its unique physical and chemical properties.In this paper,Pseudomonas sp.HS-2 was used as a model strain,the effect of GO on the anaerobic biotransformation of BPF was studied,and the response of strain HS-2 to anaerobic transformation of BPF mediated by GO was analyzed by using transcriptomics technology.GO can promote anaerobic transformation of BPF into 4,4-dihydroxybenzophenone(DHBP)by Pseudomonas sp.HS-2.When 20 mg/L BPF was used as the sole electron donor,the optimal conditions for GO-mediated transformation of BPF were as follows: 10 mg/L GO,pH =7 and temperature of 30?.Strain HS-2 can only use nitrate as an electron acceptor,and GO cannot be used as an electron acceptor.Fourier transform infrared,Raman and photoelectron spectroscopy characterization of GO during the reaction showed that GO was partially reduced and functioned as an electron mediator to promote anaerobic biotransformation of BPF.Based on the fact that the reaction occurred under poor nutrition conditions,through the analysis of the changes in the total number of bacterial colonies during the reaction,it was found that nutrient substances released from necromass might be used by the strain HS-2.Some genes related to electron transport were up-regulated in GO-mediated anaerobic transformation of BPF.Compared with the initial moment,transcriptomic analysis of the control and GO-supplemented systems showed that the number of differentially expressed genes was 502 in control system,of which 33 genes were up-regulated;the number of differentially expressed genes was 458 in GO-supplemented system,of which 374 genes were up-regulated.In both systems,in addition to the up-regulated genes encoding superoxide dismutase,thioredoxin,porin,and heat shock protein involved in the stress response,substance transport and energy metabolism,it was assumed that the up-regulated genes encoding shikimate dehydrogenase and unknown protein may be involved in the anaerobic transformation of BPF to DHBP.Some up-regulated genes encoding quinone reductases and cytochrome c556 in GO-supplemented system may participate in GO reduction and electron transport process.