Physiological Response And Molecular Mechanism Of White-rot Fungi Under Decabromodiphenylethane Pollution Stress

China contains a large number of "electronic waste dumps",Brominated flame retardants are the most common pollutants in e-waste.They have the characteristics of high toxicity,durability and strong migration.In recent years,due to the prohibition of traditional brominated flame retardants,new brominated flame retardants have been widely used as their substitutes and have received widespread attention.Decabromodiphenyl ethane(DBDPE)is widely used as an ideal substitute for decabromodiphenyl ether because no harmful substances such as dioxins and furans are produced during the combustion process.DBDPE is detected in water,soil,particulate matter,and animal,plant,and human hair.In view of the widespread and serious risks of DBDPE,it is imperative to explore cost-effective methods to remove it from the environment.In recent years,white rot fungi have shown good prospects in microbial remediation due to their strong adaptability and unique degradability to xenobiotics.Only by clarifying the physiological response mechanism of white rot fungi under pollutant stress can it be targeted to improve Its resistance to pollutants and degradation performance make better use of white rot fungi to repair the polluted environment.In this study,Pleurotus ostreatus(Pleurotus ostreatus),the representative bacterium of white rot fungi,was used as the research object.The cell activity,biomass,and key enzyme(such as ATPase)activity of Pleurotus ostreatus in the DBDPE exposure system were detected.The body has obvious biological toxicity and shows a certain dose-effect relationship.ATPase activity not only affects biomass and protein content,but also plays an important role in the degradation process.The changes of antioxidant components such as superoxide dismutase(SOD),catalase(CAT),reduced glutathione(GSH)and malondialdehyde(MDA)under DBDPE pollution stress were also studied.It was found that DBDPE can lead to impaired function of the bacterial antioxidant system.It can be seen from the cell surface image that DBDPE causes the fungal mycelium to rupture and the content flows out,and the higher the concentration,the more serious the damage.Using Illumina Hi Seq technology(RNA-Seq),transcriptomics analysis of gene expression in Pleurotus ostreatus in different concentrations of DBDPE(0,5 mg/L,20mg/L)treatment system was performed.The results show that DBDPE can cause most of the transcription to be suppressed,increasing the concentration of DBDPE,resulting in fewer differential genes,indicating that the concentration has relatively little effect on the transcriptome.After annotation of the differential gene GO,it was found that the energy metabolism was the most important to the physiological function of Pleurotus ostreatus,followed by nucleotide metabolism and lipid metabolism.According to the KEGG annotation,DBDPE mainly affects the global metabolism of Pleurotus ostreatus,followed by energy metabolism,carbohydrate metabolism,signal transduction and otherprocesses.By classifying the differential gene descriptions that can be annotated,it is found that DBDPE mainly affects energy metabolism,catabolism and anabolic metabolism,stress,and down-regulation of transport-related proteins.After increasing the concentration of DBDPE,the expressions of hydrolases and glycosyltransferases were up-regulated,indicating that the bacteria also had a certain stress response to DBDPE and promoted the degradation of DBDPE.The relative and absolute quantitative(i-TRAQ)proteome analysis technology was used to analyze the differential expression of Pleurotus ostreatus in different concentrations of DBDPE exposure system.The results showed that DBDPE caused most protein expression to be induced.As the concentration of DBDPE increases,the number of differential proteins increases,and the number of down-regulated proteins remains basically unchanged.It is speculated that the activity of ATPase may increase,which promotes the expression of proteins to help remove contaminants.The GO annotation and enrichment results of differential proteins indicate that DBDPE has a greater influence on the cellular processes,metabolic processes and catalytic activities of the cells.As the concentration of DBDPE increases,the metabolic process,catalytic activity,and regulatory activity are up-regulated,indicating that the bacterial body enhances the removal of pollutants by promoting metabolic activity.The KEGG annotation and enrichment results of the differential proteins show that DBDPE has a greater influence on the cell metabolism,and the metabolic pathway is different at different concentrations.Analysis of key differential protein functions shows that DBDPE mainly promotes anabolic catabolism,energy metabolism and stress response,related proteins in the transportation process,enhances tolerance to pollutants and accelerates degradation and metabolism of pollutants by enhancing transportation and energy supply.The joint analysis of transcriptome and proteome shows that the expression gap between transcripts is larger than that of proteomes,and most of the transcripts are down-regulated,and the expression of proteomes does not change much.Through joint analysis of KEGG notes,it was found that increasing the concentration of DBDPE(5mg/L-20 mg/L)caused changes in carbohydrate metabolism,amino acid metabolism,transportation and catabolism,as well as affecting cell growth and apoptosis,which can be speculated Large concentration(20 mg/L)of DBDPE will affect the growth of cells and promote apoptosis,and at the same time different concentrations will induce different degradation-related proteins.This achievement has important theoretical and practical significance for the research and development of environmental remediation technologies for white rot fungi to degrade brominated flame retardants.