Degradation Performance Of Decabromodiphenylethane By Pleurotus Ostreatus And Its Toxicological Response

Decabromodiphenyl ethane(DBDPE)is one of the typical new brominated flame retardants(NBFRs)widely existing in the dismantling of electronic waste.DBDPE presents a certain toxicity,which does harm to the environment and humans.White rot fungi can degrade BFRs very well,among them,Pleurotus ostreatus,as one of the typical strains of white rot fungi,can effectively degrade a variety of organic pollutants.However,there are few reports about the research on the degradation of DBDPE by P.ostreatus.This paper applies degradation performance of DBDPE by P.ostreatus and its toxicological response,which the chief research consequences of this paper are as follows:(1)When the initial DBDPE concentration was 5 mg/L,the initial pH was 5,the glucose concentration was 3 g/L and the degradation time was 120 h,the degradation rate of DBDPE reached 47.73%.The coexistent Pb had a certain inhibitory effect on the degradation of DBDPE,especially at high concentrations(200 mg/L).The intracellular enzyme(P450 enzyme)and three extracellular enzymes(Li P,Mn P,Lac)secreted by P.ostreatus played a synergistic role in the degradation process of DBDPE,of which Lac was the major degrading enzyme.At the same time,DBDPE also had an inhibitory effect on the three extracellular enzymes of the fungus,which when the concentration of DBDPE was 5 mg/L,the maximum inhibition rate of Lac was 80.95%.Lipids,proteins and polysaccharides on the surface of P.ostreatus all participated in the degradation of DBDPE and P.ostreatus debromized,hydroxylated,and oxidized the DBDPE which a total of 88 intermediate products were detected.(2)Through the detection of oxidative stress and cell apoptosis in P.ostreatus during the degradation of DBDPE,the results showed that DBDPE could induced a large amount of ROS production in the fungus,leading to the activity of superoxide dismutase(SOD)and catalase(CAT)increasing first and then decreasing with the increase of DBDPE concentration,which enzyme activity was the highest at 36 h and they had a synergistic effect.The content of the fungus protein first increased and then decreased with the degradation time,the highest content was at 36 h,and first increased and then decreased with the increase of DBDPE concentration.At the same time,it was observed by scanning electron microscope that DBDPE could also cause mycelial damage,which the higher concentration of DBDPE,the greater degree of cell apoptosis,and the degree of DNA damage was not significant.Compared with DBDPE,coexisting substance Pb had a stronger toxic effect on the fungus,which affected the degradation efficiency of the fungus on DBDPE.(3)The results showed that during the degradation of DBDPE,the fungus could resist the damage of DBDPE and Pb by secreting a large amount of protein,and Pb had a stronger toxic effect on fungus than DBDPE.Differential proteins in P.ostreatus were mainly concentrated in metabolic process and cellular process,cell anatomy entity and cell,catalytic activity and binding.Cytochrome P450 enzymes,glycosyltransferases,and salicylate 1-monooxygenase are the key functional proteins for P.ostreatus to degrade DBDPE.DBDPE induces the upregulation of peroxisomes,ABC transporter and imidazole glycerol phosphate synthase,while inhibiting the expression of NADH ubiquinone oxidoreductase and succinate dehydrogenase to affect fungus decomposition and anabolism.In addition,the expression of heat shock protein and ribosomal protein in degradation system was up-regulated to resist the toxicity caused by DBDPE and Pb,which others included mitogen-activated protein kinase,serine protein kinase,ribonuclease and so on.This study has important theoretical and practical significance for the microbial degradation of new brominated flame retardants.