Regulation Of Extracellular Reactive Oxygen Species Of Pseudomonas Aeruginosa NY3 And Its Effect On The Degradation Of Tetrabromobisphenol A

Tetrabromobisphenol A,as a class of chemical additives,has been widely used in electronic products,plastic products and furniture.During the process of production and usage,large amount of tetrabromobisphenol A(TBBPA)was released into the environment,resulting the pollution of water,air and soil,which seriously threaten the human health and ecological safety.Due to the low cost and environmentally friend,biological treatment has been considered has a prior in treating TBBPA..Based on the reported work,the abiotic degradation of TBBPA resulted by the extracellular reactive oxygen species(ROS)has been thought as the main driving force in the biological treatment of TBBPA.As the dual role of ROS in biological systems,the level of ROS has become a key factor in the biodegradation of TBBPA.However,there is no reports relative to the regulation of ROS.In this paper,Pseudomonas aeruginosa NY3 was used as the tested strain to study the influence of different factors on the production of extracellular ROS,the regulation mechanism and its effect on the degradation rate of TBBPA of ROS has been studied.The main results were presented as following:(1)Based on the effect of glucose,oxalic acid,glutaric acid,butenedioic acid,citric acid,sodium lactate,sodium acetate,sodium citrate and iron on the production of ROS,it was found that,except iron,the exogenous substances used in this work increased the level of extracellular ROS of strain NY3,as well as the degradation efficiency of TBBPA.Among them,the degradation system of that added glucose,oxalic acid or sodium lactate resulted a higher degradation efficiency of TBBPA and a higjer level of extracellular ROS of strain NY3.After 10 days,the degradation efficiencies of TBBPA reache 77.36 %,91.86 % and 74.07 % when exogenous substances of glucose,oxalic acid and sodium lactate has been added in the degradation system of strain NY3,respectively.(2)Degradation system of strain NY3 added glucose,oxalic acid or sodium lactate has been selected as that with high level of ROS.For which,degradation of TBBPA by the cell free extracellular fluid and the corresponding resting cells were studied.The results showed that the cell free extracellular fluids were more effective on the degradation TBBPA than the resting cells.The degradation efficiency of TBBPA by the cell free extracellular fluid of strain NY3 incubated for 24 h reached 57.15 % within 8 h.When proteinase K was added to the cell free extracellular fluid,the degradation efficiency of TBBPA was usually improved,the degree of improvement was varied with the exogenous substances added.It suggested that the protein enzymes were unfavourable for the abiotic degradation of TBBPA.(3)Extraction and characterization of the small molecule secretions in the extracellular fluid of NY3 bacteria showed that,there are four main types of small molecule substances secreted by NY3 bacteria,including quinolones,phenazines,pyochelin,and rhamnolipids.The correlation analysis showed that,the relationships of the four types of small molecule substances and ROS were positive.Among the four types of small molecule substances,the positive correlation between ROS and quinolones and phenazine were the strongest,following with pyochelin and rhamnolipids.the positive correlation between ROS and rhamnolipids were weakest.Between the four types of small molecule substances,the concentration of phenazines were positively correlated with the concentrations of quinolones and cheloferrin;the concentration of rhamnolipids was negatively correlated with the concentrations of pyochelin and quinolones,the concentration of rhamnolipids was positively correlated with the concentration phenazines.(4)Degradation systems of strain NY3 added sodium lactate and oxalic acid were selected to treat the simulated TBBPA wastewater through batch shake flask experiment.The results showed that the degradation system with sodium lactate as the exogenous substance was better for degradation of TBBPA than that with oxalic acid.When the degradation time is 48 h,the degradation efficiency of TBBPA resulted by the system with sodium lactate as an exogenous substance of 10 days was higher than 98.9 %.the value of BOD/COD of the corresponding effluent was 1.77,which ndicated that the refractory wastewater turned into a biodegradable wastewater.Experimental results of this paper demonstrated the influence of different exogenous substances on the production of ROS and revealed the influence of extracellular secretions in the formation of ROS.It provided theoretical guidance for understanding the formation mechanism of extracellular ROS and its usage in treatmenting organic pollutants.