| Tetrabromobisphenol A(TBBPA)has been widely applied as a kind of flame retardant in the production of electronic products,plastic products and furniture.During its production and the subsequent usage procedure,large amount of TBBPA released into the environment.Due to the biological toxicity and refractory property,the released TBBPA accumulated in the environment and posed seriously threaten the human health and ecological safety.Biological method has the obvious advantage in treating the pollution of TBBPA,such as low operating cost and green pollution-free.Earlier research in our laboratory showed that pseudomonas aeruginosa NY3 was an efficient bacterium in degrading TBBPA.In this paper,pseudomonas aeruginosa NY3 was immobilized on the surface of PE packaging material,the influence of the coexistence of small molecule carbon sources on the degradation of TBBPA by immobilized pseudomonas aeruginosa NY3 were studied;the culturable strains accumulated on the biofilm of strain NY3 after degrading TBBPA were isolated and identified,finally,immobilized pseudomonas aeruginosa NY3 was applied in treating TBBPA wastewater in open systems with the coexistence of glucose.Main results obtained were as the following:(1)Studies of the influence of co-existing small molecule carbon sources showed that glucose was the most efficient co-existing carbon source in promoting the degradation of TBBPA by the biofilm of strain NY3.When the glucose concentration was 8 g/L,the cycle degradation time was 12 h,the initial concentration of TBBPA was50 mg/L,final concentration of TBBPA reduced to 3.3～23.6 mg/L after treated by the biofilm of strain NY3.when glucose was co-existed in the degradation system,the degradation pathway of TBBPA contained β-break and debromination,which were more abundant than that only through β-break when sodium lactate was co-existed.(2)Microbial population structure on the surface biofilm of strain NY3 after degrading TBBPA for 18 days with the coexistence of glucose was obviously different to that with the coexistence of sodium lactate.Microbial diversity and richness in the system with glucose as a co-existing carbon source were higher than that with sodium lactate as a co-existing carbon source.From the aspect of the gate level,the highest abundance three gates were proteobacter phylum,bacteroides phylum and actinomycete phylum,which was same in the system with glucose and sodium lactate as co-existing carbon source.The microbial species was significantly higher when glucose was the co-existing carbon source.(3)A total of 7 culturable strains were isolated from the cycle-degradation system of TBBPA by the biofilm of strain NY3 with sodium lactate or glucose as co-existing carbon source.Results showed that TB-1 bacteria and TB-3 bacteria both accumulated in the system of that with sodium lactate and glucose were the most efficient for degrading TBBPA.Both strain TB-1 and strain TB-3 could use TBBPA as the sole carbon source,they could grow slowly even when the concentration of TBBPA was as high as 1000 mg/L.According to the results of 16 S r RNA and physiological biochemistry,TB-1 bacteria and TB-3 bacteria were identified as Brevundimonas diminuta and Serratia marcescens,respectively.(4)Compared to the system of wastewater containing 50 mg/L TBBPA without any co-existing carbon source,TBBPA in the system with 8 g/L glucose as the coexisting carbon source could be removed lower than 2.7 mg/L during the cyclic degradation process(degradation time 12 h)of 60 days by the immobilized strain NY3.The results showed that hydrogen peroxide,super-oxide negative ion radicals and hydroxyl radicals in the system with glucose as the coexisting carbon source were higher than those of the control system without the coexisting carbon source.This suggested that the extracellular reactive oxygen species was significantly promoted by the coexistence of glucose,which subsequently increased the extracellular degradation of TBBPA.(5)The analysis of microbial diversity of the biofilm which degraded TBBPA for60 days showed that,dominant microorganisms of the biofilm in the control system without any coexisting carbon source were Pseudomonas,Methyloversatilis and Flavobacterium,in the system with glucose as coexisting carbon source,dominant microorganisms were Klebsiella,Enterobacter and Veillonella.Prediction results of the microbial surface show that,compared to that with sodium lactate or without co-existing carbon source,the environmental stress tolerance and electronic transmission rate were significantly improved in the system with glucose,which is beneficial to the degradation of TBBPA.These results had an important theoretical guidance on the treatment of TBBPA pollution by Pseudomonas aeruginosa NY3,and provided two excellent strains for the treatment of TBBPA pollution,which is of great significance for the biological treatment of TBBPA pollution. |
