Study On The Effects Of Tetrabromobisphenol A On Soil Microbial Community Structure,Diversity And Selectivity

Tetrabromobisphenol A(TBBPA),as the most extensively used brominated flame retardants(BFRs)in manufacturing and industrial applications,has caused an environmental concern worldwide.Owing to its high lipophilicity and hydrophobicity,TBBPA will inevitably tend to accumulate in soil.Previous studies of TBBPA have mainly focusedon either the degradation or metabolites in several environmental media,but there is lessdetailed information about its effects on microbial community.Microbial community is an important component of soil which is the main power of transformation and circulation of organic matter and nutrients in soil.It also plays an essential role in the ecological system of soil.Here we exposed surface soil to TBBPA at different concentrations,and investigated the microbial community structure and diversity responses under aerobic and anaerobic incubation.The results showed that TBBPA had significantly effects on soil microbial communitystructure and diversity,and the effects were different between aerobic and anaerobic condition.Microbial communitydiversity was influenced by TBBPA concentration,incubation time and conditions.High concentration(40 mg/kg)of TBBPA could significantly decrease the microbial community anundnace and diverisity.We further demonstrated found that TBBPA had selectively antimicrobial properties,which could specifically inhibit the growth of typical Gram-positice(G+)bacteria,but had little effect on the tested Gram-negative(G")bacteria in pure bacteria culture.Then,by the experiments of bacterial oxidation system,we found that TBBPA has caused oxidative stress on bacteria,and induce intracellar antioxidant system to produce stress effects.TBBPA could change the activities of superoxide dismutase(SOD),catalase(CAT)and glutathione(GSH)of bacteria.And with the increasing of TBBPA concentration,the activities of CAT in two strains of G+was gradually suppressed,then the reactive oxygen accumulated and damaged bacterial cells.The increase of malondialdehyde(MDA)content showed that TBBPA had more damage to G+.In addition,in this paper,we also investigated the effects of TBBPA on microbes related tonitrogen cycling,and found that the soil nitrification,denitrification and anaerobic ammonium oxidation process were inhibited by high concentration of TBBPA.Therefore,TBBPA might havepotential effects on soil nitrogen cycle.The research results provided necessary scientific basis for comprehensive evaluation of TBBPA for ecotoxicological effects,and basic theory and technical support for soil repair and pollution prevention.