Isolation,Screening And Activity Study Of Facultative Anaerobic Bacteria Degrading Paes In The Shore Of Baiyangdian Lake

Phthalate?PAEs?is a kind of refractory organic compound,which exists widely in atmosphere,soil and water environment.Because of its great harm to human body,how to effectively degrade PAEs in the environment has become an urgent problem to be solved.Microbial degradation of PAEs has attracted much attention because of its unique advantages such as high degree of mineralization,low economic cost,no secondary pollution and so on.In this study,the active silt along the bank of Baiyangdian Lake around Nanliuzhuang in Anxin County was taken as the sampling point,and five kinds of PAEs?DMP,DEP,DBP,DOP and DIOP?with high concentration were taken as the object of study.The main contents and results are as follows:?1?30 facultative anaerobes with PAEs degradation activity were screened by concentration gradient pressure domestication and enrichment method.The results of species diversity analysis showed that 30 strains were located in 7 different genera and 14 different species,among which Pseudomonas had the highest abundance.?2?The conditions for determining the degradation rate of five kinds of PAEs were determined.By HPLC determination,it was found that the selected strains all had a certain effect on the degradation of five kinds of PAEs.The strains with the degradation rate of more than 70%of the five kinds of PAEs accounted for about 23%of the total strains,and the strains with the degradation rate of more than 80%accounted for about 10%of the total strains.It can be concluded that in the silt along the bank of Baiyangdian Lake,the dominant bacteria with significant degradation capacity of PAEs were Pseudomonas?Pseudomonas?and Bacillus?Bacillus?;?3?The degradation intermediates of the strain were determined by HPLC-MS method.It was found that DBP was produced when the degradation rate of DOP and DIOP was the highest.And strains could continue to degrade DBP.In order to verify whether the strain can completely degrade PAEs,the substrate utilization experiment of PA was carried out,and it was found that all bacteria could grow well with PA as the only carbon source,so it was speculated that PA was not detected as an intermediate due to the rapid production and utilization of PA.It can be inferred that the main degradation pathway of PAEs by the strain is:PAEs?DBP?PA?CO₂?+H₂O.It can also be proved that the screened strain can degrade PAEs well.It has great potential in practical application.?4?The degradation characteristics of the strain were studied:firstly,the optimum conditions for the degradation of the strain were determinedto be 30?as the culture temperature,pH7.0 and 2%as the initial inoculation ratio;By adding different concentrations of metal cations,anions,surfactants and exogenous carbon sources to the culture medium,it was found that high concentrations of Cd²⁺,Cr⁶⁺,Zn²⁺,Pb²⁺,Cu²⁺and Mn²⁺all inhibited the degradation of the strain,but lower concentrations of Pb²⁺,Cu²⁺and Mn²⁺could promote the degradation to a certain extent.Both too high and too low concentrations of NO₃^-could inhibit the degradation of the strain,but its concentration promoted the degradation of the strain at 100-300 mg/L.The addition of NO₂^-inhibited the degradation of the strain,and the inhibition intensity increased with the increase of concentration.Nonionic surfactant Tween-80 promoted the degradation of the strain,but the ionic surfactant SDS had the opposite effect.The addition of glucose,soluble starch and sucrose inhibited the degradation of the strain to some extent,and the inhibitory effect of soluble starch was the most significant.This research laid a certain foundation for the development of highly effective microbial remediation bacteria agents.