Research On Steroid Estrogens Toxicity In Wastewater And Steroid Estrogens Biodegradable Characteristics

In this paper E2 toxicity on protozoan community was studied.In the 12h-acute toxicity testing, the range between maximal tolerance and minimal all lethal were 1-150mg/L,the half lethal concentration(LC50) was 67.4 mg/L; When this protozoa community exposed to low dose E2 for a long time, it becomes single.In this article, one strain of E2 high efficiency degradation bacteria was isolated from active sludge of Nanjing Sewage Treatment Plants. Morphological and physiological and biochemical results show that this strain was K.pneum.pneumoniae.It can use E2 as the only carbon source and energy source. In the liquid medium with E2 concentration was 1 mg/L, after 72h reaction, degradation rate reached to 89.8%, and after one week, E2 degradation rate reached to above 95%.Strain growth and degradation characteristics analysis results showed that, the optimum temperature,pH and optimal concentration were 30℃,7.0 and 1-2 mg/L respectively;Heavy metal ion such as Fe3+,Na+,Ca2+, didn't have much influence on strain growth and degradation ability; Zn2+,Mn2+,Cu2+ and Ag+ can greatly restrain the growth and E2 degradation by K.pneum.pneumoniae; Glucose and lactose were very helpful for the growth of bacteria and the degradation of E2, thus, starch has no significant effect; Nitrogen source material such as peptone and yeast can help to the growth of strain and E2 degradation, meanwhile, degradation rate reached to 83% and 85%, respectively; Ammonium sulfate has no significant influence on strain growth and E2 degradation rate.The degrading-enzymes produced by K.pneum.pneumoniae was located in cells, it is a kind of inducible enzyme.The research analyzed the influence of various factors on enzymatic activity, this enzymatic reaction optimal conditions of this enzyme protein extract were:30℃, pH 7.0 (protein content 266.67μg/mL, reaction time 30 min). In acidic conditions, especially strong acidic conditions, this enzyme protein were likely to denaturation, alkali environment also can lead to enzyme extraction became instability. This enzyme thermal stability was excellent in 30-35℃, it can maintain higher enzyme activity, but higher temperatures than 35℃,enzyme activity decreased, heat stability.Under the low temperature (below 15℃), enzyme gradually to be deactivation.Through the enzyme extraction degradation ability dynamics analysis can be concluded that the enzyme reaction Vmax was 0.265 mmol/h, Km was 3.68×10-4 mol/L, Km was lower and,it illustrated that the value of the enzyme extraction strains protein extracts E2 affinity is stronger, after continuous domestication and cultivation, it can quickly and effectively degradate E2. Using GC/MS analysis E2 degradation metabolites, the results showed that E2 degradation products are E1, but at the early stages appeares a lactone structure and unstable compounds, it suggested structure is:5-hydroxy-15-methyl-13-oxatetracyclo[8.7.0.0<2,7>.0. <11,15>]-heptadeca-2(7),3,5-trien-14-one.And a possible metabolic pathways was proposed.