Degradation Characteristics Of Ethinylestradiol And Cold-adapt Mechanism Of Psychrotrophs Pseudomonas SP. CBZ-4

Ethinylestradiol (EE2) is a synthetic emerging endocrine disrupting chemical,which has the highest estrogen activity among similar estrogens, and a more stablestructure making it less biodegradable. Through metabolization, EE2can be degradedcompletely by microbes, which are harmless products. However, this function can beinhibited by low temperature, which leads to poor removal efficiency. In order to solvethe problem of low temperature inhibition of complex organic pollutants biodegradation,researches on cold-adapt degrader Pseudomonas sp. CBZ-4were carried out. Growthcharacteristics and EE2degradating characteristics of CBZ-4were investigated, andcold-shock proteins (CSPs) genes were cloned and expressed, which set a base forresearches on cold-adapt mechanism.In this study, the optimal growth conditions for CBZ-4degrading EE2were asfollows: temperature of10℃, pH of7, rotation speed of150r/min, and inoculationvolume of10%. After continuous culture for240h under an initial concentration of100mg/L of EE2, an EE2removal of44%was achieved. CBZ-4performed a total removalof52%when continuously cultured with a mixture of EE2, E2, E1and CBZ for7d.The initial concentration of each chemical was25mg/L. Analysis of TOC variation anddegradation products of EE2with GC-MS showed that EE2was first transformed to E1,and then transformed to H2O and CO2.In order to know the effects of EE2concentration on CBZ-4growth anddegradation, growth trends of CBZ-4under different EE2initial concentrations weredetected, and a bacterial growth kinetic model was constructed using Logistic equation.The maximum growth rate of CBZ-4was0.011, and the maximum biomass was0.128mg/L. According to resting cell experiment under different EE2initial concentration,EE2degradation kinetic of CBZ-4conformed to the first-order reaction, with anaverage specific degradation rate of0.068/h, and an EE2initial concentration of higherthan120mg/L could inhibit degradation.After sequencing, data jointing, assembling and annotation of CBZ-4genome,gene sequence analysis indicated that CBZ-4contained6497331base pairs, with24kinds of gene functions, which contained63aromatic compounds degradation relatedgenes,42fatty acid synthetic and metabolism related gene, as well as6CSPs genes,which might relate to cold-adaption. Each CSPs gene was cloned and expressed with E.coli. Culturing results showed that CSPs genes could effectively enhance cold-adapting ability of E. coli, which meant that CPSs could play an important role in maintainingnormal growth and metabolism of CBZ-4in low temperature environment.