Isolation And Identification Of Natural Estrogen-degrading Bacteria And Characteristics Research On Them

Recently, environmental estrogen had received worldwide attention due to their negative effects on the endocine system of animals and humans. Several studies of estrogen pollution status and its degradation in environment had been conducted. This paper focuses on natural estrogen-degrading bacteria isolated from Xiamen Bay, Yundang Lagoon and sewage treatment plants in Xiamen. Ninteen17(3-estradiol (E2)-degrading bacteria were isolated while one of which is a novel stain belongs to Altererythrobacter, which could provid some novel strain materials and some basic parameters for the biodegradation in wastewater containing estrogens.The paper summarizes the degradation pathway of E2and testosterone(T), examines degradation effects of degrading bacteria to E2, estriol (E3)17a-ethynylestradiol (EE2), testosterone (T) and phenol. In addition, this article compares degradation effects between degrading bacteria isolated in the paper and strain KC8to E2and examines degradation effects of two type strain of KC8to E2.The main conclusions of this paper are as follows:1. Ninteen E2-degrading bacteria were isolated from activated sludge and lagoon. Strain MH-B is a novel specie of Altererythrobacter isolated from Yundang lagoon and is the first strain isolated from lagoon which is identified according to the relevant literatures.2. Determined the concentration of E1, E2and E3in the sewage treatment plants where strains AX-B, AHC-F and AHC-A were isolated. Acquired the estrogens condition of the Yundang Lagoon where strain MH-B was isolated from. By the results, the estrogens concentration in sewage treatment plants are higher than those in Yundang Lagoon and both of them are polluted.3. Acquired two microbial degradation modes of E2. Mode Ⅰ:strains can transform E2to E1but cannot degrade E1. Strain AHC-A and other strains which can only degrade E2belong to this mode. Mode Ⅱ:strains can degrade El quickly after degraded E2completely and strains AX-B, AHC-F, MH-B and two other strains AH-E and AH-A belong to this mode.4. In the E2degradation test, all of strains AX-B, AHC-F and MH-B can degrade100ml2mg/L E2completely in eight hours. In the growth test with E1as the only carbon source, strain MH-B got the highest degradation rate when cultured sixth days and cannot degraded E1thoroughly. Strain AX-B degraded El thoroughly when cultured twenty-second days.5. The growth temperature range of strain MH-B is from4℃to40℃and the optimum temperature is35-40℃. The pH range is from4.5-10.0and optimum PH is7.5. The range of salt content is from0to7%and the optimum is1%.6. According to production analysis by GC-MS, it could be conducted that T was oxidized to dehydrotestosterone (DHT) and androstenedione (AD) firstly, secondly, Androsta-1,4-diene-3,17-dione (ADD) was produced, then9a-hydroxy-1,4-diene-3,17-dione was produced, and finally degraded to CO2and H2O after a series of reactions.7. The conclutions of the degradation test of E2, E1, E3, EE2, T and Phenol are as follows:Strains AX-B and AHC-F could degrade E1, E2, E3, T and Phenol. Strain MH-B could degrade El, E2, E3and T but could not degrade Phenol. Strain AHC-A could degrade E2and T preliminary but could not degrade E3and Phenol. All strains above cannot degrade EE2.