Degradation of estrogens by bacteria isolated from animal farm soils

Abstract

Estrogens, a major group of hormone in female, are responsible for regulation of sexual characteristics. The excretion of estrogens from human or animals leads to contamination in soil and water resources. When contaminated to downstream water, estrogens can interfere with the hormonal system of aquatic livings resulting in unusual development. It is therefore needful to reduce the risk of endocrine disruption from these contaminants. This study aimed to screen for the bacteria capable of degrading estrone (E1), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) from animal farm soils and to study their degradation patterns. The bacteria from soil suspension were cultured in enrich media, containing E1 or E2 or EE2 as the carbon and energy source. Different colonies were picked and cultured in liquid medium containing each of estrogen at 30°C with shaking at 250 rpm. The remaining estrogens and their metabolites in the liquid media were determined by high-performance liquid chromatography. The results showed the existence of 4 bacterial isolates with E1 degradation activities. Two bacterial isolates were also found to degrade E2 to form E1, while other 7 isolates degraded E2 without any detected metabolite. Eight isolates having high degradation activities were identified by their 16S rRNA gene sequences and biochemical properties. They were distributed from family Alcaligenaceae, genus Microbacterium, genus Planococcus and genus Pseudomonas. The representative of E1-degrading bacteria and E2-degrading bacteria were selected to study their abilities to degrade E1, E2, EE2 and methyltestosterone (MT). Both of them showed degradation ability for E1 and E2, but not for EE2 and MT