No abstract

Due to the ecotoxicity of 17β-estradiol (E2), residual E2 in the environment poses potential risks to human and animal health and ecosystems. Biodegradation is considered one of the most effective strategies to remove E2 from the environment. Here, a novel, efficient E2-degrading bacterial strain Microbacterium resistens MZT7 was isolated from activated sludge and characterized. The genome of strain MZT7 contained 4,011,347 bp nucleotides with 71.26% G + C content and 3785 coding genes. There was 86.7% transformation efficiency of 10 mg/L E2 by strain MZT7 after incubation for 5 d at optimal temperature (30 °C) and pH (7.0). This strain was highly tolerant to ranges in pH (5.0–11.0), temperature (20–40 °C), and salinity (2–8%). Adding sources of carbon (glucose, maltose, sucrose, or lactose) or nitrogen sources (urea, peptone, or beef extract) promoted the degradation of E2 by strain MZT7. However, when yeast extract was added as a nitrogen source, the degradation efficiency of E2 was inhibited. Metabolites were analyzed by LC-MS and three metabolic pathways of E2 degradation were proposed. Further, the intermediates dehydroepiandrosterone and androsta-1,4-diene-3,17-dione were detected, as well as identification of kshB and fadD3 genes by KEGG, confirming one E2 degradation pathway. This study provided some insights into E2 biodegradation.

Estrogen contamination is widespread and microbial degradation is a promising removal method; however, unfavorable environments can hinder microbial function. In this study, a natural estrogen 17β-estradiol (E2) was introduced as a degradation target, and a new combination of bacterial carrier was investigated. We found the best combination of polyvinyl alcohol (PVA) and sodium alginate (SA) was 4% total concentration, PVA:SA = 5:5, with nano-Fe3O4 at 2%, and maltose and glycine added to promote degradation, for which the optimal concentrations were 5 g·L−1 and 10 g·L−1, respectively. Based on the above exploration, the bacterial carrier was made, and the degradation efficiency of the immobilized bacteria reached 92.3% in 5 days. The immobilized bacteria were reused for three cycles, and the degradation efficiency of each round could exceed 94%. Immobilization showed advantages at pH 5, pH 11, 10 °C, 40 °C, and 40 g·L−1 NaCl, and the degradation efficiency of the immobilized bacteria was higher than 90%. In the wastewater, the immobilized bacteria could degrade E2 to about 1 mg·L−1 on the 5th day. This study constructed a bacterial immobilization carrier using a new combination, explored the application potential of the carrier, and provided a new choice of bacterial immobilization carrier.

Environmental estrogen pollution has long been a concern due to adverse effects on organisms and ecosystems. Biodegradation is a vital way to remove estrogen, a strain of Lysinibacillus sp. was isolated, numbered strain GG242. The degradation rate of 100 mg·L−1 17β-estradiol (E2)) > 95% in one week, and compared with extracellular enzymes, intracellular enzymes have stronger degradation ability. Strain GG242 can maintain a stable E2 degradation ability under different conditions (20–35 °C, pH 5–11, salinity 0–40 g·L−1). Under appropriate conditions (30 °C, pH 8, 1 g·L−1 NaCl), the degradation rate increased by 32.32% in one week. Based on the analysis of transformation products, inferred E2 was converted via two distinct routes. Together, this research indicates the degradation potential of strain GG242 and provides new insights into the biotransformation of E2.

Background 17β-estradiol (E2) residues exhibit harmful effects both for human and animals and have got global attention of the scientific community. Microbial enzymes are considered as one of the effective strategies having great potential for removal E2 residues from the environment. However, limited literature is available on the removal of E2 from wastewater using short-chain dehydrogenase. Results In this study, 17β-estradiol degrading enzyme (17β-HSD-0095) was expressed and purified from Microbacterium sp. MZT7. The optimal pH and temperature for reaction was 7 and 40 °C, respectively. Molecular docking studies have shown that the ARG215 residue form a hydrogen bond with oxygen atom of the substrate E2. Likewise, the point mutation results have revealed that the ARG215 residue play an important role in the E2 degradation by 17β-HSD-0095. In addition, 17β-HSD-0095 could remediate E2 contamination in synthetic livestock wastewater. Conclusions These findings offer some fresh perspectives on the molecular process of E2 degradation and the creation of enzyme preparations that can degrade E2. Graphical Abstract