Characterization of 17ß-estradiol-degrading enzyme from Microbacterium sp. MZT7 and its function on E2 biodegradation in wastewater.

BACKGROUND: 17ß-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, 17ß-estradiol degrading enzyme (17ß-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 17ß-HSD-0095. In addition, 17ß-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.

Transcriptome profiling of Microbacterium resistens MZT7 reveals mechanisms of 17ß-estradiol response and biotransformation.

17ß-estradiol (E2) pollution has attracted much attention, and the existence of E2 poses certain risks to the environment and human health. However, the mechanism of microbial degradation of E2 remains unclear. In this study, the location of E2-degrading enzymes was investigated, and transcriptome analysis of Microbacterium resistens MZT7 (M. resistens MZT7) exposed to E2. The degradation of E2 by M. resistens MZT7 was via the biological action of E2-induced intracellular enzymes. With the RNA sequencing, we found 1109 differentially expressed genes (DEGs). Among them, 773 genes were up-regulated and 336 genes were down-regulated. The results of the RNA sequencing indicated the DEGs were related to transport, metabolism, and stress response. Genes for transport, transmembrane transport, oxidoreductase activity, ATPase activity, transporter activity and quorum sensing were up-regulated. Genes for the tricarboxylic acid cycle, ribosome, oxidative phosphorylation and carbon metabolism were down-regulated. In addition, heterologous expression of one enzymes efficiently degraded E2. These findings provide some new insights into the molecular mechanism of biotransformation of E2 by M. resistens MZT7.

Construction of Magnetic Composite Bacterial Carrier and Application in 17ß-Estradiol Degradation.

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 17ß-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.