Characterization of a rapid 17β-estradiol-degrading strain, Microbacterium proteolyticum ZJSU01.

Estrogens, particularly 17β-estradiol, are prevalent endocrine-disrupting chemicals in aquatic environments, posing risks to ecosystems and human health. Biodegradation is considered one of the most effective and environmentally friendly methods for removing estrogen. In this study, a novel bacterial strain, Microbacterium proteolyticum ZJSU01, was isolated from pig manure. It completely degraded 5 mg/L of 17β-estradiol (E2) within 4 h, as well as its major transformation product, estrone (E1). The strain ZJSU01 displayed strong adaptability to high temperatures (37℃, 42℃) and a broad pH range (6-11), E2 (5 mg/L) could be completely removed by the strain under these conditions. Transformation intermediates were analyzed using UHPLC and HPLC-Q-TOF-MS to identify key metabolites and trace the degradation pathways. Four potential degradation pathways were identified, including the 4,5-seco pathway, which is widely conserved in most E2-degrading bacteria. Whole-genome sequencing predicted a chromosome with a size of 3,828,432 bp, and a series of functional genes, and transcriptomics analysis identified several genes involved in E2 degradation. The budC gene, a member of the short-chain dehydrogenases/reductases (SDRs) family, was identified as critical for E2 degradation and exhibited a nearly 170-fold upregulation. Meanwhile, genes such as fdeE and catA were associated with downstream degradation. Microbacterium proteolyticum ZJSU01 demonstrated strong acid-base and high-temperature resilience, highlighting its strong potential for practical applications due to its degradation capability and adaptability. This strain could be applied in wastewater treatment to effectively remove estrogenic pollutants from contaminated water. KEY POINTS: • Microbacterium proteolyticum ZJSU01 removed 100% of E2 (10、5、1 mg/L) within 4 h. • Strain ZJSU01 showed great tolerance to high temperature and acid-base conditions. • A novel gene, budC, was identified as the primary driver of E2 degradation by ZJSU01.