Genome analysis of the steroid-degrading denitrifying Denitratisoma oestradiolicum DSM 16959 and Denitratisoma sp. strain DHT3

Abstract

Steroid hormones (androgens and estrogens) are crucial for development, reproduction, and communication of multicellular eukaryotes. The ubiquitous distribution and persistence of steroid hormones in our ecosystems have become an environmental issue due to the adverse effects on wildlife and humans upon long-term exposure. Microbial degradation is critical for the removal of steroid hormones from ecosystems. The aerobic degradation pathways for androgens and estrogens and the anaerobic degradation pathway for androgen have been studied into some details; however, the mechanism for anaerobic estrogen degradation remains completely unknown. Here, we presented the circular genomes of D. oestradiolicum DSM 16959 and Denitratisoma sp. strain DHT3, two betaproteobacteria capable of anaerobic estrogen degradation. We identified the genes involved in steroid transformation and in the anaerobic 2,3-seco pathway in both genomes. Additionally, the comparative genomic analysis revealed that genes exclusively represented in estrogen-degrading anaerobes might play a role in anaerobic estrogen catabolism.