Common bacteria living in the human urinary tract are capable of synthesizing testosterone directly.
April 1, 2026
Original Paper
The Urinary Tract Commensal Peptoniphilus spp. Encodes a Novel 17β-Hydroxysteroid Dehydrogenase
bioRxiv · 10.64898/2026.03.29.714803
The Takeaway
Microbial metabolism is usually thought to handle digestion or waste, but this study found that commensal bacteria in the male microbiome can convert precursors into active sex hormones. This suggests our microbiome acts as an 'extra gland' that can influence host hormone levels and drug resistance.
From the abstract
Microbial steroid metabolism represents an underappreciated extension of the vertebrate endocrine system, with growing evidence that host-associated microbes contribute to the diversity and bioavailability of sex steroids within human tissues. Emerging studies have linked microbial androgen metabolism to urinary microbiome composition and to resistance to androgen deprivation therapy (ADT) in prostate cancer. While microbial pathways capable of converting steroid precursors such as cortisol to a