Urinary Bacterium Converts DHEA to Testosterone in Laboratory Study

Laboratory Discovery in the Human Urinary Microbiome

A bacterium found in the human urinary tract can convert the precursor steroid dehydroepiandrosterone (DHEA) into testosterone under laboratory conditions. The multi-institutional study, published in [Nature Communications](https://medicalxpress.com/news/2026-09-bacteria-testosterone-prostate-cancer.html), analyzed bacterial isolates from urine samples collected from men before prostate biopsy procedures. Researchers used a screening method called the Human Sterolbiome Discovery High-throughput (HSDH) assay to test organisms for steroid-altering chemistry.

The screening identified Actinobaculum massiliense as a functional steroid-transforming microbe. For decades, conventional medical education considered urine sterile. Modern sequencing confirms that a resident microbial community, called the urinary microbiome or urobiome, inhabits the lower urinary tract.

When researchers supplied Actinobaculum massiliense with DHEA in cell culture, the bacterium yielded intermediate steroids and generated testosterone. DHEA is an abundant circulating steroid produced by human adrenal glands. The human body routinely uses DHEA as a raw building block for stronger androgens, and this experiment showed a resident bacterium performing that same conversion.

The Enzymatic Mechanism of Actinobaculum Massiliense

Actinobaculum massiliense relies on two specific enzymes to process steroid precursors into active androgens. Computational biophysicists at [Auburn University](https://www.auburn.edu) modeled the bacterial structures at atomic resolution to examine how the proteins bind hormone substrates. Genomic sequencing identified two primary candidate genes, designated DHEA isomerase reductase A (dirA) and DHEA isomerase reductase B (dirB).

Laboratory assays showed distinct operational limits between the two related enzymes. The DirA enzyme demonstrated broad activity, completing multiple steroid conversions and enabling several chemical routes to testosterone. In contrast, the DirB enzyme executed only a single step of the transformation pathway.

The structural simulations explained how small variations in active-site geometry account for these functional differences. Understanding these protein structures gives researchers specific genetic targets to measure in patient samples.

What the Evidence Shows and What Remains Unproven

The study confirms a biochemical capability in isolated bacteria rather than an active driver of human disease. Study co-author Rafael Bernardi and senior author Jason M. Ridlon stated that the data do not demonstrate that Actinobaculum massiliense causes cancer. The experiment also did not measure whether bacterial testosterone reaches prostate tissue in living humans.

Many prostate tumors rely on androgen receptor activation to fuel cell division. Established medical treatments for advanced prostate cancer use medications to lower circulating testosterone levels or block hormone receptors. Whether localized bacterial production in the urinary tract produces enough testosterone to influence that tissue environment remains untested.

Considerations for Metabolic and Endocrine Health

The discovery of a microbial route to testosterone provides a new target for urological research without altering current clinical practice. For people tracking hormonal markers or taking over-the-counter DHEA supplements, this finding reflects early in vitro microbiology rather than clinical toxicology. Patients should not alter their cancer therapies, hormone regimens, or supplement schedules based on preliminary laboratory assays.

Follow-up investigations are underway to evaluate whether these bacterial genes are expressed in patient tissues. Future studies will need to measure local steroid concentrations in vivo before clinicians can determine whether targeting urinary bacteria provides any therapeutic value.