Dr. Liisa Veerus, Anushka Subrahmanian, and Dr. Martin Blaser have published a new review article in npj Biofilms and Microbiomes introducing the concept of the testobolome—the collection of gut microbial populations and enzymes involved in testosterone metabolism. Building on the estrobolome framework, the authors synthesize evidence that intestinal microbes can deconjugate and transform androgens, positioning the microbiome as an active participant in endocrine biology rather than a passive responder to host hormones. By framing testosterone metabolism as a host–microbiome co-regulated process, this work provides a conceptual foundation for future mechanistic studies examining how microbial androgen metabolism shapes systemic physiology and sex-biased health outcomes.