Toward Sustainable Testosterone Manufacturing: Green Chemistry and Microbial Biotransformation Approaches

Testosterone is a vital steroid hormone with important physiological roles and broad clinical significance, serving as a central molecular precursor in the synthesis of many pharmacologically active steroids. Testosterone is traditionally produced through complex chemical synthesis routes that involve hazardous reagents, harsh conditions, and produce significant toxic waste. In recent decades, growing regulatory requirements and environmental sustainability goals have spurred the development of alternative biotechnological methods that use microbial biotransformation. This review offers a comparative analysis of chemical and biological methods for producing testosterone, focusing on microbial steroid biotransformation pathways and the key enzymatic steps involved in testosterone biosynthesis. It examines key advances in sterol breakdown, pathway engineering, and enzyme driven modifications, including the roles of 17β-hydroxysteroid dehydrogenases and cytochrome P450 monooxygenases. The performance, specificity, and environmental impacts of bacterial and fungal cells as cell factories, especially Mycolicibacterium and Aspergillus species, are critically analyzed within the framework of modern green chemistry principles. Overall, by combining molecular insights with process considerations, this review illustrates how microbial platforms could complement and gradually transform traditional chemical synthesis methods, promoting a shift toward more sustainable steroid hormone production through engineered biocatalysts.