A highly efficient mixed strain fermentation strategy to produce 11α-Hydroxyandrost-4-ene-3,17-dione from phytosterols.

11α-Hydroxyandrost-4-ene-3,17-dione (11α-OH AD) is an essential steroid hormone drug intermediate that exhibits low biotransformation efficiency. In this study, a mixed-strain fermentation strategy was established for the efficient production of 11α-OH AD from phytosterols (PS). Initially, strains were screened for efficient transformation of AD to produce 11α-OH AD. Subsequently, a dual-strain mixed-culture fermentation technique was established, with Mycolicibacterium neoaurum CICC 21097 ΔksdD (MNR) showing highly effective results. Ultimately, a one-step conversion process for the production of 11α-OH AD was achieved at a molar yield of 76.5 % under optimal conditions using PS as a substrate, the highest reported yield to date. Additionally, studies revealed synergistic metabolic interactions between MNR and Aspergillus ochraceus in the mixed-culture system. These findings provide valuable insights for the industrial production of high-value products using mixed-strain fermentation.