Investigation into the treatment and resource recovery of rifamycin mycelial dreg with thermal alkaline pretreatment-anaerobic digestion

Rifamycin, a highly potent drug for the treatment of tuberculosis should raise environmental concerns due to its massive production of mycelial dreg (RMD). The RMD treatment by anaerobic digestion (AD) is a highly promising endeavor, but has still far from explicit. Herein, the thermal alkaline pretreatment (TAP)-AD process with RMD as substrate was performed. The optimal temperature, pH, and reaction time for TAP were 140 °C, 12, and 3 h, respectively. The optimal RMD concentration (1%) and inoculation ratio (2:1, sludge: RMD, mass ratio) were subsequently determined, leading to an increase of 86.4% in cumulative methane production. Correspondingly, a functional core taxa including fermentative bacteria and methanogens was enriched. Molecular ecological network (pMEN) revealed an ecological niche-based functional redundancy, which facilitated the efficiency and stability of the AD system. Notably, representative draft genome recovered from raw RMD possessed the potential fermentation capability, and the phosphotransferase component for carbohydrate transport may not be affected by rifamycin-B according to the results of molecular docking. Taking these factors, an innovative insight into the natural suitability of RMD as native fermentation inoculum was carefully presented. This study clarifies the feasibility of TAP-AD in the treatment of RMD. Moreover, it contributes to a deeper understanding of the ecological properties and microbial mechanisms in AD systems.