Enhanced removal of carbamazepine by microalgal-fungal symbiotic systems in the presence of Mn(II): Synergistic mechanisms and microbial community dynamics

Abstract

Microalgal-fungal symbiotic systems (MFSS) have emerged as a promising approach for wastewater treatment, yet the mechanisms driving reactive oxygen species (ROS) generation and pharmaceutical pollutant removal remain underexplored. This study investigates the synergistic interactions within MFSS and their role in Mn(II) oxidation, with a focus on enhancing carbamazepine (CBZ) degradation and microbial community dynamics. The results reveal that microalgal-fungal interactions inhibit Fe-S cluster activity, disrupting electron transport chains and promoting extracellular superoxide production. This superoxide surge directly accelerates Mn(II) oxidation, while Mn(III) and ROS drive synergistic effects to amplify CBZ removal efficiency. Notably, system-specific variations in superoxide generation were observed across different MFSS configurations, determining their degradation performance. Water quality factors, such as microbial community complexity and nitrate concentration, play crucial roles in CBZ degradation in natural water systems. High-throughput sequencing reveals dynamic shifts in bacterial and eukaryotic communities, highlighting their synergistic interactions in pollutant degradation. Temporal and spatial changes in microbial community structure suggest that the system evolves into a more adaptive configuration during pollutant treatment, enhancing long-term stability. These findings advance the mechanistic understanding of ROS-mediated pollutant degradation in MFSS and provide actionable strategies for optimizing bioremediation systems in engineered and natural water environments.