Insights into the effect of sertraline on anaerobic digestion: stimulating CH4 and CO2 production

Pharmaceuticals, particularly antidepressants, are emerging contaminants with potential far-reaching environmental impacts. However, their effect on anaerobic digestion and subsequent CH₄ and CO₂ production remains largely unexplored. This study revealed that sertraline, ranked among the top antidepressants, unexpectedly stimulated the of CH₄ and CO₂ production by 24.29% and 27.13% at environmental levels. Mechanistically, sertraline significantly disrupted the COD balance leading to altered carbon transformation pathways. Specifically, sertraline enhanced intermediary ecosystem metabolism, especially acetogenesis and acetoclastic to CH₄. These metabolic shifts reflected in microbial community changes, with a 48.11% increase in the relative abundance of Methanothrix. Notably, sertraline enriched the relative abundance key genes involved in substrate metabolism (e.g., gapN, prdA) and methanogenesis (e.g., mtrA, mcrC) by 12.58 to 111.13%. It also directly interacts with and alters the expression of crucial proteins (e.g., GLUT, RPB2, ERK) involved in substrate transport, transcription, and cellular signaling. These findings unveil a previously unrecognized contribution of sertraline to CH₄ and CO₂ production, underscoring the urgent need to reassess the impact of antibiotic-like substances on anaerobic carbon conversion.