Cross-feeding promotes strong ammonia resilience in the high-sulfate wastewater treatment system

Abstract

Under high ammonia stress, there remains limited understanding regarding the genetic and metabolic responses of key players within the high-sulfate wastewater treatment system. In this study, the influence of high ammonia concentrations (1000–2000 mg/L) on pollutants removal and microbial response in high-sulfate wastewater was investigated. Surprisingly, our study found a robust ammonia resilience, as demonstrated by the stable removal efficiencies of chemical oxygen demand (COD) at 60.64% and sulfate at 79.76%. The core functional bacteria, Desulfovibrio and Erysipelatoclostridium, responsible for sulfate and COD removal, were discovered to remain at a relative abundance of up to 47.61% and 40.22%, respectively. Metagenomic analysis showed that three bins assigned to Desulfovibrio contain genes encoding glucokinase (glk), phosphofohexokinase (PFK) and pyruvate kinase (PK), indicating their capability for complete carbon metabolism. Of significance, this study revealed a remarkable amount of gene up-regulation involved in sulfur metabolism, showing resilience against ammonia stress. Unexpectedly, a positive correlation (p < 0.05) was observed between genes (aroAC and trpABDFG) responsible for tryptophan biosynthesis and the relative abundance of Erysipelatoclostridium. The complete genetic pathway for tryptophan biosynthesis was uncovered in two bins associated with Erysipelatoclostridium, suggesting potential interspecies cross-feeding between Erysipelatoclostridium and Desulfovibrio for maintaining functional stability. Overall, the microbial collaboration from key players in the high-sulfate wastewater enhances the system's resilience to withstand ammonia stress, thereby contributing to the stability for treating high-sulfate wastewater.