Sulfide-induced inhibition: metabolic adaptations and translation activity of microorganisms in anammox process

Anaerobic ammonia-oxidizing bacteria (AnAOB) are highly sensitive to environmental stress, limiting the anammox process in wastewater treatment. This study investigated the short-term inhibitory effects of different sulfide concentrations on the anammox system. Amino acid metabolism analysis showed AnAOB regulated amino acid synthesis to promote extracellular polymeric substance secretion for cell protection and shifted to producing low-cost amino acids to conserve energy under high sulfide levels (60 mg/L). Isotope tracing revealed sulfide had a stronger inhibitory effect on anammox metabolic pathway I than pathway II, explaining the greater sulfide resistance of Candidatus Brocadia compared with Candidatus Kuenenia. Bioorthogonal nonclassical amino acid tagging combined with fluorescence-activated cell sorting identified that enhanced activity of dissimilatory nitrate reduction to ammonium bacteria facilitated sulfide consumption and reduced its toxicity to AnAOB. This study provides insights into the adaptive strategies of anammox consortia under sulfide stress, advancing the understanding of their resilience in wastewater treatment.