Multi-omics analysis of nitrifying sludge under carbon disulfide stress: Nitrification performance and molecular mechanisms.

Carbon disulfide (CS ₂ ) is a widely used enzyme inhibitor with cytotoxic properties, commonly employed in viscose fibers and cellophane production due to its non-polar characteristics. In industry, CS ₂ is often removed by aeration, however, residual CS ₂ may enter the wastewater treatment plants, impacting the performance of nitrifying sludge. Currently, there is a notable dearth of research on the response of nitrifying sludge to CS ₂ -induced stress. This study delves into the alterations in the performance of nitrifying sludge under short-term and long-term CS ₂ stress, scrutinizes the toxic effects of CS ₂ on microbial cells, elucidates the succession of microbial community structure, and delineates changes in microbial metabolic products. The findings from short-term CS ₂ stress revealed that low concentrations of CS ₂ induced oxidative stress damage, which was subsequently repaired in cells. However, at concentrations of 100-200 mg/L, CS ₂ inhibited reactive oxygen species, superoxide dismutase, and catalase, which are associated with metabolic and antioxidant activities. The inhibition of nitrite oxidoreductase activity by high concentrations of CS ₂ was attributed to its impact on the enzyme's conformation. Prolonged CS ₂ stress resulted in an increase in the secretion of soluble extracellular polymeric substances in sludge, while CS ₂ was assimilated into sulfate. The analysis of sludge microbial community structure revealed a decline in the relative abundance of Rhodanobacter, which is associated with nitrification, and an increase in Sinomonas, involved in sulfur oxidation. Metabolite analysis results demonstrated that high concentrations of CS ₂ affect pantothenate and CoA biosynthesis, purine metabolism, and glutathione metabolism. This study elucidated the microbial response mechanism of nitrifying sludge under short-term and long-term CS ₂ stress. It also clarified the composition and function of microbial ecosystems, and identified key bacterial species and metabolites. It provides a basis for future research to reduce CS ₂ inhibition through approaches such as the addition of metal ions, the selection of efficient CS ₂ -degrading strains, and the modification of strain metabolic pathways.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024. Published by Elsevier Ltd.)