From "resistance genes expression" to "horizontal migration" as well as over secretion of Extracellular Polymeric Substances: Sludge microorganism’s response to the increasing of long-term disinfectant stress

• Published in: Journal of hazardous materials Vol. 469; p. 133940
• Main Authors: Li, Yuxin, Xu, Yanbin, Zhou, Xiao, Huang, Lu, Wang, Guan, Liao, Jingsong, Dai, Ruizhi
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05.05.2024
• Subjects: Activated sludge; African Swine Fever; Animals; Defense mechanism; Disinfectants - toxicity; Ecosystem; Extracellular Polymeric Substance Matrix; Extracellular polymeric substances; Long term exposure to disinfectants; Resistant gene; Sewage - chemistry; Swine; Waste Disposal, Fluid - methods; Activated sludge; SBR; PS; ARGs; Resistant gene; SDBS; TB-EPS; Long term exposure to disinfectants; EPS; MGE; GFI; Extracellular polymeric substances; RMSEA; LB-EPS; GDs; AGFI; DNRA; Defense mechanism; GA; DDAB; PN; SEMs
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2024.133940

Glutaraldehyde-Didecyldimethylammonium bromides (GDs) has been frequently and widely employed in livestock and poultry breeding farms to avoid epidemics such as African swine fever, but its long-term effect on the active sludge microorganisms of the receiving wastewater treatment plant was keep unclear. Four simulation systems were built here to explore the performance of aerobic activated sludge with the long-term exposure of GDs and its mechanism by analyzing water qualities, resistance genes, extracellular polymeric substances and microbial community structure. The results showed that the removal rates of CODCr and ammonia nitrogen decreased with the exposure concentration of GDs increasing. It is worth noting that long-term exposure to GDs can induce the horizontal transfer and coordinated expression of a large number of resistance genes, such as qacE, sul1, tetx, and int1, in drug-resistant microorganisms. Additionally, it promotes the secretion of more extracellular proteins, including arginine, forming a "barrier-like" protection. Therefore, long-term exposure to disinfectants can alter the treatment capacity of activated sludge receiving systems, and the abundance of resistance genes generated through horizontal transfer and coordinated expression by drug-resistant microorganisms does pose a significant threat to ecosystems and health. It is recommended to develop effective pretreatment methods to eliminate disinfectants. [Display omitted] •Concentration inhibiting effects of GDs on running of activated sludge system is obvious.•Inhibition on denitrification was weaker than other nitrogen transfers steps.•Bacteria defense low stress of GDs by inducing plasmid-carried qacΔE, sul1, tetx, int1.•Bacteria increase EPS secretion to defense the long-term stress of GDs over 10 mg/L.•Methods for eliminating GDs before discharge were suggested to reduce ecological damage.