Mechanisms underlying the effect of chlorination and UV disinfection on VBNC state Escherichia coli isolated from hospital wastewater

Zhu, Lin; Shuai, Xin-Yi; Xu, Like; Sun, Yujie; Lin, Ze-Jun; Zhou, Zhen-Chao; Meng, Ling-Xuan; Chen, Hong

doi:10.1016/j.jhazmat.2021.127228

Cited by 42 publications

(26 citation statements)

References 59 publications

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“…Therefore, decreasing the overall yields of the TCA cycle would most likely lead to an overall decrease in cellular energy charge. Limited energy contributes to the quiescence of growth and metabolism, which may subsequently lead to the formation of the viable but non-culturable (VBNC) state ( Zhu et al., 2021 ). Moreover, VBNC state cells will have greater resistance to chlorine ( Dong et al., 2020 ).…”

Section: Discussionmentioning

confidence: 99%

Transcriptomic Responses of Salmonella enterica Serovars Enteritidis in Sodium Hypochlorite

Wang

Xiao

Qiu

et al. 2022

Front. Cell. Infect. Microbiol.

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Salmonella enterica serovars Enteritidis (S. Enteritidis) can survive extreme food processing environments including bactericidal sodium hypochlorite (NaClO) treatments generally recognized as safe. In order to reveal the molecular regulatory mechanisms underlying the phenotypes, the overall regulation of genes at the transcription level in S. Enteritidis after NaClO stimulation were investigated by RNA-sequencing. We identified 1399 differentially expressed genes (DEG) of S. Enteritidis strain CVCC 1806 following treatment in liquid culture with 100 mg/L NaClO for 20 min (915 upregulated and 484 downregulated). NaClO stress affects the transcription of genes related to a range of important biomolecular processes such as membrane damage, membrane transport function, energy metabolism, oxidative stress, DNA repair, and other important processes in Salmonella enterica. First, NaClO affects the structural stability of cell membranes, which induces the expression of a range of outer and inner membrane proteins. This may lead to changes in cell membrane permeability, accelerating the frequency of DNA conversion and contributing to the production of drug-resistant bacteria. In addition, the expression of exocytosis pump genes (emrB, yceE, ydhE, and ydhC) was able to expel NaClO from the cell, thereby increasing bacterial tolerance to NaClO. Secondly, downregulation of genes related to the Kdp-ATPase transporter system (kdpABC) and the amino acid transporter system (aroP, brnQ and livF) may to some extent reduce active transport by bacterial cells, thereby reducing their own metabolism and the entry of disinfectants. Downregulation of genes related to the tricarboxylic acid (TCA) cycle may drive bacterial cells into a viable but non-culturable (VBNC) state, resisting NaClO attack by reducing energy metabolism. In addition, significant upregulation of genes related to oxidative stress could mitigate damage caused by disinfectants by eliminating alkyl hydroperoxides, while upregulation of genes related to DNA repair could repair damage to bacterial cells caused by oxidative stress. Therefore, this study indicated that S. Enteritidis has genomic mechanisms to adapt to NaClO stress.

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Section: Discussionmentioning

confidence: 99%

Transcriptomic Responses of Salmonella enterica Serovars Enteritidis in Sodium Hypochlorite

Wang

Xiao

Qiu

et al. 2022

Front. Cell. Infect. Microbiol.

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“…The SOS response (a conserved response to DNA damage) triggered by oxidative stress renders bacteria chlorine resistant (Tong et al, 2021). Nutrient limitations result in quiescence of growth and metabolism that may subsequently lead to bacteria in the viable but nonculturable (VBNC) state for chlorine stress adaptations (Zhu et al, 2022). E. coli, Enterococcus and Salmonella can enter into a VBNC state after disinfection, and Salmonella was more resistant to chlorine in reclaimed water (Li et al, 2013).…”

Section: Mechanisms Of Chlorine Tolerance In Bacteriamentioning

confidence: 99%

Chlorine Tolerance and Cross-Resistance to Antibiotics in Poultry-Associated Salmonella Isolates in China

Xiao

Bai²,

Wang³

et al. 2022

Front. Microbiol.

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Chlorine disinfectants have been widely used in the poultry supply chain but this exposure can also result in the development of bacterial tolerance to chlorine and this is often linked to antibiotic cross-resistance. The objectives of this study were to investigate sodium hypochlorite (NaClO) tolerance of Salmonella isolated from poultry supply chains and evaluate cross-resistance. We collected 172 Salmonella isolates from poultry farms, slaughter houses and retail markets in China during 2019–2020. We found that S. Enteritidis, S. Kentucky, and S. Typhimurium constituted > 80% of our Salmonella isolates. Overall, 68% of Salmonella isolates were resistant to > 3 antibiotics and S. Kentucky displayed a significantly (p > 0.05) higher frequency (93.2%) of multidrug resistance than the other serovars. Tolerance to chlorine at MIC > 256 mg/L was detected in 93.6% of isolates (161/172) and tolerant isolates displayed higher decimal reduction times (D value) and less ultrastructural damage than did the suspectable strains under chlorine stress. Spearman analysis indicated significant positive correlations between chlorine tolerance (evaluated by the OD method) and antibiotic resistance (p < 0.05) to ceftiofur, tetracycline, ciprofloxacin and florfenicol and this was most likely due to efflux pump over-expression. The most frequently detected chlorine resistance gene was qacEΔ1 (83.1%, n = 143) and we found a positive correlation between its presence and MIC levels (r = 0.66, p < 0.0001). Besides, we found weak correlations between chlorine-tolerance and antibiotic resistance genes. Our study indicated that chlorine disinfectants most likely played an important role in the emergence of chlorine tolerance and spread of antibiotic resistance and therefore does not completely control the risk of food-borne disease. The issue of disinfectant resistance should be examined in more detail at the level of the poultry production chain.

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“…Higher HOCl exposure is generally needed for iARG degradation than for ARB deactivation. − For instance, 0.5 mg min/L HOCl exposure could destroy the cell membrane integrity and culturability of E. coli DH5α containing ampicillin resistance genes ( amp R ), while 4-log removal in amp R occurred until the HOCl dose reached 80 mg min/L (Table S2, SI).…”

Section: Elimination Efficiencies Of Iargs and Eargsmentioning

confidence: 99%

Elimination and Redistribution of Intracellular and Extracellular Antibiotic Resistance Genes in Water and Wastewater Disinfection Processes: A Review

Liu

et al. 2022

ACS EST Water

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Antibiotic resistance genes (ARGs) have been identified as emerging contaminants in water and wastewater. Concerns have been raised of whether disinfection processes can effectively eliminate ARGs and thus mitigate their spread. Due to the different existing forms and dissemination pathways, intracellular ARGs (iARGs) and extracellular ARGs (eARGs) have different responses to disinfection processes. This review compares the elimination of iARGs and eARGs in representative disinfection processes applied at water and wastewater treatment plants, including treatment by chlorine, chloramine, chlorine dioxide, ozone, ultraviolet irradiation (UV), and combination of UV with chemicals. Meanwhile, the redistribution of ARGs upon disinfection processes is highlighted. Elimination efficiencies of ARGs generally follow the order: ozone > chlorine ≫ chlorine dioxide > chloramine. The elimination of naked eARGs could be up to 4-log higher than that of iARGs. Notably, these disinfectants and the resulting disinfection byproducts formed in disinfection process can select antibiotic resistant bacteria (ARB) and increase relative abundances of iARGs. Under practical disinfectant exposure, elevated abundances of eARGs may be observed. Low doses of chlorine and chloramine tend to enhance the transfer of ARGs from intracellular to extracellular forms. To selectively control ARGs and associated risks and meanwhile minimize the unintended consequences, the disinfection practice may warrant optimization.

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Mechanisms underlying the effect of chlorination and UV disinfection on VBNC state Escherichia coli isolated from hospital wastewater

Cited by 42 publications

References 59 publications

Transcriptomic Responses of Salmonella enterica Serovars Enteritidis in Sodium Hypochlorite

Transcriptomic Responses of Salmonella enterica Serovars Enteritidis in Sodium Hypochlorite

Chlorine Tolerance and Cross-Resistance to Antibiotics in Poultry-Associated Salmonella Isolates in China

Elimination and Redistribution of Intracellular and Extracellular Antibiotic Resistance Genes in Water and Wastewater Disinfection Processes: A Review

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