Removal of artificial sweeteners and their effects on microbial communities in sequencing batch reactors

Li, Shaoli; Geng, Jinju; Wu, Gang; Gao, Xingsheng; Fu, Yingying; Ren, Hongqiang

doi:10.1038/s41598-018-21564-x

Cited by 20 publications

(5 citation statements)

References 52 publications

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“…In this study, the dose of artificial sweeteners (0.3-3 mg/L) is environmentrelated range (2.5 mg/L in WWTPs [70]). The concentrations of artificial sweeteners in the environment would be higher because of persistence, accumulation and the growing consumption of artificial sweeteners [71][72][73]. Moreover, extracellular DNA molecules are very abundant (over 100 µg/g dry sludge [74] or up to 30 ng/µL [75], which is far higher than 0.8 ng/µL used in the present study) and can be persistent over 20 weeks [76] in the environment.…”

Section: Implications To Public Health and Environmental Risk Managementmentioning

confidence: 63%

Artificial sweeteners stimulate horizontal transfer of extracellular antibiotic resistance genes through natural transformation

Wang

Henderson

et al. 2021

The ISME Journal

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Antimicrobial resistance has emerged as a global threat to human health. Natural transformation is an important pathway for horizontal gene transfer, which facilitates the dissemination of antibiotic resistance genes (ARGs) among bacteria. Although it is suspected that artificial sweeteners could exert antimicrobial effects, little is known whether artificial sweeteners would also affect horizontal transfer of ARGs via transformation. Here we demonstrate that four commonly used artificial sweeteners (saccharin, sucralose, aspartame, and acesulfame potassium) promote transfer of ARGs via natural transformation in Acinetobacter baylyi ADP1, a model organism for studying competence and transformation. Such phenomenon was also found in a Gram-positive human pathogen Bacillus subtilis and mice faecal microbiome. We reveal that exposure to these sweeteners increases cell envelope permeability and results in an upregulation of genes encoding DNA uptake and translocation (Com) machinery. In addition, we find that artificial sweeteners induce an increase in plasmid persistence in transformants. We propose a mathematical model established to predict the long-term effects on transformation dynamics under exposure to these sweeteners. Collectively, our findings offer insights into natural transformation promoted by artificial sweeteners and highlight the need to evaluate these environmental contaminants for their antibiotic-like side effects.

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Section: Implications To Public Health and Environmental Risk Managementmentioning

confidence: 63%

Artificial sweeteners stimulate horizontal transfer of extracellular antibiotic resistance genes through natural transformation

Wang

Henderson

et al. 2021

The ISME Journal

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“…In the environmental setting, although various techniques, including adsorption, advanced oxidation processes, and biological treatment, are used to remove nonnutritive sweeteners, the removal efficiency of these sweeteners is generally low (less than 30%) [41][42][43]. We also found that nonnutritive sweeteners used were metabolically resistant to the tested bacterial strains (p = 0.062~0.700; see in Text S4; Fig.…”

Section: Discussionmentioning

confidence: 76%

Nonnutritive sweeteners can promote the dissemination of antibiotic resistance through conjugative gene transfer

et al. 2021

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Antimicrobial resistance (AMR) poses a worldwide threat to human health and biosecurity. The spread of antibiotic resistance genes (ARGs) via conjugative plasmid transfer is a major contributor to the evolution of this resistance. Although permitted as safe food additives, compounds such as saccharine, sucralose, aspartame, and acesulfame potassium that are commonly used as nonnutritive sweeteners have recently been associated with shifts in the gut microbiota similar to those caused by antibiotics. As antibiotics can promote the spread of antibiotic resistance genes (ARGs), we hypothesize that these nonnutritive sweeteners could have a similar effect. Here, we demonstrate for the first time that saccharine, sucralose, aspartame, and acesulfame potassium could promote plasmid-mediated conjugative transfer in three established conjugation models between the same and different phylogenetic strains. The real-time dynamic conjugation process was visualized at the single-cell level. Bacteria exposed to the tested compounds exhibited increased reactive oxygen species (ROS) production, the SOS response, and gene transfer. In addition, cell membrane permeability increased in both parental bacteria under exposure to the tested compounds. The expression of genes involved in ROS detoxification, the SOS response, and cell membrane permeability was significantly upregulated under sweetener treatment. In conclusion, exposure to nonnutritive sweeteners enhances conjugation in bacteria. Our findings provide insight into AMR spread and indicate the potential risk associated with the presence of nonnutritive sweeteners.

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“…The completed degradation of paracetamol in the CAS system was previously reported 168 . Similarly the complete removal of caffeine, paraxanthine, cyclamate, saccharin, cotinine and OH-cotinine were largely comparable to the previously reported removal (%) in the CAS treatment process 118,124,146 (appendix B, Table B2).…”

Section: Fate Of Mps In the Steady-state Sbr Reactorsupporting

confidence: 86%

Investigating the fate of organic micropollutants due to the dosing of iron salt or iron rich drinking water treatment sludge in urban wastewater system

Kulandaivelu¹

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Hydrogen sulfide production in the sewer network is the major cause for sewer corrosion and odour related issues. Iron (Fe) salt dosing is one of the efficient methods for sulfide control in the sewer network by precipitating the biologically formed sulfide to iron sulfide (FeS) particles. Though Fe salt is efficient in controlling sulfide, it requires continuous dosing that necessitates the search for alternative cheap sources.Meanwhile, water utilities are seeking an efficient management strategy for the discharge of sludge by-product from the drinking water treatment process. This byproduct also known as drinking water treatment sludge (DWTS) is either Fe-rich or aluminium (Al)-rich based on the coagulant used. The high Fe content in Fe-DWTS, could potentially be used to replace Fe salts for sulfide control in the sewer network.During Fe salt/Fe-DWTS dosing, formation of FeS particles is considered as the major sulfide control mechanism in the sewer network. Previous studies explored the multiple benefits of upstream sewer Fe dosing in the downstream processes such as phosphates removal in the bioreactor and sulfide mitigation in the anaerobic digester of the receiving wastewater treatment plant (WWTP). However, it is also well known that Fe salt is an effective coagulant for organic micropollutants (MPs) removal in the water treatment processes. As organic MPs such as pharmaceuticals, licit and illicit drugs, food additives etc., are ubiquitous in wastewater, the impact of dosing Fe salt/Fe-DWTS in the sewer network on the fate of these MPs is important but largely unknown. This thesis aims to address this research gap by investigating the impact of upstream Fe salt/Fe-DWTS dosing in sewers on the fate of organic MPs in the downstream sewer network and treatment process.Firstly, the impact of Fe salt dosing on the fate of selected organic MPs (8 compounds) was studied in a lab-scale rising main sewer reactor. The sulfide produced by sewer biofilms reacted with Fe 3+ forming black coloured FeS. Among the selected MPs, morphine, methadone and atenolol had >90% initial rapid removal within 5 min of Fedosing in the sewer reactor. The ultimate removal after 6 hr of retention time in the reactor reached 93-97%. Other compounds, ketamine, codeine, carbamazepine and acesulfame had 30-70% decrease of aqueous concentrations. The ultimate removal varied between 35 and 70% depending on their biodegradability. In contrast, paracetamol had no initial removal. Adsorption to the surface of FeS particles was likely responsible for the rapid MPs removal. viii Contribution by others to the thesisThis thesis contains some significant and substantial contribution from others as described below.

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Removal of artificial sweeteners and their effects on microbial communities in sequencing batch reactors

Cited by 20 publications

References 52 publications

Artificial sweeteners stimulate horizontal transfer of extracellular antibiotic resistance genes through natural transformation

Artificial sweeteners stimulate horizontal transfer of extracellular antibiotic resistance genes through natural transformation

Nonnutritive sweeteners can promote the dissemination of antibiotic resistance through conjugative gene transfer

Investigating the fate of organic micropollutants due to the dosing of iron salt or iron rich drinking water treatment sludge in urban wastewater system

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