Non-caloric artificial sweeteners modulate conjugative transfer of multi-drug resistance plasmid in the gut microbiota

ABSTRACT

Non-caloric artificial sweeteners have been widely permitted as table sugar substitutes with high intensities of sweetness. They can pass through the intestinal tract without significant metabolization and frequently encounter the gut microbiome, which is composed of diverse bacterial species and is a pool of antibiotic resistance genes (ARGs). However, little is known about whether these sweeteners could accelerate the spread of ARGs in the gut microbiome. Here, we established an in vitro conjugation model by using Escherichia coli that carries chromosome-inserted Tn7 lacI^q-pLpp-mCherry and plasmid-encoded gfpmut3b gene as the donor and murine fecal bacteria as the recipient. We found that four commonly used artificial sweeteners (saccharin, sucralose, aspartame, and acesulfame potassium) can increase reactive oxygen species (ROS) production and promote plasmid-mediated conjugative transfer to the gut microbiome. Cell sorting and 16S rRNA gene amplicon sequencing analysis of fecal samples reveal that the tested sweeteners can promote the broad-host-range plasmid permissiveness to both Gram-negative and Gram-positive gut bacteria. The increased plasmid permissiveness was also validated with a human pathogen Klebsiella pneumoniae. Collectively, our study demonstrates that non-caloric artificial sweeteners can induce oxidative stress and boost the plasmid-mediated conjugative transfer of ARGs among the gut microbiota and a human pathogen. Considering the soaring consumption of these sweeteners and the abundance of mobile ARGs in the human gut, our results highlight the necessity of performing a thorough risk assessment of antibiotic resistance associated with the usage of artificial sweeteners as food additives.

KEYWORDS:

• Antibiotic resistance
• non-caloric artificial sweeteners
• gut microbiota
• conjugation
• plasmid
• reactive oxygen species
• 16S rRNA

Acknowledgments

The authors would like to thank Dr U. Klümper (Technical University Dresden) for sharing the GFP-labelled strain, J. Rooke for collecting mice faeces, C. Icke for donating Klebsiella pneumonia ECL8 strain, and K. Pullela for assisting FACS analysis. We also appreciate the technical support from V. Sagulenko for flow cytometry analysis and S. Mason for imaging acquisition.

Authors’ contributions

Z.Y. designed and performed the experiments, analyzed data, interpreted the results, and wrote manuscript. I.H. assisted with data interpretation and manuscript revision. J.G. conceived and designed the research, and assisted with data interpretation and manuscript writing.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All 16S rRNA gene amplicon sequencing raw data were deposited in the National Centre for Biotechnology Information (NCBI) Sequence Read Archive (SRA; https://dataview.ncbi.nlm.nih.gov/object/PRJNA759753) under BioProject number PRJNA759753.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/19490976.2022.2157698

Additional information

Funding

This work was supported by through the Australian Research Council projects (FT170100196 and DP22010) awarded to J.G.