Xi Li

Bio: Xi Li is an academic researcher from Fujian Agriculture and Forestry University. The author has contributed to research in topics: Gene & Plasmid. The author has an hindex of 4, co-authored 5 publications receiving 66 citations.

Herbicide Selection Promotes Antibiotic Resistance in Soil Microbiomes.

Abstract: Herbicides are one of the most widely used chemicals in agriculture. While they are known to be harmful to nontarget organisms, the effects of herbicides on the composition and functioning of soil microbial communities remain unclear. Here we show that application of three widely used herbicides-glyphosate, glufosinate, and dicamba-increase the prevalence of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in soil microbiomes without clear changes in the abundance, diversity and composition of bacterial communities. Mechanistically, these results could be explained by a positive selection for more tolerant genotypes that acquired several mutations in previously well-characterized herbicide and ARGs. Moreover, herbicide exposure increased cell membrane permeability and conjugation frequency of multidrug resistance plasmids, promoting ARG movement between bacteria. A similar pattern was found in agricultural soils across 11 provinces in China, where herbicide application, and the levels of glyphosate residues in soils, were associated with increased ARG and MGE abundances relative to herbicide-free control sites. Together, our results show that herbicide application can enrich ARGs and MGEs by changing the genetic composition of soil microbiomes, potentially contributing to the global antimicrobial resistance problem in agricultural environments.

Herbicide promotes the conjugative transfer of multi-resistance genes by facilitating cellular contact and plasmid transfer

Abstract: The global dissemination of antibiotic resistance genes (ARGs), especially via plasmid-mediated horizontal transfer, is becoming a pervasive health threat. While our previous study found that herbicides can accelerate the horizontal gene transfer (HGT) of ARGs in soil bacteria, the underlying mechanisms by which herbicides promote the HGT of ARGs across and within bacterial genera are still unclear. Here, the underlying mechanism associated with herbicide-promoted HGT was analyzed by detecting intracellular reactive oxygen species (ROS) production, extracellular polymeric substance composition, cell membrane integrity and proton motive force combined with genome-wide RNA sequencing. Exposure to herbicides induced a series of the above bacterial responses to promote HGT except for the ROS response, including compact cell-to-cell contact by enhancing pilus-encoded gene expression and decreasing cell surface charge, increasing cell membrane permeability, and enhancing the proton motive force, providing additional power for DNA uptake. This study provides a mechanistic understanding of the risk of bacterial resistance spread promoted by herbicides, which elucidates a new perspective on nonantibiotic agrochemical acceleration of the HGT of ARGs.

A critical review of antibiotic removal strategies: Performance and mechanisms

Abstract: Environmental pollution by antibiotics has severely affected human health and development. Antibiotic resistance genes (ARGs) have also been recognized as emerging pollutants because of their persistence and adverse impacts in aquatic ecosystems, even at low concentrations. For the alleviation and elimination of antibiotics stress, several approaches have been proposed, some of which have been applied in practice. This review systematically summarizes the removal strategies for various antibiotics and their corresponding mechanisms, including chemical, physical, biological, condition-based and combined strategies. Moreover, a comparison among these methods is made with a focus on the performance and efficiency. Further research needs are also proposed, which provides a guidance for the establishment of a control strategy to achieve simultaneous removal of nitrogen, antibiotics and ARGs.