A neglected risk of nanoplastics as revealed by the promoted transformation of plasmid‐borne ampicillin resistance gene by Escherichia coli

Abstract

Plastic pollution and antibiotic resistance are two emerging environmental and human health crises today. Although it was revealed that microplastics can serve as vectors for the dissemination of antibiotic resistance, it is still unclear how the nanoplastics influence the horizontal transfer of antibiotic resistance genes (ARGs). Herein, we firstly compared the effect of polystyrene (PS) micro/nanoplastics on the transformation of plasmid‐borne ARG, using a transformation model consisting of plasmid pUC19 (ampR) and Escherichia coli DH5α (recipient). Due to its size effect, PS nanoplastics (10–500 mg/L) significantly enhanced the transformation efficiency (2.8–5.4 folds) and frequency (3.2–8.4 folds) of exogenous ampR into E. coli, while PS microplastics exerted no influence. The detailed mechanisms were found that nanoplastics induced reactive oxygen species (ROS) overproduction, activated SOS response, increased cell membrane permeability and changed the secretion systems, thereby facilitating the uptake of exogenous DNA by bacteria. Moreover, the co‐presences of nanoplastics with humic acid or Fe3+ relieved to some extent, but did not completely alleviate the promoting effect of nanoplastics on plasmid transformation. Our findings suggest that the risk of nanoplastics on promoting the dissemination of antibiotic resistance should not be neglected, and further studies are needed to investigate such risk in complex environments.

Dichotomous Role of Humic Substances in Modulating Transformation of Antibiotic Resistance Genes in Mineral Systems

“…The cultures were chilled on ice for 10 min followed by centrifugation for 5 min at 4 °C and 4500 g . The cell pellets were resuspended using ice-cold 0.1 mol/L CaCl 2 and then placed in an ice-water bath for 30 min to obtain the competent cell solution. , Thereafter, 500 μL of competent E. coli suspensions (OD 600 = 0.5) were diluted 10-fold in fresh CM.…”

“…The cell pellets were resuspended using ice-cold 0.1 mol/L CaCl 2 and then placed in an ice-water bath for 30 min to obtain the competent cell solution. 43,44 Thereafter, 500 μL of competent E. coli suspensions (OD 600 = 0.5) were diluted 10-fold in fresh CM. The 5 mL of cultures were then mixed with 10 mg/mL mineral−HA composite and 0.1 μg/mL plasmid pHTG.…”

Phthalates Promote Dissemination of Antibiotic Resistance Genes: An Overlooked Environmental Risk

“…Given the continuous releasing and environmental-persistence nature of PAEs, our results suggest that the environmental and ecological risks of plastics might have been underestimated previously, especially for the niches with biofilms colonized on the plastic surface. Indeed, plastics are rapidly proliferating anthropogenic vectors for the colonization and transportation of microbial communities and act as a reservoir and refuge for ARGs in aquatic ecosystems. , Thus, plastisphere is a potential hotspot for evolution and spreading of antimicrobial resistance via both direct and indirect pathways. − In particular, the biofilms colonized on plastics surfaces, which are widespread in the natural environment and engineering systems such as sewers and wastewater treatment biocarriers, may profoundly strengthen the PAE environmental impacts due to high microbial density and local accumulation of PAEs. , …”

Polystyrene nanoplastics foster Escherichia coli O157:H7 growth and antibiotic resistance with a stimulating effect on metabolism

“…Similar observations were found in E. coli DH5a and E. coli K12 MG1655, in which a higher ROS production or an increased activity of intracellular antioxidants (like SOD and CAT) was obtained with the presence of small PS-NPs. [55][56][57] It was thus evident that the smaller size of PS-NPs resulted in a higher oxidative stress to the E. coli type strains, which also made a positive response via activating its diverse antioxidant systems at the same time. In general, bacterial responses to environmental changes are often characterized by the induction of specific stress responses, 58 which is a complicated process that currently lacks a thorough understanding.…”