Urbanization has led to many environmental concerns, one of which is the microplastics in waterways that serve as a cozy home to antibiotic-resistant bacteria. Researchers analyzed antibiotic-resistance genes (ARGs) on five types of microplastics at different parts of the Beilun River in China. They found that it is more abundant in urban compared to rural regions.
Scientists explained that discarded polystyrene breaks down into microplastics and its chemicals contaminate the free-floating genetic materials that make the bacteria antibiotic-resistant.
Urbanization and Microplastics Create Hotspots for Antibiotic-Resistant Bacteria
Last March, Science Daily reported that a study led by researchers from the American Chemical Society found that microplastics prevalent in rivers serve as hotspots for antibiotic-resistant bacteria and ARGs.
They said that microplastics are ideal homes for bacteria to colonize and grow into biofilms and spread ARGs among themselves. They pointed out that the immersed samples of microplastics from 14 different locations in the Beilun River with different levels of urbanization revealed high ARGs.
Researchers used a high-throughput quantitative polymerase chain reaction to analyze the ARGs and genetic elements that help bacteria spread to other bacteria. The abundance of these genes increased 1,000 times from rural regions to urban areas.
Additionally, they found that among the five types of microplastics they analyzed, polypropylene had the highest abundance of ARGs and the greatest risk of spreading it, perhaps due to larger surface area and their ability to release dissolved matter. The findings suggest that urbanization introduced new ARGs into rivers.
They published their study, titled "Impact of Urbanization on Antibiotic Resistome in Different Microplastics: Evidence from a Large-Scale Whole River Analysis," in Environmental Science & Technology.
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Ultraviolet Aging Makes Microplastics a Good Platform for ARGs
According to Phys.org, a similar study led by researchers from Rice University's George R. Brown School of Engineering describes how ultraviolet aging of microplastics in the environment makes them a good platform for ARGs. Researchers noted that when ARGs are ingested, it could lower humans' ability to fight infections.
Rice civil and environmental engineer Pedro Alvarez, the lead author of the study, and his team collaborated with researchers from China and the University of Houston to show that chemicals leaching from microplastics increase the susceptibility of vectors to horizontal ARG transfer.
In the study, titled "UV-Aging of Microplastics Increases Proximal Arg Donor-Recipient Adsorption and Leaching of Chemicals That Synergistically Enhance Antibiotic Resistance Propagation" published in the Journal of Hazardous Materials, researchers wrote that microplastics aged by the ultraviolet part of sunlight have high surface areas that trap bacteria, and their chemicals breach the membranes of these microbes that give ARGs to invade.
The team emphasized that microplastic surfaces could serve as a cozy home for susceptible bacteria and accelerate gene transfer through direct contact with each bacteria. With released chemicals from the microplastics, they explained that they enrich environmental conditions favorable to antibiotic resistance.
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