Microbial communities that grow on plastic waste in rivers may have the capacity to harbor potentially pathogenic microbes and act as reservoirs of antimicrobial resistance genes, according to a study published in the specialized journal Microbiome.
The findings also highlight differences in the potential pathogens and antimicrobial resistance genes that new and degraded plastics may have the capacity to harbor.
Vinko Zadjelovic, Elizabeth Wellington, Joseph Christie-Oleza and their colleagues characterized the microbial communities found on the surface of low-density polyethylene plastic films after they were submerged in the River Sowe, United Kingdom, one kilometer downstream from a plant. wastewater treatment for seven days in February 2020.
Half of the plastic samples were new and the other half had been heated in an oven for six months to mimic the degradation or erosion of plastic that often occurs in the environment. The researchers then compared them to microbial communities found on a control surface (wooden sticks) that had been submerged in the same river for seven days and to microorganisms extracted from river water samples.
The authors found that all plastic, wood, and water samples harbored potentially pathogenic microbes, but that the types of potential pathogens extracted from the plastic and wood samples differed from those in the river water samples.
Plastic and wood samples harbored potential pathogens Pseudomonas aeruginosa, Acinetobacter, and Aeromonas (known as "opportunistic" bacteria that pose a greater risk to people with compromised immune systems), while water samples contained potential human pathogens Escherichia, Salmonella, Klebsiella and Streptococcus.
Similarly, the authors found that although antimicrobial resistance genes were present in microorganisms extracted from all samples, the types of antimicrobials to which these genes conferred resistance differed between those in the plastic and wood samples and those of water samples.
When the authors compared the microbial communities growing on new and degraded plastics, they found that P. aeruginosa (which can cause infections in hospital patients) was particularly abundant in samples of degraded plastic. They speculate that this could be because degraded plastics release greater amounts of organic compounds that stimulate microbial growth than new plastics.
They also found that the relative abundance of antimicrobial resistance genes present in microbial communities was higher among those from degraded plastic samples than among those from fresh plastic samples; However, they note that the reasons for this are unclear.
The authors suggest that more research is needed to investigate the potential risks that plastic pollution with the capacity to harbor potentially pathogenic microbes and antimicrobial resistance genes could pose to human health, and to investigate the spread of antimicrobial resistance genes. antimicrobials in the environment.
