The plastic packaging protecting our food may be doing more than just preserving its freshness. New research from the University of Illinois Urbana-Champaign suggests that microscopic plastic particles shedding from food containers could be increasing the virulence of Salmonella, a common cause of foodborne illness. The findings, published in the journal Science of the Total Environment, raise emerging questions about the potential impact of nanoplastics on food safety and the growing concern of antimicrobial resistance.
Researchers focused on polystyrene, a plastic widely used in food packaging and disposable utensils, and its interaction with Salmonella enterica, a pathogen frequently found in meat, poultry, and ready-to-eat foods. The study began after routine testing of ground turkey purchased from local grocery stores consistently revealed the presence of Salmonella. While proper cooking eliminates the risk, the team wanted to understand how the bacteria behave when in contact with plastic polymers commonly used in packaging.
The research team, led by Pratik Banerjee, associate professor in the Department of Food Science and Human Nutrition, discovered that exposure to polystyrene nanoplastics altered the physiology of Salmonella. Specifically, they observed an increased expression of genes related to virulence – the ability of the bacteria to cause disease – and a tendency to form thicker biofilms. Biofilms, as explained in a New Food Magazine article, are protective layers formed by clusters of microorganisms that increase bacterial survival and make them more resistant to cleaning and disinfection.
A Shifting Bacterial Strategy
The study similarly revealed a dynamic response from Salmonella when exposed to nanoplastics. Lead author Jayita De explained that the bacteria initially enter an “offensive mode,” becoming more virulent. However, as resources dwindle, they switch to a “defensive mode,” allowing them to persist longer in the environment. “If the concentration of nanoplastics rises, they can again switch to an offensive mode,” De said. “It’s a trade-off between offense and defense.”
This adaptability is concerning, as it suggests Salmonella can leverage nanoplastics to enhance its survival and potentially increase the risk of infection. Researchers are now investigating whether this exposure could also contribute to antimicrobial resistance. Banerjee’s team has previously studied the interaction of nanoplastics and E. Coli O157:H7, another dangerous foodborne pathogen, and found similar effects. He explained that stressors like nanoplastics can trigger resistance mechanisms in bacteria, even without direct exposure to antibiotics.
The Link to Antimicrobial Resistance
Early findings from the ongoing research indicate that polystyrene nanoplastics may increase the expression of antimicrobial-resistant genes in Salmonella. This represents particularly troubling given the global rise in antibiotic-resistant bacteria, which threatens to undermine modern medicine. The World Health Organization has identified antimicrobial resistance as one of the top 10 global public health threats facing humanity.
While the research highlights a potential risk, the scientists emphasize that it’s too early to draw definitive conclusions about the real-world implications for the food industry. Banerjee cautioned against sounding the alarm, noting that plastic packaging offers significant benefits, including reducing food spoilage and waste while keeping costs down. “We don’t know yet whether this is something we should be worried about,” he said.
This study is among the first to examine the interaction between nanoplastics and foodborne pathogens from a food safety perspective. Researchers hope that further investigation, both nationally and internationally, will help determine the extent of the risk and inform future food safety policies. The University of Illinois Urbana-Champaign team plans to continue exploring the effects of different types of nanoplastics on various foodborne pathogens.
The findings underscore the complex and often unforeseen consequences of plastic pollution. As plastics break down into ever-smaller particles, they are entering the food chain and interacting with biological systems in ways we are only beginning to understand. Further research is needed to assess the long-term health effects of nanoplastic exposure and to develop strategies for mitigating the risks.
The team’s next steps involve investigating the impact of nanoplastics on a wider range of foodborne pathogens and exploring potential interventions to reduce the transfer of nanoplastics from packaging to food. Updates on their research will be available through the University of Illinois Urbana-Champaign’s Department of Food Science and Human Nutrition.
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