In recent years, the infiltration of plastic particles into the human food supply has emerged as a pressing environmental and public health concern. With plastic products omnipresent from farm to table, the inevitable shedding of microplastics has brought to light an even more insidious threat: nanoplastics. These minuscule plastic fragments, often less than 100 nanometers in size, possess unique physicochemical properties that allow them to interact intimately with biological systems in ways that are only beginning to be understood. Researchers at the University of Illinois Urbana-Champaign have now delved into how nanoplastics specifically influence the behavior of Salmonella enterica, a predominant foodborne pathogen, revealing complexities that could reshape our understanding of food safety in an increasingly plasticized world.

Salmonella enterica has long been recognized as a major culprit in foodborne infections, frequently contaminating meat, poultry, and ready-to-eat foods. Traditionally, rigorous cooking practices have been the primary method for mitigating its risk. However, the ubiquitous packaging of these foods in plastic materials introduces a new vector for interaction. The researchers, led by Pratik Banerjee, an associate professor specializing in Food Science and Human Nutrition, sought to explore how the ubiquitous nanoplastics might affect the physiology and virulence of Salmonella once they come into contact with plastic polymers commonly used in food packaging, specifically polystyrene.

Prior studies by Banerjee’s lab illuminated the complex interplay between nanoplastics and E. coli O157:H7, a notorious pathogen responsible for severe gastrointestinal outbreaks. Building on this foundation, the current investigation centers on Salmonella enterica, exposing the bacteria to polystyrene nanoplastics to observe changes in virulence expression, biofilm formation, and stress response mechanisms. This focus is crucial, given the prevalence of polystyrene in disposable food containers and packaging materials, which heightens the likelihood of direct pathogen exposure to nanoplastics in everyday scenarios.

Their findings are striking. Upon initial exposure to polystyrene nanoplastics, Salmonella exhibits a significant upregulation of virulence-related genes. This genetic activation translates into the formation of thicker and more robust biofilms—a collective of microbial cells embedded within a protective matrix, which enhances bacterial survival under hostile conditions. Biofilms are well-known to facilitate persistent infections and resist antimicrobial interventions, making this behavioral shift particularly alarming from a food safety perspective.

Interestingly, while the initial response is aggressive or ‘offensive,’ the research uncovered a temporal dimension to this interaction. Over prolonged exposure, Salmonella transitions to a ‘defensive’ mode wherein its stress response mechanisms slow down, presumably conserving energy to endure in hostile environments. This dynamic toggling between offensive virulence and defensive persistence underscores the adaptability of Salmonella when confronted with the stress imposed by nanoplastic particles.

Jayita De, a graduate student and lead author of the study, elaborates on this phenomenon by highlighting the trade-offs faced by bacteria: “Exposure to nanoplastics forces Salmonella to oscillate between states of heightened virulence and resource-conserving dormancy. This plasticity in behavior could potentially facilitate survival and pathogenicity in environments laden with nanoplastic contaminants.” This adaptability may have profound implications for microbial ecology in food processing and storage environments, where plastic materials are ubiquitous.

Beyond virulence, the interplay between nanoplastics and antimicrobial resistance constitutes a significant dimension of concern. Banerjee’s team posits that while nanoplastics themselves are not antimicrobial agents, the physiological stress they impose can inadvertently induce cross-resistance mechanisms within Salmonella. This means that exposure to nanoplastics might enable bacteria to increase the expression of genes conferring resistance to antibiotics, potentially complicating treatment outcomes for infections originating from foodborne pathogens.

This phenomenon prompts a reconsideration of how non-traditional environmental stressors, like nanoplastics, contribute to the broader global challenge of antimicrobial resistance (AMR). The initial experimental evidence points toward polystyrene nanoplastics acting as a catalyst for cross-resistance, raising urgent questions about the unintended side effects of our reliance on plastic packaging in the food industry.

However, the researchers emphasize a cautious interpretation of their findings. Banerjee reminds us not to hastily vilify plastic materials outright, as they play a critical role in preventing food spoilage and reducing waste, thereby supporting food security and affordability. The study instead highlights a pressing need for balanced, evidence-based approaches that inform future regulations and innovations in packaging technology, considering both benefits and emerging risks.

This pioneering study contributes significantly to an emerging field that intersects environmental science, microbiology, and food safety. By investigating the nuanced interactions between foodborne pathogens and nanoplastics, the University of Illinois team has opened new avenues for understanding how synthetic materials in our environment can subtly but profoundly influence microbial behavior. It also underscores the importance of multidisciplinary collaboration and continued research globally to unravel the full scope and mechanisms of these interactions.

Further investigations are warranted to elucidate the precise molecular pathways underpinning virulence modulation and antibiotic resistance induced by nanoplastics. Additionally, exploring a broader spectrum of pathogens and different types of plastic polymers would provide a more comprehensive risk assessment framework. Such research is critical not only to inform regulatory policies but also to innovate safer packaging materials designed to minimize adverse impacts on public health.

The study titled “Polystyrene nanoplastics and pathogen plasticity: Toxic threat or tolerated stressor in Salmonella enterica?” was published on January 26, 2026, in the Journal of Hazardous Materials. It marks a significant step in recognizing the intersection between emerging contaminants and microbial pathogenesis, an area that promises to shape future food safety paradigms amid growing environmental challenges.

Subject of Research: Interaction between polystyrene nanoplastics and the foodborne pathogen Salmonella enterica, focusing on virulence and antibiotic resistance.

Article Title: Polystyrene nanoplastics and pathogen plasticity: Toxic threat or tolerated stressor in Salmonella enterica?

News Publication Date: January 26, 2026

Web References:

Journal Article DOI
University of Illinois Department of Food Science and Human Nutrition

References: Banerjee, P., De, J., et al. (2026). Polystyrene nanoplastics and pathogen plasticity: Toxic threat or tolerated stressor in Salmonella enterica? Journal of Hazardous Materials. DOI: 10.1016/j.jhazmat.2026.141264

Image Credits: College of Agricultural, Consumer and Environmental Sciences (ACES), University of Illinois Urbana-Champaign; Marianne Stein

Keywords

Food science, Human health, Nanoplastics, Salmonella enterica, Polystyrene, Biofilm formation, Virulence genes, Antimicrobial resistance, Food safety, Microbial pathogenesis, Environmental contaminants, Cross-resistance

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