Introduction

Food scientists at the National University of Singapore (NUS) have made a significant breakthrough by unveiling crucial traits of the elusive Salmonella dry surface biofilm (DSB). This previously underestimated type of biofilm thrives in dry food processing environments, bringing to light new challenges in food safety and sanitation.

Research Context

In the food industry, the formation of bacterial biofilms poses a serious threat. While existing studies have primarily focused on wet surface biofilms (WSBs), the prevailing assumption was that microorganisms could not thrive under dry conditions. However, recent recalls and a surge of Salmonella-related outbreaks linked to low-moisture food (LMF) have reshaped this narrative, demonstrating that these pathogens are resilient even in arid settings.

Research Findings

The research team, led by Assistant Professor LI Dan from the NUS Department of Food Science and Technology, meticulously examined the characteristics of Salmonella DSBs compared to their wet counterparts. Published in *Applied and Environmental Microbiology* on November 4, 2024, their findings provide unprecedented insights into managing biofilms in the food industry.

Utilizing advanced microscopy techniques, including confocal laser scanning, transmission electron, and scanning electron microscopy, the researchers revealed several unique features of DSBs. Contrary to WSBs, which exhibit a distinct plasma and outer membrane, DSB cells are cloaked in a dense, compact capsule, likely enhancing their resistance to antimicrobial agents. The structure of DSBs resembles a “sandwich,” with intact cells at the core and damaged ones on the periphery—a revelation that adds depth to our understanding of pathogen survival strategies.

Methodological Approach

To further explore the role these biofilms play, the research team applied single-cell transcriptomics. This method unveiled bacterial clusters showing active antioxidative and virulent traits, raising concerns about their implications for low-moisture foods.

Innovative Solutions

In a notable stride towards tackling this issue, the researchers developed an innovative, water-free antibiofilm strategy using a combination of the flavonoid morin and 70% isopropyl alcohol—a promising sanitation approach that doesn’t rely on water.

Expert Insights

Assistant Professor Li emphasized the critical nature of these findings, stating, “By illuminating the structural and functional properties of Salmonella DSB, we shed light on how these biofilms withstand desiccation and challenge basic sanitation practices prevalent in LMF settings.” He also pointed out that single-cell RNA sequencing exposes the diversity within DSB populations, debunking the myth that dehydrated biofilm cells are merely dormant and emphasizing the lingering threat they pose.

Impact on Food Industry

The innovative flavonoid-based sanitization approach offers the food industry a pathway to implementing eco-friendly, efficient, and scalable solutions for managing biofilms. "Adopting these strategies could significantly mitigate contamination risks, bolster consumer confidence, and curb financial losses from product recalls and health outbreaks," noted Li.

Conclusion

This research not only marks a pivotal moment in food safety but also reaffirms the importance of translating scientific knowledge into practical applications that ensure public health. As the food industry grapples with biofilm contamination, the findings from NUS could be a game-changer in the fight against foodborne pathogens like Salmonella.