Our Research

Our research is specialized in pathogen detection, microbial ecology, and bacterial stress response, with the interest of understanding how bacteria survive and adapt in food processing environments. We study the mechanisms used by foodborne pathogens to persist in food production facilities (e.g. biofilm formation) and explore novel strategies to control them.

Recently, our investigations have centered around pre- and post-harvest interventions to control different Salmonella serovars, challenge studies to evaluate the fate of foodborne pathogens, and characterization of S. aureus strains associated with outbreaks in a dairy farm.

Current Research Interests

By integrating microbiology, molecular tools, and applied food safety approaches, we aim to generate science-based strategies that improve pathogen control across the food chain.

SALMONELLA SEROVAR DIFFERENCES

We investigate how different Salmonella serovars vary in their tolerance to disinfectants and other control strategies, both as free-living cells and within biofilms.

These differences can determine whether an intervention succeeds or fails in food environments. Our goal is to identify serovar-specific patterns of resistance that explain why some strains persist, and to use this knowledge to design more effective, broadly protective sanitation protocols.

DIRECT-FED MICROBIALS

We explore the use of beneficial acid-producing bacteria as natural allies against foodborne pathogens.

By testing individual strains and synergistic combinations, we examine how these microbes lower pH, produce organic acids, and create environments that suppress foodborne pathogens. Our goal is to develop direct-fed microbial interventions that serve as sustainable, pre-harvest tools to reduce pathogen carriage in animals and enhance food safety at its sources.

CHALLENGE STUDIES IN FOOD PROCESSING

We perform microbial challenge studies to evaluate how interventions during food processing influence the survival of foodborne pathogens.

Using real food matrices like dairy products, we track microbial populations under authentic processing and storage conditions. Our goal is to generate data that informs safe product design, guides regulatory policy, and supports producers in implementing effective interventions without compromising product quality.

Recent Studies

Differences in Salmonella serovars’ response to lactic and peracetic acid on pork.

Recent Studies

Differences in Salmonella serovars’ response to lactic and peracetic acid on pork.

Differences in Salmonella serovars’ response to lactic and peracetic acid on pork.

Post-harvest acid sprays (lactic acid - LA, peracetic acid - PAA) are widely used to reduce Salmonella on meat, but it’s unclear how effective are the industry used concentrations on real pork surfaces, and whether some Salmonella serovars could be more susceptible than others.

We inoculated pork with multistrain cocktails of seven Salmonella serovars, then applied commonly used acid sprays by the food industry (LA 2% & 4%; PAA 200 & 400 ppm) and measured survivors after 30 minutes. Across treatments reductions were around: LA 2% ≈ 0.24 log, LA 4% ≈ 0.39 log, PAA 200 ppm ≈ 0.47 log, and PAA 400 ppm ≈ 0.68 log.

Some serovars were more susceptible to PAA treatments than others, with S. Dublin, S. Kentucky, and S. Heidelberg being the most affected by these interventions. Understanding the behavior of different Salmonella serovars under stress conditions can provide an insight into how it survives processing.

Read Article in sciencedirect.com

Virulence factors and strain similarity of Staphylococcus aureus from a dairy farm: Environmental transmission risk

Staphylococcus aureus is commonly associated with milk and dairy products, and it’s enterotoxin production represents a food safety hazard. This pathogen can persist in farm processing environments.

We conducted our study in a dairy facility that suffered a mastitis outbreak, with the purpose of understanding how Staphylococcus aureus moves around a farm and characterizing the isolates recovered from sampling. From one commercial dairy farm we recovered 40 isolates across milk and environmental samples (towels, drains, mats, surfaces) and characterized them with antimicrobial susceptibility testing, biofilm assays, typing, proteomics, and whole-genome sequencing on a subset. Most isolates were susceptible to the antibiotics tested except for gatifloxacin, to which they showed intermediate resistance.

Around 10% of isolates tested positive for enterotoxin in the screening assay, and all isolates produced biofilm (stronger at 48 h). Typing and genomic data (e.g., ST151/ST351, spa types) revealed the same strains present across different farm sites, clear evidence the environment facilitates strain movement. The study highlights the farm environment as a transmission network for S. aureus, reinforcing the need for targeted hygiene measures and environmental surveillance.

Read Article in sciencedirect.com

Acid-producing bacteria: superior inhibition of Salmonella vs. regular organic acids

Organic acids are commonly used to inhibit pathogens, but direct-fed microbials may have extra antimicrobial tools (bacteriocins, metabolites).

We compared the inhibitory activity of 15 acid-producing bacteria (APB) strains to equivalent regular organic acids against seven Salmonella serovars. High-Performance Liquid Chromatography showed APB supernatants contained high levels of lactic (278 mM) and propionic (217 mM) acids. In agar-well assays APB supernatants produced inhibition zones of about 2.5 - 15.6 mm, and several strains inhibited Salmonella more effectively than the organic acids on its own, with Propionibacterium freudenreichii being the most effective against Salmonella.

This study demonstrates that acid-producing bacteria consistently outperformed equivalent organic acids in inhibiting Salmonella, highlighting their potential as more effective antimicrobial tools in food safety applications.

Read Article in sciencedirect.com

Our Labwork, Fieldwork, Conference Presentations, And International Outreach

Involvement With Our Scientific Community Peers

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