Colorimetric assay for biofilms in wet processing conditions

Area of Science:

• Food Safety and Microbiology
• Industrial Microbiology
• Biofilm Research

Background:

• Bacterial biofilms pose significant challenges to food safety and industrial hygiene.
• Effective control of biofilms is crucial in clean room environments, particularly in food processing.
• Quantitative measurement methods are needed for pathogen biofilms under realistic conditions.

Purpose of the Study:

• To develop and validate a quantitative method for measuring bacterial biofilms.
• To assess biofilm formation by Listeria monocytogenes under simulated wet poultry processing conditions.
• To establish a reliable assay for biofilm control strategies.

Main Methods:

• Utilized stainless steel and glass coupons incubated in reduced-nutrient media.
• Exposed coupons to Listeria monocytogenes under controlled temperature and humidity.
• Quantified biofilms using a crystal violet assay, viable cell density, spectrophotometry, and microscopy.

Main Results:

• Listeria monocytogenes successfully formed biofilms on all tested substrata.
• The crystal violet assay provided distinct groupings compared to cell density measurements.
• Microscopy revealed a transition from dispersed cells to clumped biofilm structures.
• Bacterial viability was maintained throughout the experiment, reaching equilibrium within 24 hours.

Conclusions:

• The developed crystal violet assay is effective for quantifying Listeria biofilms on stainless steel.
• This method is applicable to other bacteria and surfaces in food processing environments.
• The findings support the development of strategies for controlling bacterial biofilms in industrial settings.