Related Experiment Video
Updated: Apr 12, 2026
Inactivation of Pathogens via Visible-Light Photolysis of Riboflavin-5′-Phosphate
Published on: April 6, 2022
Inactivation of Vibrio parahaemolyticus by antimicrobial photodynamic technology using methylene blue
Xi Deng1, Shuze Tang1, Qian Wu1
1Department of Food Science and Engineering, Jinan University, Guangzhou, 510632, China.
Background:
Vibrio parahaemolyticus is the leading causative pathogen of gastroenteritis often related to contaminated seafood. Photodynamic inactivation has been recently proposed as a strategy for killing cells and viruses. The objective of this study was to verify the bactericidal effects caused by photodynamic inactivation using methylene blue (MB) over V. parahaemolyticus via flow cytometry, agarose gel electrophoresis and sodium dodecyl sulfate polyacrylamide gel electrophoresis. Vibrio parahaemolyticus counts were determined using the most probable number method. A scanning electron microscope and a transmission electron microscope were employed to intuitively analyze internal and external cell structure.
Results:
Combination of MB and laser treatment significantly inhibited the growth of V. parahaemolyticus. The inactivation rate of V. parahaemolyticus was >99.99% and its counts were reduced by 5 log10 in the presence of 0.05 mg mL(-1) MB when illuminated with visible light (power density 200 mW cm(-2)) for 25 min. All inactivated cells showed morphological changes, leakage of cytoplasm and degradation of protein and DNA.
Conclusion:
Results from this study indicated that photodynamic technology using MB produced significant inactivation of V. parahaemolyticus mainly brought about by the degradation of protein and DNA.
Insights
Photodynamic inactivation using methylene blue (MB) effectively eliminated over 99.99% of Vibrio parahaemolyticus. This method degraded essential cell components, offering a novel approach to combat foodborne pathogens.
Area of Science:
- Microbiology
- Photochemistry
- Food Safety
Background:
- Vibrio parahaemolyticus is a primary cause of seafood-associated gastroenteritis.
- Photodynamic inactivation (PDI) is an emerging strategy for microbial and viral inactivation.
- Methylene blue (MB) is a photosensitizer with potential antimicrobial applications.
Purpose of the Study:
- To evaluate the bactericidal efficacy of PDI using MB against Vibrio parahaemolyticus.
- To investigate the mechanisms underlying PDI-induced cell damage.
Main Methods:
- Flow cytometry and microscopy (SEM, TEM) for cell analysis.
- Agarose gel electrophoresis and SDS-PAGE for DNA and protein degradation assessment.
- Most probable number (MPN) method for bacterial enumeration.
Main Results:
- PDI with MB achieved >99.99% inactivation of V. parahaemolyticus.
- A 5 log10 reduction in bacterial counts was observed under specific MB concentration and light conditions.
- Morphological alterations, cytoplasmic leakage, and degradation of DNA and proteins were evident in treated cells.
Conclusions:
- Photodynamic technology with MB demonstrates significant bactericidal effects against V. parahaemolyticus.
- Cellular damage, particularly DNA and protein degradation, is the primary mechanism of inactivation.
More Related Videos
05:13LED-Based In Vitro Screening for Assessing Photoactivable Molecules in Bacterial Photodynamic Inactivation
Published on: January 24, 2025
09:29In Vivo Investigation of Antimicrobial Blue Light Therapy for Multidrug-resistant Acinetobacter baumannii Burn Infections Using Bioluminescence Imaging
Published on: April 28, 2017