title: Photodynamic inactivation of methylene blue and tungsten-halogen lamp light against food pathogen Listeria monocytogenes.
abstract: The aim of this study was to verify the bactericidal effect and the damage of photodynamic inactivation (PDI) using methylene blue (MB) and tungsten-halogen lamp over Listeria monocytogenes via atomic force microscopy, absorption spectrophotometry, agarose gel electrophoresis, real-time PCR and SDS-PAGE. The obtained data indicated that the viability of L. monocytogenes was ca 7-log reduced by illumination with 10 min tungsten-halogen lamp light under the presence of 0.5 μg mL(-1) MB, and this bactericidal activity against L. monocytogenes of PDI increased proportionally to the concentration of MB and the duration of irradiation. Moreover, after irradiation with MB and visible light, the leakage of intracellular contents was estimated by spectrophotometer at OD(260) and OD(280), which correlated with morphological alterations. Furthermore, genomic DNA cleavage and protein degradation were also detected after PDI treatment. Consequently, breakage of the membrane, damage of the genomic DNA and degradation of bacterial proteins may play an important role in the mechanisms involved in PDI-MB bactericidal activity on L. monocytogenes.
authors.affiliation: Department of Food Science and Engineering, Jinan University, Guangzhou, China.
authors.forename: Shao-ling
authors.initials: SL
authors.lastname: Lin
authors.forename: Jia-miao
authors.initials: JM
authors.lastname: Hu
authors.forename: Shu-shu
authors.initials: SS
authors.lastname: Tang
authors.forename: Xi-yang
authors.initials: XY
authors.lastname: Wu
authors.forename: Zhen-qiang
authors.initials: ZQ
authors.lastname: Chen
authors.forename: Shu-ze
authors.initials: SZ
authors.lastname: Tang
mesh_terms: D001427:Bacterial Toxins / Q000737:chemistry; D053938:DNA Fragmentation / Q000187:drug effects / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D004587:Electrophoresis, Agar Gel; D004591:Electrophoresis, Polyacrylamide Gel; D005502:Food / Q000528:radiation effects; D005516:Food Microbiology; D006360:Heat-Shock Proteins / Q000737:chemistry; D006460:Hemolysin Proteins / Q000737:chemistry; D008027:Light; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects*; D008751:Methylene Blue / Q000737:chemistry / Q000494:pharmacology*; D050296:Microbial Viability / Q000187:drug effects / Q000528:radiation effects; D018625:Microscopy, Atomic Force; D010782:Photolysis; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D059748:Proteolysis / Q000187:drug effects / Q000528:radiation effects; D060888:Real-Time Polymerase Chain Reaction; D013053:Spectrophotometry
chemical_list: D001427:Bacterial Toxins; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D017319:Photosensitizing Agents; C038705:hlyA protein, Listeria monocytogenes; D008751:Methylene Blue