Inactivation of Gram (-) bacteria Salmonella enterica by chlorophyllin-based photosensitization: Mechanism of action and new strategies to enhance the inactivation efficiency
| Autor: | Danute Labeikyte, Laura Kaziukonyte, Rita Kokstaite, Irina Buchovec, Viktorija Lukseviciūtė, Zivile Luksiene |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
0106 biological sciences
0301 basic medicine Salmonella Membrane permeability Ultraviolet Rays 030106 microbiology Population Biophysics Down-Regulation medicine.disease_cause Real-Time Polymerase Chain Reaction 01 natural sciences Microbiology 03 medical and health sciences chemistry.chemical_compound Anti-Infective Agents Bacterial Proteins 010608 biotechnology medicine Radiology Nuclear Medicine and imaging education education.field_of_study Radiation Photosensitizing Agents Radiological and Ultrasound Technology biology Chlorophyllides Chlorophyllin Salmonella enterica biology.organism_classification chemistry Microscopy Electron Scanning Sodium azide Intracellular Bacteria |
| Zdroj: | Journal of photochemistry and photobiology. B, Biology. 172 |
| ISSN: | 1873-2682 |
| Popis: | This study is focused on the enhancement of susceptibility of Gram (−) bacteria S. enterica to chlorophyllin-based (Chl) photosensitization combining it with other antimicrobial tools. In order to find best combinations, the mechanism by which Chl-based photosensitization inactivates bacteria must be identified. Data confirmed that photosensitization (Chl 1.5 × 10 − 5 M, for 1–120 min, 405 nm, 0–46.1 J/cm 2 ) reduced S. enterica population, just by 2.05 log (CFU/ml). Fluorimetric measurements indicated that just minor part of Chl was bound to Salmonella in suspension. Addition of sodium azide (NaN 3 ) (10 mM) protected bacteria from killing, what means that 1 O 2 took place in photochemical reactions. Gene expression data confirmed that Chl-based photosensitization induced oxidative stress in bacteria cells, since mostly genes responsible for detoxification of ROS ( OxyR , AhpC , GrxA ) have been expressed in Salmonella . Moreover, the expression of genes, responsible for the inhibition of oxidative respiration ( AtpC ), cell division and down-regulation of metabolism ( SulA ) have been detected. In addition, Chl-based photosensitization induced significant release of intracellular components (absorbing at λ 260 nm and λ 280 nm) in bacteria that indicated increased membrane permeability. Thus, the combination of two antimicrobials (Chl-based photosensitization and chitosan (CHS)) with the same target (cellular membrane) in the presence of light drastically reduced viable Salmonella population (by 7.28 log). Combined treatment of photosensitization and high power pulsed UV light (HPPL) was also very effective, since reduced viable Salmonella by 7.5 log. Bacterial regrowth experiments clearly indicated that after both combined treatments Salmonella lost its ability to proliferate, and SEM images confirmed that after both treatments no viable bacteria have been found at all. |
| Databáze: | OpenAIRE |
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