Understanding Escherichia coli damages after chlorophyllin‐based photosensitization

Abstract

Pathogenic strains of bacteria are causing various illnesses all around the world and have a major socioeconomic impact. Thus, fast-and low-cost methods for the microbial control of foods are needed. One of them might be photosensitization. This study looks deeper into the mechanism of Escherichia coli damage by chlorophyllin-based photosensitization. Fluorimetric data indicate that after 15 minute incubation with chlorophyllin (Chl) (1.5 × 10 −5 M Chl) 0.73 ± 0.03 μM of this compound was associated with E. coli cell surface. After photoactivation (405 nm, 6-30 J/cm 2) significant reduction (88.2%) of bacterial viability was observed. Higher concentration of Chl (5 × 10 −4 M Chl) reduced viability of bacteria more than by 98%. Results indicated that reactive oxygen species (ROS) took place in this inactivation. Colloidal surface enhanced Raman scattering (SERS) spectroscopy was employed to detect the molecular changes in the treated bacteria. It was found that Chl-based based photosensitization triggers multiple surface structure changes in E. coli what induce lethal unrepairable damages and inactivation of pathogen.

Inactivation of Opportunistic Pathogens Acinetobacter baumannii and Stenotrophomonas maltophilia by Antimicrobial Photodynamic Therapy

“…Another relatively new PS used in this study is non-copperrized chlorophyllin sodium salt (Chl) with Mg 2+ in the center of the ring. Chl is known as a water-soluble negatively charged (anionic) chlorophyll derivative with a main absorption maximum at 405 ± 2 nm, that exhibits antimicrobial activity that generates ROS after exposure to visible light [ 30 , 50 , 51 ]. The absorption spectra showed that RF and Chl in PBS solutions (7.4 pH) have main absorption bands at about 402 nm and 444 nm, respectively.…”

Evaluation of visible light and natural photosensitizers against Staphylococcus epidermidis and Staphylococcus saprophyticus planktonic cells and biofilm

“…1 , A). There is data in the literature that both types of photochemical reactions occur during Chl-API, but type II reactions, during which 1 O 2 is formed, predominate [ [ 29 , 30 , 65 ]]. Although a small generation of O 2 •‒ was obtained in the work, it shows that during the photoactivation of Chl by 402 nm light, the Chl radical transfers the newly acquired electron to oxygen as a result superoxide radicals are forming.…”