Photodynamic inactivation of Shigella flexneri by curcumin
Zuxin Liang, Xuling Liu, Zhiran Qin, Jingshu Li, Jianhai Yu, Xiaoen He, Lixia Zhu, Hongying Fan, Yushan Hu, Jinxiu Yao, Chenguang Shen, Chengsong Wan, Bao Zhang, Wei Zhao
Abstract
This study aimed to inactivate Shigella flexneri using curcumin-based photosensitization and determine the sensitivity of S. flexneri to the combination of epsilon (ε)-polylysine (ε-PL) and curcumin-based photosensitization for decontamination. Bacterial numbers were reduced by 4.65 log CFU/mL after incubation with 80 μM curcumin and illumination for 20 min. Photosensitization resulted in cell morphology changes and increased cell permeability and protein degradation. Oxidative stress gene (oxyR) and efflux pump genes (marA, acrA) were upregulated. Decontamination of S. flexneri after incubation with curcumin and ε-PL for 1 h followed by photoactivation for 60 s has been investigated. It was found that the growth of bacteria was completely inhibited. Additionally, the number of bacteria was reduced by > 6 log CFU/mL. Experiments on the uptake of curcumin molecules by bacteria showed that ε-PL promoted the penetration of bacterial cells by curcumin, thus enhancing the effects of photosensitization.