Microbial Photoinactivation by Visible Light Results in Limited Loss of Membrane Integrity

Interest in visible light irradiation as a microbial inactivation method has widely increased due to multiple possible applications. Resistance development is considered unlikely, because of the multi-target mechanism, based on the induction of reactive oxygen species by wavelength specific photosen...

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Main Authors: Katharina Hoenes (Author), Richard Bauer (Author), Barbara Spellerberg (Author), Martin Hessling (Author)
Format: Book
Published: MDPI AG, 2021-03-01T00:00:00Z.
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042 |a dc 
100 1 0 |a Katharina Hoenes  |e author 
700 1 0 |a Richard Bauer  |e author 
700 1 0 |a Barbara Spellerberg  |e author 
700 1 0 |a Martin Hessling  |e author 
245 0 0 |a Microbial Photoinactivation by Visible Light Results in Limited Loss of Membrane Integrity 
260 |b MDPI AG,   |c 2021-03-01T00:00:00Z. 
500 |a 10.3390/antibiotics10030341 
500 |a 2079-6382 
520 |a Interest in visible light irradiation as a microbial inactivation method has widely increased due to multiple possible applications. Resistance development is considered unlikely, because of the multi-target mechanism, based on the induction of reactive oxygen species by wavelength specific photosensitizers. However, the affected targets are still not completely identified. We investigated membrane integrity with the fluorescence staining kit LIVE/DEAD<sup>®</sup> BacLight™ on a Gram positive and a Gram negative bacterial species, irradiating <i>Staphylococcus carnosus</i> and <i>Pseudomonas fluorescens</i> with 405 nm and 450 nm. To exclude the generation of viable but nonculturable (VBNC) bacterial cells, we applied an ATP test, measuring the loss of vitality. Pronounced uptake of propidium iodide was only observed in <i>Pseudomonas fluorescens</i> at 405 nm. Transmission electron micrographs revealed no obvious differences between irradiated samples and controls, especially no indication of an increased bacterial cell lysis could be observed. Based on our results and previous literature, we suggest that visible light photoinactivation does not lead to rapid bacterial cell lysis or disruption. However, functional loss of membrane integrity due to depolarization or inactivation of membrane proteins may occur. Decomposition of the bacterial envelope following cell death might be responsible for observations of intracellular component leakage. 
546 |a EN 
690 |a photoinactivation 
690 |a antimicrobial blue light (aBL) 
690 |a reactive oxygen species (ROS) 
690 |a membrane damage 
690 |a membrane permeabilization 
690 |a 405 nm 
690 |a Therapeutics. Pharmacology 
690 |a RM1-950 
655 7 |a article  |2 local 
786 0 |n Antibiotics, Vol 10, Iss 3, p 341 (2021) 
787 0 |n https://www.mdpi.com/2079-6382/10/3/341 
787 0 |n https://doaj.org/toc/2079-6382 
856 4 1 |u https://doaj.org/article/c89a2e68f68d449c95faeccfec3b7117  |z Connect to this object online.