Killing bacterial spores with blue light: When innate resistance meets the power of light

This article is a highlight of the study by Maclean et al. in this issue of Photochemistry and Photobiology describing the sporicidal effects 405 nm visible light alone on endospores of the Clostridium and Bacillus genera. 1.73 kJ cm^-2 was capable of reducing endospore colony-forming units by up to 4-log₁₀. These findings have never been previously demonstrated and may be incorporated into decontamination methods that span medical, military and food preparatory applications. Blue (405-nm) light can kill Bacillus endospores such as those responsible for anthrax by exciting endogenous chromophores such as coproporphyrin.