Dose fractionation as a promising strategy to improve UV disinfection

See t.ly/emb8 — Survival curves for bacteria exposed to germicidal radiation (254 nm) usually exhibit a decreased slope at high doses, because bacterial populations contain a small proportion of cells able to tolerate the effects of the radiation. These cells could survive due to external shielding by aggregation or association with inert particles. However, it has been proposed that transient and reversible phenotypic changes modifying UV susceptibility also occur and lead to a phenomenon of persistence. Using Escherichia coli as a model organism, and comparing the effects of continuous exposures to those of irradiations separated by incubations in the dark, we found that in…