Small but powerful: Light-emitting diodes for inactivation of Aspergillus species in real water matrices

Abstract

This study addressed the effectiveness of light emitting diodes to achieve inactivation of three different Aspergillus species (Aspergillus fumigatus, Aspergillus niger and Aspergillus terreus) in a real water matrix. Three single small ultraviolet-C diodes emitting light at two different wavelengths were tested: 255 nm that is similar to the wavelength emitted by low pressure mercury lamps and 265 nm that is closer to the maximum absorbance wavelength of DNA. The ultraviolet-C diodes emitting light at 265 nm were found to be more effective than the 255 nm, achieving 3-log, 1-log and 5-log inactivations of Aspergillus fumigatus, Aspergillus niger and Aspergillus terreus using less than 20 mJ/cm² (13,97 mJ/cm²; 7,28 mJ/cm²; 19,74 mJ/cm²). The diodes have also affected the morphology of the fungal spores and increased the percentage of damaged and dead spores.

Keywords: Aspergillus species; Disinfection; Enzymatic activity; Light emitting diodes; Membrane permeability; Spores morphology.