The impact of dose, irradiance and growth conditions on Aspergillus niger (renamed A. brasiliensis) spores low-pressure (LP) UV inactivation

Lizbeth Taylor-Edmonds, Tovit Lichi, Adi Rotstein-Mayer, Hadas Mamane*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The use of Aspergillus niger (A. niger) fungal spores as challenge organism for UV reactor validation studies is attractive due to their high UV-resistance and non-pathogenic nature. However A. niger spores UV dose-response was dependent upon sporulation conditions and did not follow the Bunsen-Roscoe Principle of time-dose reciprocity. Exposure to 8 h of natural sunlight for 10 consecutive days increased UV resistance when compared to spores grown solely in dark conditions. Application of 250 mJ cm-2 at high irradiance (0.11 mW cm-2) resulted in a 2-log inactivation; however, at low irradiance (0.022 mW cm-2) a 1-log inactivation was achieved. In addition, surface electron microscopy (SEM) images revealed morphological changes between the control and UV exposed spores in contrast to other well accepted UV calibrated test organisms, which show no morphological difference with UV exposure.

Original languageEnglish
Pages (from-to)341-347
Number of pages7
JournalJournal of Environmental Science and Health - Part A Toxic/Hazardous Substances and Environmental Engineering
Volume50
Issue number4
DOIs
StatePublished - 21 Mar 2015

Keywords

  • Aspergillus niger
  • Bunsen-Roscoe law
  • reactor validation
  • scanning electron microscopy
  • ultraviolet disinfection

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