Inactivation of Fungal Spores Collected on Fibrous Filters by Melaleuca alternifolia (Tea Tree Oil)

Microbial aerosols could cause various human and animal health problems and their control is becoming a significant scientific and technological topic for consideration. Filtration is considered to be one of the main processes of the removal of biological aerosols from the air carrier minimizing bioaerosol concentration in industrial and domestic dwellings. However, with regards to biologically active particles, their removal from the air carrier does not solely solve the problem of microbial contamination of the ambient air. Considering that in some situations bioaerosol particles collected on the filter could re-enter the air carrier, some disinfection is required to ensure that no biologically active particles could possibly be removed from the filter surface and reach human occupied areas. This article describes the results of laboratory investigations involving Melaleuca alternifolia (tea tree oil) as disinfecting media for inactivation of common environmental fungal spores on the filter surface. It was found that 50% and 40% of Aspergillus niger and Rhizopus stolonifer spores, respectively, were inactivated over a period of 60 minutes. A single factor ANOVA test confirmed that the reported rates of inactivation were statistically significant (> 95%). For Rhizopus statistically significant inactivation by 31% was also observed after 30 minutes with no inactivation occurring over shorter time periods. No statistically significant inactivation occurred for Aspergillus niger for any time shorter than 60 min.