Environmental characteristics and taxonomy of microscopic fungi isolated from washing machines

This study is focused on the diversity of fungal species colonising washing machines, and investigates the possible relationship between the habits of washing machine users and the colonising species. Housekeeping conditions and habits of washing machine users were assessed in Hungary with a questionnaire. After sampling, several different fungal species were identified by microscopy and sequence analysis of diagnostic loci. Based on the results, 32% of the sampled washing machines were highly polluted with various species of fungi. Forty six percent of the observed devices were colonised also by opportunistically human pathogenic species. In total, 32 yeast and 39 filamentous fungal strains were isolated. Growth tests were conducted with five selected taxa (Cutaneotrichosporon dermatis, Cystobasidium slooffiae, Meyerozyma guilliermondii, Candida parapsilosis and the Fusarium oxysporum species complex (FOSC)) to ascertain their tolerance ranges. None of the examined isolates were able to grow above 50 °C, under pH=4.10 and above pH=10.88. Interestingly, the examined representative of the FOSC could grow at the extremely high salinity of 12%. Significantly more (2.9×) species were detected in washing machines operated in rooms without heating systems (p=0.0025). The number of species was significantly higher in washing machines located in the kitchen than the ones kept in bathroom or in other rooms (p=0.0205). The results of this study suggest that washing machines may serve...
Source: Fungal Biology - Category: Biology Source Type: research