Fungal isolates from dust from the indoor environment: Isolation, identification, and evaluation of polyurethane-degradation potential

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The Ohio State University

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Humans spend 90% of their time indoors where dust is ubiquitous. House dust is an important source of human exposure to microorganisms, many of which are associated with illness, such as asthma. However, many of the microbes that are commonly studied originated from the outdoor environment and may differ in important ways from those that we are commonly exposed to indoors. We need additional information on the specific organisms that commonly occur in our homes. Additionally, it is unclear how these organisms may interact with common indoor materials, such as plastics. This research aims to isolate microorganisms that are prevalent in house dust and evaluate their capability to degrade polyurethane, a common polymer in the indoor environment. Dust was collected from carpet and a vacuum bag from a home in San Francisco, California and another in Columbus, Ohio. Individual organisms were isolated from the samples on culture plates. DNA extractions were performed on 25 purified species and each sample was sent for Sanger sequencing to to detect the highly variable ITS1 and ITS2 sequences and to verify the identity of each species. A total of 18 unique fungal species were putatively identified, including four different species from the Penicillium genera, three from the Epicoccum genera, and two from the Aspergillus genera. Other species included Alternaria alternata, Aureobasidium pullulans, Nigrospora sphaerica, Rhodosporidiobolus colostri, Pithomyces chartarum, and Rhodotorula mucilaginosa. The species collected were further characterized and grown on Impranil-containing plates to determine their capacity for polyurethane degradation. The results of this experiment showed Impranil clearing by three of the species, including Aureobasidium pullulans, Aspergillus oryzae, and Holtermanniella wattica, indicating that there are fungal species in the home environment with the ability to degrade common plastics. This research provides a better understanding of which fungi thrive in our dust and the implications of this growth at home. Future work can further determine how microbes may interact with common materials in the indoor environment, such as plastics.



Fungi, House dust, Plastic degradation, Fungal isolates