People spend most of their time indoors, both at work or at home. The quality of indoor air is therefore crucial for the well-being of the population.

The composition of bioaerosol as a part of indoor air, has not yet been sufficiently characterized. Previously established, usually culture-based, analysis methods do not allow a full characterization of bioaerosols in indoor spaces. Therefore, modern omics methodologies may provide a more comprehensive characterization of bioaerosols. As part of the presented project, proteomic analysis of bioaerosols will be established and applied to bioaerosol samples from various indoor spaces.

A challenge in indoor air analysis is the choice of filter material used to collect the bioaerosols. The filter material plays an important role, as its properties determine sample yield. While quartz filters are commonly used, they generally show lower bioaerosol recovery in comparison to hydrophilic poly-carbonate (PC) or polyvinylidene fluoride (PVDF) filters. The length of the sampling period can also have an effect, as bioaerosols might dry out on the filter over time. Furthermore, bioaerosol size plays a role in recovery as well, as smaller microorganisms can be embedded deeper into the fibers of the filters. Therefore, the choice of filter material plays an important role regarding the optimization of protein extraction.

To establish a pipeline for proteome analysis of indoor air, a standard sample consisting of a mixture of microorganisms was applied to different filter materials. Furthermore, we tested different lysis methods and compared the extracted protein amounts to the standard sample to determine the optimal filter material and lysis method for indoor bioaerosol proteomics.

For verification of the method bioaerosol samples were collected by filtration from varying indoor spaces for metaproteomic analysis. As bioaerosol concentrations in indoor spaces are generally low, an optimized analysis pipeline for proteomics may improve detectability of low abundance proteins otherwise overlooked.