Next-generation sequencing revealed dominant fungal populations in collected dust from selected public school classrooms in Metro Manila

Fungal contaminants inside classrooms may increase the chance of health-related problems for school children and teachers, reducing their learning and productivity. Recent initiatives have utilized next-generation sequencing (NGS) technology in order to understand dust ecology and were used to significantly correlate some genera with health-related conditions. To our knowledge, this paper is the first report, describing the fungal community profile of collected dust using 454 pyrosequencing of the ITS region of the 18S rRNA gene from public school classrooms in Metro Manila, Philippines. Culture-dependent technique was done by gravimetric sampling on Sabouraud Dextrose Agar (SDA) to note the importance of existing viable spores present in the rooms. Composite samples of settled dust from each classroom were collected and pooled to represent one sample per school. The fungal ITS rRNA genes amplified from genomic DNA with barcoded primers were sent for pyrosequencing on a 454 GS FLX titanium platform, and sequences were analyzed using the ITScan pipeline. Fungal sequences from the collected dust samples clustered in 108 operational taxonomic units (OTUs), most of which occur as singleton. The number of OTUs that correspond to fungal species varied from 16 to 29 per sample. Rarefaction curves indicated that sampling coverage was partial and that the remaining fraction of the species diversity remains to be discovered. Genera that were detected by both NGS and by cultivation on SDA include Alternaria, Aspergillus, Cladosporium and Penicillium.