The advent of high-throughput sequencing methods allowed researchers to fully characterize microbial community in environmental samples, which is crucial to better understand their health effects upon exposures. In our study, we investigated bacterial and fungal community in indoor and outdoor air of nine classrooms in three elementary schools in Seoul, Korea. The extracted bacterial 16S rRNA gene and fungal ITS regions were sequenced, and their taxa were identified. Quantitative polymerase chain reaction for total bacteria DNA was also performed. The bacterial community was richer in outdoor air than classroom air, whereas fungal diversity was similar indoors and outdoors. Bacteria such as Enhydrobacter, Micrococcus, and Staphylococcus that are generally found in human skin, mucous membrane, and intestine were found in great abundance. For fungi, Cladosporium, Clitocybe, and Daedaleopsis were the most abundant genera in classroom air and mostly related to outdoor plants. Bacterial community composition in classroom air was similar among all classrooms but differed from that in outdoor air. However, indoor and outdoor fungal community compositions were similar for the same school but different among schools. Our study indicated the main source of airborne bacteria in classrooms was likely human occupants; however, classroom airborne fungi most likely originated from outdoors.

中文翻译：

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16S rRNA基因及ITS区域测序对小学教室室内外空气细菌和真菌群落的调查

高通量测序方法的出现使研究人员能够充分表征环境样品中的微生物群落，这对于更好地了解暴露后的健康影响至关重要。在我们的研究中，我们调查了韩国首尔三所小学九间教室的室内和室外空气中的细菌和真菌群落。对提取的细菌16S rRNA基因和真菌ITS区域进行测序，并对其分类群进行鉴定。还进行了总细菌 DNA 的定量聚合酶链反应。室外空气中的细菌群落比教室空气中的丰富，而室内和室外的真菌多样性相似。细菌如脱水杆菌、微球菌和葡萄球菌通常存在于人体皮肤、粘膜和肠道中的物质被大量发现。对于真菌来说，枝孢属、Clitocybe和Daedaleopsis是教室空气中最丰富的属，主要与室外植物有关。教室空气中的细菌群落组成在所有教室中相似，但与室外空气中的不同。然而，同一学校的室内和室外真菌群落组成相似，但学校之间不同。我们的研究表明，教室中空气传播细菌的主要来源很可能是人类居住者；然而，教室空气传播的真菌很可能来自户外。