Analyzing Viable Bacteria Captured by Antimicrobial Prefilters in an Underground Subway Platform

초록

In confined indoor environments, microorganism-laden aerosols potentially contribute to the transmission of contagious diseases. Moreover, recent pandemics have underscored the importance of understanding microbial communities in real-world environments to assess public health risks and inform mitigation strategies. In this study, frequently replaceable antimicrobial prefilters were installed upstream of efficient particulate air filters in air purifiers at an underground subway station, and the viable bacteria captured by the prefilters were analyzed. The antimicrobial prefilters were fabricated using a roll-to-roll coating process with a chitosan？copper？citric acid complex and installed in air purifiers at a subway station for one- and two-week periods. Compared with the control prefilters, the antimicrobial prefilters showed reduced colony counts after both one and two weeks of operation. The biocidal performance of the antimicrobial prefilter was further examined in a chamber test using MS2 bacteriophage, exhibiting a more rapid reduction of MS2 than the control prefilter. Based on 16S rRNA gene sequencing of isolates cultured in tryptic soy broth, 11 culturable bacterial species were identified, with differences in the species detected between the control and test groups and across the operating periods. The identified species were mainly associated with anthropogenic and environmental sources, including Staphylococcus hominis and Bacillus flexus.

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