Temporal dynamics in diversity and composition of the air mycobiome and dominant allergenic fungi in the subway environment

Abstract

AbstractAnalyzing and monitoring air microbiomes in the subway environment has a great impact on public health, especially in urban cities. In this study, temporal distribution profile of air mycobiome at Bangkok's Sukhumvit subway station (MRT‐SKV) was explored over 12 samplings during December 2021–November 2022 by the environmental DNA‐metabarcoding approach. The top 5 most abundant fungal genera identified were Yarrowia, Cladosporium, Hortaea, Cutaneotrichosporon, and Leptobacillum. Among the 496 genera found, 24 genera could be considered “core mycobiome” of the MRT‐SKV air, as they were consistently found in ≥85% of the samples. Many members of the core mycobiome constituted human commensal genera, but several of them can elicit allergic reactions in humans and thus pose a potential health risk. Cladosporium was the most abundant allergenic fungi found in the MRT‐SKV, which is in contrast to Malassezia, Ustilago, or Aspergillus being the most abundant allergenic fungi in subway environments in other countries. The fungal compositions in the subway environment differed temporally, and the abundances of allergenic fungi were the highest in   samples obtained during the first and seventh samplings (done in December 2021–June 2022). These compositional variations were most likely influenced by air quality variables, including particulate matter (PM), temperature, and relative humidity, which showed seasonal variations. Finally, certain fungal genera were shown to co‐occur together in co‐occurrence network. Many of the allergenic fungal genera formed networks more prominently in rush hour than in other traffic hours. The co‐occurrence network suggested associations among certain fungal genera, such as the association between Malassezia–Nigrospora, Alternaria–Aspergillus, and Aspergillus–Cutaneotrichosporon in the MRT‐SKV bioaerosols. The implied associations between these fungi are worth further investigation since they may point toward their impact on human health (as they are opportunistic fungi found in human). Our results thus facilitate understanding the ecological and health impacts of fungal components of the subway air environment.