Metabarcode insights into the airborne fungal diversity in the indoor and outdoor environments in archives from Yunnan, Southwestern China

Abstract

Monitoring dynamics of airborne fungal species and controlling of harmful ones are of vital importance to conservation of cultural relics. However, the evaluation of air quality and the community structure characteristics of microorganisms, especially fungi, in the atmosphere of archives is in a stage of continuous exploration though more than 4,000 archives were constructed in China. Seventy-two air samples were collected in this study under different spatial and weather conditions from the archives of Kunming Medical University, located in the Kunming metropolitan area, Yunnan province, southwestern China. A total of 22 airborne fungal classes, 160 genera and 699 ASVs were identified, the species diversity is on the rise with the strengthening of air circulation with the outside space, and thus the intensive energy metabolism and activity were found in the spaces with window and sunny weather, except for the higher lipid synthesis of indoor samples than that of outdoor ones. Furthermore, there were significant differences in fungal community composition and abundance between sunny and rainy weathers. A considerable number of species have been identified as indicator in various environmental and weather conditions of the archives, and temperature and humidity were thought to have significant correlations with the abundance of these species. Meanwhile, Cladosporium and Alternaria were the dominant genera here, which may pose a threat to the health of archive professionals. Therefore, monitoring and controlling the growth of these fungal species is crucial for both conservation of paper records and health of archive professionals.

Keywords: Air pollution; Archive warehouse; Fungal biome; Microbiome; Relative humidity control.

Fig. 1

Rarefaction curves of the estimated ASV richness in the samples. A, B, and C: Room 114; D: Room 111; E: Room 112; F: the corridor of Room 114. 1, 2, and 3: sunny weather; 4: rainy weather

Fig. 2

The microbial community structure of all samples at the class (a) and genus (b) levels

Fig. 3

Principal coordinate analysis (PCoA) of fungal communities for four types of grouping based on Jaccard distance. (a) windowless room (NW) and windowed room (W) samples; (b) indoor and outdoor samples; (c) sunny and rainy samples; (d) indoor rainy (IR), outdoor rainy (OR), indoor sunny (IS), and outdoor sunny (OS) samples

Fig. 4

The shared ASVs between (a) windowless room (NW) and windowed room (W) samples, (b) indoor and outdoor samples, (c) sunny and rainy samples, (d) indoor rainy (IR) and outdoor rainy (OR) samples, (e) indoor sunny (IS) and outdoor sunny (OS) samples

Fig. 5

The top 30 genera with higher relative abundance. (a) windowless room (NW) and windowed room (W) samples; (b) indoor and outdoor samples; (c) sunny and rainy samples; (d) indoor rainy (IR), outdoor rainy (OR), indoor sunny (IS), and outdoor sunny (OS) samples

Fig. 6

LDA was combined with the effect size (LEfSe). The LDA score of each taxon was > 3. (a) windowless room (NW) and windowed room (W) samples, (b) indoor and outdoor samples, and (c) sunny and rainy samples

Fig. 7

Redundancy analysis (RDA) highlighting correlations among the top ten fungal genera and the relative humidity (RH) and temperature (T). A, B, and C represent three different sampling sites in Room 114, with the numbers 1, 2, and 3 following A, B, and C representing sunny weather and 4 representing rainy weather

Fig. 8

Differentially abundant metabolic pathways in (a) W vs. NW (b) indoor vs. Outdoor (c) Rainy vs. Sunny samples (P ≤ 0.005 for all comparisons)