Seasonal dynamics of airborne fungi in different caves of the Mogao Grottoes, Dunhuang, China

Fungal spores are ubiquitous and can be found in both outdoor and indoor air samples, we investigated the temporal and spatial distributions, compositions, and determinants of ambient airborne fungi in Mogao Grottoes of Dunhuang, China. Culturable fungi in three categories of caves, Open Cave (OC) to visitors, Semi-open Cave (SC), and Closed Cave (CC) and an outdoor area (OD) in Mogao Grottoes monthly from September 2008 to August 2009, using a six-stage Anderson FA-1 sampler. The grand mean of total culturable fungi was 187.45 ± 37.76 colony-forming units (CFU)/m3 for all sites considered, and the number was 110.52 ± 17.40 CFU/m3, 137.81 ± 26.67 CFU/m3, 245.39 ± 37.20 CFU/m3, 240.87 ± 54.91 CFU/m3 in OC, SC, CC, OD. The most prevalent fungi were Cladosporium spp., non-sporing fungi, Penicillium spp., Alternaria spp. and Aspergillus spp. at all four sampling sites. Airborne fungal numbers and their diversity were generally higher in CC and OD than in OC and SC. Most fungal genus had significant seasonal variations, higher levels were observed in summer and autumn. Pearson correlation analysis showed that the levels of ambient fungi were correlated positively with temperature and visitor numbers, but negatively with relative humidity and rainfall. The results suggested that the visitors have an obvious influence on concentrations and compositions of ambient fungi in Mogao Grottoes providing information to be considered in conservation and management.