NAGase activity in airborne biomass dust and relationship between NAGase concentrations and fungal spores

摘要

Inhalation of airborne fungal spores or fungal enzymes may cause adverse pulmonary health effects. The enzyme NAGase (N-acetyl-β-D-glucosaminidase) is a chitinase presumed to be secreted by all fungi. In this study, NAGase activities and concentrations of fungi are estimated in airborne biomass dust to acquire knowledge about the level of NAGase activity and the relationship between NAGase activity and concentrations of airborne fungal spores. NAGase was sampled on both teflon and polycarbonate filters, and polycarbonate filters proved to be better for extraction of NAGase than teflon filters. NAGase was found in airborne dust at a biofuel plant and in dust generated from biomass. At a biofuel plant, the median level of exposure to NAGase was 21 pmol s~(-1) m~(-3). Significant correlations were found between NAGase activities, total number of fungal spores and CFU of fungi, with the highest degree of correlation being between the total number of fungal spores and the NAGase activity (r = 0.802, n = 76). Furthermore, when dust was stored for different periods, the culturability of fungal spores was strongly reduced and the NAGase activity was not or only slightly reduced after up to 40 days of storage. Accordingly, NAGase activity may be used as a rapid method to get an estimate of the exposure level to airborne fungal spores. Whether pure NAGase or the NAGase concentrations observed here cause any health effects is not known, although it has been shown that other fungal enzymes can cause respiratory disorders and a chitinase is described as an allergen.