Microbial diversity in bioaerosol samples causing ODTS compared to reference bioaerosol samples as measured using Illumina sequencing and MALDI-TOF

Abstract

The importance of the microbial diversity of bioaerosols in relation to occupational exposure and work related health symptoms is not known. The aim of this paper is to gain knowledge on the bacterial and fungal communities in dust causing organic dust toxic syndrome (ODTS) and in reference dust not causing ODTS. Bacterial and fungal communities were described in personal exposure samples from grass seed workers developing ODTS, in dust generated from grass seeds causing ODTS and in dust generated from reference seeds not causing ODTS. Amplicon sequencing of the bacterial 16S rRNA gene and the fungal ITS region, as well as matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) were used for identification of fungi and bacteria in personal exposure samples and in dust samples from grass seeds causing ODTS and in dust from reference grass seeds. Furthermore, activities of enzymes were measured in the same samples. The sequencing data revealed more than 150 bacterial and 25 fungal genera present in each sample. Streptomyces spp., Aspergillus fumigatus and Rhizopus microsporus were dominating in the dust causing ODTS but not in the reference dust. The dustiness in terms of Mucor sp. and R. microsporus were 100-1000 times higher for problematic seeds compared to reference seeds. The bacterial species in the dust causing ODTS included pathogenic species such as Klebsiella pneumonia and Streptomyces pneumonia, and it contained increased concentrations of total protein, serine protease, chitinase, and β-glucosidase. Twenty-three bacterial genera covered more than 50% of the total reads in the personal and problematic seed dust. These 23 genera accounted for less than 7% of the total reads in the reference seed dust. The microbial community of the dust from the problematic seeds showed great similarities to that from the personal air samples from the workers. In conclusion, we have shown for the first time a shift in the microbial community in aerosol samples that caused ODTS compared to the reference samples that did not cause the ODTS. Furthermore, elevated enzyme activities were found in the dust causing ODTS.

Characterisation of Arctic Bacterial Communities in the Air above Svalbard

“…Bacteria found in the atmosphere are diverse. Airborne bacterial assemblages in both terrestrial and marine environments contain more than 150 genera of bacteria [21,22,23], a level of diversity comparable to other nutrient poor environments such as Antarctic snow, which has been shown to contain in the region of 250 genera of bacteria [24]. Barberán et al [25] collated over 1000 sampling efforts and found more than 110,000 different species of airborne bacteria in the USA alone.…”

“…Barberán et al [25] collated over 1000 sampling efforts and found more than 110,000 different species of airborne bacteria in the USA alone. Most bacterial communities in the atmosphere comprise four main phyla: Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria, a fact that remains consistent in the atmosphere surrounding both marine and terrestrial habitats [23,26]. However, aerial microbial diversity at genus level is more variable and depends on environmental conditions, such as proximity to agricultural sites, meteorological conditions and season [18,22].…”

Occupational Exposure to Bioaerosols in Norwegian Crab Processing Plants

“…A previous study found that there is trypsin and trypsin-like enzyme activity in extracted tissue samples from crustaceans (Sun and Lopata 2010), but there are no previous publications that have quantified the level of airborne trypsin activity during seafood processing. Trypsin is a common serine protease enzyme and inhaled by workers may have an immunological or non-immunological effect on the lungs (Sun and Lopata 2010;Baur 2005;Florsheim et al 2015;Madsen et al 2015). Optimal conditions for several crustacean trypsins are around 40˚C and pH6, which is close to the physiological conditions found in human lungs (Sun and Lopata 2010).…”

“…Endotoxin levels of 1350 EU/m 3 have been reported in herring industry (Bang et al 2005). Endotoxins are suggested to be a cause of occupational respiratory symptoms in occupational settings including among seafood processing workers (Sigsgaard and Schlunssen 2004;Sherson, Hansen, and Sigsgaard 1989;Madsen et al 2015).…”

“…There is a growing body of literature (Muzzarelli 2010) suggesting that NAGase may have a negative impact on health by eliciting an immunological response (Allermann, Wilkins, and Madsen 2006). Exposure to enzymes in occupational settings has been linked to sensitisation and asthma (Green and Beezhold 2011) as well as ODTS (Madsen et al 2015).…”