On distinguishing the natural and human-induced sources of airborne pathogenic viable bioaerosols: characteristic assessment using advanced molecular analysis

Ambient air consists of bioaerosols that constitute many microbes from biosphere due to natural and anthropogenic activities. Size-dependent ambient measurements of bioaerosols at two seminatural and three anthropogenic coastal sites in southern tropical India were taken during the summer 2017. All the five sites considered in this study considerably contributed to the bioaerosol burden with larger contribution from the dumping yard site followed by the marshland site, wastewater treatment plant, composting site, and Indian Institute of Technology Madras. The colony-forming units concentration for all the sites ranged from 17 to 2750 m−3 for bacteria and 42–2673 m−3 for fungi. Firmicutes and Actinomycetes were the dominant phyla observed in 698 bacterial OTUs obtained, and Ascomycota and Zygomycota were the dominant phyla observed in 159 fungal OTUs obtained in the study. Further, the study revealed the presence of pathogenic and ice-nucleating bacteria and fungi in the bioaerosols that can largely affect the well-being of the human population and vegetation in this region. Moreover, the statistical analysis revealed high bacterial abundance and diversity at the grit chamber of wastewater treatment plant and high fungal abundance and diversity at the dumping yard. Further, principal coordinate analysis of the sites studied inferred that the marshland, wastewater treatment plant, and the dumping yard sites shared similar microbial community composition indicating the existence of similar source materials and activities at the sites. Further, this study evidently brings out the fact that urban locations may play an important role in anthropogenic contribution of both pathogenic and ice-nucleating microorganisms. © 2020, Springer Nature Switzerland AG

Terrestrial macrofungal diversity from the tropical dry evergreen biome of southern India and its potential role in aerobiology - PONE - D -16- 26852 - Additional DATA files

Additional files for the paper, "Terrestrial macrofungal diversity from the tropical dry evergreen biome of southern India and its potential role in aerobiology"are provided here. This mutiple data file set includes the following,<div>1. Gallery of macrofungi/mushroom images </div><div>2. Study area map</div><div>3. Spore dispersal calculations for continuous spore release</div><div>4. Macrofungi found on other tropical dry evergreen biome in the world</div><div>5. Bootstrap simulations</div><div>6. List of species and abundance</div><div>7. Additional information on species</div><div>8. Aerobiology associated calculations</div><div>9. Terminal velocity of fungal spores calcualtions</div><div>10. List of ground dwelling and tree dwelling macrofungi species.</div><div><br></div

Terrestrial Macrofungal Diversity from the Tropical Dry Evergreen Biome of Southern India and Its Potential Role in Aerobiology.

Macrofungi have long been investigated for various scientific purposes including their food and medicinal characteristics. Their role in aerobiology as a fraction of the primary biological aerosol particles (PBAPs), however, has been poorly studied. In this study, we present a source of macrofungi with two different but interdependent objectives: (i) to characterize the macrofungi from a tropical dry evergreen biome in southern India using advanced molecular techniques to enrich the database from this region, and (ii) to assess whether identified species of macrofungi are a potential source of atmospheric PBAPs. From the DNA analysis, we report the diversity of the terrestrial macrofungi from a tropical dry evergreen biome robustly supported by the statistical analyses for diversity conclusions. A total of 113 macrofungal species belonging to 54 genera and 23 families were recorded, with Basidiomycota and Ascomycota constituting 96% and 4% of the species, respectively. The highest species richness was found in the family Agaricaceae (25.3%) followed by Polyporaceae (15.3%) and Marasmiaceae (10.8%). The difference in the distribution of commonly observed macrofungal families over this location was compared with other locations in India (Karnataka, Kerala, Maharashtra, and West Bengal) using two statistical tests. The distributions of the terrestrial macrofungi were distinctly different in each ecosystem. We further attempted to demonstrate the potential role of terrestrial macrofungi as a source of PBAPs in ambient air. In our opinion, the findings from this ecosystem of India will enhance our understanding of the distribution, diversity, ecology, and biological prospects of terrestrial macrofungi as well as their potential to contribute to airborne fungal aerosols

Source vs. Ambient spore morphological similarities.

<p>Panel of figures (Sa–Sc) at the top show manually extracted fungal spores identified to the species level. Panel of figures (Aa–Ac) at the bottom show the fungal spores collected from the ambient air on a polycarbonate filter paper as reported by Valsan et al., 2015 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169333#pone.0169333.ref041" target="_blank">41</a>]. It is to be noted that the ambient fungal spores reported and depicted here were mainly observed during the NE monsoon season, the season with the fungal bloom. Both of the studies are from the same study region, IIT Madras and from same season of October–January (monsoon and winter in southern India, Chennai). Kindly refer Valsan et al., 2015 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0169333#pone.0169333.ref041" target="_blank">41</a>] for further details regarding the bioaerosols SEM study.</p

Incidence (%) of macrofungal species incidence during the sampling period (Oct–Feb 2015) comprising the winter season with rainfall (Oct–Jan 2015) and summer (Feb 2015).

<p>Macrofungal incidence is correlated with cumulative rainfall (mm) that occurred, % relative humidity (RH) and the temperature (°C). Incidence of macrofungi was found to be the maximum during November; the rainfall of October and highest % RH (80%) seemed conducive for the increased incidence of macrofungi during November. Again the rainfall during December further supported its growth and persistence throughout the months December and January. The decrease in the macrofungi incidence from December to February can be associated with the decrease in rainfall and increase in temperature.</p

Diversity indices calculated for the ground-dwelling and tree-dwelling macrofungi.

<p>Tree-dwelling species were found to be more diverse and even in both the categories of ‘observed’ and ‘simulated/resampled (res)’ data.</p

% Species richness and relative abundance of various families over this study region calculated on the basis of the Berger-Parker dominance index.

<p>The dominance index was calculated for two categories: (i) for the samples observed (exact observations, n_obs)–‘d_obs’ and (ii) for the observations simulated 50 times incorporating the bootstrapping technique (resampled simulations, n_res)–‘d_res’. Based on this index, the observed families were classified into three major categories: (i) dominant (D), (ii) general (G), and (iii) rare (R). The dominant, general and rare species differed significantly for the observed species, whereas all of the simulated observations of the macrofungal species were general in the study region. Please refer to the main text for more details related to the methodology of obtaining the relative dominance index.</p

Conceptual spore movement framework in the study region.

<p>Macrofungi source is at a height of 10m from the ground. Spore release and dispersal viewed at a height (z) of 10 m, downwind distance (x) of 10–100 m and at a crosswind distance (y) of 10 to 100 m (crosswind not depicted). Spores released through convective currents had an U_g of 0.06 m/s and the wind velocity that existed (ambient) was U = 1.79 m/s. Spores released from the macrofungi can act as a potential bioaerosol as proven by GPM. DNA analysis of PM₁₀ measurements done during the same period (not a part of this study), confirmed the presence of <i>Agaricaceae</i> and <i>Polyporaceae</i> found at the source.</p

Fungal spore presence and the concentration distribution predicted at a height of 10m from the source using the Gaussian plume model.

<p>Spore concentrations were highest near the source. Gradients are also large near the source but gradually become less steep with the increasing downwind distance (x, m). Color shading indicates the spores/m3 of air for a stability class A. Release (C_initial) was 540 × 10⁴ spores/m²/s and the ambient wind speed was 1.79 m/s; Presence of spores could also be seen at a location of (100, 100, 10) m from the source.</p