Passive Release of Fungal Spores from Synthetic Solid Waste Surfaces

Abstract

Passive release of fungal spores can occur from various natural and anthropogenic sources leading to significant concentrations in ambient air with potential effect on health and climate. The estimation of fungal spore release is a critical parameter necessary for the realistic assessment of health risk using dispersion models and in global climate modeling. This paper presents results from experiments conducted to seek a better understanding of the process of passive fungal spore due to wind. Laboratory studies were conducted to measure emission fluxes of a test fungal species (Penicillium chrysogenum) grown on two test surfaces (aluminum foil and cardboard) in a flux chamber in response to air flow. Spore growth on the aluminum foil correlated with the amount of nutrient, while for cardboard, fungal growth was observed just with the presence of water without any external nutrients. The released spores were collected using a commercially available impinger (Biosampler ® ) and quantified using fluorescence microscopy. Spore flux correlated positively with the number of spores on the surface and with air velocity above a threshold velocity. Fungal spore flux decreased on continuous exposure to air. Microscopic inspection of the surface revealed that the normally upright hyphae bearing the fungal spores collapsed after exposure to air thus suggesting that the decrease in flux was due to a decrease in the aerodynamic drag on the spores. Fungal hyphae also collapsed when there was depletion of nutrients for spore growth leading to reduction in flux. A preliminary mathematical model that estimates spore flux based on the energy transfer between the air and the fungal spores and the energy required to remove the spores is presented. A characteristic energy parameter for aerosolisation was obtained from the model fit. Using this parameter, the model predicted experimental fluxes under various conditions reasonably well.

Seasonal variation of the dominant allergenic fungal aerosols – One year study from southern Indian region

“…cladosporioides ) with the two dry air spora, however the correlation values obtained were relatively lower compared to the wind speed. This reveals that high wind speed >8 ms −1 may inhibit the fungal spore release from conidia 40 , 42 . A .…”

“…The ascus is said to rupture when the water content inside it increases by water absorption from the atmospheric moisture (humidity) and when the water content decreases due to the evaporation from the ascus (at high atmospheric temperature) 41 . On the other hand, when the spores get dislodged from the conidiophore due to the external disturbances caused by air currents or by insect landing on the fungi, then such a release mechanism is termed as a ‘passive’ release 39 , 42 . Thus, higher temperature (>30 °C) and lower relative humidity (<70%) are primarily responsible for the active release 34 , 43 whereas higher wind speed plays an important role in passive release of the spores 34 , 44 .…”

Prediction of Aerosolized Fungal Spores by Determining Respiratory Intensity of the Growing Colony

“…The spore release rate from colonies was found to increase with the blowing air speed. Previous studies found that gusty airflow with high turbulence intensity could enhance spore aerosolization (Gopalakrishnan et al, 2016).…”

“…When a fungal colony develops on a moldy surface, fungal propagules may be released from the surface into the indoor air (Gopalakrishnan et al, 2016). Fungal spores can easily be detached from the colonies by disturbance and then dispersed into the air (Frankel et al, 2014;Piekarska et al, 2018).…”

Fungal Spore Aerosolization at Different Positions of a Growing Colony Blown by Airflow

“…After a period of vegetative growth, the foot cells grow into air and form aerial hyphae. The aerial hyphae can differentiate into conidiophores, which give rise to a large number of spores (Wang et al, 2020;Gopalakrishnan et al, 2016). Previous studies have showed that significant amounts of visible molds were found in ceiling tiles and wallpapers (Nielsen, 2003).…”