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

Abstract

Aerosolization of fungal spores from moldy surfaces can cause adverse health effects. The spores of an older colony are more easily detached than those of a younger colony. When the growth age of a colony is known, the aerosolization of spores can be more accurately predicted. This study proposed the adoption of respiratory intensity as an indicator of the growth age of Aspergillus niger colonies. Respiratory intensity is the mass of carbon dioxide produced by the respiration of a colony per unit quantity of spores within a certain time. Two types of colonies, with homogeneous and heterogeneous age distributions, were aerosolized in a wind tunnel to determine the spore release proportion and validate the method. The results revealed that the respiratory intensity of the homogeneous colony is closely correlated with the growth age when the age of the colony is less than 14 days under standard growth conditions. The spore release proportion increases with the growth age and the blowing speed. The predicted spore release proportion for a heterogeneous colony is more precise when the colony is divided into multiple sub-colonies to characterize the growth age for each individual spore release proportion. The relative errors of the predicted spore release proportions as compared with the test values were less than 10%.

Aspergillus niger causing fruit rot disease on rose apple in Malaysia

“…Plates were incubated at 25°C for seven days and colonies grew that initially appeared white, then turned dark green (Figure 2). Based on the morphological characteristics, particularly the range of conidia sizes (3.0 to 5.4 μm), shape (ellipsoidal) and the colour, the fungus was identified as Aspergillus niger (Silva et al., 2011; Li et al., 2020). For molecular confirmation, the internal transcribed spacer (ITS) region was amplified using ITS1 and ITS4 primers (Santos et al., 2016).…”