Measurement of dead fungal counts on window frames via real-time PCR

In winter, condensation often causes fungal contamination on glazing beads inside the lower frames of windows. In this study, live and dead fungi present on 12 windows were examined during different seasons. Cladosporium halotolerans was predominantly detected, followed by Aureobasidium pullulans, both of which are common dark fungi. The total fungal including both live and dead fungi was quantified by real-time PCR. A significant correlation was noted between the counts of live and total fungi on different beads. The average live fungal count on beads sharply decreased under severe conditions, such as exposure to drought and heat, from February-October. Comparatively, the number of dead fungi gradually decreased as fragments remained attached to beads. Notably, dead cell counts were higher than those of live cells, with dead fungi contributing to dirt more than live fungi did. Therefore, common fungicidal treatment is ineffective for cleaning beads. The degree of dirt on beads likely depends on the melanin levels in dead fungal cells (predominantly C. halotolerans). Despite the dead cell counts of C. halotolerans decreasing to one-quarter of the initial values from winter to autumn, dirt levels on beads remained unchanged.