Comparison of methods for assessing temporal variation of growth of fungi on building materials

Abstract

Fungal growth on indoor surfaces can decay building materials and release hazardous substances that affect indoor air quality. Despite the numerous methods available for growth determination, there is no commonly accepted standard. The goal of this study was to compare five different assay methods for the measurement of fungal growth: cultivation, MS-based determination of ergosterol, beta-N-acetylhexosaminidase activity, quantitative PCR and microscopic spore counting. Three fungal species (Aspergillus puulaauensis, Cladosporium montecillanum and Penicillium polonicum) were grown on three different building materials (two types of acoustic board and wood). Fungal load was determined at different time points. Results from all of the methods, except the spore count, showed good correlation between each other (r=0.6-0.8). Results obtained with the cultivation method had the highest variability among replicate samples (65 %), making it the least reproducible in repeated measurements. However, it also displayed the highest variability in incubation times (149 %), indicating its suitability for detecting transient changes in the physiological state of cells. Similar to the cultivation method, quantitative PCR correlated well with the other methods and had high variability in incubation times but had lower variability among replicate samples. Ergosterol and beta-N-acetylhexosaminidase enzyme activity seemed to be the methods least dependent on the physiological state of the cells. Varying growth dynamics were observed for different species over time with the different assay methods. Each one of the tests provides a different perspective on fungal quantification due to its specific responses to the various stages of fungal growth.

Bioburden Assessment by Passive Methods on a Clinical Pathology Service in One Central Hospital from Lisbon: What Can it Tell Us Regarding Patients and Staff Exposure?

“…As such, the assessment and control of microbial contamination in health care facilities is currently a mandatory and vital part of the strategies to prevent and control hospital-acquired infections [7,8]. Aiming at addressing this challenging assessment, several studies have already reported the upmost importance of applying passive sampling methods [9][10][11][12][13]. These methods allow characterization of the contamination from a larger period of time (weeks to several months) [14].…”

Análisis sobre el crecimiento de hongos en diferentes revestimientos aplicados a sistemas ligeros

“…Shirakawa et al (2002) noticed fungal growth on the interface between layers of paint and on the interface between paint and substrate. Mensah-Attipoe et al (2016) stress that the fungal grown visible on construction materials is caused by prolonged moisture on their surfaces and that the increase of fungal biomass brings about the difference of antifungal resistance. Johansson, Svensson and Ekstrand-Tobin (2013) concluded that fungal growth is induced when the combination of temperature and humidity exceeds the growth limit curves calculated.…”

“…According to the authors, these results can be explained by two reasons: either the paints had extents of inefficient biocides or the fungi acquired resistance to these agents. Mensah-Attipoe et al (2016) noticed that Aspergillus fungus are more sensitive to variations of humidity than those species of Cladosporium and Penicillium. Still regarding genus Aspergillus, these authors noted that from day 0 to week 1 there was a significant reduction in colony forming units followed by a significant increase until week 4.…”

Evaluation of different hurdles on Penicillium crustosum growth in sponge cakes by means of a specific real time PCR

“…However, since early detection of fungal growth is relevant to food safety especially when spoilage fungi produce mycotoxins, the use of more sensitive methods of detection is needed. The measurement of biochemical markers such as ergosterol (Taniwaki et al 2006;Mensah-Attipoe et al 2016) could be an option. However, this is a time consuming and laborious method which lacks of specificity, since it could not distinguish between different fungal species in a mixed culture (Arquiza and Hunter 2014).…”