Date Published: April 9, 2019
Publisher: Public Library of Science
Author(s): Zbigniew Suchorab, Magdalena Frąc, Łukasz Guz, Karolina Oszust, Grzegorz Łagód, Agata Gryta, Nina Bilińska-Wielgus, Jacek Czerwiński, Petr Karlovsky.
The aim of the study was to develop a method for early detection and identification of fungal contamination of building materials using an electronic nose. Therefore, the laboratory experiments based on the analysis of the air in the vicinity of fungal isolates potentially found in the building materials were performed. The results revealed that the employed gas sensors array consisting of MOS-type sensors enables the detection of the differences among the examined samples of fungi and distinguishing between the non-contaminated and contaminated samples, shortly after fungal contamination occurs. Electronic nose readouts were analysed using Principal Component Analysis and the results were verified with standard chromatographic analysis by means of SPME-GC/MS method, which proved that gas sensors array can be applied for early detection of fungal contamination.
Microorganisms inhabit different types of biological niches on the Earth, due to their adaptability to varying environmental conditions. It is well-known that microorganisms cause deterioration of various materials. Microscopic fungi induce biological corrosion of construction materials, as well as rotting of food. Fungal metabolic products can be detrimental to the human health due to their toxicity. Therefore, a quick preliminary assessment of the occurrence of fungi in buildings is recommended and vital for maintaining healthy population, as well as high quality of building materials and indoor air .
Experiments involved performing the analysis of the air in the vicinity of fungi potentially found in the human environment as moulds in the residential buildings. The study included testing of 10 fungal strains isolated from contaminated building materials belong to the following genera: Penicillium sp. (G5/15, G6/15, G11/15, G13/15a, G14/15), Aspergillus (G8/15, G9/15), Acremonium sp. (G7/15), Paecilomyces sp. (G10/15), Cladosporium sp. (G13/15). The fungal isolates used in the study were selected based on their dominance in tested buildings materials. Representatives of Penicillium and Aspergillus were dominant in fungal community, whereas Acremonium, Paecilomyces and Cladosporium were represented only by single isolates.
The conducted research is divided into the following stages: (i) differentiation between contaminated and non-contaminated samples, (ii) identification of individual genera of fungi, (iii) chromatographic analyses of fungal metabolites.
In the traditional approach, the degree of fungal contamination in buildings is expressed as the amount of spores in the air, settling dust, surface or samples collected from construction materials. Therefore, the use of traditional mycological methods is time-consuming and long-lasting. Although many highly-sensitive and precise molecular and immunological methods were developed to fast detection and identification of fungi in the last decade, they are still very expensive and require adequate laboratories, equipment and experienced staff . As a viable alternative, one may employ the method consisting in measuring the concentration of fungal metabolic products in the indoor air, including MVOCs .
According to the research on the air analysis performed by means of MOS-type sensors array on the headspace of building materials contaminated and non-contaminated by fungal isolates, following conclusions may be formulated: