Fungi in Indoor Environments

A special issue of Journal of Fungi (ISSN 2309-608X). This special issue belongs to the section "Environmental and Ecological Interactions of Fungi".

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 16566

Special Issue Editors


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Guest Editor
Department of Food and Indoor Mycology, Westerdijk Fungal Biodiversity Centre, Utrecht, The Netherlands
Interests: indoor mycology; food mycology

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Guest Editor
Department of Biology, Hong Kong Baptist University, Hong Kong
Interests: indoor mycology; aeromicrobiology; urban microbiology

Special Issue Information

Dear Colleagues,

Filamentous fungi, also known as molds, occur in many indoor environments. Water is an absolute requirement for fungal growth. The indoor environment is highly complex and dynamic in this respect. This is caused by varying occupants’ activities, such as showering and cooking. Further, the use of air diffusers, window gaps, air-conditioners, etc. introduce variations in air movement and humidity. Different types of furnished surfaces (e.g., glass, non-treated wood boards, porous gypsum materials) behave differently in their moisture content and water activity, which create micro-environments for fungal development.

In addition, changes in temperature and nutrient availability (which is often scarce) also occur. In laboratory studies, growth conditions are often static in time and include optimal nutrient conditions—this is very different from the conditions that prevail in indoor situations.

Indoor mycology includes the study of the different fungi which are well-adapted to the indoor environment. The topics of interest to this Special Issue include (but are not limited to): 1) adaptation of fungi to indoor conditions; e.g., growth during changes in humidity and survival under more stressful conditions; 2) taxonomy of indoor fungi; 3) (volatile) secondary metabolites including mycotoxins; 4) fungal growth after climate events (tsunamis, hurricanes, and floods); and 5) allergy or other health concerns. We also invite researchers to submit research papers related to topics including physiological, genetic, or molecular mechanisms in the survival of indoor fungi. The aim of this Special Issue is to advance both fundamental and applied research in the field of indoor fungi.

Dr. Jan Dijksterhuis
Dr. Haoxiang Wu
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • indoor fungi
  • buildings
  • fungal responses
  • taxonomy
  • health concerns
  • genetics
  • molecular mechanisms

Published Papers (6 papers)

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Research

9 pages, 664 KiB  
Article
Temperature versus Relative Humidity: Which Is More Important for Indoor Mold Prevention?
by Haoxiang Wu and Jonathan Woon Chung Wong
J. Fungi 2022, 8(7), 696; https://doi.org/10.3390/jof8070696 - 30 Jun 2022
Cited by 6 | Viewed by 2542
Abstract
Temperature is known as one of the abiotic factors that can affect mold growth. Many mold growth prediction models consider temperature as one of the parameters that can significantly impact mold growth indoors, and hence temperature has been targeted by different indoor mold [...] Read more.
Temperature is known as one of the abiotic factors that can affect mold growth. Many mold growth prediction models consider temperature as one of the parameters that can significantly impact mold growth indoors, and hence temperature has been targeted by different indoor mold prevention strategies on different premises. For example, European guidelines for libraries suggest a temperature of 19 °C to preserve books. However, running low temperature air-conditioning (AC) costs substantially more energy, and thus a higher temperature (e.g., 25.5 °C) has been regularly proposed as the recommended indoor temperature for general indoor environments in Hong Kong. It is, therefore, needed to understand whether or not the reduction of indoor temperature would lead to better effectiveness of mold prevention. Using Cladosporium cladosporioides (C. cladosporioides) as the model, its germinating spores were challenged in C. cladosporioides to wet-dry cycles with different combinations of relative humidity (RH, 40%, 60% and 80%) and temperature (19 °C and 28 °C) levels. The survival, lipid peroxidation and catalase (CAT) activity of the treated spores were monitored and compared. C. cladosporioides spores showed similar levels of viability, lipid peroxidation and CAT activity when they were exposed to 19 °C and 28 °C at the same RH, but substantially lower survival and higher oxidative stress were observed under the wet-dry cycles with 40% RH dry periods compared with 60% and 80% RH at both temperatures, suggesting that indoor temperature does not tend to affect the resistance of C. cladosporioides to wet-dry cycles as significantly as the RH level of the dry period. Collectively, this study suggests a more important role for moisture over temperature in indoor mold prevention. The outcome of this study may facilitate the sustainable management of indoor mold problems in buildings. Full article
(This article belongs to the Special Issue Fungi in Indoor Environments)
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6 pages, 917 KiB  
Communication
Air Sampling for Fungus around Hospitalized Patients with Coronavirus Disease 2019
by Yi-Chun Chen, Yin-Shiou Lin, Shu-Fang Kuo and Chen-Hsiang Lee
J. Fungi 2022, 8(7), 692; https://doi.org/10.3390/jof8070692 - 30 Jun 2022
Cited by 1 | Viewed by 1841
Abstract
The risk of developing coronavirus disease 2019 (COVID-19)-associated pulmonary aspergillosis (CAPA) depends on factors related to the host, virus, and treatment. However, many hospitals have modified their existing rooms and adjusted airflow to protect healthcare workers from aerosolization, which may increase the risk [...] Read more.
The risk of developing coronavirus disease 2019 (COVID-19)-associated pulmonary aspergillosis (CAPA) depends on factors related to the host, virus, and treatment. However, many hospitals have modified their existing rooms and adjusted airflow to protect healthcare workers from aerosolization, which may increase the risk of Aspergillus exposure. This study aimed to quantitatively investigate airborne fungal levels in negative and slightly negative pressure rooms for COVID-19 patients. The air in neutral pressure rooms in ordinary wards and a liver intensive care unit with high-efficiency particulate air filter was also assessed for comparison. We found the highest airborne fungal burden in recently renovated slightly negative air pressure rooms, and a higher airborne fungal concentration in both areas used to treat COVID-19 patients. The result provided evidence of the potential environmental risk of CAPA by quantitative microbiologic air sampling, which was scarcely addressed in the literature. Enhancing environmental infection control measures to minimize exposure to fungal spores should be considered. However, the clinical implications of a periodic basis to determine indoor airborne fungal levels and further air sterilization in these areas remain to be defined. Full article
(This article belongs to the Special Issue Fungi in Indoor Environments)
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16 pages, 4064 KiB  
Article
Diversity and Metabolic Activity of Fungi Causing Biodeterioration of Canvas Paintings
by Cristina Lorena Văcar, Cristina Mircea, Marcel Pârvu and Dorina Podar
J. Fungi 2022, 8(6), 589; https://doi.org/10.3390/jof8060589 - 30 May 2022
Cited by 8 | Viewed by 2894
Abstract
Research into the biodeteriorative potential of fungi can serve as an indicator of the condition of heritage items. Biodeterioration of canvas paintings as a result of fungal metabolic activity is understudied with respect to both the species diversity and mechanisms involved. This study [...] Read more.
Research into the biodeteriorative potential of fungi can serve as an indicator of the condition of heritage items. Biodeterioration of canvas paintings as a result of fungal metabolic activity is understudied with respect to both the species diversity and mechanisms involved. This study brings new evidence for the physiology of fungi biodeteriorative capacity of canvas paintings. Twenty-one fungal isolates were recovered from four oil paintings (The Art Museum, Cluj-Napoca) and one gouache painting (private collection), dating from the 18th to 20th centuries. The species, identified based on the molecular markers Internal Transcribed Spacer (ITS), beta-tubulin (tub2), or translation elongation factor 1 (TEF-1), are common colonisers of canvas paintings or indoor environments (e.g., Penicillium spp., Aspergillus spp., Alternaria spp.). Fungi enzymatic profiles were investigated by means of hydrolysable substrates, included in culture media or in test strips, containing components commonly used in canvas paintings. The pigment solubilisation capacity was assessed in culture media for the primary pigments and studied in relation to the organic acid secretion. Caseinases, amylases, gelatinases, acid phosphatase, N-acetyl-β-glucosaminidase, naphthol-AS-BI-phosphohydrolase, and β-glucosidase were found to be the enzymes most likely involved in the processes of substrate colonisation and breakdown of its components. Aureobasidium genus was found to hold the strongest biodeteriorative potential, followed by Cladosporium, Penicillium, Trichoderma, and Aspergillus. Blue pigment solubilisation was detected, occurring as a result of organic acids secretion. Distinct clusters were delineated considering the metabolic activities detected, indicating that fungi specialise in utilisation of certain types of substrates. It was found that both aged and modern artworks are at risk of fungal biodeterioration, due to the enzymatic activities’ diversity and intensity, pigment solubilisation capacity or pigment secretion. Full article
(This article belongs to the Special Issue Fungi in Indoor Environments)
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24 pages, 4210 KiB  
Article
Environmental Factors Affecting Diversity, Structure, and Temporal Variation of Airborne Fungal Communities in a Research and Teaching Building of Tianjin University, China
by Yixuan Lu, Xiao Wang, Lucineidy C. S. de S. Almeida and Lorenzo Pecoraro
J. Fungi 2022, 8(5), 431; https://doi.org/10.3390/jof8050431 - 22 Apr 2022
Cited by 16 | Viewed by 2930
Abstract
Airborne fungi are widely distributed in the environment and may have adverse effects on human health. A 12-month survey on the diversity and concentration of culturable airborne fungi was carried out in a research and teaching building of Tianjin University. Indoor and outdoor [...] Read more.
Airborne fungi are widely distributed in the environment and may have adverse effects on human health. A 12-month survey on the diversity and concentration of culturable airborne fungi was carried out in a research and teaching building of Tianjin University. Indoor and outdoor environments were analyzed using an HAS-100B air sampler. A total of 667 fungal strains, belonging to 160 species and 73 genera were isolated and identified based on morphological and molecular analysis. The most abundant fungal genera were Alternaria (38.57%), Cladosporium (21.49%), and Aspergillus (5.34%), while the most frequently appearing species was A. alternata (21%), followed by A. tenuissima (12.4%), and C. cladosporioides (9.3%). The concentration of fungi in different environments ranged from 0 to 150 CFU/m3 and was significantly higher outdoor than indoor. Temperature and sampling month were significant factors influencing the whole building fungal community, while relative humidity and wind speed were highly correlated with fungal composition outdoor. Variations in the relative abundance of major airborne fungal taxa at different heights above-ground could lead to different community structures at different floors. Our results may provide valuable information for air quality monitoring and microbial pollution control in university building environments. Full article
(This article belongs to the Special Issue Fungi in Indoor Environments)
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15 pages, 1710 KiB  
Article
Il Silenzio: The First Renaissance Oil Painting on Canvas from the Uffizi Museum Restored with a Safe, Green Antimicrobial Emulsion Based on Citrus aurantium var. amara Hydrolate and Cinnamomum zeylanicum Essential Oil
by Debora Minotti, Lara Vergari, Maria Rita Proto, Lorenzo Barbanti, Stefania Garzoli, Francesca Bugli, Maurizio Sanguinetti, Luigia Sabatini, Alice Peduzzi, Roberto Rosato, Maria Grazia Bellardi, Paola Mattarelli, Daphne De Luca and Maura Di Vito
J. Fungi 2022, 8(2), 140; https://doi.org/10.3390/jof8020140 - 29 Jan 2022
Cited by 4 | Viewed by 3311
Abstract
Preserving artworks from the attacks of biodeteriogens is a primary duty of humanity. Nowadays, restorers use chemicals potentially dangerous for both artworks and human health. The purpose of this work was to find a green and safe formulation based on natural substances with [...] Read more.
Preserving artworks from the attacks of biodeteriogens is a primary duty of humanity. Nowadays, restorers use chemicals potentially dangerous for both artworks and human health. The purpose of this work was to find a green and safe formulation based on natural substances with fungicidal activity to restore ancient oil paintings, particularly “Il Silenzio” (by Jacopo Zucchi) preserved at the Uffizi Museum in Florence, Italy. The study was divided into two phases. First phase (in vitro study): three essential oils (EOs) and four hydrolates (Hys) were analysed by GC-mass spectrometry and in vitro tested against six ATCC strains of molds. An emulsion based on the more active natural compounds was tested on aged and unaged canvases samples to evaluate both their fungicidal activity and the impact on chemical-physical parameters. Finally, an in vivo toxicity test performed on the Galleria mellonella model assessed the safety for health. Second phase (in situ application): the emulsion was sprayed on the back of the painting and left to act for 24 h. Biodeteriogens present on the “Il Silenzio” painting were microbiologically identified before and after the treatment. The emulsion formulated with C. zeylanicum EO and C. aurantium var. amara Hy showed the best antifungal activity both in vitro and in situ without altering the chemical-physical characteristics of paintings. Furthermore, no in vivo toxicity was shown. For the first time, a green antimicrobial emulsion based on Hy and EO, safe for operators, was used to decontaminate an artwork colonised by fungi before the restoration practices. Full article
(This article belongs to the Special Issue Fungi in Indoor Environments)
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13 pages, 591 KiB  
Article
Cytotoxicity of Aspergillus Section Fumigati Isolated from Health Care Environments
by Carla Viegas, Magdalena Twarużek, Beatriz Almeida, Marta Dias, Edna Ribeiro, Elisabete Carolino, Ewelina Soszczyńska and Liliana Aranha Caetano
J. Fungi 2021, 7(10), 839; https://doi.org/10.3390/jof7100839 - 7 Oct 2021
Cited by 4 | Viewed by 1745
Abstract
This study analyzed 57 Aspergillus section Fumigati (AF) isolates collected by active and passive sampling (N = 450) in several health care facilities and from biological sampling of health care workers (N = 25) and controls (N = 22) in Portugal. All isolates [...] Read more.
This study analyzed 57 Aspergillus section Fumigati (AF) isolates collected by active and passive sampling (N = 450) in several health care facilities and from biological sampling of health care workers (N = 25) and controls (N = 22) in Portugal. All isolates were cultured in different media and screened for azole resistance. Cytotoxicity was assessed for 40 isolates in lung epithelial cells and kidney cells using the MTT assay. Aspergillus section Fumigati was prevalent in the health care facilities and in nasal swabs from health care workers and controls. All AF isolates reduced cell viability and presented medium to high cytotoxicity, with cytotoxicity being significantly higher in A549 lung epithelial cells. The cytotoxicity of isolates from air and nasal swab samples suggested the inhalation route as a risk factor. Notably, 42% of AF isolates exhibited a pattern of reduced susceptibility to some of the most used antifungals available for the treatment of patients infected with these fungi. In sum, the epidemiology and clinical relevance of Aspergillus section Fumigati should continue to be addressed. A deeper understanding of the mechanisms underlying Aspergillus-mediated cytotoxicity is necessary. Full article
(This article belongs to the Special Issue Fungi in Indoor Environments)
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