Analysis of culturable airborne fungi in outdoor environments in Tianjin, China

A review of pathogenic airborne fungi and bacteria: unveiling occurrence, sources, and profound human health implication

Airborne fungi and bacteria have been extensively studied by researchers due to their significant effects on human health. We provided an overview of the distribution and sources of airborne pathogenic microbes, and a detailed description of the detrimental effects that these microorganisms cause to human health in both outdoor and indoor environments. By analyzing the large body of literature published in this field, we offered valuable insights into how airborne microbes influence our well-being. The findings highlight the harmful consequences associated with the exposure to airborne fungi and bacteria in a variety of natural and human-mediated environments. Certain demographic groups, including children and the elderly, immunocompromised individuals, and various categories of workers are particularly exposed and vulnerable to the detrimental effect on health of air microbial pollution. A number of studies performed up to date consistently identified Alternaria, Cladosporium, Penicillium, Aspergillus, and Fusarium as the predominant fungal genera in various indoor and outdoor environments. Among bacteria, Bacillus, Streptococcus, Micrococcus, Enterococcus, and Pseudomonas emerged as the dominant genera in air samples collected from numerous environments. All these findings contributed to expanding our knowledge on airborne microbe distribution, emphasizing the crucial need for further research and increased public awareness. Collectively, these efforts may play a vital role in safeguarding human health in the face of risks posed by airborne microbial contaminants.

Unmanaged grasslands are a reservoir of Alternaria and other important fungal species with differing emission patterns

Alternaria is a ubiquitous fungal genus with many allergenic and pathogenic species inhabiting grasslands. We hypothesise that grasslands (natural/man-made) host a diversity of fungal species whose spores have varying emission patterns. Therefore, the purpose of this study was to examine the potential of grasslands for emission, diversity and composition of Alternaria and other fungal species. To test the hypothesis, Hirst-type and multi-vial Cyclone samplers collected air samples from two grassland sites (unmanaged and managed) and a non-grassland site at Lakeside campus of the University of Worcester, United Kingdom for the period May to September 2019. The unmanaged grassland was originally planted with grasses and left uncut for three years. The managed grassland was a roadside verge that was cut once every year, typically after most grasses have flowered. We used optical microscopy and Illumina MiSeq sequencing to investigate the emission, abundance, diversity and composition of the fungal spores from each site alongside meteorological variables. Kruskal-Wallis and Wilcoxon tests examined differences in the bi-hourly Alternaria concentrations between the sites. Shannon's and Simpson's Index determined the diversity of the fungal spores between the unmanaged and non-grassland sites. The results showed that grasslands are a strong source of Alternaria spores with considerably higher numbers of clinically important days compared with the non-grassland site. The managed grassland varied in Alternaria spore emission pattern from the unmanaged, probably due to differences in environmental variables and cutting frequency. The unmanaged grassland and non-grassland sites showed a high diversity of fungi including Alternaria, Cladosporium, Ascochyta, Botrytis and Aureobasidium. Overall, the study shows that grasslands are a strong source of fungal spores with allergenic and pathogenic potential and have varying emission patterns, compared with nearby urban areas where monitoring stations are located. This information is useful for atmospheric modelling of airborne fungal spore sources and has implications for allergy sufferers in particular.

Characterization of microbial community assembly in parasitic plant systems and the influence of microorganisms on metabolite accumulation in parasitic plants: case study of Cistanche salsa and Kalidium foliatum

Introduction

Cistanche salsa (C.A.Mey.) G. Beck is a perennial holoparasitic herb recognized for its medicinal properties, particularly in kidney-tonifying and laxative treatments. Despite its therapeutic potential, little is known about the endophyte communities inhabiting C. salsa and its host plants, and how these microorganisms may impact the production and accumulation of metabolites in C. salsa.

Methods

We conducted a dual analysis focusing on metabolomics of wild C. salsa and microbiome characterization of both C. salsa and its host plant, Kalidium foliatum (Pall.) Moq. The metabolomics analysis revealed variations in metabolite composition across different parts of C. salsa. Additionally, the microbiome analysis involved studying endophytic bacteria and fungi, comparing their community structures between parasitic C. salsa and its host plant.

Results

Significant variations in metabolite composition were observed through metabolomic profiling, which identified 93 secondary metabolites and 398 primary metabolites across various parts of C. salsa. Emphasis was placed on differences in metabolite composition within the flowers. Microbiome analysis revealed differential community compositions of endophytic bacteria between the parasitic and host plants, whereas differences in endophytic fungi were less pronounced. Certain endophytes, such as Bacteroidota, Proteobacteria, Ascomycota, and Basidiomycota, were associated with the production of specific secondary metabolites in C. salsa, including the plant-specific compound salsaside.

Discussion

Our findings highlight the intricate relationship between C. salsa and its endophytic microbiota, suggesting a potential role of these microorganisms in modulating the biosynthesis of bioactive compounds. The differential preferences of endophytic bacteria and fungi across various microenvironments within the parasitic plant system underscore the complexity of these interactions. Further elucidation of these dynamics could enhance our understanding of C. salsa's medicinal properties and its ecological adaptations as a holoparasitic herb.

An evaluation of fungal contamination and its relationship with PM levels in public transportation systems

Transmission of fungi in the air and its impact on health are regarded as important public health issues. Bioaerosols play an important role in causing or exacerbating infectious diseases, acute toxic effects, allergies, and cardiopulmonary symptoms. As many people use the public transportation system daily, it is necessary to determine the type and manner of dispersal and abundance of airborne fungi in public transport places. Three public transportation systems including a bus station, a train station, and an airport in Ahvaz city (Iran) were examined. At each of these stations, the air samples were taken from inside and outside the hall stations, and in-vehicle. A bio-stage Anderson sampler was used by suctioning air and passing it over a Petri dish containing culture medium Sabouraud Dextrose Agar (SDA). Relative humidity (RH, %), temperature (T, ◦C), and mass concentration of particulate matter (PM1, PM2.5, and PM10, μg/m3) at the sampling points were measured. The highest concentration of airborne fungi was observed in the airport. The concentration of fungi in the ambient air was higher than that in the indoor air of halls and in-vehicle. In all sampling points, the ambient predominant airborne fungi were Cladosporium and Alternaria, while the indoor predominant airborne fungi were Cladosporium, Aspergillus, and Penicillium. The indoor to outdoor ratio showed that the fungi were of an external origin. Due to the influence of the ambient air on indoor air, it is recommended to use proper ventilation and enhance the hygiene level of vehicles in public transportation systems to reduce exposure to environmentally pathogenic bioaerosols.

The influence of car traffic on airborne fungal diversity in Tianjin, China

Little is known about the effect of car traffic on airborne fungal communities. We investigated the environmental factors affecting the diversity and concentration of airborne fungi at high-traffic density junctions, in Tianjin, China. A total of 244 fungal strains belonging to 78 species and 45 genera of Ascomycota (78.69%) and Basidiomycota (21.31%) were isolated and identified using morphological and molecular analysis. Aspergillus was the species-richest genus, with 9 recorded species, followed by Alternaria and Cladosporium, both with 8 species. Coprinellus radians was the most abundant fungal species, with 31 isolated strains, followed by Alternaria alternata (26 strains), Cladosporium cladosporioides (21), Alternaria compacta (13), and Cladosporium tenuissimum (11). We found a higher diversity and concentration of airborne fungi in the analysed urban air environments when the road traffic was at its highest intensity. Higher level of car traffic resulted in higher concentrations of fungal particles in the air for various taxa, including Alternaria, Aspergillus, and Cladosporium, which are known to cause respiratory allergies and infections. This result suggests that reducing vehicular traffic could be an effective measure to control airborne fungal exposure and microbial pollution.

Prevalence of airborne fungi in Brazil and correlations with respiratory diseases and fungal infections

Airborne fungi are dispersed through the air. The aim of this study was to determine the prevalence of airborne fungi in Brazil and understand the relationship between fungal growth and respiratory diseases and infections. We conducted an integrative literature review of studies conducted in Brazil based on searches of the PubMed, MEDLINE-BIREME, SciELO, and LILACS databases for full-text articles published between 2000 and 2022. The searches returned 147 studies, of which only 25 met the inclusion criteria. The most prevalent genera of airborne fungi in Brazil are Aspergillus, Penicillium, Cladosporium, Curvularia, and Fusarium. The studies were conducted in the states of Maranhão, Ceará, Piauí, Sergipe, Mato Grosso, Pernambuco, Rio Grande do Sul, Santa Catarina, Rio de Janeiro, São Paulo, and Minas Gerais. The findings also show the relationship between fungi and meteorological factors and seasonality, the sensitivity of atopic individuals to fungi, and the main nosocomial mycoses reported in the literature. This work demonstrates the importance of maintaining good microbiological air quality to prevent potential airborne diseases.

Bioaerosol assessment in indoor and outdoor environments: a case study from India

Exposure to bioaerosols has been associated with the occurrence of a variety of health impacts, including infectious illnesses, acute toxic effects, allergies, and cancer. This study aimed at evaluating airborne bacteria and fungi populations at different indoor and outdoor sites on a college campus in Bengaluru, India. Bioaerosol samples were collected using a two-stage Andersen air sampler; and isolates were identified using standard procedures. Six air samples and meteorological data were collected in March and April 2014 to examine the effects of temperature and relative humidity on bioaerosol concentration using linear regression modeling. Among all sites, the canteen showed the highest bioaerosol levels both indoors and outdoors. Specific bacterial identification was not possible, but gram staining and microscopic analysis helped to identify gram positive and gram negative bacteria. The most prevalent fungal species in the samples were Cladosporium, Aspergillus niger, Penicillium, Rhizopus, Fusarium, Mucor, and Alternaria. Due to the impact of weather conditions, such as temperature and relative humidity, the bioaerosol concentration varied greatly at each site according to the regression model. The indoor bioaerosol concentrations at all sites exceeded the values established by the American Industrial Hygiene Association (< 250 CFU/m3 for total fungi and < 500 CFU/m3 for total bacteria). Higher concentrations of bioaerosols may be attributed to the transportation of microbes from the ground surface to suspended particles, the release of microbes from the respiratory tract, higher rate of shredding of human skin cells, and many other factors.

Pathogenicity of Aspergillus Airborne Fungal Species Collected from Indoor and Outdoor Public Areas in Tianjin, China

Airborne fungi play an important role in air pollution and may have various negative effects on human health. In particular, Aspergillus fungi are pathogenic to humans and several domestic animals. In this work, Aspergillus strains isolated from airborne fungal communities sampled from different indoor and outdoor environments in Tianjin University were tested for pathogenicity on Drosophila melanogaster. Airborne fungi were sampled using an HAS-100B air sampler, over a one-year sampling period. Isolated fungal strains were identified based on morphological and molecular analysis. The Aspergillus-centered study was conducted as part of a larger work focusing on the total airborne fungal community in the analyzed environments, which yielded 173 fungal species. In this context, the genus Aspergillus showed the second-highest species richness, with 14 isolated species. Pathogenicity tests performed on male adults of Drosophila melanogaster through a bodily contact bioassay showed that all analyzed airborne Aspergillus species were pathogenic to fruit flies, with high insect mortality rates and shortened lifespan. All the studied fungi induced 100% mortality of fruit flies within 30 culture days, with one exception constituted by A. creber (39 days), while the shortest lifespan (17 days) was observed in fruit flies treated with A. tubingensis. Our results allow us to hypothesize that the studied airborne fungal species may have a pathogenic effect on humans, given the affinity between fruit flies and the human immune system, and may help to explain the health risk linked with Aspergillus fungi exposure in densely populated environments.

Analysis of Airborne Fungal Communities on Pedestrian Bridges in Urban Environments

Airborne fungal spores constitute an important type of bioaerosol and are responsible for a number of negative effects on human health, including respiratory diseases and allergies. We investigated the diversity and concentration of culturable airborne fungi on pedestrian bridges in Tianjin, China, using an HAS-100B air sampler. We compared the airborne fungal communities at the top central area of the selected pedestrian bridges and along the corresponding sidewalk, at ground level. A total of 228 fungal strains belonging to 96 species and 58 genera of Ascomycota (68.86%), Basidiomycota (30.26%), and Mucoromycota (0.88%) were isolated and identified using morphological and molecular analysis. Alternaria was the dominant genus (20.61%), followed by Cladosporium (11.48%), Schizophyllum (6.14%), Sporobolomyces (5.70%), and Sporidiobolus (4.82%). Alternaria alternata was the most frequently occurring fungal species (6.58%), followed by Schizophyllum commune (5.26%), Alternaria sp. (4.82%), Sporobolomyces carnicolor (4.39%), and Cladosporium cladosporioides (3.95%). The recorded fungal concentration ranged from 10 to 180 CFU/m3. Although there was no significant difference in the distribution and abundance of the dominant airborne fungal taxa between the two investigated bridges' sites, numerous species detected with a low percentage of abundance belonging to well-known pathogenic fungal genera, including Alternaria, Aspergillus, Aureobasidium, Cladosporium, Penicillium, and Trichoderma, were exclusively present in one of the two sites. The relative humidity showed a stronger influence compared to the temperature on the diversity and concentration of airborne fungi in the investigated sites. Our results may provide valuable information for air quality monitoring and for assessing human health risks associated with microbial pollution.

Seasonal variation of airborne fungal diversity and community structure in urban outdoor environments in Tianjin, China

Airborne fungi are ubiquitous in human living environments and may be a source of respiratory problems, allergies, and other health issues. A 12 months study was performed to investigate the diversity, concentration and community structure of culturable airborne fungi in different outdoor environments of Tianjin City, using an HAS-100B air sampler. A total of 1,015 fungal strains belonging to 175 species and 82 genera of Ascomycota 92.5%, Basidiomycota 7%, and Mucoromycota 0.3% were isolated and identified using morphological and molecular analysis. The most abundant fungal genera were Alternaria 35%, Cladosporium 18%, Penicillium 5.6%, Talaromyces 3.9%, Didymella 3%, and Aspergillus 2.8%, while the most frequently occurring species were A. alternata (24.7%), C. cladosporioides (11%), A. tenuissima (5.3%), P. oxalicum (4.53%), and T. funiculosus (2.66%). The fungal concentration ranged from 0 to 340 CFU/m³ during the whole study. Environmental factors, including temperature, relative humidity, wind speed, and air pressure exerted a varying effect on the presence and concentration of different fungal taxa. The four analyzed seasons showed significantly different airborne fungal communities, which were more strongly influenced by air temperature and relative humidity in spring and summer, whereas wind speed and air pressure had a stronger effect in autumn and winter. Fungal communities from green and busy sites did not show significant differences over the four analyzed seasons, which may be due to the effect of the surrounding environments characterized by high human activities on the air of the relatively small parks present in Tianjin. The present study provided valuable information on the seasonal dynamics and the environmental factors shaping the diversity and concentration of the analyzed outdoor airborne fungal communities, which can be of help for air quality monitoring, microbial contamination control, and health risk assessment in urban environments.

Recent Advances in the Allergic Cross-Reactivity between Fungi and Foods

Airborne fungi are one of the most ubiquitous kinds of inhalant allergens which can result in allergic diseases. Fungi tend to grow in warm and humid environments with regional and seasonal variations. Their nomenclature and taxonomy are related to the sensitization of immunoglobulin E (IgE). Allergic cross-reactivity among different fungal species appears to be widely existing. Fungus-related foods, such as edible mushrooms, mycoprotein, and fermented foods by fungi, can often induce to fungus food allergy syndrome (FFAS) by allergic cross-reactivity with airborne fungi. FFAS may involve one or more target organs, including the oral mucosa, the skin, the gastrointestinal and respiratory tracts, and the cardiovascular system, with various allergic symptoms ranging from oral allergy syndrome (OAS) to severe anaphylaxis. This article reviews the current knowledge on the field of allergic cross-reactivity between fungal allergens and related foods, as well as the diagnosis and treatment on FFAS.

About the Biodiversity of the Air Microbiome

This brief review focuses on the properties of bioaerosols, presenting some recent results of metagenomic studies of the air microbiome performed using next-generation sequencing. The taxonomic composition and structure of the bioaerosol microbiome may display diurnal and seasonal dynamics and be dependent on meteorological events such as dust storms, showers, fogs, etc., as well as air pollution. The Proteobacteria and Ascomycota members are common dominants in bioaerosols in different troposphere layers. The microbiological composition of the lower troposphere air affects the composition and diversity of the indoor bioaerosol microbiome, and information about the latter is very important, especially during exacerbated epidemiological situations. Few studies focusing on the bioaerosol microbiome of the air above Russia urge intensification of such research.

Environmental Factors Shaping the Diversity and Spatial-Temporal Distribution of Indoor and Outdoor Culturable Airborne Fungal Communities in Tianjin University Campus, Tianjin, China

Airborne fungi have significant influence on air quality and may pose adverse effects on human health due to their allergenic and pathogenic effect. We carried out a 1-year survey on the airborne fungal diversity and concentration of indoor and outdoor environments, within the Tianjin University campus. Airborne fungi were sampled using an HAS-100B air sampler. Isolated fungal strains were identified based on morphological and molecular analysis. A total of 641 fungal strains belonging to 173 species and 74 genera were identified in this study. The dominant fungal genera were Cladosporium (29.49%), Alternaria (25.9%), and Epicoccum (6.24%), while the most frequently occurring species were A. alternata (15.44%), C. cladosporioides (11.86%), and E. nigrum (5.77%). The mean fungal concentration at different sites ranged from 0 to 420 CFU/m³, which is lower than the permissive standard level. There was a seasonal variation in the airborne fungal community, while temperature and relative humidity were positively correlated with the fungal concentration and diversity at almost all the sites. Higher fungal diversity was recorded in peak period of human traffic at the two canteens, whereas the two dormitories showed higher fungal diversity in off-peak period. Our study provides the first report on the diversity and concentration of airborne fungal species within different Tianjin University campus environments and clarifies the role played by environmental factors on the analyzed fungal community. Our results may represent valuable information for air quality monitoring and microbial pollution control in densely populated human living environments.

Molecular identification of some allergenic fungi found in household dust in Mosul city

The study included isolating and diagnosing the fungi found in dust samples from homes and buildings such as basements and walls containing fungal growth in separate areas from the left side of the city of Mosul in northern Iraq, such as Al-Ghufran neighborhood, Al-Mazare’ neighborhood, and Al-Mohandesin neighborhood during October and November, and the relationship of these fungi to human diseases, including allergies and asthma. The isolation results showed many fungal genera, including Cladosporium, Penicillium, Aspergillus, Alternaria and Trichoderma. The research aims to study the fungi Alternaria and Trichoderma, where the percentage of the presence of Alternaria in the wall sample containing the previous fungal growth was 28.57%. Whereas the percentage of the presence of Trichoderma fungus in dust and gypsum falling on the surfaces of poorly ventilated rooms in the cellars was 42.86%, and the molecular diagnosis of fungal isolates was carried out, as it was confirmed that there is a match with the standard strains found in the gene bank. The Alt a1 and Exp genes responsible for asthma were also examined and detected in fungal isolates using PCR technology and polymerase chain reaction; the new genes in both isolates were recorded. On behalf of both the supervisor and the researcher with international numbers in the global gene bank. Keywords: Household dust, allergies and asthma, indoor environments, Alternaria and Trichoderma, Mosul local fungi.

Spatiotemporal assessment of aeromycoflora under differing urban green space, sampling height, and meteorological regimes: the atmospheric fungiscape of Thessaloniki, Greece

We studied the diversity and abundance of the airborne fungal spores in the city of Thessaloniki, Greece, for two consecutive years. Air samples were collected at one rooftop station (at 30 m) and six near-ground stations (at 1.5 m) that differed in the size and composition of adjacent green spaces. The effects of meteorological factors on airborne fungal spore concentrations were also explored. Cladosporium spores were dominant everywhere in the air of the city. The total concentration of the airborne fungal spores at 30 m was 10 times lower than near the ground. Differences in concentration and composition were far less pronounced among near-ground stations. The attributes of the fungal spore season did not change in a consistent way among stations and years. Concentrations at the near-ground stations matched the grouping of the latter into stations of high, intermediate, and low urban green space. Minimum air temperature was the primary meteorological factor affecting spore abundance, followed by relative humidity. Airborne fungal spores are more homogeneously distributed in the air of the city, but their concentrations decrease more rapidly with height than pollen.

Environmental Factors Affecting Diversity, Structure, and Temporal Variation of Airborne Fungal Communities in a Research and Teaching Building of Tianjin University, China

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.

Fungal Allergen and Mold Allergy Diagnosis: Role and Relevance of Alternaria alternata Alt a 1 Protein Family

Alternaria is a genus of worldwide fungi found in different habitats such as soil, the atmosphere, plants or indoor environments. Alternaria species are saprobic-largely involved in the decomposition of organic material-but they can also act as animal pathogens, causing disease in humans and animals, developing infections, toxicosis and allergic diseases. A. alternata is considered one of the most important sources of fungal allergens worldwide and it is associated with severe asthma and respiratory status. Among the A. alternata allergens, Alt a 1 is the main sensitizing allergen and its usefulness in diagnosis and immunotherapy has been demonstrated. Alt a 1 seems to define a protein family that can be used to identify related pathogenic fungi in plants and fruits, and to establish taxonomic relationships between the different fungal divisions.