Spores Research Articles

Insights into human–environment interactions in tropical Africa during the Late Holocene based on the sediment sequence from Saiwa Swamp, Kenya

ABSTRACTThe present landscapes that define the tropical African region have evolved through the intricate interplay of climate and human interventions across various spatial and temporal scales. The late Holocene period is a valuable window for investigating how the environment responded to human influence. This study examined paleoenvironmental changes in the African tropics over the past 3500 years using proxy data, encompassing pollen, fungal spores, loss‐on‐ignition and microscopic charcoal extracted from core SS4 collected from Saiwa Swamp in western Kenya. The results show that Afromontane forests, represented by Podocarpus, Olea, Celtis and Juniperus, persisted in the region for much of the late Holocene despite prevailing conditions that favored the expansion of open savanna‐like vegetation and drought‐adapted taxa. The charcoal record reveals continuous fire occurrences throughout the sequence, raising questions about human‐induced fires and their potential role in shaping the landscape. The emergence of Sordaria fungal spores in the record between approximately 925 bce and 970 ce points to early human settlements engaging in livestock farming. Yet, these initial anthropogenic impacts did not trigger extensive forest clearing, hinting at a nuanced interplay between human activities and the environment during that era. The study emphasizes the importance of considering natural and human factors when interpreting environmental changes. It highlights the complex interplay of climatic, ecological and anthropogenic factors in shaping the landscape and vegetation dynamics over time.

Effect of preparations containing humic substances and pure humic acids on colony growth and spore germination of entomopathogenic fungi from the Beauveria genus

The experiment examined the effect of commercially available preparations containing humic substances in comparison with pure humic acids on the growth and germination of spores of entomopathogenic fungi (EPF) of the genus Beauveria in vitro. AmiAGRA, HumiAGRA, AlgoHUM (recommended field dose) and pure humic acids extracted from peat, brown coal and mushroom substrate were added to Sabouraud's culture substrate. Observation of the growth of colonies of the tested species of EPF was carried out every 5 days until day 20, measuring their diameter (mm). In the second stage of the experiment, the culture medium with the addition of preparations and pure humic acids was applied in a thin layer to the surface of glass slides and 0.1 ml of an aqueous solution with spores was introduced. Observation was carried out after 24 and 48 hours, and the results obtained were expressed as percentages of the control. The conducted research showed that on the 20th day of culture (on average), preparations containing humic substances had a stimulating effect, while pure acids slightly limited the growth of colonies of the tested isolates. The growth of the colony of the fungus B. basianna was most strongly stimulated by AmiAGRA, and B. brongniartii by HumiAGRA. The share of germinated spores of the tested isolates after 48 hours of contact with the substrate was higher than after 24 hours. It was found that more spores germinated on substrates with the addition of preparations containing humic substances than on pure humic acids.

Mycological and Genomic Characterization of Fusarium vorosii, a Potentially Pathogenic Fungus, Isolated from Field Crops and Weeds in Korea.

Fusarium vorosii (Fv) is one of the least studied species of the Fusarium graminearum species complex, a major plant pathogen causing Fusarium head blight (FHB) in a variety of crops. In this study, we isolated 12 strains of Fv from cereal samples with FHB symptoms and gramineous weeds. Trichothecene genotyping of Fv strains showed that 10 strains were nivalenol (NIV) type and 2 strains were 15-acetyldeoxynivalenol (15ADON) type. Fv strains have similar mycological characteristics to Fusarium asiaticum, a major FHB pathogen of rice in Asia, however, asexual sporulation was at least 100 to 1,000 times higher in Fv. In comparison of pathogenicity, the Fv-15ADON type was more pathogenic than the NIV type in both rice and wheat, and had a similar level of pathogenicity as the F. asiaticum-NIV type. Among the 12 Fv strains, two representative ones, Fv-NIV type RN1 and Fv-15ADON type W15A1, were selected and their whole genomes were sequenced and analyzed. Complete genome sequences of two Fv strains, RN1 and W15A1, were assembled at the chromosome level with high quality compared to known Fv genomes. The genome data of the two Fv strains were compared with the reference strains already known. As a result of comparative genome analysis, it was found that they are phylogenetically related according to the trichothecene biosynthetic gene cluster, that is, toxin chemotype. Through this study, we provided important information about Fv species that can be potential pathogens in domestic crops about biological and genomic characteristics.

Xizang meadow degradation alters resource exchange ratio, network complexity, and biomass allocation tradeoff of arbuscular mycorrhizal symbiosis.

The response of arbuscular mycorrhizal (AM) symbiosis to environmental fluctuations involves resource exchange between host plants and fungal partners, associations between different AM fungal taxa, and biomass allocation between AM fungal spore and hyphal structures; yet a systematic understanding of these responses to meadow degradation remains relatively unknown, particularly in Xizang alpine meadow. Here, we approached this knowledge gap by labeling dual isotopes of air 13CO2 and soil 15NH4Cl, computing ecological networks of AM fungal communities, and quantifying AM fungal biomass allocation among spores, intra- and extraradical hyphae. We found that the exchange ratio of photosynthate and nitrogen between plants and AM fungi increased with the increasing severity of meadow degradation, indicating greater dependence of host plants on this symbiosis for resource acquisition. Additionally, using 18S rRNA gene metabarcoding, we found that AM fungal co-occurrence networks were more complex in more degraded meadows, supporting the stress gradient hypothesis. Meadow degradation also increased AM fungal biomass allocation toward traits associated with intra- and extraradical hyphae at the expense of spores. Our findings suggest that an integrated consideration of resource exchange, ecological networks, and biomass allocation may be important for the restoration of degraded ecosystems.

M6A demethylase CpALKBH regulates CpZap1 mRNA stability to modulate the development and virulence of chestnut blight fungus.

N6-methyladenosine (m6A) is the most abundant eukaryotic mRNA modification and is involved in various biological processes. Methyltransferases and demethylases regulate the m6A modification, but the regulatory role of m6A demethylases in fungi remains poorly understood. Here, we demonstrated that CpALKBH functions as a demethylase in Cryphonectria parasitica. The deletion of CpALKBH leads to a significant increase in m6A levels and a reduction in fungal growth, sporulation, and virulence. We identified CpZap1 as a downstream target of CpALKBH, with CpALKBH regulating CpZap1 mRNA stability in an m6A-dependent manner. Additionally, our findings indicate that methylation at position 1935A of CpZap1 is regulated by both the CpALKBH demethylase and the CpMTA1 methyltransferase. Given its critical role in fungal development and virulence, overexpression of CpZap1 can rescue abnormal phenotypes of ∆CpALKBH mutant. Overall, these findings contribute to improving our understanding of the role of m6A demethylase in fungi.

Transcriptomic and genetic analysis reveals a Zn2Cys6 transcription factor specifically required for conidiation in submerged cultures of Thermothelomyces thermophilus.

Filamentous fungi are important producers of enzymes and secondary metabolites. The industrial thermophilic species, Thermothelomyces thermophilus, is closely related to the model fungus, Neurospora crassa. A critical aspect of the filamentous fungal life cycle is the production of asexual spores (conidia), which are regulated by various stimuli, including nutrient availability. Several species of fungi, including T. thermophilus, produce conidia under submerged fermentation conditions, which can be detrimental to product yields. In this study, transcriptional profiling of T. thermophilus was used to map changes during asexual development in submerged cultures, which revealed commonalities of regulation between T. thermophilus and N. crassa. We further identified a transcription factor, res1, whose deletion resulted in a complete loss of conidia production under fermentation conditions, but which did not affect conidiation on plates. Under fermentation conditions, the ∆res1 deletion strain showed increased biomass production relative to the wild-type strain, indicating that the manipulation of res1 in T. thermophilus has the potential to increase productivity in industrial settings. Overexpression of res1 caused a severe growth defect and early conidia production on both plates and in submerged cultures, indicating res1 overexpression can bypass regulatory aspects associated with conidiation on plates. Using chromatin-immunoprecipitation sequencing, we identified 35 target genes of Res1, including known conidiation regulators identified in N. crassa, revealing common and divergent aspects of asexual reproduction in these two species.IMPORTANCEFilamentous fungi, such as Thermothelomyces thermophilus, are important industrial species and have been harnessed in the Biotechnology industry for the production of industrially relevant chemicals and proteins. However, under fermentation conditions, some filamentous fungi will undergo a switch from mycelial growth to asexual development. In this study, we use transcriptional profiling of asexual development in T. thermophilus and identify a transcription factor that specifically regulates the developmental switch to the production of unwanted asexual propagules under fermentation conditions, thus altering secreted protein production. Mutations in this transcription factor Res1 result in the loss of asexual development in submerged cultures but do not affect asexual sporulation when exposed to air. The identification of stage-specific developmental regulation of asexual spore production and comparative analyses of conidiation in filamentous ascomycete species have the potential to further manipulate these species for industrial advantage.

Long-term survival of asexual Zymoseptoria tritici spores in the environment

BackgroundThe fungal phytopathogen Zymoseptoria tritici, causal agent of the economically damaging Septoria tritici blotch of wheat, is different from most foliar fungal pathogens in that its germination occurs slowly and apparently randomly after arrival on the leaf surface and is followed by a potentially prolonged period of epiphytic growth and even reproduction, during which no feeding structures are formed by the fungus. Thus, understanding the cues for germination and the mechanisms that underpin survival in low-nutrient environments could provide key new avenues for disease control.ResultsIn this work, we examine survival, culturability and virulence of spores following transfer from a high nutrient environment to water. We find that a sub-population of Z. tritici spores can survive and remain virulent for at least 7 weeks in water alone, during which time multicellular structures split to single cells. The fungus relies heavily on stored lipids; however, if cell suspensions in water are dried, the cells survive without lipid utilisation. Changes in gene expression in the first hours after suspension in water reflect adaptation to stress, while longer term starvation (7 days) induces changes particularly in primary metabolism and cytochrome P450 (CYP) gene expression. Importantly, we also found that Z. tritici spores are equally or better able to survive in soil as in water, and that rain-splash occurring 49 days after soil inoculation can transfer cells to wheat seedlings growing in inoculated soil and cause Septoria leaf blotch disease.ConclusionsZ. tritici blastospores can survive in water or soil for long periods, potentially spanning the intercrop period for UK winter wheat. They rely on internal lipid stores, with no external nutrition, and although a large proportion of spores do not survive for such an extended period, those that do remain as virulent as spores grown on rich media. Thus, Z. tritici has exceptional survival strategies, which are likely to be important in understanding its population genetics and in developing novel routes for Septoria leaf blotch control.

Exploring mechanisms of gene expression control during Ustilago maydis teliospore germination

Fungal plant pathogens produce spores for survival and dispersion. Developing an understanding of the mechanisms involved in spore dormancy and germination will aid in mitigating the impact of diseases they cause. The thick-walled diploid teliospores of Ustilago maydis were used as a model for studying fungal spore dormancy and germination. These spores develop only in infected maize tissue and can remain dormant for long periods of time. Teliospores germinate under favourable conditions, resume meiosis, and produce basidiospores to initiate new rounds of infection. Previous research identified changing gene transcripts during teliospore germination, but analysis was hampered by asynchronous germination. The more comprehensive RNA-seq analysis of U. maydis teliospore germination presented here aimed to identify gene altered transcript levels detectable above the background of fluctuating changes resulting from asynchronous germination. The analyses identified 18 different patterns of gene transcript level changes. It also indicated that gene expression is controlled at the transcriptional and post-transcriptional levels. Gene ontology term enrichment analyses of these patterns revealed genes that are involved in cell morphogenesis, metabolism, and RNA metabolism.

Fusarium spp. in Metalworking Fluid Systems: Companions Forever.

Water-miscible metalworking fluids (MWFs) are utilized in a variety of metal removal and forming operations. For end-use, formulation concentrates are diluted in water, creating conditions conducive to microbial growth and metabolism, possibly compromising the fluid's integrity and mechanically obstructing filters or piping systems. Metalworking machines offer additional habitats on surfaces that are in permanent or temporary contact with MWFs. For that reason, biocides have been incorporated into concentrates for years, but legal constraints will restrain their use in the future. While bacterial contamination of MWFs is well documented, fungal contamination is often overseen and infrequently reported in the literature. In this study, we report fungal prevalence in in-use MWFs sampled worldwide over 10 years, and we are convinced that the presence of fungi is the norm rather than the exception. In addition, we evaluated the inhibitory effect of fungicides on fungal growth, sporulation and spore viability using traditional culture-dependent methods and flow cytometry. In essence, we show that the effectiveness of these fungicides is limited and dependent on the chemical construction of the fluid. We think that the ecology created by water-diluted MWFs is of higher importance than the anti-fungal activity of single components.

Mortality Effects of Beauveria bassiana and Purpureocillium lilacinum Isolates and Efficacy of a Wettable Formulation on Palemona prasina (Hemiptera: Pentatomidae) Nymphs

In this study, the mortality effect of two Beauveria bassiana and two Purpureocillium lilacinum isolates on the 4th stage nymphs of Palemona prassiana was determined. The most lethal isolate was formulated as wettable powder and tested on the pest. Furthermore, Y-tube olfactometry tests were conducted to detect behavioral response of the nymphs in presence of the fungus. All the experiments were carried out under controlled conditions. The mortality varied depending on the isolates between 28.51% and 82.14% on the 12th day. Beauveria bassiana FAI-38 caused the highest mortality (82.14% at 1x108 conidia ml-1) with LC50 and LT50 estimations of 3.3x106 conidia ml-1 and 8.4 days, respectively. According to data taken 6 and 12 days after application, the wettable powder formulation was found to be significantly more effective (89.65% at 1x107 conidia ml-1, LT50 6.08 days). According to the Y-tube olfactometry tests, the nymphs exhibited avoidance from unformulated B. bassiana spores; however, once the spores were formulated as wettable powder, the behavior of the insects changed to neutral. It is concluded that Beauveria bassiana FAI-38 presents a potential as a control agent, and the wettable powder formulation of the fungus improves its effectiveness by increasing mortality and removing repellency effect of the fungal spores.

Cell wall nanoparticles from hyphae of Alternaria infectoria grown with caspofungin, nikkomycin, or pyroquilon trigger different activation profiles in macrophages.

Alternaria infectoria causes opportunistic human infections and is a source of allergens leading to respiratory allergies. In this work, we prepared cell wall nanoparticles (CWNPs) as a novel approach to study macrophage immunomodulation by fungal hyphal cell walls. A. infectoria was grown in the presence of caspofungin, an inhibitor of β(1,3)-glucan synthesis; nikkomycin Z, an inhibitor of chitin synthases; and pyroquilon, an inhibitor of dihydroxynaphthalene (DHN)-melanin synthesis. Distinct CWNPs were obtained from these cultures, referred to as casCWNPs, nkCWNPs, and pyrCWNPs, respectively. CWNPs are round-shaped particles with a diameter of 70-200 nm diameter particles that when added to macrophages are taken up by membrane ruffling. CWNPs with no DHN-melanin and more glucan (pyrCWNPs) caused early macrophage activation and lowest viability, with the cells exhibiting ultrastructural modifications such as higher vacuolization and formation of autophagy-like structures. CasCWNPs promoted the highest tumor necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β) increase, also resulting in the release of partially degraded chitin, an aspect never observed in macrophage-like cells and fungi. After 6 h of interaction with CWNPs, only half were viable, except with control CWNPs. Overall, this work indicates that compounds that modify the fungal cell wall led to CWNPs with new properties that may have implications for the effects of drugs during antifungal therapy. CWNPs provide a new tool to study the interaction of hyphal fungal cell wall components with phagocytic cells and enable to show how the modification of cell wall components in A. infectoria can modulate the response by macrophages.IMPORTANCEAlternaria species are ubiquitous environmental fungi to which the human host can continuously be exposed, through the inhalation of fungal spores but also of fragments of hyphae, from desegregated mycelia. These fungi are involved in hypersensitization and severe respiratory allergies, such as asthma, and can cause opportunistic infections in immunodepressed human host leading to severe disease. The first fungal structures to interact with the host cells are the cell wall components, and their modulation leads to differential immune responses. Here, we show that fungal cells grown with cell wall inhibitors led to cell wall nanoparticles with new properties in their interaction with macrophages. With this strategy, we overcame the limitation of in vitro assays interacting with filamentous fungi and showed that the absence of DNH-melanin leads to higher virulence, while caspofungin leads to cells walls that trigger higher hydrolysis of chitin and higher production of cytokines.

Enrichment and characterization of foodborne fungal spores by ferric ion-based surface-assisted laser desorption/ionization mass spectrometry

We developed a novel surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) method to detect fungal spores, which is a critical concern in food safety. A combination of Fe3+ and trifluoroacetic acid (TFA) was initially confirmed as an effective light absorber, facilitating the desorption and ionization of small organics in SALDI-MS. This approach was then successfully applied to the analysis of small organics derived from Aspergillus niger, aflatoxigenic Aspergillus flavus, and non-aflatoxigenic A. flavus, enabling the differentiation of closely related species and strains. Additionally, Fe3+ and Gd3+ were used as magnetic probes to trap and concentrate spores from sample solutions, and TFA-mediated lysis and SALDI-MS analysis were performed. We demonstrated that the proposed method can be used to trap trace amounts of fungal spores in a peanut extract and complement Fe3+-SALDI MS analysis. The limit of detection of the method against fungal spores was as low as ~104 spores mL−1.

First evidence of off-flavour haloanisole production by dormant fungal spores in drinking water: formation pattern, influencing factors and transcriptome analysis

Fungi are major producers of off-flavour haloanisoles (HAs) in drinking water supply systems. However, evidence of HA production by dormant fungal spores remains unclear. This study investigated the microbial O-methylation of dormant spores from a fungus Aspergillus sp. from drinking water treatment plants. Dormant spores were capable of O-methylating 2,4,6-trichlorophenol (2,4,6-TCP) to produce 2,4,6-trichloroanisole (2,4,6-TCA). A pronounced linear correlation was identified between the precursor load and the 2,4,6-TCA formation capability, with a function lg(y)=0.542lg(x) - 4.28 (R2 = 0.838). The effects of metal ions on fungal spore O-methylation were multifaceted and highly concentration-dependent. Natural organic matters could inhibit 2,4,6-TCA formation. NH2Cl presented higher efficacy than free chlorine in inhibiting spore O-methylation. However, O-methylation inhibition rates were lower than spore inactivation rates, suggesting spores in viable but non-culturable state still possessed partial ability to form 2,4,6-TCA. Transcriptome analysis revealed that 50nM 2,4,6-TCP treatment had no impact on the spore’s transcriptional profile, whereas 1mM Cu2+ treatment significantly inhibited O-methylation process by down-regulating genes involved in ATP generation. This study provides a first evidence that dormant fungal spores are capable of producing 2,4,6-TCA, raising concerns about the potential off-flavour risk and the development of targeted control strategies in drinking water systems.

Reduction of microbial load in soil by gas generated using non-thermal atmospheric pressure plasma

Elevation of the microbial load in soil resulting from contamination with organic wastes of biological origin increases the chances of emerging soil-borne pathogens and disturbance of nutrient cycling. We analyzed the potential of gas generated using atmospheric-pressure non-thermal plasma as a tool for reducing the microbial load in soil and its impact on the soil microbial community and fertility. The gas generated by a cylinder-type single pair of dielectric barrier discharge (DBD) electrode plasma inactivated over 90 % of bacterial cells and fungal spores after 5 and 20 min of treatment, respectively, in both suspension and vermiculite. Gas generated using four pairs of DBD electrode plasma eradicated approximately 50 % of bacterial cells and 40 % of fungal spores in nursery soil. It also eliminated approximately 10–29 % of aerobic natural microbiota in field soil after 60 min of treatment. The diversity of microbial species in the plasma gas-treated field soil was slightly lower than that in the untreated soil, and the relative abundances of the phyla Proteobacteria and Basidiomycota were reduced in the plasma gas-treated soil. Spinach plant growth and nitrate levels increased significantly in the plasma gas-treated field soil. Our data suggest that plasma-generated gases can be used for soil sanitation with no drastic changes to the soil microbial community and soil fertility enhancement.

Inverse Trend Between Tree Pollen and Fungal Concentrations With Allergic Sensitization Rates in Seoul for 25 Years.

A growing number of individuals are developing allergic diseases due to pollen exposure. Seasonal variations and increased pollen concentrations have occurred with the increased rates of allergic sensitization among both children and adults. Temperature significantly influences pollination, particularly in spring- and early summer-flowering plants, with weather conditions affecting pollen allergen levels. Human activities, including agriculture and deforestation, increase carbon emissions, leading to higher atmospheric CO₂ levels that may enhance allergenic plant productivity. Climate change affects the range of allergenic plant species and length of pollen season. Studies indicate that higher CO₂ and temperature levels are linked to increased pollen concentrations and allergenicity, whereas atmospheric fungal concentrations have declined annually over the past 25 years. Despite more intense precipitation in summer and autumn, the number of rainy days has decreased across all seasons. This concentration of rainfall over shorter periods likely prolongs the dry season and shortens the period of fungal sporulation. Future climate changes, including atmospheric dryness, drought, and desertification could further decrease allergenic fungal sporulation. It remains unclear whether the inverse relationship between pollen and fungal concentrations and distributions directly results from climate change. It is crucial to evaluate the patterns of aeroallergens and their associated health risks.

Perspectives on blastomycosis in Canada in the face of climate change.

Blastomycosis is a disease of potentially varied presentations caused by thermally dimorphic fungi that appear as mold at ambient temperatures and transform to yeast at body temperature. Inhalation of aerosolized fungal spores represents the primary mode of transmission. Exposure may follow outdoor activities that disturb soil, which is warm, moist, acidic and rich in organic debris, particularly within forested areas and in proximity to waterways. Blastomycosis is endemic to several parts of Canada, but is only reportable in Ontario and Manitoba, with Northwestern Ontario being considered a hyperendemic area with average annual incidence rates of over 25 cases per 100,000 population. Delays in diagnosis and treatment are frequently observed as the symptoms and imaging findings of blastomycosis may initially be mistaken for community-acquired pneumonia, tuberculosis or malignancy, which can result in interim disease progression and worsening clinical outcomes. Risks from fungal infections such as blastomycosis are likely to increase with climate change-associated shifts in temperature and rainfall, and this may contribute to the geographic expansion of cases, a phenomenon that appears to be already underway. Further research investigating the ecological niche of Blastomyces and its climate sensitivity could help facilitate better modelling of the potential impacts of climate change on risks to Canadians and inform more effective methods of exposure prevention. Early clinical recognition and treatment of blastomycosis remain the key to minimizing morbidity and mortality.

Intestinal bacterium Bacillus siamensis M54 from Allomyrina dichotoma is a potential biocontrol agent against maize stalk rot

Maize stalk rot, caused by Fusarium spp., is a significant disease that adversely impacts the yield and quality of corn. Biological control plays a crucial role in managing numerous crop diseases, including maize stalk rot. Biocontrol agents are predominantly derived from soil and plant tissues, with limited reports on isolating highly efficient biocontrol agents from insects. In this study, 144 bacterial strains were isolated from the intestinal tract of third instar larvae of Allomyrina dichotoma. Through dual culture tests, twelve strains exhibiting strong antagonism against two maize stalk rot pathogens, F. graminearum and F. verticillioides, were identified. Among them, the M54 strain exhibited the most potent antagonistic effect against the two pathogenic fungi and was identified as Bacillus siamensis through 16S rRNA gene sequence analysis. The complete genome for M54 was assembled using PacBio single-molecule real-time (SMRT) and Illumina sequencing technologies. Whole genome phylogenetic analysis further confirmed M54 was B. siamensis. Microscopic examination revealed that M54 had the ability to inhibit the fungal spore germination and hyphal formation. Furthermore, M54 exhibited effective colonization in the maize rhizosphere and enhanced maize growth. It showed that treatment with M54 significantly suppressed lesion expansion induced by F. graminearum on maize stalks in the seedling and adult plant assays. Genomic analysis using antiSMASH revealed 11 gene clusters for secondary metabolite synthesis. This study provides a novel approach for isolating biocontrol agents to manage plant diseases and highlights B. siamensis M54 as a potential efficient biocontrol agent for maize stalk rot.

Observing super-coarse carbonaceous aerosol particles containing chloride in a tropical savanna climate at an agro-forest site in Thailand

Coarse aerosol particles containing chloride in tropical forests are significant for understanding biogeochemical cycles and atmospheric processes, with implications for environmental health and climate change mitigation. This study explored the sources of super-coarse carbonaceous aerosol particles containing chloride in a tropical savanna climate. Aerosol samples were collected from an agro-forest site in Thailand during the dry season and analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared (FTIR) spectroscopy. By examining the morphology and elemental compositions of individual aerosol particles, along with employing Positive Matrix Factorization (PMF) and backward trajectory analysis, potential sources were identified. The findings revealed two primary sources for the super-coarse aerosol particles: a mixture of biomass burning smoke and inorganic salts (likely from saline soil and sea salt), as well as halophilic fungal spores. FTIR analysis indicated the presence of compounds linked to biomass burning and clay minerals, influenced by prevailing northeast and southeast winds. Recommendations for future research include continued monitoring, correlation with meteorological parameters, and the application of transmission electron microscopy (TEM) for more detailed visualization and confirmation of aerosol sources.

A PCR-Based Approach for Early Diagnosis of Head and Neck Aspergillosis: A Pilot Study.

Aspergillosis is a fungal disease caused by the inhalation of fungal spores of the genus Aspergillus spp. This fungus mainly affects the lungs but can spread and infect the maxillofacial region through the bloodstream or inoculation of the fungus after extraction or endodontic treatment, especially in the upper posterior teeth. The disease has nonspecific clinical manifestations that hinder its early diagnosis. Although the Polymerase Chain Reaction (PCR) technique holds promise as a diagnostic tool for aspergillosis, anatomopathological analysis services do not routinely adopt this method. Therefore, the present study aimed to evaluate the applicability of PCR and standardise the techniques of preparation of biological samples for the detection of the three species: Aspergillus niger, Aspergillus fumigatus and Aspergillus flavus. Methods: Six samples of formalin-fixed, paraffin-embedded tissue (FFPE) with a histopathological diagnosis suggestive of aspergillosis were investigated using PCR. As a positive control for the PCR reaction, morphologically and genetically characterized cultures were used, with their sequences deposited at NCBI under accession codes MW837777 (A. fumigatus) and MW837779 (A. niger). The A. flavus culture used is reference RC 2053. Four of the six samples evaluated were positive for Aspergillus spp., of which one was co-infected with A. fumigatus and A. flavus species, while two others were positive only for A. flavus, and one sample was positive only for A. fumigatus. These findings suggest that PCR can be used as an auxiliary method for diagnosing aspergillosis. However, this was a pilot study, and expansion of the sample size and the evaluation of PCR in comparison with other diagnostic tests for aspergillosis are essential to determine the accuracy of the method.

Comparative analysis of airborne fungal spore distribution in urban and rural environments of Slovakia

Monitoring airborne fungal spores is crucial for public health and plant production since they belong to important aeroallergens and phytopathogens. Due to different land use, their concentration can differ significantly between urban and rural areas. We monitored their spectrum and quantity on two geographically close sites with a different degree of urbanisation: Bratislava City and Kaplna Village in Slovakia, located 38 km apart. We recorded the spectrum of airborne fungal spores over a year and confirmed the microscopic results by amplicon-based metagenomic analysis. The main spore season of the most frequent genera lasted over a week longer in Kaplna, but its intensity was approximately two-fold higher in Bratislava. This can be possibly connected to the microclimatic conditions of the urban area (especially wind speed and heat island effect) and the lesser use of fungicides. Cladosporium was the dominant genus on both sites, influencing the intensity most significantly. Through statistical analysis of the influence of meteorological parameters on airborne fungal spore levels, we identified a significant relationship with temperature, while the impact of other parameters varied depending on the spore type and release mechanism. Our results show the differences in airborne fungal spore levels between urban and rural areas and highlight the necessity for more monitoring stations in various environments.