Developmental regulators in <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis>

The filamentous fungus Aspergillus fumigatus is the most prevalent airborne fungal pathogen causing severe and usually fatal invasive aspergillosis in immunocompromised patients. This fungus produces a large number of small hydrophobic asexual spores called conidia as the primary means of reproduction, cell survival, propagation, and infectivity. The initiation, progression, and completion of asexual development (conidiation) is controlled by various regulators that govern expression of thousands of genes associated with formation of the asexual developmental structure conidiophore, and biogenesis of conidia. In this review, we summarize key regulators that directly or indirectly govern conidiation in this important pathogenic fungus. Better understanding these developmental regulators may provide insights into the improvement in controlling both beneficial and detrimental aspects of various Aspergillus species.     

Characterization of the velvet regulators in <Emphasis Type="Italic">Aspergillus flavus</Emphasis>

Fungal development and secondary metabolism are closely associated via the activities of the fungal NK-kB-type velvet regulators that are highly conserved in filamentous fungi. Here, we investigated the roles of the velvet genes in the aflatoxigenic fungus Aspergillus flavus. Distinct from other Aspergillus species, the A. flavus genome contains five velvet genes, veA, velB, velC, velD, and vosA. The deletion of velD blocks the production of aflatoxin B1, but does not affect the formation of sclerotia. Expression analyses revealed that vosA and velB mRNAs accumulated at high levels during the late phase of asexual development and in conidia. The absence of vosA or velB decreased the content of conidial trehalose and the tolerance of conidia to the thermal and UV stresses. In addition, double mutant analyses demonstrated that VosA and VelB play an inter-dependent role in trehalose biosynthesis and conidial stress tolerance. Together with the findings of previous studies, the results of the present study suggest that the velvet regulators play the conserved and vital role in sporogenesis, conidial trehalose biogenesis, stress tolerance, and aflatoxin biosynthesis in A. flavus.     

Effects of wind speed and direction on monthly fluctuations of <Emphasis Type="Italic">Cladosporium</Emphasis> conidia concentration in the air

This study determined the relationship between airborne concentration of Cladosporium spp. spores and wind speed and direction using real data (local wind measured by weather station) and modelled data (air mass flow computed with the aid of HYbrid Single Particle Lagrangian Trajectory model). Air samples containing fungal conidia were taken at an urban site (Worcester, UK) for a period of five consecutive years using a spore trap of the Hirst design. A threshold of ≥6000 s m^?3 (double the clinical value) was applied in order to select high spore concentration days, when airborne transport of conidia at a regional scale was more likely to occur. Collected data were then examined using geospatial and statistical tools, including circular statistics. Obtained results showed that the greatest numbers of spore concentrations were detected in July and August, when C. herbarum, C. cladosporioides and C. macrocarpum sporulate. The circular correlation test was found to be more sensitive than Spearman’s rank test. The dominance of either local wind or the air mass on Cladosporium spore distributions varied between examined months. Source areas of this pathogen had an origin within the UK territory. Very high daily mean concentrations of Cladosporium spores were observed when daily mean local wind speed was v _s ≤ 2.5 m s^?1 indicating warm days with a light breeze.     

The influence of meteorological parameters on <Emphasis Type="Italic">Alternaria</Emphasis> and <Emphasis Type="Italic">Cladosporium</Emphasis> fungal spore concentrations in Beja (Southern Portugal): preliminary results

Introduction Fungal spores constitute an important fraction of bioaerosols in the atmosphere. Objectives To analyse the content of Alternaria and Cladosporium spores in the atmosphere of Beja and the effect of meteorological conditions on their concentrations. Methodology The daily and hourly data of Alternaria and Cladosporium fungal spores concentration in the atmosphere of Beja were monitored from April 12, 2012 to July 30, 2014, based on the Portuguese Aerobiology Network methodology. The influence of meteorological conditions on the studied types of fungal spore concentrations was assessed through Spearman’s correlation analysis. Results During the study period, 20,741 Alternaria spores and 320,862 Cladosporium spores were counted. In 2013, there were 5,822 Alternaria spores and 123,864 Cladosporium spores. The absolute maximum concentrations of Alternaria and Cladosporium spores were recorded on November 8, 2013, with 211 and 1301 spores/m³, respectively. Temperature, insolation and wind direction parameters showed a positive correlation with Alternaria and Cladosporium spore levels, while relative humidity and precipitation presented a negative correlation, which is statistically significant. Wind speed only showed a statistically significant positive correlation in terms of Alternaria spore levels. Conclusion Alternaria and Cladosporium spores are present in the atmospheric air of Beja throughout the year, with the highest concentration period occurring during spring and autumn. There was a clear effect of meteorological parameters on airborne concentrations of these fungal spores.     

Germination of spores of mycelial fungi in relation to exogenous dormancy

Comparative analysis of germination of asexual sporulation spores (conidia and sporangiospores) and of specific features of dormancy release was carried out for ascomycete mycelial fungi Aspergillus tamarii VKM F-64 and A. sydowii VKM F-441, as well as for zygomycete fungi Cunninghamella echinulata VKM F-663 and Umbelopsis ramanniana VKM F-582. The spores of these strains were shown to be in a state of exogenous dormancy and differed in lag phase duration and germination rate, which depended on the presence of nutrients in the medium. Only the strain C. echinulata VKM F-663 exhibited 100% spore germination, with the germination rate and lag phase duration not depending on the composition of the medium. While in A. tamarii strain VKM F-64, the total number of spores germinating on rich and poor media was also almost the same, in the absence of nutrients lag phase duration increased and the germination rate decreased. For strains U. ramanniana VKM F-582 and A. sydowii VKM F-441, the degree of spore germination in the absence of nutrients in the medium was considerably lower than on the rich medium, while the lag phase was longer. These data indicate that the spores of C. echinulata VKM F-663 are in the state of exogenous dormancy, which does not require for release any compounds except water. The spores of U. ramanniana strain VKM F-582 and of the Aspergillus strains exhibited another variant of exogenous dormancy, which required for release, apart from water, also the sources of carbon and nitrogen. Thus, the character of dormancy release may differ even within a single genus (Aspergillus).     

Carbohydrate Specificity of Antibodies against Phytopathogenic Fungi of the <Emphasis Type="Italic">Aspergillus</Emphasis> Genus

Brush rabbits were immunized with injections prepared from the fungi Aspergillus fumigatus, Aspergillus niger, and Aspergillus repens. A library of synthetic biotinylated oligosaccharides containing the key fragments of antigenic polysaccharides of the fungal cell wall—galctomannan, α- and β-glucans, mannan, and chitin—was used to analyze carbohydrate specificity. The anticarbohydrate antibodies obtained from animals immunized with preparations from A. fumigatus and A. repens predominantly recognized epitopes containing galactofuranoside residues, while the majority of the antibodies against A. niger bound the chitooligosaccharide ligand. These results are the basis for the identification of specific markers required for the development of immunoenzyme test systems.     

A 10-year study of <Emphasis Type="Italic">Alternaria</Emphasis> and <Emphasis Type="Italic">Cladosporium</Emphasis> in two Polish cities (Szczecin and Cracow) and relationship with the meteorological parameters

Alternaria and Cladosporium spores belong to the most frequent and allergenic particles in bioaerosol in the temperate climate. The investigation of Alternaria and Cladosporium spore concentrations was performed in two cities in Poland, Szczecin and Cracow, in 2004–2013. The meteorological parameters taken to assess their impact on fungal spores were average, maximum and minimum temperature, relative humidity and average wind velocity. In order to reveal whether changes in dynamics of spore seasons are driven by meteorological conditions, ordination methods were applied. Canonical correspondence analysis was used to explore redundancy among the predictors (meteorological parameters). Prior to ordination analyses, the data were log(x)-transformed. Concentrations of Alternaria and Cladosporium spores were significantly higher in Szczecin comparing to Cracow, but it was also observed the decreasing trend in the spore concentrations in Szczecin. As regards temperature, it was higher in Cracow and was still increasing in the studied years. Relative humidity and wind velocity were significantly lower in Cracow. In Szczecin meteorological conditions did not explain changes in spore season characteristics (insignificant redundancy analysis models), while in Cracow’s redundancy analysis models indicated that spore season parameters were in over 40 % determined by meteorological conditions, mainly air temperature and wind velocity. If they increase, the peak value, total number of spores and their average concentrations in a season will also increase.     

Lipid composition of the spores of zygomycetous and ascomycetous fungi during cessation of the exogenous dormancy state

The composition of lipids and fatty acids was studied in the spores of exogenously dormant (spores 0) and germinating (spores G) spores in distilled water for sporangiospores of zygomycetous fungi Cunninghamella echinulata VKM F-663 and Umbelopsis ramanniana VKM F-582 and for conidia of ascomycetous fungi Aspergillus tamarii VKM F-64 and A. sydowii VKM F-441. Compared to spores 0, the lipids of spores G contained higher shares of unsaturated fatty acids, lower levels of massive phospholipids (phosphatidylcholine and phosphatidylethanolamine), and elevated levels of phosphatidylglycerol and phosphatidic acid. The level of cardiolipin, the main phospholipid of the mitochondrial membranes, increased when the spores of both zygomycetes exited from the dormant state. While a certain increase in the content of free and esterified sterols in the neutral lipids of the slowly germinating U. ramanniana G spores was observed, germination of sporangiospores and conidia of the studied fungi generally did not result in significant changes in the composition of the neutral lipid classes, which may be due to the fact that they are not the major reserve mobilized at the stage of exit from the dormant state.     

Compatibility and combination of selected bacterial antagonists in the biocontrol of sisal bole rot disease

Sisal (Agave sisalana Perrine ex Engelm; Asparagaceae) bole rot is a devastating disease caused by Aspergillus niger Tiegh, which contributes to the decline of this crop in Brazil. Currently, there are no control measures available, but biocontrol is being investigated as a promising management strategy. Five previously selected bacterial isolates were identified by 16S rRNA sequencing as Paenibacillus sp. 512, Brevibacterium sp. 90 and Bacillus sp. 105, BMH and INV, and tested for their capacity to control bole rot in vitro and in field experiments. Individual bacterial isolates and their combinations significantly inhibited mycelial growth and spore germination of A. niger. In two independent field experiments, the application of isolates 512, 105, 90, INV, and 127 + INV reduced disease incidence to levels varying from 44 to 75%. Although there was no synergistic effect in their combined use, these bacteria have potential to be used against bole rot disease in the field.     

A new species ofScopulariopsis from soil

A new species ofScopularoipsis described from soil is characterized by the conidiophores, branches, and sporogenous cells being distinctly swollen. The conidia have a well-marked germ slit running more or less longitudinally down the spore. TheScopulariopsis state ofMicroascus doguetii is re-examined and evidence is presented which indicates that the striations on the walls of the spores are germ slits.     

Electron Microscopy of Cells of <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> infected with Double Stranded RNA Viruses from <Emphasis Type="Italic">Aspergillus niger</Emphasis> and <Emphasis Type="Italic">Penicillium stoloniferum</Emphasis>

LHOAS¹ has demonstrated the infection of mating pairs of Saccharomyces cerevisiae with double stranded RNA viruses from Aspergillus niger and Penicillium stoloniferum (preceding communication). I wish to give details of the appearance of the virus particles within the infected yeast cells as determined by electron microscopy.     

Determination of airborne fungal spores of Gaziantep (SE Turkey)

The aim of this study was to present the first airborne fungal spore research results of SE of Turkey. The presence and abundance of fungal spores were investigated with a Hirst-type volumetric spore trap (Lanzoni, VPSS 2000) for 2 years between the periods January 2010 and December 2011. A total of 211,521 spores and 47 fungal taxa belonging to Anamorphic Fungi, Phyla Ascomycota and Basidiomycota were recorded. Aspergillus/Penicillium spores type, unidentified spores, spores of Myxomycota and hyphal fragments were also recorded as groups. The relationship between fungal spore counts and several meteorological parameters was examined. Cladosporium was determined as the predominant genus (56.48 %); hyphal fragments (14.94 %), Ustilago (13.96 %) and Alternaria (5.79 %) were revealed as the common fungal aerosols of Gaziantep atmosphere. With this study, the first aeromycological survey of SE of Turkey has been conducted and new information on the field of aerobiology in Turkey has been introduced.     

The survival of micromycetes exposed to space conditions

Original data on the survival of fungal spores exposed to space conditions are presented. The experiment was carried out on the Earth-orbiting Russian satellite Foton-M4. The flight duration of the satellite was 45 days. Thirteen fungal species (hyaline as well as pigmented) from 10 genera recovered from destructed stone materials were studied. Sterile quartz sand was inoculated by the fungal spores and was placed into Eppendorf tubes. During the space flight, the Eppendorf tubes with fungal spores were kept inside the Foton descent capsule in the “Biokont” containers and on the external surface of the capsule in the “Exobiofrost” containers exposed to the open space as well. Spores of ten species (77% of all tested species), i.e. Acremonium charticola, Aspergillus niger, Aspergillus versicolor, Chaetomium globosum, Cladosporium sphaerospermum, Penicillium chrysogenum, Penicillium verrucosum, Purpureocillium lilacinum, Sarocladium kiliense, and Trichoderma harzianum, survived after the flight both inside and outside the descent capsule. Only three species (23% of all tested species), i.e. Acremonium furcatum, Engyodontium album and Verticillium zaregamsianum, failed to survive outside as well as inside the capsule. Spore viability differed depending on the fungal species. Thus, spores of some fungal species are able to survive under the complex of stress factors such as low temperature values, radiation, etc. We have shown that micromycetes can be used as a model group for study of eukaryotic organisms’ resistance to stress factors, due to their high tolerance not only to extreme terrestrial environments, but to the extraterrestrial ones as well.     

Identification and genomic analysis of antifungal property of a tomato root endophyte <Emphasis Type="Italic">Pseudomonas</Emphasis> sp. p21

Pseudomonas sp., which occupy a variety of ecological niches, have been widely studied for their versatile metabolic capacity to promote plant growth, suppress microbial pathogens, and induce systemic resistance in plants. In this study, a Pseudomonas sp. strain p21, which was isolated from tomato root endophytes, was identified as having antagonism against Aspergillus niger. Further analysis showed that this strain had the ability to biosynthesise siderophores and was less effective in inhibiting the growth of A. niger with the supplementation of Fe³⁺ in the agar medium. Genomic sequencing and the secondary metabolite cluster analysis demonstrated that Pseudomonas sp. p21 harboured 2 pyoverdine biosynthetic gene clusters, which encode compounds with predicted core structures and two variable tetra-peptide or eleven-peptide chains. The results indicated that siderophore-mediated competition for iron might be an important mechanism in Pseudomonas suppression of the fungal pathogen A. niger and in microbe-pathogen-plant interactions.     

Atmospheric concentrations of selected allergenic fungal spores in relation to some meteorological factors,in Timişoara (Romania)

Present investigation was undertaken to study the dynamics of relationships between atmospheric fungal spores and meteorological factors in western Romania. The airborne spore sampling was carried out by employing volumetric sampling. A total of nine meteorological parameters were selected for this investigation. During 2008–2010, it was found the same pattern of behaviour in the atmosphere for selected spore types (Alternaria, Cladosporium, Pithomyces, Epicoccum and Torula). The spores occurred in the air throughout the whole year, but maximum concentrations were reached in summer. Cladosporium and Alternaria peak levels were observed in June. Epicoccum peak value was found in September. The relationships between airborne spore concentrations and environmental factors were assessed using the analysis of Spearman’s rank correlations and multiple linear regressions. Spearman’s rank correlation analysis revealed that maximum, minimum and mean temperature, and number of sunshine hours were strongly (p < 0.01) and directly proportional to the concentration of all analysed fungal spores. Negative and significant correlations were with daily mean relative humidity. The variance explained percentage by regression analyses varied between 30.6 and 39.6 % for Alternaria and Cladosporium airborne spores. Statistical methods used in this study are complementary and confirmed stable dependence of Alternaria and Cladosporium spore concentrations on meteorological factors. The climate change parameters either increased temperatures, changed precipitation regimes or a combination of both affected allergenic fungal spore concentrations in western Romania. This study demonstrates the need for investigations throughout the year, from month to month, regarding the correct interpretation of airborne spore relationships with meteorological parameters.     

Metabolic activity of <Emphasis Type="Italic">Aspergillus niger</Emphasis> and <Emphasis Type="Italic">Fusarium lateritium</Emphasis> induced by ethoxylated oleyl cetyl alcohol and their bioremediation and biotechnological potential

The effect of ethoxylated oleyl cetyl alcohol (Henkel, Serbia) on the growth and metabolic activity of Aspergillus niger and Fusarium lateritium was in the focus of this paper. The fungi were isolated from wastewater of Lepenica River (Kragujevac, Serbia) at a place where municipal wastewater discharged into the river. The fungi were grown in Czapek-Dox liquid nutrient medium without and with addition of 0.5% pollutant. The physico-chemical and biochemical changes of pH, total biomass dry weight, quantity of free and total organic acids, proteolytic activity and quality of carbohydrates were evaluated from 4-th to 19-th day of fungal growth. The capacity of fungi to decrease concentration of pollutant in medium was determined by cobalt thiocyanate method. The pollutant caused an inhibitory effect on biomass dry weight of A. niger and F. lateritium for 8.50 and 30.61%, respectively. Among tested fungi, A. niger had the better biodegradation capacity (83%) than F. lateritium (65%). Alkaline protease activity of A. niger enhanced in the presence of pollutant for 7.6% whereas the enzyme of F. lateritium retained about 62.2% activity. Overall, the obtained results indicate the potential application of tested fungi in wastewater treatment, detergent industry and biotechnology.     

The Role of <Emphasis Type="Italic">sho1</Emphasis> in Polarized Growth of <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis>

Aspergillus fumigatus is an opportunistic pathogen that may cause severe invasive disease in immunocompromised patients. The filamentous fungi undergo polarized growth, searching for nutrients in the environment and causing invasive growth in tissue. Sho1 is a sensor of the high osmolarity glycerol pathway, and the sho1 mutant showed a decrease in growth rate. We found that sho1 is involved in the polarized growth of A. fumigatus. The sho1 mutation resulted in extended isotropic growth of germinating conidia followed by multiple germ tubes and wide hyphae with short intercalary cells by calcofluor white staining. The mechanism by which sho1 gene affected polarized growth is investigated. A reduced number of apical vesicles with greater dispersion were observed by transmission electron microscopy in the Spitzenkörper body of the sho1 mutant. Actin patches were distributed randomly at low density at early stages of mutant strain fungal development and reaggregated to the hyphal tip of later stages when long filamentous fungi formed. Actin patches located at the tip of polarized wild-type cells. RNA levels of polarized growth-related genes Rho GTPases were detected by real-time PCR. The sho1 gene did not affect the RNA expression when strains were cultured at 37°C for 6 h. At 17 h, the RNA expression of rho1, rho3 and CDC42 in the sho1 mutant were 0.18-, 0.18- and 0.33-fold of that in the wild type. The sho1 gene affected the polarized growth through affecting the expression of Rho GTPases, the distribution of actin cytoskeleton, vesicle quantity and distribution.     

First volumetric record of fungal spores in the atmosphere of Montevideo City,Uruguay: a 2-year survey

In Uruguay, aeromycological studies are restricted to a gravimetric analysis performed from December 1942 to March 1944 in Montevideo where spores of Pucciniaceae, Alternaria and Helminthosporium were the only specimens identified. Daily monitoring of airborne fungal spores was carried out for the first time in Montevideo, from April 2012 to March 2014, using a Rotorod sampler in order to evaluate the seasonal variation and influence of meteorological parameters. A total of 548,309.68 spores/m³ were recorded which belong to anamorphs of Higher Fungi (69.18 %), Phyla Ascomycota (12.62 %), Basidiomycota (8.01 %), Oomycota (0.37 %) and Myxomycota (0.06 %). Airborne spores occurred in Montevideo throughout the whole year. However, a seasonal pattern was revealed, with the highest concentrations recorded in autumn and summer. The most abundant spore types were Cladosporium (53.22 %), Alternaria (6.62 %), Didymella Group (5.86 %), Leptosphaeria Group (4.37 %) and Coprinus (4.3 %). Temperature appeared to be the most influential meteorological factor correlating significantly and positively with total spore, Cladosporium, Alternaria and Didymella Group abundance. Relative humidity influenced positively total spore, Cladosporium and Didymella Group concentrations while a weak negative association was obtained for Alternaria. Wind speed correlated negatively with total spore, Cladosporium, Alternaria and Didymella Group. Precipitation showed a negative influence on Alternaria, while positive correlations were observed for Didymella Group. For the first time, fungal spores considered allergenic were recorded in Montevideo atmosphere and the risk of exposure would have been high from December to June. However, long-term sampling is needed to define seasonal prevalence patterns and the influence of meteorological conditions on spore abundance.