Estimation of fungal spore concentrations associated to meteorological variables

A 1-year time series of fungal spore concentrations has been used to calibrate an artificial neural network for the estimation of Alternaria and Pleospora concentrations associated to observed meteorological variables. Analysis of the results revealed that the daily average values of these meteorological variables are suitable to predict with high confidence the number of fungal spores that are actually observed. The calibrated neural network has also been used randomizing each single input parameter in order to evaluate which meteorological variable contributes more to the formation and the depletion of the selected fungal spores. Emphasis is given to the possibility of using the proposed model for operational activities, predicting the future spore concentrations on the basis of meteorological forecasts.     

Comparison of airborne spore concentrations and fungal allergen content

The exposure to spores causing health effects is usually assessed by determining the concentration of viable spores per cubic meter of air (CFU/m³).Since allergens might also be present in dead spores or smaller particles, the objective of this study was to investigate the correlation between the viable spores of Alternaria and Cladosporium at different indoor and outdoor sites and the corresponding allergen concentration detected with a specially developed ELISA (Enzyme Linked Immunosorbent Assay). In outdoor air, the results show a strong correlation between the different sampling techniques applied for viable spores (Slit-Sampler and Multistage Liquid Impinger) and between the viable spores and the allergen concentrations detected in the liquid samples of the impingers. Indoors, the number of viable spores and the allergen concentration do not correlate and the allergen load is underestimated if colony counting methods are used. This revised version was published online in June 2006 with corrections to the Cover Date.     

Variation in the airborne fungal spore population of the Tuscarawas Valley II

For years the medical profession has recognized a relationship between fungal airspora and the incitement of respiratory allergies. An evaluation of outdoor fungal airspora on an eastern Ohio campus during June 1988 revealed significant differences in quality and quantity with respect to microenvironments. Type of vegetation, diurnal periodicities, and daily weather conditions affected the airspora at each site. Shaded lawns within groves and windbreaks, unshaded lawns, and asphalt-covered parking lots presented varying dynamics for fungal spore liberation. Unshaded lawns produced airspora most abundantly during morning and least abundantly during afternoon. Arboreal sites produced airspora most prolifically at midday. A deciduous sycamore grove produced fewer afternoon airspora than evergreen pine and arborvitae stands. Evening airspora at all vegetated sites increased after experiencing afternoon troughs. Frequently encountered molds included Cladosporium spp., brightly pigmented sterile mycelia, and Alternaria spp.     

Seasonal variation of airborne fungal spore concentrations in a vineyard of North-West Spain

Conidial types collected daily in the air above a vineyard in northwest Spain were identified and counted. A total of 26 fungal spore types were recognised; ten of which (Cladosporium, Botrytis, Fusarium-Leptosphaeria type,Torula, Puccinia, Alternaria, Uncinula, Helminthosporium type,Agrocybe andStemphylium) gave a seasonal total concentration exceeding 1000 spores. Seasonal patterns are shown for 12 of the identified taxa.     

Diurnal variation in airborne pollen concentrations of the selected taxa in Zagreb, Croatia

The number of individuals allergic to plant pollen has recently been on a constant increase. The knowledge of diurnal distribution and abundance of allergenic pollen types, their patterns and response to source position and weather is useful to correlate hay fever symptoms with the presence of allergenic pollen in the atmosphere. The aim of this study was to determine diurnal distribution of total airborne pollen, pollen of particular allergenic taxa, possible variation in diurnal pollen distribution at measuring sites placed at different heights, and effect of some meteorological parameters on airborne pollen concentrations. A 7-day Hirst-type volumetric pollen trap was used for pollen sampling. Qualitative and quantitative pollen analysis was performed under a light microscope (magnification x400). Total pollen of all plant taxa (Ambrosia sp., Betula sp., Cupressaceae, Urticaceae, Poaceae, Quercus sp., Fraxinus sp., Alnus sp., Corylus sp., Populus sp., Pinus sp., Picea sp.) observed showed a regular diurnal distribution at both sampling sites in both study years, with a rise in the pollen concentration recorded after 4.00 a.m. and 6.00 a.m., respectively. The peak pollen concentration occurred between 12.00 a.m. and 4.00 p.m., and the lowest diurnal pollen concentrations were recorded overnight. About 50% of the 24-h pollen concentration were released to the atmosphere between 10.00 a.m. and 4.00 p.m. The timing and size of diurnal peaks were closely related to high temperature, low humidity and south-west maximum wind direction.     

Photocontrol of fungal spore germination

Germination of Puccinia graminis f. sp. tritici uredospores is inhibited by continuous irradiation. Prehydration of spores enhances both dark germination and photoinhibition. Simultaneous irradiation with ineffective red (653 nanometers) and inhibitory far red light (720 nanometers) results in partial nullification of the inhibition brought about by far red light alone. This result would be consistent with the involveent of a photoreversible pigment system similar to phytochrome, operating via the high irradiance reaction.     

Water relations of fungal spore germination

Summary A simple mathematical model, based on the physiology of spore germination of Penicillium roqueforti and Trichoderma viride TS, is proposed and tested to determine germination kinetics of filamentous fungi. The influence of water and of the nature of the solute used to depress the water activity on conidial germination of these two fungi are discussed. The water activity value of the medium is the main factor but the water molar fraction seems to explain certain observed variations in germination kinetics. The best solutes for germination are those which present the greatest deviation from Raoult's law.     

Preliminary studies on the effect of the Burkard alternate orifice on airborne fungal spore concentrations

The Burkard 7-day spore trap with standard orifice is commonly used by researchers in sampling outdoor air. The alternate orifice is reported to have higher efficiency in collecting small airborne fungal spores; however, no previous studies compared Burkard samplers with different orifices. This study was conducted to study the effect of the alternate orifice on the concentration of airborne fungal spores. Air samples were collected from July to October 2005 with two Burkard spore traps, one had the standard orifice and the second had the alternate orifice. The two spore traps were located on the roof of a building (12 m height) at the University of Tulsa, Oklahoma. Burkard daily slides were analyzed for airborne spores by light microscopy. The data from the two samplers were statistically analyzed using t-tests. The results indicated that the alternate orifice had significantly higher concentrations of Penicillium/Aspergillus-type spores and basidiospores than the standard orifice. By contrast, the standard orifice had significantly higher concentrations of Alternaria, ascospores, and other spores than the alternate orifice. The alternate orifice can be used to increase the efficiency of trapping small spores, which can be underestimated by using the standard orifice. However, additional comparison in other months of the year is recommended.     

Low allelochemical concentrations detected in garlic mustard-invaded forest soils inhibit fungal growth and AMF spore germination

Garlic mustard’s (Alliaria petiolata, Brassicaceae) invasive success is attributed in part to its release of allyl isothiocyanate (AITC) into the soil. AITC can disrupt beneficial arbuscular mycorrhizal fungi (AMF) associated with native plant roots, which limits their soil resource uptake. However, AITC and its precursor, sinigrin, have never been detected in garlic mustard-invaded forest soils. Here, we use high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC–MS) to assess the concentration and bioactivity of these putative allelochemicals in paired forest plots uninvaded or invaded by garlic mustard. Our methods detected AITC and sinigrin only where garlic mustard was present and our recovery of AITC/sinigrin coincided with adult senescence. A bioassay of in situ fungal hyphae abundance revealed significantly reduced hyphal abundance in the presence of garlic mustard relative to uninvaded soils. Finally, the lowest concentration of AITC measured in the field (~0.001 mM) is highly inhibitory to the spore germination of a forest AMF species, Glomus clarum. Together, our data provide the first direct evidence of garlic mustard-produced sinigrin and AITC in forest soils and demonstrate that even low levels of these chemicals have the potential to significantly suppress AMF growth and spore germination, strengthening their status as allelopathic novel weapons.     

A comparative study of hourly and daily relationships between selected meteorological parameters and airborne fungal spore composition

Air sampling was conducted in Szczecin (Poland) throughout April–September 2013. The final data set included 177 daily and 4248 hourly samples. The total of 21 types of spores, which occurred in a number >10 in the season, were taken into account. The following meteorological parameters were analyzed: air temperature, relative humidity, precipitation and wind speed. Effects of individual weather parameters on hourly and daily concentrations of different fungal spore types were examined using Spearman’s rank association test, whereas effects of complex of meteorological factors on hourly and daily compositions of spore were assessed using detrended correspondence analysis (DCA) and redundancy analysis (RDA). Airborne fungal spore distribution patterns in relation to meteorological variables were determined by RDA, after DCA results detected a linear structure of the spore data. The RDA results obtained indicated that all the applied variables accounted for 20 and 22% of the total variance in the hourly and daily spore data, respectively. The results of stepwise forward selection of variables revealed all included hourly and daily meteorological variables were statistically significant. The largest amount of the total variance in the spore composition was explained by the air temperature in both cases (16%). Multivariate ordination did not show large differences between the hourly and daily relationships (with exception of wind speed impact), while the differences between simple hourly and daily correlations were more clear. Correlations between daily values of variables were in most cases higher than between hourly values of variables.     

Form and function of fungal spore appendages

A wide variety of fungi have spores with appendages or mucilaginous sheaths, which are most elaborate in aquatic ascomycetes, especially marine species. The form and structure of a wide range of appendaged spores are documented from both taxonomic and ecological fungal groups, and their role in nature is discussed. The effect of environmental factors on appendage development and how ascospores are adapted for release from asci are reviewed. How fungi evolved such a variety of appendages in form and structure is also discussed. This article is dedicated to the late Professor Keisuke Tubaki for his invaluable contribution to mycology and for all his encouragement and support to the author over many years. I appreciate the invitation of the Japanese Mycological Society to write on the above subject, congratulate the society on their 50th anniversary, and wish it well in the coming years.     

Obtaining a spore free fungal community composition

Understanding basic ecological processes within fungal communities is complicated by the cryptic and often below-ground habitat of most fungi. Up to now, molecular methods, enabling analyses of community processes and interaction strategies, have been mainly based on internal transcribed spacer (ITS) DNA analyses. The fact that these DNA profiles are contaminated by dormant propagules and dead material is a well known draw-back, obscuring sound conclusions. Recently, precursor ITS rRNA was suggested as a solution to this problem, as it was hypothesised that dormant and dead material contains little or no precursor rRNA. Our results show that basidiospores do not contain precursor ITS rRNA and thus confirm this hypothesis. This implies that the precursor ITS rRNA should be used for analysis and characterization of active species composition, when contamination of ungerminated basidiospores should be avoided.     

Mitochondrial DNA synthesis during fungal spore germination

Summary Germinating spores of the fungus Botryodiplodia theobromae incorporated guanine-8-C¹⁴ into both the nuclear DNA and mitochondrial DNA fractions. Ethidium bromide inhibited the synthesis of mitochondrial DNA without having a significant effect on nuclear DNA synthesis or on the rate and extent of spore germination. Rates of leucine and uracil incorporation and of oxygen uptake were not significantly affected by ethidium bromide until germination was nearly completed. Mitochondrial DNA synthesis is apparently not required for germination of the spores of B. theobromae but is probably essential to continued vegetative growth.Abbreviations DNA deoxyribonucleic acid - mit-DNA mitochondrial DNA - nuc-DNA nuclear DNA - RNA ribonucleic acid - EB ethidium bromide - Tris tris (hydroxymethyl)aminomethane Published with the approval of the Director as Paper No. 3331, Journal Series, Nebraska Agricultural Experiment Station. Research reported was conducted under Project No. 21-17. Paper No. 7877, Scientific Journal Series, Minnesota Agricultural Experiment Station.     

Lateral fungal spore movement inside a simulated wall

Moisture inside walls can facilitate mold growth if left untreated. Once spores become airborne they may interact with pressures inside walls. Two laboratory experiments were conducted to determine if airborne spores have the potential to migrate laterally inside walls with and without wiring installations. A simulated wall was fabricated, and Penicillium chrysogenum spores were aerosolized into a distant stud bay and an adjacent stud bay. The wall was subjected to a typical indoor pressure. Spore levels inside the bays were sampled, and a total of 36 trials (n = 36) were conducted. Results of Kruskal–Wallis tests revealed that spore levels inside the sampling bay and the distant bay with wiring installations were not significantly different. Spore levels inside the sampling bay were significantly lower than the adjacent bay without wiring installations (P < 0.05). The findings of the study suggest airborne fungal spores have the potential to move laterally inside walls.     

An evaluation of two methods used for microscopic analysis of airborne fungal spore concentrations from the Burkard Spore Trap

The Burkard Volumetric Spore Trap is a common and efficient instrument used to collect outdoor air samples. In North America, two slide counting methods have been widely used by aerobiologists: the single longitudinal traverse method and the twelve transverse traverse method. The purpose of this study was to compare the two counting methods by assessing fungal spore concentrations of ascospores, basidiospores, smut teliospores, Cladosporium, Alternaria, Epicoccum, Curvularia, Drechslera, Pithomyces, other spores, and total spores at two metropolitan Tulsa, Oklahoma sites (Tulsa and Hectorville) during September 1996. Results showed that both methods were sensing parallel fluctuations in average daily spore concentration, although the twelve transverse traverse method usually resulted in higher concentrations. At the Tulsa site, the twelve transverse traverse method gave statistically higher concentrations than the single longitudinal traverse method except for Epicoccum, Pithomyces, smut teliospores, and other spores. At the Hectorville site, however, only Cladosporium and basidiospores showed that the twelve transverse traverse method was statistically higher than the single longitudinal traverse method. Comparison with concentrations obtained by counting the total slide surface of two slides indicated that neither method was equivalent to the total slide spore count, although the twelve transverse traverse method gave a lower absolute percent difference from the total slide surface concentration. While the twelve transverse traverse method gave slightly better approximations of the spore concentration, the increase in accuracy may not justify the extra effort required to analyze with this method.     

A study of fungal spore poupulations in the atmosphere of Kuwait

The fungal air-spora of Kuwait was investigated using the Petri-dish trapping technique. During the period from 1st April, 1974 to 30th June, 1975, a total of 3685 colonies were recorded from 2 % malt agar plates. Fifty-five genera and 116 species were identified. Alternaria occupied the first place in the order of percentage incidence, being represented by 18.3% of the entire catch, followed by Aspergillus (17.1%), Penicillium (14%), Cladosporium (13.6%), Drechslera (13.3%), and Ulocladium (7.1%). The widest spectrum of species was displayed by Aspergillus (possessed 19 species) followed by Penicillium (17 species), Alternaria (6 species), Drechslera (5 species), and Ulocladium (4 species). The monthly total number of fungi showed marked seasonal periodicity with the greatest number of colonies occurring in March–April and November. The lowest counts were recorded in mid-summer (July) and mid-winter (January). Only 220 colonies and 17 species of thermophilous fungi were reported from plates incubated at 45 °C. The most common species were Aspergillus fumigatus and A. terreus.     

Airborne fungal spore monitoring: between analyst proficiency testing

Aerobiologia - This study presents the results of a Europe-wide training and Quality Control (QC) exercise carried out within the framework of the European Aerobiology Society’s QC Working...