Airborne Spore Concentrations Research Articles

Airborne fungal spores in the coastal plain of Israel: A preliminary survey

Airborne spores were monitored during the years 1993–1995 in three cities along the coastal plain of Israel: Ramat Gan, Tel Aviv (Ramat Aviv) and Haifa. Seasonal fluctuations in the concentration of airborne spores were recorded. The following genera of fungi were identified:Alternaria, Cladosporium, Coprinus, Curvularia, Drechslera. Diplococcum, Epicoccum, Fusarium, Leptosphaeria, Pithomyces, Puccinia, Sphacelotheca, Stemphylium andUstilago. Unidentified spores were very rare and in negligible numbers. The dominant airborne fungal spores wereCladosporium andAlternaria. The monthly variations in airborne spores, observed among the three cities, seem to be rather minor. The recorded levels of airborne spores were below the concentrations that are accepted as threshold levels for provocation of clinical responses.

Fusarium toxins and fungi associated with handling of grain on eight Finnish farms

Farmers' exposure to airborne dust, fungi and possibly also to Fusarium toxins during the drying and milling of grain and feeding of cattle was studied on eight Finnish farms. Airborne viable and total spores were collected on polycarbonate filters. Spore concentrations and fungal flora were determined by cultivation and epifluorescence microscope counting. Eighteen airborne dust samples were taken on glass-fiber filters with a high-volume sampler, and biological toxicity was tested from those samples. In toxic dust samples, Fusarium toxins were analyzed with a gas chromatography-mass spectroscopy. Fungi and Fusarium toxins were also analyzed in ten grain samples collected from the farms during the air sampling. Yeasts, as well as species of Cladosporium, Penicillium, Aspergillus, Absidia and Fusarium occurred in the air at all three stages of grain handling. Airborne spore concentrations ranged from 103 to 10 6 cfu m −3 for viable fungi and from 10 5 to 10 7 spores m −3 for total spores; airborne dust concentrations varied from 0.04 to 81.1 mg m −3. Low deoxynivalenol concentrations (3 and 20 ng m −3) were found in two air samples collected during milling. Fusarium spp. were identified in eight grain samples, and DON concentrations of 0.004–11 mg kg −1 were detected in all samples analyzed. Although any conclusion on Finnish farmers' exposure to mycotoxins cannot be done on the basis of this small data, it can be assumed that toxigenic fungi and Fusarium toxins may occur in the air and inhalation exposure of farmers to Fusarium toxins is possible in agricultural environment.

Indoor aeromycota in relation to residential characteristics and allergic symptoms

The indoor aeromycota in several rooms of each of 15 residences in Kitchener-Waterloo, Ontario, Canada was studied from December 1991 to September 1993. There were significant differences in airborne spore concentrations among the types of rooms investigated. Numbers of airborne propagules were highest in the living rooms, followed by family rooms, kitchens, bathrooms and bedrooms. The highest fungal diversity was found in kitchens. Generally, presence of dampness and of carpets led to increased numbers of airborne spores. Forced air heating systems, humidifiers, air filters and air conditioners reduced concentrations of airborne fungi. Patients with respiratory allergies and known sensitivity to moulds reported allergic symptoms significantly less severe than average in residences with air conditioners, air filters, humidifers and forced air heating systems. In damp residences, their symptoms were significantly more severe than the average.

Prevalence of microfungi in Finnish cow barns and some aspects of the occurrence of Wallemia sebi and Fusaria.

The occurrence of microfungi in the air and in feeding and bedding materials was studied on 32 Finnish dairy farms. Air samples for determining viable and total spore concentrations were collected on membrane filters and with a cascade impactor. Genera of mesophilic, xerophilic, and thermophilic fungi were identified in four culture media. Total spore counts were done with the aid of an epifluorescence microscope. To identify fungal flora in agricultural materials, feeding and bedding material samples were also taken from the farms. The airborne spore concentrations varied for viable mesophilic, xerophilic, and thermophilic fungi from 10(1) to 10(7) colony-forming units per cubic meter, and for total spores from 10(5) to 10(7) spores per cubic meter. Aspergillus, Penicillium, Cladosporium, Absidia species, Wallemia sebi and yeasts were the predominant fungi in the air, as well as in the material samples. In general, the airborne spore concentrations were high although the variation in the concentrations of different fungal groups was large between the farms. Along with using new growth media, two fungi whose prevalence was earlier poorly known in Finland were detected. W sebi proved to be the most abundant xerophilic fungi in the air and hay samples, while Fusarium spp were very common in grain and straw but rare in air.

Monitoring airborne fungal spores in an experimental indoor environment to evaluate sampling methods and the effects of human activity on air sampling.

Aerobiological monitoring was conducted in an experimental room to aid in the development of standardized sampling protocols for airborne microorganisms in the indoor environment. The objectives of this research were to evaluate the relative efficiencies of selected sampling methods for the retrieval of airborne fungal spores and to determine the effect of human activity on air sampling. Dry aerosols containing known concentrations of Penicillium chrysogenum spores were generated, and air samples were taken by using Andersen six-stage, Surface Air System, Burkard, and depositional samplers. The Andersen and Burkard samplers retrieved the highest numbers of spores compared with the measurement standard, an aerodynamic particle sizer located inside the room. Data from paired samplers demonstrated that the Andersen sampler had the highest levels of sensitivity and repeatability. With a carpet as the source of P. chrysogenum spores, the effects of human activity (walking or vacuuming near the sampling site) on air sampling were also examined. Air samples were taken under undisturbed conditions and after human activity in the room. Human activity resulted in retrieval of significantly higher concentrations of airborne spores. Surface sampling of the carpet revealed moderate to heavy contamination despite relatively low airborne counts. Therefore, in certain situations, air sampling without concomitant surface sampling may not adequately reflect the level of microbial contamination in indoor environments.

Occupational exposure to fungal and actinomycete spores during the handling of wood chips

Abstract Concentrations of airborne spores of fungi and actinomycetes were investigated from 20 samples collected during the handling of wood chips by using a six-stage fractionating impactor (Andersen sampler). Ten samples were taken on wood chip piles or beside the chip conveyor belts of cellulose factories, and ten samples were taken beside chip conveyor belts in central heating plants of saw mills. The spore exposure level varied from 103 to 106 cfu/m3 air. Wood chips used for cellulose production released large numbers of mesophilic and thermotolerant fungi, especially Aspergillus fumigatus, indicating that spontaneous heating had occurred during the storage. By contrast, heavy exposure to Penicillium species and other mesophilic fungi was characteristic of the handling of fuel chips, which are usually only stored for short periods in saw mills. The greatest spore concentration, 3×106 cfu/m3 air (mainly Penicillium), was measured during the handling of fuel chips stored for four months. Heavy exposur...

The infection process, sporulation and survival of Alternaria helianthi on sunflower

SUMMARYElectron microscopy was used to study the infection of sunflower leaves by Alternaria helianthi. Conidia germinated by producing one to many germ tubes which grew across the leaf surface before forming appressoria. The fungus directly penetrated its host through the cuticle and epidermis. Entry into the host through wounds and stomates was also observed. Extracellular sheaths were found to be associated with germ tubes and intercellular hyphae of A. helianthi. Conidiophores developed through collapsed stomates, from leaf veins, trichomes and also from mycelium growing across the host leaf surface. Microcylic conidia were produced directly from parent conidia under certain conditions. Studies using a volumetric spore trap showed that the airborne spore concentration followed a distinct periodicity with peaks occurring between 0900 and 1100 h each day. Laboratory studies showed that safflower, noogoora burr and bathurst burr could serve as alternative hosts for A. helianthi. The pathogen was readily isolated from sunflower crop debris from a diseased crop that had been harvested 1 yr earlier.

Patterns of Diurnal and Seasonal Airborne Spore Concentrations of Fusicladium effusum and its Impact on a Pecan Scab Epidemic

Patterns of Diurnal and Seasonal Airborne Spore Concentrations of Fusicladium effusum and its Impact on a Pecan Scab Epidemic

Aerobiological studies based in Derby. III. A comparison of simultaneous pollen and spore counts from the east coast, Midlands and west coast of England and Wales.

The air spora of two sites on the east coast of Britain and one on the west coast were compared with each other and with the regular sampling site in Derby by the simultaneous operation of volumetric spore traps. Concentrations of airborne spores and pollen were found to be usually less at the coastal sites than in Derby. The effect of wind direction was shown to be important at coastal sites because daily counts often showed rises and falls corresponding to off- and on-shore winds respectively. Counts at the west coast site were nearly always lower than those on the east. These findings, together with the prevalence of westerly winds over Britain and the different land use in the east and west, suggest that fewer airborne allergens may be encountered on the west coast.

Quantitative relationships between infection by the hop downy mildew pathogen, Pseudoperonospora hutnuli, and weather and inoculum factors

SUMMARYExperiments are described in which successive groups of healthy, susceptible, potted hop‐plants were exposed, each 24 h, to the weather and to sources of Pseudoperonospora kumuli inoculum in an unsprayed hop garden for 48 h periods during May and June in 1969, 1970 and 1971. The infection which arose after standardized incubation in isolation was measured and then related, both by inspection and by multiple regression analysis, to the conditions during exposure.Severe infection could be associated with certain sequences of events in which rain contributed substantially to plant wetness; relatively light or no infection developed when dew provided the wetness of a period. Infection was markedly correlated with the occurrence of infection periods, as defined from earlier growth‐room studies, especially when dew‐wetness was omitted.The regression analysis showed that, in all years, infection was highly correlated with variables reflecting wet conditions. It was inconsistently correlated with vapour pressure deficit (VPD) and with sunshine, not at all with temperature, and with airborne spore concentration only in the combined years. The spore catches of a funnel trap, used in 1971, which depended upon rain varied closely with infection. R2 values for multiple regression equations indicated that, in the years separately and together, well over 70% of the variation in infection could be explained by the environmental variables and, in 1971, almost 90%. Variables (temperature, VPD, airborne spores) which singly were poorly correlated with infection often significantly improved regression equations which were based on variables expressing wetness. When prediction of each year's infection levels was attempted using selected regression equations calculated from data of the other 2 years there was, in general, very good agreement between measured and estimated values. The best predictions were given by an equation utilizing rain‐wetness duration, rainfall amount and airborne spore concentration while an equation based solely on relative humidity and rainfall was only slightly inferior.The results are discussed in relation to the possible value of the regression models for short‐term forecasting of hop downy mildew.

New Orleans asthma: V. Relationship between Charity Hospital asthma admission rates, semiquantitative pollen and fungal spore counts, and total particulate aerometric sampling data

A 2 year study of the relationship between climatologic variables, semiquantitative rotoslide pollen and fungal spore aerometric sampling data, and emergency room asthma admission rates at New Orleans Charity Hospital was made. An interrelationship between certain climatologic factors, high airborne spore and pollen concentrations, and asthma admission rates was noted. Large asthma “epidemics” (above 40 asthma admissions per 24 hours) occurred almost exclusively from June through December and in greater magnitude during September, October, and November. High summer asthma admission rates were significantly associated with high “total spore and pollen,” “basidiospore-like,” and “small spore” rotoslide counts. Asthma “epidemics” occurring during the peak September and October local Ambrosia pollination season were not necessarily associated with sudden influxes of Ambrosia pollen, but there was a significant relationship between high daily asthma admission rates (above 20 daily asthma admissions) and 24 hour rotoslide Ambrosia counts during September and early October. Asthma “epidemics” of considerable magnitude occurred in late October and November immediately following the peak Ambrosia pollination season. High total and “basidiospore-like” rotoslide spore concentrations plus heavy deposits of amorphous chitinous material resembling plant debris were noted on slide samples during these episodes. We currently postulate that New Orleans epidemic asthma does not involve a point source chemical or particulate pollutant but rather results from sensitization of the local atopic population by diverse natural inhalant allergens acting in seasonal patterns.

The dispersal of spores of Botrytis cinerea fr. in a raspberry plantation

The dispersal of spores of B. cinerea has been studied in a raspberry plantation at Invergowrie over 5 years. Spores are released from the conidiophores by a hygroscopic mechanism and are then dispersed by air currents or rain splash. Maximum airborne spore concentrations occur when the relative humidity is rising or falling rapidly between the approximate limits 65–85 %, but rainfall often induces dispersal at other times. Concentrations depend on the amount of sporulating material available, which in turn depends on temperature, humidity, the magnitude of previous dispersals and on the stage of development of the crop, since generally only ripe fruit and freshly exposed receptacles support sporulation. Levels of the order of 104 spores/m.3 of air have been recorded frequently during the fruiting period. The implications of the dispersal mechanisms in relation to disease control are discussed.

The infection of strawberry and raspberry fruits by Botrytis cinerea Fr.

SUMMARY Botrytis cinerea occurs abundantly throughout the year as a saprophyte and facultative parasite on a wide variety of plant materials in raspberry and strawberry plantations. Despite high concentrations of airborne spores at the time of fruit development, relatively few infections have resulted from penetration of fruit surfaces following the germination of spores in drops or films of water, uninfluenced by the presence of necrotic tissues. The majority of fruit infections are initiated from mycelium growing saprophytically in contiguous plant material or from spores germinating in solutions trapped between such material and the fruit surface.Dry spores of B. cinerea on the surface of strawberry fruits do not readily germinate in a saturated atmosphere but germinate rapidly in a water film. Although ripe and unripe fruits differ markedly in susceptibility, fruit maturity induces only small differences in the rates of spore germination. Field observations suggest that water films generally do not persist on the surface of the fruit long enough for the post‐germination infection process to be completed. Such films, however, may persist much longer when trapped between floral parts, and spores germinating there are able to initiate infections almost as soon as the buds open. The process may be accelerated by the presence of necrotic tissue, for example, in flowers damaged by frost. Mycelium infecting floral parts may subsequently invade the proximal end of both strawberry and raspberry receptacles. This mycelium may remain quiescent until the fruit ripens; consequently infected fruit may escape notice during picking and marketing.Some methods of supplementing fungicidal control measures by reducing the incidence of sources of infection are suggested.

Trapping the airspora by inhalation.

AEROBIOLOGISTS have developed various sampling techniques for investigating the concentration of airborne pollen and spores. The methods have been summarized by P. H. Gregory1. The gravity sedimentation methods on slides and Petri dishes have been superseded mainly by methods of sampling by impaction and allowing a quantitative estimation of the airspora for a given quantity of air. The two main principles of sampling by impaction are to move an object through air on a rotating device, that is, Rotorod sampler2,3, or to draw the air by pumps, fans or aspirators through niters or on to slides. So far as I know none of the impaction methods trap spores by inspiration although such devices might give the nearest estimations of the number of particles inhaled. In these experiments air is drawn through the filter of a respiratory mask.

Concentration of airborne spores in dwellings under normal conditions and under repair.

Concentration of airborne spores in dwellings under normal conditions and under repair.