REVIEW ARTICLES AAEM Ann Agric Environ Med 2008, 15, 1–7
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REVIEW ARTICLES AAEM Ann Agric Environ Med 2008, 15, 1–7 AEROMYCOLOGY – MAIN RESEARCH FIELDS OF INTEREST DURING THE LAST 25 YEARS Idalia Kasprzyk Department of Environmental Biology, University of Rzeszów, Poland Kasprzyk I: Aeromycology – main research fi elds of interest during the last 25 years. Ann Agric Environ Med 2008, 15, 1–7. Abstract: Fungal spores occur very numerously in the air and, on account of their di- mensions (several micrometers), are classed as bioaerosols. They are always observed in natural air and their concentration changes depending on environmental conditions. Aero- mycology investigates their occurrence in the air of the indoor-outdoor environment. The methods of sampling can be divided into the gravimetric method when the spores fall onto a catching surface by force of gravity, and the volumetric method consisting of analysis of spores contained in a given air unit. The content of fungal spores in air is characterized by a specifi c seasonal and diurnal cycle. Among other things, these cycles depend on climate and weather conditions, on the accessibility of fresh substrates for the development of the fungus, circadian cycle of light and darkness, and other environmental hardly defi nable factors. Many fungi undesirably affect human health, cause immunotoxic diseases, and are a frequent cause of allergic diseases. Knowledge of concentrations of airborne fungal spores is especially important for agricultural and occupational medicine. Aeromycology has its application in agrobiology, particularly with respect to pathogenic fungi, and in the conservation of the artistic heritage. Address for correspondence: Dr Idalia Kasprzyk, Department of Environmental Biology, University of Rzeszów, Rejtana 16c, 35-959 Rzeszów, Poland. E-mail: [email protected] Key words: aeromycology, allergy, bioaerosol, fungi, fungal spores, indoor fungal spores, outdoor fungal spores, seasonal variation. INTRODUCTION Fungi produce varied forms of spores which are dif- ferently, i.e. actively or passively released (blown away, Numerous airborne organisms, their fragments as well rinsed-off or shaken out); however, their further fate usu- as particles of biological origin passively fl oat in the at- ally depends on the wind [19, 31, 35, 50]. The wind is a mosphere. Small insects, bacteria; viruses; plant pollen; blind vector, hence an abundant production of spores is diaspores; fragments of tissues and talli, and such organic necessary for the fulfi llment of their biological function compounds as mycotoxins or allergens can be found in the [19]. Because of their size, fungal spores can cover enor- air. Fungal spores are in this group of particles which are mous distances with air currents [32]. The distant transport very numerous in the air and, on account of their dimen- is unimportant for the development of the fungus unless its sions (several micrometers), are classed as a bioaerosol [6]. spores are viable [19, 35]; however, even a dead spore can They are always observed in natural air and their concen- contain an allergen dangerous for humans. tration changes depending on environmental conditions. Airborne spores occur detached from the spawn which Aerobiology, and especially its branch aeromycology, in- produced them. This is one of many reasons which make vestigates their occurrence in the air of the indoor-outdoor their precise identifi cation diffi cult or even impossible. environment. Rare spores only can be easily identifi ed in spite of their Received: 20 May 2005 Accepted: 6 December 2007 2 Kasprzyk I abundance. Usually, the spores are identifi ed as to spe- occur in the indoor environment, produce mycotoxins cies and the result is often debatable, hence in numerous noxious for living organisms, and often cause allergic, cases the identifi cation is limited to the type, for example immunotoxic diseases [5, 22, 27, 28, 34]. Conidia of the Drechslera, Penicillium/Aspergillus or even to groups: genera Alternaria and Cladosporium are most frequently “coloured basidiospores” or “hyaline ascospores” [1]. The identifi ed using the volumetric method because they occur problem is more diffi cult because the taxonomy of fungi is at high concentrations in air at almost all geographical lati- not complete [29]. Hence, Southworth [63] advises begin- tudes [1, 35, 52, 56, 68] and are important both in medicine ing aeromycological investigations by concentrating on a and agrobiology [10, 11, 22, 27, 64]. Among other genera few to several well discernible spores. of fungi whose spores can be identifi ed on the basis of their This paper is a revision of the different types of the aero- morphology are Botrytis, Chaetomium, Coprinus, Didy- mycological researches published during the last 25 years. mella, Entomophtora, Epiccocum, Erysiphe, Ganoderma, The articles concern the seasonal and diurnal occurrence Nigrospora, Pithomyces, Polythrincium, Stemphyllium, of fungal spores in outdoor and indoor environments, the Torula and Ustilago [8, 12, 16, 22, 28, 52, 57]. infl uence of weather conditions on the fungal spore counts in air, the duration and course of fungal spore seasons. FUNGAL SPORES IN AIR The second part of the references refers to the possibility of practical applications, mainly in medicine, agriculture, The content of fungal spores of every taxon in air is followed by heritage. This revision concerns mainly a Eu- characterized by a specifi c seasonal and diurnal cycle [7, ropean study. 37, 38, 39, 51, 56, 70]. Among other things, these cycles depend on climate and weather conditions [29, 32, 41, 41, METHODS IN AEROMYCOLOGY 66], on the accessibility of fresh substrates for the develop- ment of the fungus, circadian cycle of light and darkness, Various investigative techniques are used in aeromyco- and other environmental hardly defi nable factors [27, 63]. logical studies. The method of sampling can be divided in The effect of all these factors is fairly complicated and dif- the gravimetric method, when the spores fall down on a fi cult to investigate. catching surface by force of gravity, and the volumetric Airborne fungal spores occur throughout almost the method consisting in an analysis of spores contained in a whole year, but the seasonal rhythm in the occurrence of given air unit [35]. When the method of analysis is consid- airborne spores and their spectrum depends on the type of ered, we can speak about the method of culturing on media climate [1, 7, 9, 16, 52, 61]. In the conditions of a mod- (e.g., the Koch sedimentation method) and microscopic erate climate the maximum concentration of most spores analysis (the Burkard or Lanzoni apparatus). The Andersen occurs in summer or early autumn (Fig. 1) [10, 38, 57]. impactor is a facility that combines the volumetric method In Europe, differences in the pattern of these phenomena with the culture on media. It is constructed of six segments are fairly inconspicuous [12]. In tropical and subtropical with fi lters of diminishing diameters and with Petri dishes. regions the greatest abundance of spores is noted in cold The apparatus sucks in a defi nite volume of air and biologi- months (November-February) and the smallest in the warm cal particles of specifi c diameter are caught on respective ones (May-September) [2, 30, 46]. Daily concentrations segments. They are then cultured on standard agar media may differ signifi cantly in the following seasons and in dif- in Petri dishes. The content of spores in air is estimated on ferent habitats. The differences may concern seasonal sums the basis of the obtained colonies. In the Hirst spore trap of total spores, the concentrations, duration of seasons, as (Burkard or Lanzoni apparatuses), biological particles are well as time of maximum occurrence (Fig. 1) [38, 39, 57]. sampled together with sucked in air (10 l/min) and are stuck Calderon et al. [8] stress the role of the microclimate. In to a sticky band on a cylinder moving at a constant speed. highly urbanized areas the phenomenon of an urban heat The material is microscopically analysed and the obtained island can affect seasonal and circadian changes in the con- result expressed as a daily average of fungal spores/1 m3 of centration of airborne spores. air [6]. The assessment of the concentration of spores in a Weather conditions affect the sporulation, dispersal and 24 h/cycle is also possible; however, in this case the viabil- deposition of spores and their elements correlate with each ity of the spores cannot be established [35]. The different other. Conditions that prevailed a few days earlier fre- methods have their drawbacks and merits and the results quently infl uenced the current concentrations [32, 41, 49, cannot be directly compared, as depending on the method 61]. In spite of these complicated dependences, and the ef- applied the list of spores occurring in air and reliably iden- fect of weather conditions being taken into consideration, tifi cation is different [31, 57, 64, 61]. Thus, if we use the most authors divide fungal spores into the wet and dry culture on media we can precisely assess the occurrence of weather. The fi rst group consists of spores whose concen- conidia of numerous species of the genera Aspergillus spp. tration increases in wet and warm weather. Ganoderma, and Penicilium spp. [24, 34, 70], but it would be very diffi - Leptosphaeria and Didymella are classed in this group. cult to identify them using the volumetric method owing to In the circadian cycle the greatest concentrations occur at their great morphological similarity. These fungi frequently night and in early morning in conditions of the highest air Figure 1. Figure Epicoccum development, sporulationanddispersalof anddryweatherfavoursthe Warm humidity [1,7,30,37]. where they can grow. Fungalsporesoccurintheairalmost where theycangrow. concentration ofsporesisthe accessibilityofsubstrates ues ofhumidityarerecorded [1, 4,37,63,64]. when thehighesttemperature prevailsandthelowestval- genera usuallyoccursatnoon andintheafternoonhours, greatest dailyconcentrationofconidiatheabove-given Another signi spores/m3 spores/m3 spores/m3 12000 200 400 600 800 100 200 300 3000 6000 9000 0 0 Daily fungalsporeconcentrationsofchosentypesintheatmospherea ruralarea(Krasne,SEPoland)in2001–2002years.