Airborne fungi in flourmills in Croatia

Fungi are ubiquitous microorganisms that can colonise many kinds of substrata and develop in extreme environmental conditions, soils, plants and animal remains. From there they are airborne. Airspora of several species (Alternaria sp., Cladosporium sp., Aspergillus sp., Penicillium sp., Rhizopus sp.), are known to induce numerous human diseases, such as chronic bronchitis, asthma, fungal allergies, hypersensitivity pneumonitis, aspergillosis, and mucormicosis. Spores of Penicillium sp. and Aspergillus sp., as “ ; ; storage fungi” ; ; , were found in higher concentrations in cereal dust, and they can be expected in the air of grain elevators and flourmills, which present a high health risk in professional exposure according to their allergic and toxic (production of mycotoxins) potential. The aim of our study was to determine the presence and variation in occurrence of airborne fungi in flourmills in Croatia. Airspora samples ( ; ; N=172) were collected in 4 flourmills, including Jertovec (N=50), Kurilovec (N=50), Cakovec (N=32) and Hudi Bitek (N=40). Samples were collected by exposure of open Sabouraud agar plates to air for 1 hour during the manufacturing. Agar plates were incubated at 250C  ; ; 2, and qualitative and quantitative evaluation of the results was carried out after 8 days of culture. Colony forming units (CFU) were counted and identified by standard mycological techniques based upon cultural and microscopic morphology. Results were expressed as average of CFU/m2/min for fungi (moulds and yeasts) and bacteria. Frequency of mould genera was also presented with percentage of positive samples. The higher airspora concentration was found in mills Kurilovec (CFU/m2/min=68, 96) and Jertovec (CFU/m2/min=53, 28), than in Hudi Bitek (CFU/m2/min=40, 88) and Cakovec (CFU/m2/min=21, 17). The highest number of yeasts was found in Cakovec (CFU/m2/min=132, 8), and lowest in Jertovec (CFU/m2/min=0, 83). In Hudi Bitek we found great number of Gram-positive bacteria (CFU/m2/min=335, 42) and Mucoraceae, and after 10 days the growth of penicillia was observed. In all mills the most frequent genera was Penicillium sp. (from 81 to 94%). Aspergillus sp. was present with high frequency in Cakovec (47%), Kurilovec (66%) and Jertovec (88%), but it was not found in Hudi Bitek. Rhizopus sp. was found with highest frequency in Hudi Bitek (92%), while it was present with lower percentage in other 3 mills (from 19 to 54%). Mucor sp. was found in relative high frequency in Cakovec (37%) and Hudi Bitek (47%), low in Kurilovec (4%) and it was not detected in Jertovec. Cladosporium sp. was present in all mills but with relative low frequency (from 10% to 28 %). Other isolated genera including Absidia sp., Alternaria sp., Cladophora sp., Botrytis sp., Pithomyces sp., Phoma sp., Trichoderma sp., Ulocladium sp. and other moulds varied in range from 2 to 30% of positive samples. Conclusions are: The most frequent fungi genera that can be found as contaminants of air in mills are Penicillium sp. (from 81 to 94%), Rhizopus sp. (from 19 to 92%) and Aspergillus sp. (from 47 to 88%). Absence of aspergilla in Hudi Bitek can be consequence of high contamination with bacteria. High number of bacteria can also be a reason for absence of other moulds, propulsive growth of Mucoraceae, and delayed growth of penicillia. Our data reveal that, due to their high incidence and variety, fungi can play a significant role in allergic and non-allergic diseases in working environments.