Aeromycoflora of Dhaka city, Bangladesh

Abstract

The air influences every aspect of life and the activities of organisms affect the air. Sources of air borne microorganisms are everywhere. They are in food, water, on utensils and on bed sheets. The indoor and outdoor air is an important source of aeroallergens and pathogens. During the present investigation, monthly sampling of air borne mycoflora of Dhaka Metropolitan City, during February 2013 to January 2014 was recorded. The fungal colonies developed in PDA media were isolated from five different locations in the morning and evening in monthly intervals. The total number of counted fungal colonies were 6648 out of which in the morning was 3268 and in the evening it was 3380 and 156 colonies were sterile mycelia. The sampling sites were Sher-e Bangla Agricultural University, Gulistan, Dhaka Medical College, Sadarghat and DOHS, Mohakhali. The qualitative nature of the mycoflora, their mean, standard deviation, percent frequency and correlations to the total mycoflora, monthly periodicity have been described in this investigation. In this study, fifteen genera have been recorded viz. Alternaria, Arthrinium, Aspergillus, Bipolaris, Chaetomium, Cladosporium, Colletotrichum, Curvularia, Fusarium, Nigrospora, Penicillium, Pestalotia, Rhizopus, Syncephalastrum and Trichoderma under the class Ascomycetes, Zygomycetes and Deuteromycetes. Local fluctuations of the air borne fungi in relation to some meteorological parameters were also studied. The three most dominant fungal species were Aspergillus, Cladosporium and Penicillium contributing 30.71, 18.10 and 12.79% in the evening and in the morning it was 28.82, 15.78 and 11.53% in twelve months counting of the total colonies, respectively. Aspergillus was found in the highest frequency in the present investigation among the identified genera. In the present study Cladosporium was found 2nd position in term of its percent frequency. Maximum number of fungal colonies were found in Gulistan and Sadarghat in the morning and evening. During the twelve months investigation maximum fungal colonies were found in August and September as all the climatic factors were favorable for the fungal growth, their dispersal and survival. Among the fungi, found in the present investigation Alternaria, Aspergillus, Chaetomium, Cladosporium, Curvularia, Fusarium, Penicillium and Rhizopus were reported as pathogenic to plants and/or human and strongly allergenic to human. Bipolaris, Colletotrichum, and Pestalotia were reported as only plant pathogens. The present study contributes to our knowledge of air borne spores in the Dhaka City. Regular monitoring of air borne fungi can be helpful in the prevention of fungal allergic diseases in the city.