Morphological And Molecular Identifications Of Aspergillus spp. Isolated From Enclosed Buildings In Peninsular Malaysia
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Date
2012-03
Authors
Abdul Rahman, Wardah
Journal Title
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Publisher
Universiti Sains Malaysia
Abstract
Aspergillus is frequently found and easily spread in almost any type of environments. The potentially pathogenic, allergenic and toxigenic of Aspergillus have been reported previously. As most individuals spent more than 80% of their time indoors, the occurrence of Aspergillus in indoor environment is crucial to human health. Moreover, bioaerosols which also consists of Aspergillus spores could be one of the main factors in controlling a good Indoor Air Quality (IAQ). In Malaysia, reports on the occurrence of Aspergillus in indoor environments are still limited and rarely reported. In the present study, Aspergillus species were consistently found in all indoor air environments with a total of 117 isolates were obtained from nine states in Peninsular Malaysia. Through morphological identification, Aspergillus niger (45 isolates; 38%) were the most common species isolated from the indoor environment followed by Aspergillus japonicus (32 isolates; 27%), Aspergillus flavus (21 isolates; 18%), Aspergillus fumigatus (14 isolates; 12%), Aspergillus sclerotiorum (3 isolates; 3%) and Aspergillus ochraceus (2 isolates; 2%). Each species were identified and characterized based on primary characteristics or micromorphology (seriation, sizes and shapes of vesicles, conidia and conidiophores) and secondary characteristics or macromorphology (conidial and mycelia colour,
colony diameters and the presence of exudates and sclerotia). In molecular study, DNA sequences of non-coding regions of ribosomal DNA (rDNA), namely Internal Transcribed Spacer (ITS1 and ITS2) were analyzed separately. BLAST search for sequence similarity by using the GenBank database demonstrated 81% to 100% sequence similarity in ITS1 region, and 82% to 100% in ITS2 region. In both regions, phylogenetic trees which were constructed by using Neighbour Joining (NJ) and Maximum-Parsimony (MP) methods showed higher interspecies variation with most of the isolates were successfully clustered according to the species. The present study proved that both ITS1 and ITS2 regions should be used for a more accurate identification and characterization of Aspergillus species. This is the first comprehensive record of Aspergillus species from enclosed buildings in Peninsular Malaysia.
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Keywords
Morphological and molecular identifications of Aspergillus spp , isolated from enclosed buildings In peninsular Malaysia