BIOAEROSOL SAMPLING AND IDENTIFICATION OF AIRBORNE BACTERIA IN INDOOR AND OUTDOOR ENVIRONMENTS

Abstract

People are exposed every day to a variety of bioaerosols, including airborne bacteria, which can lead to both beneficial and detrimental effects to the environment and human beings. This study was conducted in July 2019 to investigate the air quality at a government premise in Selangor, Malaysia. The sampling sites were selected randomly at the same building. One of the samples was collected outdoors (garden), while the others were collected indoors which include the pantry, toilet, staff
rooms, store rooms, meeting room, prayer room, exhibition hall and training room. The 11 sampling sites differ from each other in terms of the presence of personnel, windows, air conditioning system, water source, organic substrates and flooring material. For bioaerosol sampling, the Andersen impaction method was applied using a Tryptic Soy Agar (TSA) non-selective media plate. Three units
of SKC biological air sampler (SKC Quick Take 30, USA) with setting of 2 min sampling time and volume flow rate of 28.3 L/min were used in each sampling location. The plates were incubated at 35 ºC for 24 h, before the bacterial colonies were observed and segregated into different groups based on their morphology, such as colours, shapes and sizes. The selected bacterial colonies were then
serially subcultured using the streaking method in order to obtain the pure colonies for identification purposes using a Biolog microbial identification system (Biolog Gen III Technology, USA). The isolates were from four genera, which were Bacillus, Staphylococcus, Micrococcus and Pseudomonas. Thirteen bacteria were identified at species level. The most dominant species was Bacillus marisflavi, which was found in all the indoor sampling sites. Meanwhile, for the outdoor sampling site, only Bacillus pumilus was found. In conclusion, airborne bacteria presence could possibly originate from outdoor sources, with human activities as the main vector of the
contamination.
Keywords: Bioaerosol; airborne bacteria; indoor and outdoor environments; biological air sampler; microbial identification system.

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