Determination and Identification of the Common Microorganisms of Microbial Air Quality in Ten Different Subway Stations using the Fall-out Plate Method through MCTA and SDA

The outcome of this research after gram staining and microscopy procedure showed that Gram positive cocci and bacilli are the most common microorganisms that are predominantly present among the 10 stations in Toronto. Researchers conducted biochemical test for further identification of the microorganisms. Catalase test was employed which is based on the formation of bubbles due to the catalase enzyme that converts hydrogen peroxide to water and oxygen gas. All the microorganisms that are tested negative for catalase were aseptically streak in KF Streptococcus Agar, the agar use for the detection of Streptococci. However, it gave a negative result for the presence of streptococcus. Next, Milk Agar was used for casein test. This is used to identify the organism that produces caseinase, giving a negative result for the presence of Leuconostoc. On the other hand, microorganisms that are tested positive for catalase were tested if they were able to ferment glucose or not using phenol red sucrose broth. Yellow coloration of solution was the positive result. Microorganism that was able to ferment glucose were aseptically streak to Mannitol Salt Agar for the detection of Staphylococcus. MSA after incubation gave a negative result for Staphylococcus. Another test was conducted which is the Nitrate Reduction Test, those that are negative for Nitrate Reduction Test were viewed under microscope and showed that they are the microorganism called Gaffkya, a gram positive cocci in groups of 4 which are normally isolated from air, skin of man and other animals. Those who weren’t able to ferment glucose were undergo thioglycolate broth test to determine the oxygen requirements of microorganisms, showing under microscope the presence of Sarcina, an anaerobic gram positive in groups of 8 that can be found in soil, water and air. And Micrococcus an aerobic gram positive that are in clusters. The researchers also found out that Alternaria is the most common fungi present among the 10 Stations. It is a plant pathogen that is common allergens to humans, it grows indoor and can cause hay fever or hypersensitivity reaction that sometimes lead to asthma. The researchers found Gaffkya, Sarcina, Micrococcus and Alternaria proving that people are dealing with different microorganisms along with their everyday routine with the transportation system. And according to the work conducted by a WHO expert group on assessment of health risks of biological agents in indoor environments suggested that total microbial concentration should not exceed 1000 CFU/m3 (Andualem et al., 2019) thus Kennedy, Dufferin, and Victoria Park – exceeded the total microbial concentration among the 10 stations where air sample were collected. The researchers advise the public to wear mask and use alcohol and sanitizers to be safe and healthy specially this flu endemic season.