The effect of different incubation conditions and culture media on airbone bacteria and fungi level

The choice of culture media used for airborne bacteria and fungi sampling is the most critical factor that quantitatively affects the determination of bacteria and fungi. In this study, simultaneous bacterial and fungal samples were collected in the air of Izmir city center using eight different media types. Bacterial samples were collected on Columbia blood agar (CBA), Chocolate agar (Choc), Tryptone Glucose Yeast Extract Agar (TGEA), Reasoners 2A agar (R2A) and Plate Count Agar (PCA) media, and these samples were conditioned at two different incubation temperatures and periods. The growth of bacteria was followed at 37 C-degrees for 2 days and at 50 C-degrees between 2 and 15 days. Malt-Extract Agar (MEA), Dichloran Rose Bengal Chloramphenicol (DRBC) and Potato Dextrose Agar (PDA) media were used for fungi samples. All fungal samples were incubated at 25 C-degrees for 3-7 days. At the end of the incubation period, the number of colonies and total bacteria and fungi concentrations was determined. The incubation temperature was determined to affect the total bacteria concentrations in other media except for PCA (p>0.05). Cladosporium sp was the most frequently observed genus in fungal samples collected on three media. In terms of colony numbers, the media were sorted as PDA>MEA>DRBC. Among the fungi, the number of colonies of Chrysosporium sp. formed in the MEA medium was approximately ten times higher than in PDA and DRBC. The order of the maximum number of isolated fungi in the media used for the samples collected simultaneously is MEA>DRBC>PDA. This research is the first study to determine the concentrations of stable bacteria and fungi that can withstand extreme conditions (50 C-degrees) under different incubation conditions, as it will guide future airborne microorganism sampling in urban areas with the variety of media and incubation conditions it has examined. In addition, this study is also important because the World Health Organization has invited countries to fight against the threat of Antimicrobial Resistance in recent years.