Farklı inkübasyon koşullarının ve kültür ortamlarının havadaki bakteri ve mantar düzeyine etkisi
Havadaki bakteri ve mantarların örneklenmesinde kullanılan besiyerlerinin seçimi, bakteri ve mantarların nitel ve nicel olarak doğru belirlenmesine etki eden en önemli faktördür. Bu çalışmada, 8 ayrı besiyeri türü kullanılarak İzmir kent merkezi havasında eş zamanlı bakteri ve mantar örnekleri toplanmıştır. Bakteri örnekleri, Columbia blood agar (CBA), Chocolate agar (Choc), Tryptone Glucose Yeast Extract Agar (TGEA), Reasoner's 2A agar (R2A) ve Plate Count Agar (PCA) besiyerleri üzerinde toplanmış ve bu örneklere iki farklı inkübasyon sıcaklığı ve süresi uygulanarak bakterilerin gelişimi 2 gün boyunca 37 ᵒC ve 2 ile 15 gün arasında 50 ᵒC sıcaklıkta takip edilmiştir. Mantar örnekleri için ise Malt-Extract Agar (MEA), Dichloran Rose Bengal Chloramphenicol (DRBC) ve Potato Dextrose Agar (PDA) besiyerleri kullanılmıştır. Bunların tamamı ise 25 ᵒC’de 3-7 gün inkübe edilmiştir. İnkübasyon süreleri sonunda besiyerlerinde üreme gözlenen koloni sayıları ve toplam bakteri ve mantar konsantrasyonları belirlenmiştir. İnkübasyon sıcaklığının PCA hariç (p>0.05) diğer besiyerlerinde toplam bakteri konsantrasyonlarını etkilediği belirlenmiştir. Üç besiyerinde toplanan mantar örneklerinde en çok gözlenen cins Cladosporium sp’dir. Koloni sayıları bakımından besiyerleri PDA>MEA>DRBC şeklinde sıralanmıştır. Mantarlar arasında Chrysosporium sp. cinsinin MEA besiyerinde oluşturduğu koloni sayısı, PDA ve DRBC besiyerlerindekinden yaklaşık 10 kat daha fazladır. Eş zamanlı toplanan örnekler için kullanılan besiyerlerinde maksimum sayıda izole edilen mantar cinsi sıralaması MEA>DRBC>PDA şeklindedir. Bu çalışma, incelediği besiyeri ve inkübasyon koşulları çeşitliliği ile gelecekte kentsel bölgelerde yapılacak bakteri ve mantar örneklemelerine yön göstereceği gibi ekstrem koşullara (50 ᵒC) dayanabilen havadaki dirençli mikroorganizmaların farklı inkübasyon koşulları altında konsantrasyonlarının belirlendiği ilk çalışma niteliğindedir. Ayrıca, bu çalışma son yıllarda Dünya Sağlık Örgütü’nün Antimikrobiyal Direnç tehdidine karşı ülkeleri mücadeleye davet etmesi sebebiyle de önemlidir.
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), Reasoner's 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 ᵒC for 2 days and at 50 ᵒC 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 ᵒC 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 ᵒC) 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.
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