Investigation of Heterotrophic Bacteria, Legionella and Free - Living amoeba in Cooling Tower Samples by FISH and Culture Methods

Abstract

The microorganisms living in the cooling towers water can affect both human health through inhalation of aerosolized water as well as industrial processes. In order to analyse such man-made water systems, microbiological tests that can give results in a short time are needed. In this study, the presence of heterotrophic bacteria, Legionella bacteria and free-living amoeba, FLA, including Acanthamoeba, in cooling-tower water and biofilm samples were investigated using two different methods, fluorescent in situ hybridization (FISH), and culture. For this, a total of 40 water and biofilm samples were taken from 16 different cooling towers in Istanbul. FISH and culture analysis have revealed that the number of heterotrophic bacteria within the water and the biofilm samples was above the threshold values (>10 5 cell. mL-1), generally. Despite Acanthamoeba were present in all cooling tower specimens, Legionella pneumophila serogroup 1 were only detected in the biofilm of one cooling tower. According to the results of this study, both methods are recommended to be used in conjunction. Due to the the large biodiversity of FLA such as Hartmanella sp. and Naeglaria sp, there is a need for new studies utilizing FISH method for sensitive, reliable results in a short period of time.

DVC-FISH to identify potentially pathogenic Legionella inside free-living amoebae from water sources

“…FISH technique has been reported as an efficient method, better than culture, to detect Legionella in biofilms and cooling towers (Zeybek et al, 2017). This technique is not influenced by the inhibitor substances present in the environment, is able to identify VBNC cells, which have lost their ability to grow on synthetic media, and it allows to observe the morphology and even count in situ the cells present in the sample.…”

Ecology of Legionella pneumophila biofilms: The link between transcriptional activity and the biphasic cycle

“…They developed a parallel sequential FISH (par-seqFISH) to capture cells gene expression profiles, maintaining biofilm structure integrity to study cellular physical and biogeographic context. For L. pneumophila , gene expression using FISH is a promising area yet to explore, but until the present day, this technique was only applied for Legionella detection in water samples [ 189 , 190 ], industrial settings [ 191 , 192 ] and biofilms (species detection) [ 31 , 193 ].…”

İstanbul’daki Yüzme Havuzu Suları ve Biyofilm Örneklerinde Legionella ve Serbest Yaşayan Amiplerin Görülme Sıklığının Farklı Yöntemlerle Araştırılması

“…Aynı yüzme havuzlarına ait biyofilm örnekleri havuz cidarının 10 cm 2 'lik alanından steril eküvyon yardımıyla alınıp içerisinde 10 ml steril çeşme suyu bulunan santrifüj tüpü içerisine koyularak en kısa zamanda laboratuvara ulaştırıldı 9 . Alınan tüm örnekler, kültür ve floresan in situ hibridizasyon (FISH) yöntemine göre incelenmek amacıyla, güneş ışığına maruz bırakılmadan 5ºC'de en kısa zamanda laboratuvara ulaştırıldı.…”