Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı 2

Identification of Proper Methods to Determine Legionella pneumophila Bacteria Exposed to Different Environmental Conditions
Legionella species bacteria are pathogenic bacteria that are present commonly in natural water and human-made water systems with 59 species and 70 different serotypes and that causes Legionnaries’ disease and Pontiac fever. Legionella species bacteria reproduce due to suitable conditions as they pass through the human-made water systems such as cooling tower, shower head, air conditioners, spa and pools. Legionella bacteria pass to the VBNC (viable but non-culturable) phase due to the presence of other microorganisms in the environment and the environmental conditions such as starvation, temperature, pH and disinfectants.
At the first stage of our study, it was determined lowest detection limit of L. pneumophila by using traditional culture, fluorescent in situ hybridization (FISH) and semi-nested polymerase chain reaction (PCR) methods in L. pneumophila ATCC 33152 bacteria and environmental L. pneumophila isolate at different concentrations (10²-10¹⁰ cell per liter). At the second stage of our study, it was aimed to determined the most suitable method for determination of recovery usage water samples that are contaminated by L. pneumophila bacteria at 10⁸ cell per liter concentration at different times at different temperatures (5 °C, 50 °C, 55 °C and 60 °C), pH (2.2, 5.8, 7.0, 8.2) and Huwa-san TR⁵⁰ biocide dosage (100 ppm and 200 ppm).
When the recovery results of L. pneumophila bacteria are evaluated depending on the concentration; the most suitable method for the recovery of the samples including L. pneumophila bacteria at lower concentrations were determined as the culture method (10³ cell per liter). In order to have recovery depending on concentration via the methods applied; it was found that at least 10³ cell per liter for the culture method, 10⁵ cell per liter for the FISH method and 10⁶ cell per liter L. pneumophila bacteria for the semi-nested PCR method should be present in the water sample.
When the recovery of L. pneumophila bacteria were assessed among the water samples including L. pneumophila bacteria that were exposed to different environmental conditions; it was found that the maximum recovery ratio was provided via the FISH method in biocide application at 24 hours at 5 °C (% 94), 0^th minute at pH 2.2 (%97) and 200 ppm (0^th hour) concentration. It was specified that recovery from all the samples including L. pneumophila bacteria that were exposed to different environmental conditions (temperature, pH and biocide) were examined by the semi-nested PCR.
Among the water samples including L. pneumophila bacteria were exposed to different temperature applications (24 hours at 5 °C, 30 minutes at 50 °C, 15 minutes at 55 °C and 3 minutes at 60 °C); it was determined that recovery ratio was the lowest in the FISH method at 3 minutes at 60 ^°C and the highest was 24 hours at 5 °C.
It was determined that FISH and semi-nested PCR methods are suitable methods for the recovery of L. pneumophila bacteria that are subject to different environmental conditions from the water samples.
This study places importance to be the first study that examines the recovery ratios of water samples including L. pneumophila bacteria that are exposed to different environmental conditions in our country via culture, FISH and semi-nested PCR methods.