Investigation of N-acyl homoserine lactone (AHL) molecule production in Gram-negative bacteria isolated from cooling tower water and biofilm samples

In this study, 99 Gram-negative rod bacteria were isolated from cooling tower water, and biofilm samples were examined for cell-to-cell signaling systems, N-acyl homoserine lactone (AHL) signal molecule types, and biofilm formation capacity. Four of 39 (10 %) strains isolated from water samples and 14 of 60 (23 %) strains isolated from biofilm samples were found to be producing a variety of AHL signal molecules. It was determined that the AHL signal molecule production ability and the biofilm formation capacity of sessile bacteria is higher than planktonic bacteria, and there was a statistically significant difference between the AHL signal molecule production of these two groups (p < 0.05). In addition, it was found that bacteria belonging to the same species isolated from cooling tower water and biofilm samples produced different types of AHL signal molecules and that there were different types of AHL signal molecules in an AHL extract of bacteria. In the present study, it was observed that different isolates of the same strains did not produce the same AHLs or did not produce AHL molecules, and bacteria known as AHL producers did not produce AHL. These findings suggest that detection of signal molecules in bacteria isolated from cooling towers may contribute to prevention of biofilm formation, elimination of communication among bacteria in water systems, and blockage of quorum-sensing controlled virulence of these bacteria

Comparison of Different Methods for the Detection of Salmonella spp. in Minced Meat Samples

The presence of Salmonella spp. in minced meat that is consumed in nine different sites of Istanbul is evaluated by using conventional culture (ISO 6579: 2002), immunomagnetic separation (IMS) and fluorescent in situ hybridization (FISH) methods. Salmonella spp. was isolated from five of 50 (20%) minced meat with ISO 6579 method, and three of 50 (6%) minced meat using IMS method. Bacteria isolated from both ISO and IMS methods were identified as Salmonella choleraesuis ssp. arizonae and Salmonella spp. The presence of Salmonella spp. was determined from 37 of 50 (74%) minced meat by using FISH method. In the current study, it has been shown that ISO 6579 method was found more to be susceptible than IMS method for determining presence of Salmonella spp., FISH method is the best method to determine the presence of Salmonella spp. Even if the quick determination of the epidemics of international importance occured as a result of the contamination by pathogens derivated from foods, the results of the use of new methods should be supported by the conventional culture method

Examination of the Level of Bacteriological Pollution in the Discharge Area of the Ayamama Stream to the Marmara Sea

In this study seawater samples were taken from Ayamama stream's discharge point and from around of its six different areas every 15 days, and were examined in terms of bacteria such as faecal coliform, total coliform, faecal streptococci, Salmonella spp. and total mezophilic aerobic heterotrophic bacteria from May 2007 to April 2008. It is found that in all of the seven areas from which samples were taken, bacteria counts found are over seawater quality standards. It is found that the area in the best condition is station 6 which is far away 1 km from discharge point and the worst one is station 1 which is discharge point of the Ayamama stream to Marmara sea. Also, it is determined that the number of indicator bacteria show difference depending on months and seasons. Furthermore, a hierarchical ascendant cluster analysis was used to classify the sampling stations into similar groups. Dendograms obtained from cluster analysis has revealed that stations which are far away 500 m discharge point, in front of Air Force Academy (Yesilkoy), an four-star hotel and Yesilyurt sports club were similar at the first level in terms of the number of faecal coliform, total coliform, faecal streptococci and Salmonella spp. However, station 6 which is far away 1 km from discharge point was similar at the second level. As a result, when all findings were examined it was seen that Ayamama stream was a very serious threat for the sea of Marmara

Examination of the Level of Bacteriological Pollution in the Discharge Area of the Ayamama Stream to the Marmara Sea

In this study seawater samples were taken from Ayamama stream's discharge point and from around of its six different areas every 15 days, and were examined in terms of bacteria such as faecal coliform, total coliform, faecal streptococci, Salmonella spp. and total mezophilic aerobic heterotrophic bacteria from May 2007 to April 2008. It is found that in all of the seven areas from which samples were taken, bacteria counts found are over seawater quality standards. It is found that the area in the best condition is station 6 which is far away 1 km from discharge point and the worst one is station 1 which is discharge point of the Ayamama stream to Marmara sea. Also, it is determined that the number of indicator bacteria show difference depending on months and seasons. Furthermore, a hierarchical ascendant cluster analysis was used to classify the sampling stations into similar groups. Dendograms obtained from cluster analysis has revealed that stations which are far away 500 m discharge point, in front of Air Force Academy (Yesilkoy), an four-star hotel and Yesilyurt sports club were similar at the first level in terms of the number of faecal coliform, total coliform, faecal streptococci and Salmonella spp. However, station 6 which is far away 1 km from discharge point was similar at the second level. As a result, when all findings were examined it was seen that Ayamama stream was a very serious threat for the sea of Marmara