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Some bacteria have a higher tendency to produce biofilm than others. Especially, Pseudomonas and Aeromonas strains are acknowledged to be pioneer colonizers and are predominant in biofilm formation. We examined biofilm formation and first attachment maintance of biofilms of Pseudomonas spp., Pseudomonas aeruginosa, Aeromonas spp, sulphate reducing bacteria and filamentous fungi. A simulated recirculating cooling-water system was used. Heterotrophic bacteria counts on galvanized steel and glass surfaces rose during the tidy period of 720 hours. In addition, we determined that although Pseudomonas spp., Pseudomonas aeruginosa and Aeromonas spp. were the pioneer colonizers, they surprisingly could not be determined in the biofilms on both types of surface after 456 hours. Sulphate reducing bacteria were observed in biofilms on both surfaces from the outset of the experiments. Filamentous fungi were seen on the galvanized steel and glass surfaces after 0.5 h.

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The corrosion behaviour of galvanized steel in cooling tower water containing a biocide and a corrosion inhibitor was investigated over a 10-month period in a hotel. Planktonic and sessile numbers of sulphate reducing bacteria (SRB) and heterotrophic bacteria were monitored. The corrosion rate was determined by the weight loss method. The corrosion products were analyzed by energy dispersive X-ray spectroscopy and X-ray diffraction. A mineralized, heterogeneous biofilm was observed on the coupons. Although a biocide and a corrosion inhibitor were regularly added to the cooling water, the results showed that microorganisms, such as SRB in the mixed species biofilm, caused corrosion of galvanized steel. It was observed that Zn layers on the test coupons were completely depleted after 3 months. The Fe concentrations in the biofilm showed significant correlations with the weight loss and carbohydrate concentration (respectively, p < 0.01 and p < 0.01).

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Oil fields harbour a wide variety of microorganisms with different metabolic capabilities. To examine the microbial ecology of petroleum reservoirs, a molecular-based approach was used to assess the composition of bacterial communities in produced water (PW) of Diyarbakır oil fields in Turkey. Denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA gene fragments was performed to characterise the bacterial community structure of PW samples and to identify predominant community members after sequencing of separated DGGE bands. The majority of bacterial sequences retrieved from DGGE analysis of PW samples belonged to unclassified bacteria (50%). Among the classified bacteria, Proteobacteria (29.2%), Firmicutes (8.3%), Bacteroidetes (8.3%) and Actinobacteria (4.2%) groups were identified. Pseudomonas was the dominant genus detected in the PW samples. The results of this research provide for, the first time, insight into the complexity of microbial communities in the Diyarbakır oil reservoirs and their dominant constituents.

Although bacterial contamination is widely researched in dental unit water systems, we have been unable to find any published reports to date about the presence and distribution of sulphate-reducing bacteria (SRB) in dental unit waterlines (DUWLs). The aim of this study was to evaluate microbial contamination and to determine the presence and distribution of SRB in DUWLs. One hundred twenty-three water samples were collected from the air-water syringes, high-speed drills and water sources from 41 dental units in Istanbul, Turkey. The counts of aerobic heterotrophic bacteria and SRB were investigated in the water samples. In addition, the presence of free-living amoebae (FLA) was examined. In this work, we evaluated microbial contamination and reported for the first time the distribution of SRB in DUWLs. We determined that only ten out of 123 water samples were able to meet the American Dental Association's limit (≤200 CFU ml( - 1)). SRB were observed in 102 out of 123 samples (82.9%). In addition, SRB were detected in all of the air-water syringes and high-speed drills. FLA were established in 103 out of 123 samples (83.7%).