The aim of this study was identification and characterization of highly efficient Extracellular Polymeric Substance (EPS) producing bacteria in activated sludge. Among 74 isolated bacteria, 20 EPS-producing bacteria were obtained from wastewater treatment plant of Bojnourd. EPS extraction was performed using absolute ethanol after glucose-enriched culture. Dry weight, concentration, and the ratio of carbohydrate to protein for the EPS of each isolate was then determined. Molecular identification of four bacteria with the highest EPS production was carried out using 16S rRNA gene amplification. The results showed that these bacteria are belonging to the genus Bacillus, Pseudomonas and Klebsiella. EPS productions were studied in different conditions (carbon and nitrogen sources, different levels of glucose and yeast extract and temperature) for the genus Bacillus and Pseudomonas.The production of EPS was observed highest while in the presence of 2.5 to 3% glucose and 0.5% yeast extract at temperature of 30 to 37°C.

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