Shewanella decolorationis sp. nov., a dye-decolorizing bacterium isolated from activated sludge of a waste-water treatment plant.

A highly efficient dye-decolorizing bacterium, strain S12T, was isolated from activated sludge of a textile-printing waste-water treatment plant in Guangzhou, China. The cells were Gram-negative and motile by means of a single polar flagellum. The strain was capable of anaerobic growth either by fermentation of glucose or by anaerobic respiration and utilized a variety of electron acceptors, including nitrate, iron oxide and thiosulfate. The physiological properties, tested by using the Biolog GN2 system, were similar to those of the genus of Shewanella. Analysis of the nearly complete 16S rRNA gene sequence of strain S12T showed the highest similarity (98 and 97 %, respectively) to Shewanella baltica and Shewanella putrefaciens. However, the level of gyrB similarity between strain S12T and S. putrefaciens was 87 %. DNA from strain S12T showed 41.8 and 41.9 % DNA relatedness, respectively, to the DNA of S. baltica DSM 9439T and S. putrefaciens DSM 6067T. The DNA G+C content of strain S12T was 49.3 mol%. The predominant menaquinone was MK-7 and the predominant ubiquinones were Q-7 and Q-8. The dominant fatty acids were 15 : 0, 16 : 0, iso-15 : 0 and 16 : 1omega7c, similar to the profiles of other Shewanella species. On the basis of its physiological and molecular properties, strain S12T appears to represent a novel species of the genus Shewanella, for which the name Shewanella decolorationis sp. nov. is proposed. The type strain is S12T (=CCTCC M 203093T=IAM 15094T).