Characterization of Shinella granuli CK-4, a Novel Bacterium Isolated from Industrial Wastewater Capable of Degrading 1,4-Dioxane

We have characterized a novel bacterium, strain CK-4 isolated from industrial wastewater, which is capable of utilizing 1,4-dioxane as sole carbon source and energy. Complete depletion of 1 g/L 1,4-dioxane by CK-4 cultures growing on AMS media was achieved within 168 h. Both the Biolog system and phylogenetic analysis using 16S rRNA sequencing were utilized for identification, and the strain was designated as Shinella granuli CK-4, and registered in GenBank as [MN841914]. The mortality of CK-4 was not greatly affected by 1,4-dioxane concentrations below 10 g/L but was increased with increasing 1,4-dioxane concentrations. SDS-PAGE revealed that the amount of lipopolysaccharide in CK-4 increased or decreased according to the 1,4-dioxane concentration. The expression of 60-kDa GroEL stress shock protein (SSP) was increased in proportion to concentrations below 10 g/L 1,4dioxane but was not expressed at concentrations above 15 g/L dioxane. On the other hand, 70-kDa DnaK SSP was not expressed at any 1,4-dioxane concentrations (0~20 g/mL) tested. SEM demonstrated that the surface of CK-4 cells exposed to 10 g/L dioxane was not significantly different from that of normal cells, whereas cells exposed to 20 g/L 1,4-dioxane showed the presence of perforations and irregular rod forms with wrinkled cell surfaces. These results provide clues to understanding the resistance of S. granuli CK-4 to 1,4-dioxane and the promotion of 1,4-dioxane degradation, which can be applied to the treatment of industrial wastewater with higher concentrations of 1,4-dioxane. Shinella granuli CK-4, 1,4-Dioxane, biodegradation, industrial wastewater