Isolation of a non-traditional sulfate reducing-bacteria Citrobacter freundii sp. and bioremoval of thallium and sulfate

A novel non-traditional sulfate reducing bacterium (Sr 10) was isolated from an up-flow anaerobic sludge bed for acid mine drainage treatment which contains thallium (Tl) and sulfate. Phylogenetic analysis of partial 16S rRNA gene sequence of isolate Sr 10 revealed that it was identified to Citrobacter freundii species. Sr 10 was visually rod-shaped and very motile with peri-flagellum according to transmission microscopy. The Fourier transform infrared spectroscopy analysis indicated that the stains had various functional groups for Tl and sulfate removal, including hydroxyl, carboxyl, amide and phosphate. Under anaerobic conditions, the optimized growth conditions for the stain were obtained at temperature of 35 °C and initial pH value of 7.0. Sr 10 was able to remove both Tl(I) and SO42− simultaneously with the removal efficiency up to 99.60% and 89.80%, respectively. This strain might be used for Tl and sulfate removal in the process of bioremediation restoration.