Simultaneous Removal of Setazol Navy Blue and Cr(VI) By Mixed Microbial Culture Isolated from the Çubuk Stream

Abstract

Water samples taken from the & Ccedil;ubuk Stream (Ankara, Turkey) were inoculated into nutrient broth media containing Setazol Navy Blue SBG (SNB), an organic pollutant, and heavy metal Cr(VI), an inorganic pollutant, to obtain a pollutant-resistant mixed microbial culture. Experiments were conducted with this culture to remove SNB and heavy metal. The optimum conditions, where the mixed bacterial culture removed the pollutants most effectively, were determined, showing that the highest capacity for removal took place at pH 8 with removal percentages 96.3% for Cr(VI) and 78.5% for SNB. In media with 50.4 mg/L SNB and 9.7 mg/L Cr(VI), the SNB removal was 87.3%, and the Cr(VI) removal was 96.6% at the end of the 7-day incubation period. The highest removal was observed with a biomass concentration of 8% (v/v) of mixed culture [50 mg/L SNB dye+25 mg/L Cr(VI)]. The removal was 100% for both Cr(VI) and the SNB dye. The bacteria with the highest removal were isolated and identified using 16S rDNA gene sequence analysis as Microbacterium oxydans and Leucobacter aridicollis. The role of various functional groups and the structures of the microorganisms that might be involved in the removal mechanisms were discussed using their FTIR spectra. This report is the first study that investigates a mixed bacterial culture and pure cultures (M. oxydans and L. aridicollis) isolated from that mixed culture, removing both SNB and Cr(VI) simultaneously.