Identification of the resistant bacterial strains from Kermanshah oil wastewater based on molecular 16S rDNA PCR ssequencing and the investigation of their growth in different chromium concentration

The present study was conducted to identify the resistant bacterial strains from Kermanshah oil wastewater based on molecular 16S rDNA PCR sequencing and the investigation of their growth in different chromium concentration. To identify 16S rDNS, 94 samples were isolated from Kermanshah oil wastewater. Sequencing the best strain for most removal was conducted. Bactria were identified by morphology, Gram staining, Biochemical tests, Standard microbiology. Cr (VI) was incubated in the concentrations of 25, 50, 100 and 150 mg/ml for 96 h. The maximum Cr biosorption (0.35 ppm) was observed at 28°C and a pH=7.5-8. Biological oxygen demand was 126-530. The most isolates had a need from 7.2-7.90 for chemical oxygen demand. Based on obtained results, Klebsiella variicola, Bacillus aerius, Bacillus stratosphericus and Lysinibacillus fusiformis were most resistant strains. Bacteria growth was higher in control, 25, 50, 100 and 150 mg, respectively. All the bacteria showed a fix growth after 72h. Considering high resistant of Klebsiella variicola, Bacillus aerius, Bacillus stratosphericus and Lysinibacillus fusiformis, the strains can be used for bioremediation of chromium and decreasing aontaminations, especially in oil refinery.