Study of strategies to increase biodegradation of trichloroethylene by aerobic bacteria bacterial isolate Sphingopyxis ummariensis

In the present study, an indigenous aerobic bacteria Sphingopyxis ummariensis (isolated from Iran) was used for biological degradation of the Trichloroethylene (TCE). The bacteria were grown in the presence of TCE as the sole carbon source and at an initial concentration of 5 mM, which resulted in 15.6% degradation of TCE after 48 hours. To increase the efficiency of TCE removal, glucose, toluene, glucose/yeast extract and phenol/nutrient broth were used as a co-substrate carbon sources. The highest TCE removal (16.3%) was obtained using glucose/yeast extract. Also, the biological removal of TCE, in initial concentration of 5 mM, was increased from 15.6 to 39.1% after adaptation of the bacteria to the TCE. In this condition, and in the presence of glucose/yeast extract, biodegradation of TCE was increased to 43%. The bacterial biomass and TCE biodegradability was reduced by increasing the TCE concentration from 0.5 to 5.0 mM. The highest TCE removal (94.8%) was obtained for adapted strains in the presence of glucose/yeast extract in the rate of 1.6 mg/l.h at initial concentration of 0.5 mM.