Biodegradation of tetrachloroethylene by a newly isolated aerobic Sphingopyxis ummariensis VR13

Chlorinated aliphatic solvents are major sources of groundwater and soil contamination. In this study, an aerobic bacterial strain, Sphingopyxis ummariensis VR13, which has been newly isolated from petrochemical wastewater sludge, was used for the dechlorination of PCE in relatively high concentrations. The addition of a co-substrate as glucose and yeast extract enhanced the dechlorination of PCE. An adaptation of the bacterial cells to PCE resulted in a significant increase in the PCE degradation yield (62.9-39.4%) at relatively high initial PCE concentrations (0.4-5 mM). The adapted cells achieved the highest biodegradation yield (64.8%) in 1.2mM. However, the maximum dechlorination percentage (41.6%) was measured in lower PCE concentration. The kinetic studies showed that PCE degradation was associated with the biomass growth because a higher removal of PCE (64.8%) occurred in a higher cell density. The degradation kinetics of PCE was properly fitted by Monod-like equation with the specific degradation rate of 7.2mmol PCE (g biomass)(-1)d(-1), which was even faster than the reported anaerobic bacteria at this concentration. This strain can be used in the aerobic degradation of PCE.