CONTINUOUS DEGRADATION OF TRICHLOROETHYLENE BY XANTHOBACTER SP, STRAIN PR2 DURING GROWTH ON PROPENEE

Propene-grown Xanthobacter sp. strain Py2 cells can degrade trichloroe thylene (TCE), but the transformation capacity of such cells was limit ed and depended on both the TCE concentration and the biomass concentr ation, Toxic metabolites presumably accumulated extracellularly, becau se the fermentation of glucose by yeast cells was inhibited by TCE deg radation products formed by strain Py2. The affinity of the propene mo nooxygenase for TCE was low, and this allowed strain Py2 to grow on pr opene in the presence of TCE. During batch growth with propene and TCE , the TCE was not degraded before most of the propene had been consume d, Continuous degradation of TCE in a chemostat culture of strain Py2 growing with propene was observed with TCE concentrations up to 206 mu M in the growth medium without washout of the fermenter occurring. At this TCE concentration the specific degradation rate was 1.5 nmol/min /mg of biomass, The total amount of TCE that could be degraded during simultaneous growth on propene depended on the TCE concentration and r anged from 0.03 to 0.34 g of TCE per g of biomass, The biomass yield o n propene was not affected by the cometabolic degradation of TCE.