MONITORING TRICHLOROETHYLENE MINERALIZATION BY PSEUDOMONAS-CEPACIA G4PR1

To analyze the extent of mineralization of trichloroethylene (TCE) wit hout disturbing an actively growing biofilm, a minimal growth medium w as formulated that reduces the concentration of chloride ions to the e xtent that the chloride ions generated from TCE mineralization may be detected with a chloride-ion-specific electrode. By substituting chlor ide salts with phosphates and nitrates, a chloride-free minimal medium was produced that yields a specific growth rate for Pseudomonas cepac ia G4 PR1 which was 93% of that in chloride-ion-containing minimal med ium. Furthermore, TCE degradation by resting cell suspensions was simi lar in both media (85% of 75 mu M TCE degraded in 6 h), and complete m ineralization of TCE was slightly superior in the chloride-free minima l medium (77% compared to 60% of 75 mu M TCE mineralized in 6 h). In a ddition, indole-containing, minimal-medium agar plates were developed to indicate the presence of the TCE-degrading enzyme toluene ortho-mon ooxygenase (fire-engine-red colonies) as well as to distinguish this e nzyme from other TCE-degrading enzymes (toluene dioxygenase and toluen e para-mono-oxygenase).