ISOPROPYLBENZENE (CUMENE) - A NEW SUBSTRATE FOR THE ISOLATION OF TRICHLOROETHENE-DEGRADING BACTERIA

Various bacterial isolates from enrichments with isopropylbenzene (cumene), toluene or phenol as carbon and energy sources were tested as to their potential to oxidize trichloroethene (TCE). In contrast to toluene and phenol, all isolates enriched on isopropylbenzene were able to oxidize TCE. Two isolates, strain JR1 and strain BD1, were identified as Pseudomonas spec. and as Rhodococcus erythropolis, respectively. TCE oxidation was accompanied by the liberation of stoichiometric amounts of chloride. Initial TCE oxidation rate increased proportional to the substrate concentration from 25 to 200-mu-M TCE. Maximal initial TCE-degradation rates found here were 4 to 5 nmol . min-1 . mg protein-1. The TCE degradation rate decreased with time. The two isolates showed a temperature optimum for TCE degradation between 10 and 20-degrees-C. In addition to TCE, R. erythropolis BD1 degraded only cis- and trans-dichloroethene whereas Pseudomonas spec. JR1 was able to oxidize also 1,1-dichloroethene, vinyl chloride, trichloroethane, and 1,2-dichloroethane.