ACTIVITY AND STABILITY OF A RECOMBINANT PLASMID-BORNE TCE DEGRADATIVEPATHWAY IN SUSPENDED CULTURES

The retention and expression of the plasmid-borne, TCE degradative tol uene-ortho-monooxygenase (TOM) pathway in suspended continuous culture s of transconjugant Burkholderia cepacia 17616 (TOM31c) were studied. Acetate growth and TCE degradation kinetics for the transconjugant hos t are described and utilized in a plasmid loss model. Plasmid maintena nce did not have a significant effect on the growth rate of the transc onjugant. Both plasmid-bearing and plasmid-free strains followed Andre ws inhibition growth kinetics when grown on acetate and had maximum gr owth rates of 0.22 h(-1). The transconjugant was capable of degrading TCE at a maximum rate of 9.7 nmol TCE/min.mg protein, which is compara ble to the rates found for the original plasmid host, Burkholderia cep acia PR1(31) (TOM31c). The specific activity of the TOM pathway was fo und to be a linear function of growth rate. Plasmid maintenance was st udied at three different growth rates: 0.17/h, 0.1/h, and 0.065/h. Pla smid maintenance was found to be a function of growth rate, with the p robability of loss ranging from 0.027 at a growth rate of 0.065/h to 0 .034 at a growth rate 0.17/h. (C) 1998 John Wiley & Sons, Inc.