Effect of Trichloroethylene on the Competitive Behavior of Toluene-Degrading Bacteria

Abstract

The influence of trichloroethylene (TCE) on a mixed culture of four different toluene-degrading bacterial strains (Pseudomonas putida mt-2, P. putida F1, P. putidaGJ31, and Burkholderia cepacia G4) was studied with a fed-batch culture. The strains were competing for toluene, which was added at a very low rate (31 nmol mg of cells [dry weight]−1 h−1). All four strains were maintained in the mixed culture at comparable numbers when TCE was absent. After the start of the addition of TCE, the viabilities ofB. cepacia G4 and P. putida F1 and GJ31 decreased 50- to 1,000-fold in 1 month. These bacteria can degrade TCE, although at considerably different rates. P. putida mt-2, which did not degrade TCE, became the dominant organism. Kinetic analysis showed that the presence of TCE caused up to a ninefold reduction in the affinity for toluene of the three disappearing strains, indicating that inhibition of toluene degradation by TCE occurred. While P. putida mt-2 took over the culture, mutants of this strain which could no longer grow onp-xylene arose. Most of them had less or nometa-cleavage activity and were able to grow on toluene with a higher growth rate. The results indicate that cometabolic degradation of TCE has a negative effect on the maintenance and competitive behavior of toluene-utilizing organisms that transform TCE.

Simultaneous Growth on Citrate Reduces the Effects of Iron Limitation during Toluene Degradation in Pseudomonas

“…The growth medium was a mineral salts medium (MM) as described previously [22], but without addition of iron. Toluene or citrate (Na 3 C 6 H 5 O 7 AE 2H 2 O) was added to the medium as sole carbon and energy source.…”

Effect of sorption and desorption resistance on aerobic trichloroethylene biodegradation in soils

“…In toluene‐degrading microorganisms, for example, TCE can be degraded by means of both dioxygenase [4,5,7,8] and mono‐oxygenase [9] enzyme systems. The relationship between cometabolic TCE transformation and toluene consumption has been described qualitatively by many researchers over the past decade [5,10–15].…”

Simultaneous Degradation of Trichloroethylene and Toluene by Burkholderia cepacia G4 and the Effect of Biotransformation on Bacterial Density

“…On the other hand, TCE and its transformation byproducts are toxic to micro-organisms on short or long time exposure. Toxicity of TCE (exposed to degradation microorganisms may result in the reduction of bacterial cellular growth, viability, respiratory activity, and enzyme inactivation [6][7][8][9][10][11].…”