Trichloroethylene degradation and mineralization by pseudomonads and Methylosinus trichosporium OB3b

Abstract

To examine the trichloroethylene (C2HCl3)-degrading capability of five microorganisms, the maximum rate, extent, and degree of C2HCl3 mineralization were evaluated for Pseudomonas cepacia G4, Pseudomonas cepacia G4 PR1, Pseudomonas mendocina KR1, Pseudomonas putida F1, and Methylosinus trichosporium OB3b using growth conditions commonly reported in the literature for expression of oxygenases responsible for C2HCl3 degradation. By varying the C2HCl3 concentration from 5 microM to 75 microM, Vmax and Km values for C2HCl3 degradation were calculated as 9 nmol/(min mg protein) and 4 microM for P. cepacia G4, 18 nmol/(min mg protein) and 29 microM for P. cepacia G4 PR1, 20 nmol/(min mg protein) and 10 microM for P. mendocina KR1, and 8 nmol/(min mg protein) and 5 microM for P. putida F1. This is the first report of these Michaelis-Menten parameters for P. mendocina KR1, P. putida F1, and P. cepacia G4 PR1. At 75 microM, the extent of C2HCl3 that was degraded after 6 h of incubation with resting cells was 61%-98%; the highest degradation being achieved by toluene-induced P. mendocina KR1. The extent of C2HCl3 mineralization in 6 h (as indicated by concentration of chloride ion) was also measured and varied from 36% for toluene-induced P. putida F1 to 102% for M. trichosporium OB3b. Since C2HCl3 degradation requires new bio-mass, the specific growth rate (mu max) of each of the C2HCl3-degradation microorganisms was determined and varied from 0.080/h (M. trichosporium OB3b) to 0.864/h (P. cepacia G4 PR1).

Degradation Pathways of Trichloroethylene and 1,1,1-Trichloroethane byMycobacteriumsp. TA27

“…By varying the TCE concentration from 5 mM to 75 mM, the Vmax and K m of toluene-and phenol-oxidizing bacteria were calculated as 8 to 20 nmol min "1 mg protein "1 and 4 to 10 mM for Pseudomonas cepacia G4, P. mendocina KR1 and P. putida F1. 9) Vmax and Km of 509±174 nmol min "1 mg protein "1 and 145±61 mM were obtained for Methylosinus trichosporium OB3b grown in continuous culture under copper stress with 20 mM formate. 5,9) The Vmax and Km of strain TA27 for TCE degradation were 9.81 nmol min "1 mg cells "1 (28.3 nmol min "1 mg protein "1 ) and 61.9 mM.…”

“…9) Vmax and Km of 509±174 nmol min "1 mg protein "1 and 145±61 mM were obtained for Methylosinus trichosporium OB3b grown in continuous culture under copper stress with 20 mM formate. 5,9) The Vmax and Km of strain TA27 for TCE degradation were 9.81 nmol min "1 mg cells "1 (28.3 nmol min "1 mg protein "1 ) and 61.9 mM. These values were similar to those for other bacteria, apart from Methylosinus trichosporium OB3b.…”

“…For eŠective bioaugmentation, which is the practice of clean-up of contaminated sites by amending cultured microorganisms which are able to degrade the pollutants, it is important to measure the kinetic parameters and degradation products of TCE and TCA by the microbial inocula. TCE degradation products can be oxidized by aerobic bacteria that are able to utilize methane, [1][2][3][4][5][6] toluene, 7,8) phenol, 9) propane, [10][11][12] propylene, 13) and ammonia. 14) There have been few reports on the metabolites of TCE and TCA.…”

Toluene 3-Monooxygenase of Ralstonia pickettii PKO1 Is a para -Hydroxylating Enzyme

“…Oxidizing enzymes are of great potential to the chemical and pharmaceutical industries due to their high regio-, chemo-, and stereoselectivity and their ability to facilitate reactions with chemically stable substrates (1, 2). Due to their complexity, biological oxidation reactions are often performed using growing or resting cells (17).One important group of bacterial oxygenases includes the toluene monooxygenases, which have additional potential applications in bioremediation (23,30,32). The aerobic biodegradation of toluene is well studied, and the pathway is available at the University of Minnesota databank (9).…”

“…One important group of bacterial oxygenases includes the toluene monooxygenases, which have additional potential applications in bioremediation (23,30,32). The aerobic biodegradation of toluene is well studied, and the pathway is available at the University of Minnesota databank (9).…”