Dj chloroform



Keywords: dj chloroform
Description: Final Report: Aerobic Cometabolism of Chloroform, 1,1,1-trichloroethane, 1,1-dichloroethylene, and Other Chlorinated Aliphatic Hydrocarbons by Microbes Grown on Butane and Propane Subproject:

Final Report: Aerobic Cometabolism of Chloroform, 1,1,1-trichloroethane, 1,1-dichloroethylene, and Other Chlorinated Aliphatic Hydrocarbons by Microbes Grown on Butane and Propane

Subproject: this is subproject number 019. established and managed by the Center Director under grant R825689

(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Title: Aerobic Cometabolism of Chloroform, 1,1,1-trichloroethane, 1,1-dichloroethylene, and Other Chlorinated Aliphatic Hydrocarbons by Microbes Grown on Butane and Propane

The objectives of this study are: (1) to evaluate the ability of microorganisms grown on butane or propane to degrade a broad range of chlorinated aliphatic hydrocarbons (CAHs), (2) to obtain a better understanding of factors effecting the rates and extents of transformations of these compounds by these microorganisms, (3) to learn more about of biochemistry of the microorganisms and the associated cometabolic processes.

In previously funded Center research, butane and propane were discovered as good cometabolic growth substrates for aerobic treatment of chloroform. Chloroform had previously been shown to be a fairly difficult substrate to degrade via aerobic cometabolism. Other contaminants such as 1,1,1-trichloroethane (TCA) and 1,1-dichlorethylene (1,1-DCE) have also been fairly resistant to aerobic cometabolism. Trichloroetheylene (TCE) can be effectively degraded by microbes grown on phenol or toluene, however, these growth substrates are regulated chemicals that may be difficult to add for subsurface remediation. This research therefore focuses on evaluating the potential of butane and propane as substrates for CAH cometabolism.

Transformation and kinetic studies evaluated the cometabolism of chlorinated methanes, chlorinated ethanes, and chlorinated ethenes by our butane grown enrichment obtained from the Hanford DOE site. Resting cell studies showed very high transformation capacities (mmole CAH/mg TSS cells) in the absence of an endogenous energy source. The chlorinated methanes transformation capacities were: chloromethane (CM), 23; dichloromethane (DCM), 5.8; and chloroform (CF), 0.6; showing transformation was more for effective for the less chlorinated methanes. The transformation of CF, however, promoted the most inactivation of butane-utilizing activity. The chlorinated ethanes transformation capacities ranged from 7.0 for chloroethane (CA) to 0.29 for 1,1,2-trichloroethane (1,1,2-TCA). The transformation and the resulting inactivation were strongly affected by the position of the chlorine substitution. 1,1-dichloroethane and 1,1,1-trichloroethane were more effectively transformed and caused less inactivation than their corresponding isomers with chlorine on both carbons, 1,2-dichloroethane and 1,1,2-trichloroethane. We suspect that the mechanism of cometabolism and the transformation products are causing these differences. The chlorinated ethenes had transformation capacities ranging from 2.7 for vinyl chloride to 0.1 for TCE. The dichloroethylene (DCE) isomers transformation capacities were: trans-DCE, 0.0; cis-DCE, 1.4; 1,1-DCE, 0.9, again showing large variations based on the position of the chlorine substitution. Butane-utilizers effectively transformed 1,1-DCE, however the transformation caused the greatest inactivation of all the compounds tested. Chloride release studies showed the chlorinated methanes and ethenes were the most completely dechlorinated (70 to 100%), while the chlorinated ethanes were the least dechlorinated (40 to 60 %).

Characterization of butane and chlorinated aliphatic degradation by three bacterial isolates was continued. Mycobacterium vaccae, Pseudomonas butanovora, and CF8 (an isolate from Hanford core material) all degrade chloroform when grown on butane. Studies with inactivators and inhibitors of CF degradation led to the hypothesis that each of these three bacteria produces a distinct butane monooxygenase. When cultures of each bacterium are exposed to 14C acetylene, activity is lost. When proteins from these bacteria were examined by SDS-PAGE and autoradiography, different proteins were found to be labeled. Butane oxidation is inhibited or inactivated by the same compounds which affect CF oxidation which provides further evidence that butane monooxygenase catalyzes the transformation of CF. A mixed culture (derived from Hanford core material) was grown in the presence and absence of CF. Cultures grew more slowly in the presence of chloroform. Chloroform degradation potential of resting cells taken from these cultures revealed a greater chloroform specific activity in the cultures not exposed to CF than those which were exposed to chloroform. PCR products (using a variety of primers) were similar whether the culture was grown in the presence or absence of CF, although distinct differences were also noted. These results reveal that the presence of CF during growth on butane does influence the microbial population.

In batch kinetic studies with the butane-grown enrichment the maximum degradation/ transformation rates (k), half-saturation coefficient (Ks), inhibition types (competitive, non-competitive, and mixed inhibition), and inhibition coefficients (KI and KI') of 1,1,1-TCA, 1,1-DCE, 1,1-DCA, and butane have been determined. A direct linear plot method was used to identify the types of inhibition. 1,1,1-TCA, 1,1-DCE, and 1,1-DCA all competitively inhibited each other. Competitive inhibitions kinetics were found to accurately represent the inhibition observed when all three compounds were present. However, butane (growth substrate) showed different inhibition types, that is, non-competitive inhibition on 1,1,1-TCA and 1,1-DCA and mixed inhibition on 1,1-DCE transformation. Inhibition constants were determined using a linearization method that was developed and by non-linear-least-squares-regression of the inhibition data. Good agreement was obtained for the parameters determined by both methods of analysis. When butane and two or more CAHs were present, a model, which combined both competitive and mixed inhibition kinetics, less accurately simulated our experimental results.

Strain CF8, originally isolated from a microcosm of Hanford aquifer solids, has now been brought into pure culture. Identification by 16s rDNA indicates that the bacterium is of the Nocardiodes family, the first example of an alkane oxidizer in this genus. Light sensitivity of butane oxidation and thermal aggregation of the polypeptide that labels with 14C2H2 further support a relatedness to ammonia monooxygenase and particulate methane monooxygenase.




Photogallery Dj chloroform:


Comparative Value of Sulphuric Ether and Chloroform  NEJM


Microbial degradation of chloroform - Springer


Geochemical Transformation of Trichloroacetic Acid to Chloroform ...


Terrestrial natural sources of trichloromethane (chloroform, CHCl3 ...


Chloroform degradation by butane-grown cells of Rhodococcus ...


Determination and use of a corrected control factor in the ...


EHP  Computational Toxicology of Chloroform: Reverse Dosimetry ...


Pin by Tarra Kleiser on Chloroform, Trunk, Basement, Procreate | Pint


EHP  Computational Toxicology of Chloroform: Reverse Dosimetry ...


Hepatotoxic interaction between carbon tetrachloride and ...


Regional Sources of Methyl Chloride, Chloroform and ...


Adsorption characteristics of chloroform on modified zeolites from ...


On the Use of Chloroform | Glenn Hefley - Writer


Vanda roxburghii chloroform extract as a potential source of ...


Hepatic circulation and hepatic function during anaesthesia and ...


Comparative studies of hepatotoxicity and fumonisin B1 and B2 ...


Tetraphenylporphine zinc(II) coordination with primary amines and ...


Chloroform aerobic cometabolism by butane-growing Rhodococcus ...