Document Detail

Product toxicity and cometabolic competitive inhibition modeling of chloroform and trichloroethylene transformation by methanotrophic resting cells.
MedLine Citation:
PMID:  1905516     Owner:  NLM     Status:  MEDLINE    
The rate and capacity for chloroform (CF) and trichloroethylene (TCE) transformation by a mixed methanotrophic culture of resting cells (no exogenous energy source) and formate-fed cells were measured. As reported previously for TCE, formate addition resulted in an increased CF transformation rate (0.35 day-1 for resting cells and 1.5 day-1 for formate-fed cells) and transformation capacity (0.0065 mg of CF per mg of cells for resting cells and 0.015 mg of CF per mg of cells for formate-fed cells), suggesting that depletion of energy stores affects transformation behavior. The observed finite transformation capacity, even with an exogenous energy source, suggests that toxicity was also a factor. CF transformation capacity was significantly lower than that for TCE, suggesting a greater toxicity from CF transformation. The toxicity of CF, TCE, and their transformation products to whole cells was evaluated by comparing the formate oxidation activity of acetylene-treated cells to that of non-acetylene-treated cells with and without prior exposure to CF or TCE. Acetylene arrests the activity of methane monooxygenase in CF and TCE oxidation without halting cell activity toward formate. Significantly diminished formate oxidation by cells exposed to either CR or TCE without acetylene compared with that with acetylene suggests that the solvents themselves were not toxic under the experimental conditions but their transformation products were. The concurrent transformation of CF and TCE by resting cells was measured, and results were compared with predictions from a competitive-inhibition cometabolic transformation model. The reasonable fit between model predictions and experimental observations was supportive of model assumptions.
L Alvarez-Cohen; P L McCarty
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Applied and environmental microbiology     Volume:  57     ISSN:  0099-2240     ISO Abbreviation:  Appl. Environ. Microbiol.     Publication Date:  1991 Apr 
Date Detail:
Created Date:  1991-07-29     Completed Date:  1991-07-29     Revised Date:  2010-09-09    
Medline Journal Info:
Nlm Unique ID:  7605801     Medline TA:  Appl Environ Microbiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1031-7     Citation Subset:  IM    
Department of Civil Engineering, University of California, Berkeley 94720.
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MeSH Terms
Binding, Competitive
Cells, Cultured
Chloroform / metabolism*,  toxicity
Formic Acids / metabolism
Methane / metabolism
Methylococcaceae / metabolism*
Models, Biological
Oxygenases / metabolism
Trichloroethylene / metabolism*,  toxicity
Reg. No./Substance:
0/Formic Acids; 64-18-6/formic acid; 67-66-3/Chloroform; 74-82-8/Methane; 79-01-6/Trichloroethylene; EC 1.13.-/Oxygenases; EC monooxygenase

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