Product toxicity and cometabolic competitive inhibition modeling of chloroform and trichloroethylene transformation by methanotrophic resting cells

Journal Article · Mon Apr 01 04:00:00 EST 1991 · Applied and Environmental Microbiology; (United States)

OSTI ID:5717674

Alvarez-Cohen, L ^[1]; McCarty, P L ^[2]

---

1. Univ. of California, Berkeley (United States)
2. Stanford Univ., CA (United States)

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{sup {minus}1} for resting cells and 1.5 day{sup {minus}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 CF 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.

• OSTI ID: 5717674
• Journal Information: Applied and Environmental Microbiology; (United States), Journal Name: Applied and Environmental Microbiology; (United States) Vol. 57:4; ISSN 0099-2240; ISSN AEMID
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540210* -- Environment
Terrestrial-- Basic Studies-- (1990-)
550500 -- Metabolism
59 BASIC BIOLOGICAL SCIENCES
ACETYLENE
ALKYNES
ANAEROBIC CONDITIONS
BACTERIA
BIODEGRADATION
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHLORINATED ALIPHATIC HYDROCARBONS
CHLOROFORM
COMPARATIVE EVALUATIONS
DECOMPOSITION
ENZYMES
EVALUATION
FORMIC ACID
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROCARBONS
METABOLIC ACTIVATION
METABOLISM
METABOLITES
METHANOTROPHIC BACTERIA
MICROORGANISMS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC SOLVENTS
OXIDOREDUCTASES
OXYGENASES
PROTEINS
SOLVENTS
TOXICITY