Correlation of microbial degradation rates with chemical structure

Wolfe, N. Lee; Paris, Doris F.; Steen, William C.; Baughman, George L.

doi:10.1021/es60169a009

Cited by 69 publications

(28 citation statements)

References 10 publications

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“…1 g/ml), conditions that might be expected in the environment, we have no evidence to indicate the overall second-order process is not valid. Thus, these data accord with the second-order model for microbial degradation ad- vocated by Wolfe and colleagues [38]. However, there is a falloff in rates with increasing RX in certain cases.…”

Section: A Common Rate Law?supporting

confidence: 88%

Biodehalogenation: The Kinetics and Rates of the Microbial Cleavage of Carbon-Halogen Bonds

Castro¹

1993

Environ Toxicol Chem

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Specific rate constants associated with defined molecular paths of carbon-halogen bond cleavage from a variety of alkyl halide substrates by six soil organisms are presented. Five aerobes (three pseudomonads, one methylotroph, and one flavobacterium) and one anaerobe (a methanogen) are compared. The rate constants were obtained with resting cells in phosphate buffer at pH 7.4 in the absence of nutrients or other substances. The observed general rate law is d(X-)/dt = k (RX)(organisms), wherein X-= halide ion, RX = alkyl halide, and (organisms) = number of organisms per liter. At concentrations of substrates >lop3 M, the rate may diminish or cease due to the toxicity of the substrate. At high cell densities 20.1 g/ml wet weight, the rates may saturate. This is attributed to a packing phenomenon of the cells. There is no simple correlation of rates with the chemical structure of the substrates when the conversions are grouped by reaction type; however, the order of reductive hydrogenolysis roughly follows the carbon-halogen bond dissociation energies. Several factors may contribute to a modulation of the rates observed with defined enzymatic active site models in homogeneous solution. These factors are briefly discussed. The aerobes exhibited a greater chemical diversity than the anaerobe in transforming these substances, and they react with much greater speed. In these biotransformations reductive processes occur more often than substitutions or oxidations. A surprising result was that the aerobes can reductively dehalogenate more rapidly than the methanogen.

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Section: A Common Rate Law?supporting

confidence: 88%

Biodehalogenation: The Kinetics and Rates of the Microbial Cleavage of Carbon-Halogen Bonds

Castro¹

1993

Environ Toxicol Chem

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“…It is difficult to distinguish between biotic and abiotic transformations of parent herbicides to degradation products under natural conditions, because both chemical and biological processes may occur simultaneously [12]. To separate the two processes, several researchers have examined the degradation of atrazine in both sterile and nonsterile soils.…”

Section: Introductionmentioning

confidence: 99%

Diffusion and degradation of atrazine in a water/sediment system

Mersie

McNamee

Seybold

et al. 2000

Enviro Toxic and Chemistry

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Abstract-This study determined the effects of temperature and residence time on diffusion and degradation of [ 14 C]atrazine applied to the surface of sterilized and nonsterilized river water over a sediment. Water and sediment were placed in glass columns and incubated at 5 or 24ЊC. Samples were collected at 0, 7, 14, 28, 42, 56, and 112 d before and after disturbance. The warmer temperature (24ЊC) initially increased the rate of 14 C distribution in the aqueous phase. Disturbance caused approximately 15% of the total 14 C to be removed from the aqueous phase by sterile or unsterile sediment incubated at 5ЊC. At 24ЊC, the level of 14 C in disturbed sediments incubated for more than 28 d gradually increased. This increased retention of 14 C by sediment coincided with greater detection of the polar metabolite hydroxyatrazine (HA). More HA was recovered in nonsterilized than in sterilized sediments, indicating the contribution of biological processes to the production of this metabolite. In undisturbed sediments at 24ЊC, approximately 32% and 10% of the applied 14 C permeated the top and bottom 1-cm segments, respectively. In columns incubated at 5ЊC, less than 5% of the 14 C reached the surface of the submerged sediment. The potential impact of atrazine on biota associated with sediment would diminish with time because of dilution in the aqueous phase, transformation to HA, and bound residue formation.

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“…In some cases, such as for methylcarbamates in soil, no good correlations could be found 31. In other cases, Hammett σ constants, as descriptors also reflecting electronic properties, have been found to predict hydrolysis for organophosphates,32 propyzamides8 and benzonitriles 33. Transformation of phenylureas via hydrolysis by a bacterium was also observed earlier 34.…”

Section: Resultsmentioning

confidence: 93%

Quantitative structure–transformation relationships of phenylurea herbicides

Berger

Müller

Eing

2001

Pest Management Science

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Quantitative relationships between the structure of phenylurea herbicides and their transformation in different matrices have been developed. Experimental data on microbial transformation by pure and mixed cultures of soil micro-organisms in inoculated and native soil, as well as on chemical transformation by hydrolysis in sterile soil and water, were available from previous studies. Around 60 experimental or calculated descriptors were used. Quantum chemical calculations were performed with three different semi-empirical methods. Models developed with multiple linear regression were generally easier to interpret than those derived with partial least-squares projection to latent structures. Quite simple and interpretable models could be found to predict transformation rates by pure cultures from lipophilicity, by mixed cultures from adsorption distribution coefficients, and by chemical or enzymatic hydrolysis from electronic properties. Transformation in inoculated soil could not be predicted, but for native soil the use of a quantum chemical descriptor for reactivity (energy of LUMO) together with molar refraction resulted in a general model.

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Correlation of microbial degradation rates with chemical structure

Cited by 69 publications

References 10 publications

Biodehalogenation: The Kinetics and Rates of the Microbial Cleavage of Carbon-Halogen Bonds

Biodehalogenation: The Kinetics and Rates of the Microbial Cleavage of Carbon-Halogen Bonds

Diffusion and degradation of atrazine in a water/sediment system

Quantitative structure–transformation relationships of phenylurea herbicides

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