Kinetic studies of biodegradation of insoluble compounds by continuous determination of oxygen consumption

Bouchez, M.; Blanchet, Denis; Besnainou, B.; Leveau, Jean-Yves; Vandecasteele, J. P.

doi:10.1046/j.1365-2672.1997.00371.x

Cited by 27 publications

(10 citation statements)

References 2 publications

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“…The critical issue here is that the substrate does not mix into the bulk solution, and thus, elevated concentrations can exist in this environment. Direct uptake of chemicals by bacteria at the aqueous phase/nonaqueous phase liquid interface has been demonstrated for hexadecane (8,9,17,23), pyrene (7), naphthalene (6,17,68), and fluoranthene (7). In soils, sorbed pesticides are initially held predominately on organic matter surfaces of soil particles.…”

Section: Discussionmentioning

confidence: 99%

Assessment of Bioavailability of Soil-Sorbed Atrazine

Park

Feng

et al. 2003

Appl Environ Microbiol

118

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Bioavailability of pesticides sorbed to soils is an important determinant of their environmental fate and impact. Mineralization of sorbed atrazine was studied in soil and clay slurries, and a desorption-biodegradation-mineralization (DBM) model was developed to quantitatively evaluate the bioavailability of sorbed atrazine. Three atrazine-degrading bacteria that utilized atrazine as a sole N source (Pseudomonas sp. strain ADP, Agrobacterium radiobacter strain J14a, and Ralstonia sp. strain M91-3) were used in the bioavailability assays. Assays involved establishing sorption equilibrium in sterile soil slurries, inoculating the system with organisms, and measuring the CO 2 production over time. Sorption and desorption isotherm analyses were performed to evaluate distribution coefficients and desorption parameters, which consisted of three desorption site fractions and desorption rate coefficients. Atrazine sorption isotherms were linear for mineral and organic soils but displayed some nonlinearity for K-saturated montmorillonite. The desorption profiles were well described by the three-site desorption model. In many instances, the mineralization of atrazine was accurately predicted by the DBM model, which accounts for the extents and rates of sorption/desorption processes and assumes biodegradation of liquid-phase, but not sorbed, atrazine. However, for the Houghton muck soil, which manifested the highest sorbed atrazine concentrations, enhanced mineralization rates, i.e., greater than those expected on the basis of aqueous-phase atrazine concentration, were observed. Even the assumption of instantaneous desorption could not account for the elevated rates. A plausible explanation for enhanced bioavailability is that bacteria access the localized regions where atrazine is sorbed and that the concentrations found support higher mineralization rates than predicted on the basis of aqueous-phase concentrations. Characteristics of high sorbed-phase concentration, chemotaxis, and attachment of cells to soil particles seem to contribute to the bioavailability of soil-sorbed atrazine.

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Section: Discussionmentioning

confidence: 99%

Assessment of Bioavailability of Soil-Sorbed Atrazine

Park

Feng

et al. 2003

Appl Environ Microbiol

118

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“…Time courses of oxygen uptake during degradation were recorded in respirometric flasks. Continuous monitoring of oxygen consumption is well suited to kinetic studies in heterogeneous media as oxygen consumed was shown to be proportional to the substrate consumed and to the biomass produced (Bouchez et al, 1997a). The experimentation covered a range of conditions, as presented in Table 2.…”

Section: Kinetic Study Of Growth Of Flocculating Strains On Hexadecanementioning

confidence: 99%

“…Time courses of oxygen consumed during growth on C "' were recorded using a sensitive respirometer (D12-S Sapromat, Voith) consisting of 12 conical flasks (500 ml) placed in a water bath maintained at 30 mC (Bouchez et al, 1997a). Determination of electrolytically produced oxygen supplied to the cultures at constant pressure allowed quasi-continuous recording of oxygen consumption.…”

Section: Cultures In Flasksmentioning

confidence: 99%

Evidence for interfacial uptake in hexadecane degradation by Rhodococcus equi: the importance of cell flocculation

et al. 2001

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The kinetics of hexadecane degradation were studied in four strains of Rhodococcus equi that did not produce biosurfactants. The aim was to analyse the characteristics of alkane uptake and their relevance to a mechanism of interfacial uptake. The kinetic studies involved continuous determination of degradation by electrolytic respirometry in a diphasic system where the hydrophobic phase was hexadecane or a solution of hexadecane in a non-toxic, non-biodegradable solvent, either 2,2,4,4,6,8,8-heptamethylnonane or silicone oil. The technique allowed large variations in interfacial area between the aqueous and hydrophobic phases. For the four strains, the kinetics obtained were reproducible and showed, in almost all cases, an initial short phase of exponential growth, followed by a long phase of linear growth. Specific growth rates during exponential growth varied amongst the strains from 011 to 020 h N1 and were independent of interfacial area, in accordance with the very strong adsorption of bacterial cells at the interface of solvent and aqueous media. The degradation rates during linear growth did not increase with interfacial area but increased with efficiency of stirring. These characteristics can be explained by the formation of cellular flocs due to the hydrophobicity of the strains. These flocs were observed during growth on hexadecane in almost all conditions. In one case, with a non-flocculating culture, a kinetic pattern with a longer exponential phase, closer to that expected for simple interfacial uptake, was observed. The results show that strictly interfacial uptake, limited by floc formation (occurring at moderate and higher cell densities, and controlled by stirring efficiency) is a common pattern for growth on long-chain alkanes of micro-organisms that do not produce biosurfactants.

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“…The flasks with leachate water were incubated in a water bath in a Voith Sapromat respirometer (Voith, Heldenheim/Brenz, Gemany) [30]. The Voith Sapromat continuously measure consumption of oxygen in solutions and the developed CO 2 gas in the flask is trapped with NaOH (Merck).…”

Section: Aerobic Treatment Experimentsmentioning

confidence: 99%

Aerobic treatment of selective serotonin reuptake inhibitors in landfill leachate

2015

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Background: Pharmaceuticals used in human medical care are not completely eliminated in the human body and can enter the municipal sewage sludge system and leachate water from landfill both as the parent compound and as their biologically active metabolites. The selective serotonin reuptake inhibitors (SSRIs) have a large potential for unwanted effects on nontarget organisms in the environment. Leachates from active or old closed landfills are often treated with continuous stirring and simple aeration in a pond/lagoon before infiltration into the environment. The aim of this work was to simulate the reduction of five SSRIs (citalopram, fluoxetine, paroxetine, sertraline and fluvoxamine) and three of their metabolites (desmethylcitalopram, didesmethylcitalopram and norfluoxetine) during aerobic treatment of leachate from landfills. This landfill leachate-simulation experiment was performed to see what happens with the pharmaceuticals during aerated treatment and continuous stirring of landfill leachate for 120 h. It is important to establish whether different pollutants such as pharmaceuticals can be removed (oxidized or otherwise degraded) or not before infiltration into the environment.

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Kinetic studies of biodegradation of insoluble compounds by continuous determination of oxygen consumption

Cited by 27 publications

References 2 publications

Assessment of Bioavailability of Soil-Sorbed Atrazine

Assessment of Bioavailability of Soil-Sorbed Atrazine

Evidence for interfacial uptake in hexadecane degradation by Rhodococcus equi: the importance of cell flocculation

Aerobic treatment of selective serotonin reuptake inhibitors in landfill leachate

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