Modification of the 14C most-probable-number method for use with nonpolar and volatile substrates

Somerville, Charles C.; Monti, Carol A.; Spain, Jim C.

doi:10.1128/aem.49.3.711-713.1985

Cited by 23 publications

(10 citation statements)

References 16 publications

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“…The T-MPN method was based on the method for natural water developed by Lehmicke et al [29], with modifications to use a volatile organic compound (toluene) as the sole substrate and to use a soil sample for the inoculum. Sorption of toluene into the vial material [30], which would perhaps inhibit transformation during incubation, was minimized in the current study by using glass vials with Teflon@-lined septa seals. Respirometers consisted of an inner vial containing 1 .O ml of 1 N sodium hydroxide solution, an outer vial containing a 0.…”

Section: Batch Microcosms (1 I L)mentioning

confidence: 99%

Substrate‐ and nutrient‐limited toluene biotransformation in sandy soil

Allen-King

Barker

Gillham

et al. 1994

Enviro Toxic and Chemistry

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Lab microcosm tests of the rate of toluene biodegradation were performed using soil from the A, B, and C horizons of the unsaturated zone of a sandy field site. Most of the soil samples had been previously exposed to toluene. Toluene biodegradation was rapid, occurring at a time scale comparable to the rate of sorption in many of the microcosms and demonstrating the potential for bioremediation of these contaminants in unsaturated soil. In the A horizon, with an initial toluene concentration in the solution phase of 4.5 mg/L, degradation was controlled by substrate-limited growth on toluene as the primary substrate. Soil from the B and C horizons initially showed similar behavior with a lower toluene concentration of about 2.5 mg/L.The maximum utilization rate (pmax) for soil from all three depths was 2.0 d-' . With repeated exposure to moderate to high concentrations of toluene, transformation in the B-and C-horizon soil appeared to be zero order, at a rate of 1 .O to 2.0 pg toluene/g soil/d. In C-horizon soil that had been taken directly from the field, the transformation rate was almost immeasurably slow. Addition of nitrogen as either ammonium or nitrate accelerated the degradation, showing that nitrogen was the most limiting nutrient.The apparent adaptation period observed before rapid toluene removal was fit by a substrate-limited growth model. Greater numbers of toluene-degrading microorganisms were found in soil exposed to toluene than in unexposed soil, supporting biomass growth as the explanation for the adaptation period. The results of enumeration of heterotrophs compared to the numbers of toluene degraders suggested that a small proportion of the total viable microorganisms were responsible for degradation of toluene.

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Section: Batch Microcosms (1 I L)mentioning

confidence: 99%

Substrate‐ and nutrient‐limited toluene biotransformation in sandy soil

Allen-King

Barker

Gillham

et al. 1994

Enviro Toxic and Chemistry

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“…The respiration data were also corrected for I4CO2 recovery efficiency using [ ''C]sodium bicarbonate controls that were processed simultaneously with the experimental samples. The most-probable-number of degraders was determined as described previously [I] using the technique of Lehmicke et al [16] as modified by Somerville et al [17].…”

Section: Microbial Degradation and Adaptation Measurementsmentioning

confidence: 99%

Adaptation of aquifer microbial communities to the biodegradation of xenobiotic compounds: Influence of substrate concentration and preexposure

Aelion

Dobbins

Pfaender

1989

Enviro Toxic and Chemistry

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Studies were conducted to examine the adaptation response of aquifer microbial communities to xenobiotic compounds and the influence of chemical preexposure in the laboratory and in situ on adaptation. Adaptation and biodegradation were assessed as mineralization and cellular incorporation of 14C‐radiolabeled substrates. For some compounds, such as ethylene dibromide, aniline and m‐nitrophenol, biodegradation and adaptation rates were not influenced by chemical concentration over the range tested. Biodegradation rates increased with concentration for p‐chlorophenol, and a gradient of adaptation and biodegradation responses was observed for p‐nitrophenol up to a threshold concentration. Acclimation to laboratory conditions decreased but did not eliminate the adaptation period to p‐nitrophenol. Laboratory adaptation studies and examination of uncontaminated and contaminated field samples from a single aquifer indicated that adaptation was accompanied by shifts in the metabolic fate of the substrate. The increased metabolism associated with adapted communities was predominantly the result of increased mineralization. Cellular incorporation represented a significantly smaller fraction of total metabolism in the adapted versus the unadapted communities. The results indicate that the adaptation response in aquifer solids is due to a complex set of interactions that are influenced by the physiology and growth of the degrading populations.

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“…1 filter paper. Enumeration of specific degraders was based on the MPN technique [23], as modified by Somerville et al [24], applied to samples that had not been exposed to the test chemicals.…”

Section: Enumeration Of Bacteriamentioning

confidence: 99%

Aerobic Biodegradation of Natural and Xenobiotic Organic Compounds by Subsurface Microbial Communities

Swindoll¹,

Aelion²,

Dobbins³

et al. 1988

Environ Toxicol Chem

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Studies were conducted to characterize the diversity of degradative abilities of microbial communities from pristine aquifer solids samples. Biodegradation was measured in aquifer solids slurries as both the conversion of radiolabeled substrate to I4CO2 and the incorporation of label into cell biomass. Under aerobic conditions, the microbial community metabolized the following naturally occurring compounds: acetic acid, amino acids, cellulose, cinnamic acid, glucosamine and glucose. The xenobiotic compounds aniline hydrochloride, chlorobenzene, p-chlorophenol, rn-cresol, ethylene dibromide, naphthalene, phenol, toluene and trichlorobenzene were also biodegraded. Several kinetic parameters were calculated from the uptake and mineralization data.First-order rate constants ( K l ) ranged from lo-' to h-' for the natural compounds and from low3 to 10W6 h-' for the xenobiotic compounds. Turnover times ranged from 47 to more than 1,900 h for natural compounds and from 806 to 60,000 h for xenobiotic compounds. For some compounds, respiratory enzymes became saturated, whereas incorporation into biomass was firstorder. The results show that uptake into cell biomass represents a large fraction of total metabolism for many of the xenobiotic compounds. ''C-most-probable-number (MPN) of substrate degraders was calculated. MPNs for naturally occurring compounds ranged from 10' to lo6 per gram of soil. There were generally fewer than 10 xenobiotic degraders per gram of soil. The biodegradative activity of the subsurface community appears to differ in both rate and product distribution from the activities of aquatic or surface-soil communities.

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Modification of the 14C most-probable-number method for use with nonpolar and volatile substrates

Cited by 23 publications

References 16 publications

Substrate‐ and nutrient‐limited toluene biotransformation in sandy soil

Substrate‐ and nutrient‐limited toluene biotransformation in sandy soil

Adaptation of aquifer microbial communities to the biodegradation of xenobiotic compounds: Influence of substrate concentration and preexposure

Aerobic Biodegradation of Natural and Xenobiotic Organic Compounds by Subsurface Microbial Communities

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