Effects of toluene on microbially-mediated processes involved in the soil nitrogen cycle

Fuller, Mark E.; Scowl, K.M.

doi:10.1007/bf00185886

Cited by 14 publications

(10 citation statements)

References 28 publications

(33 reference statements)

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“…-consuming process contributed to the contrasting results in humid versus semi-arid grasslands. Nitrification is much more sensitive to toluene inhibition than ammonification, and under the experimental conditions of our enzyme assays, nitrification was inhibited (Fuller and Scow 1996). Therefore, the high proteolysis:ammonification ratio in semi-arid grassland and shrubland ecosystems is likely driven by high rates of protease activity relative to amidohydrolase activity, not consumption of NH 4 ?…”

Section: Implications For N Cyclingmentioning

confidence: 86%

Amino acid abundance and proteolytic potential in North American soils

et al. 2010

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Studies of nitrogen (N) cycling have traditionally focused on N mineralization as the primary process limiting plant assimilation of N. Recent evidence has shown that plants may assimilate amino acids (AAs) directly, circumventing the mineralization pathway. However, the general abundance of soil AAs and their relative importance in plant N uptake remains unclear in most ecosystems. We compared the concentrations and potential production rates of AAs and NH(4) (+), as well as the edaphic factors that influence AA dynamics, in 84 soils across the United States. Across all sites, NH(4) (+) and AA-N comprised similar proportions of the total bioavailable N pool (approximately 20%), with NO(3) (-) being the dominant form of extractable N everywhere but in tundra and boreal forest soils. Potential rates of AA production were at least comparable to those of NH(4) (+) production in all ecosystems, particularly in semi-arid grasslands, where AA production rates were six times greater than for NH(4) (+) (P < 0.01). Potential rates of proteolytic enzyme activity were greatest in bacteria-dominated soils with low NH(4) (+) concentrations, including many grassland soils. Based on research performed under standardized laboratory conditions, our continental-scale analyses suggest that soil AA and NH(4) (+) concentrations are similar in most soils and that AAs may contribute to plant and microbial N demand in most ecosystems, particularly in ecosystems with N-poor soils.

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Section: Implications For N Cyclingmentioning

confidence: 86%

Amino acid abundance and proteolytic potential in North American soils

et al. 2010

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“…[23, [30][31][32], one would expect that soils contaminated with high levels of munitions would have elevated levels of these nitrogenous compounds. However, analysis using data from JAAP group 61 soils also indicated a strong correlation be-tween high TNT and TNB concentrations and NO 3 -N levels.…”

Section: Discussionmentioning

confidence: 99%

Evidence for Differential Effects of 2,4,6-Trinitrotoluene and Other Munitions Compounds on Specific Subpopulations of Soil Microbial Communities

Fuller¹,

Manning²

1998

Environ Toxicol Chem

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The effects of 2,4,6-trinitrotoluene (TNT) and other munitions compounds on indigenous microbial communities in several soils were examined. Culturable heterotrophs, concentrations of phospholipid fatty acid (PLFA), and basal respiration rates exhibited slight negative correlations with high TNT and 1,3,5-trinitrobenzene (TNB) levels. Heat-shock-resistant culturable heterotrophs, percentage of gram-positive soil isolates, mole percent of branched PLFA, and 10Me18:0 (tuberculostearic acid) were observed to be significantly lower in highly contaminated soils. Total soil nitrogen levels were positively correlated with high TNT and TNB concentrations, whereas total soil carbon exhibited no significant correlation with either compound. Multivariate analysis of PLFA data resulted in distinct separation of soils with respect to their degree of contamination, with specific signature PLFAs for gram-positive bacteria, fungi, and protozoa being negatively associated with high contaminant levels. Apparent concentrations of TNT resulting in 50% reductions in indicators of gram-positive populations were much higher than values from pure culture experiments, possibly as a result of low bioavailability due to sorption onto clay and soil organic matter. Few effects of other munitions compounds were observed. Closer examination of a highly contaminated soil revealed that the number of culturable heterotrophs growing on 0.3% molasses plates decreased by 50% when 67 g TNT/ml was added to the medium; a 99% decrease was observed for soil contaminated with less than 20 g TNT/g. Highly contaminated soil harbored a greater number of organisms that were able to grow on plates amended with greater than 10 g TNT/ml. Gram-positive isolates from both soils demonstrated marked growth inhibition when greater than 8-16 g TNT/ml was present in the culture medium. These results indicate that chronic exposure to munitions compounds can dramatically alter soil microbial communities.

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“…Selective toxicity to nitrification has been observed with other contaminants as well. Fuller and Scow [19] reported that toluene contamination had no significant effect on ammonification but had a large effect on nitrification. Unlike our findings, they did not observe a recovery of the nitrifying population after a 30-d incubation that followed venting-off the highly volatile contaminant.…”

Section: Discussionmentioning

confidence: 99%

“…As with microbial respiration, ammonification is one process that is carried out by many microorganisms and has been found to be suppressed [18] or unaffected [18–20] following contaminant exposure. Nitrification, however, appears to be consistently sensitive to disturbance [8,11,18–23]. Nitrification is an essential microbially mediated process that is carried out by few groups of microorganisms.…”

Section: Introductionmentioning

confidence: 99%

“…Similar to carbon cycling, different components of the nitrogen cycle appear to be better indicators of disturbance [4]. As with microbial respiration, ammonification is one process that is carried out by many microorganisms and has been found to be suppressed [18] or unaffected [18][19][20] following contaminant exposure. Nitrification, however, appears to be con-sistently sensitive to disturbance [8,11,[18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

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Recovery of microbially mediated processes in soil augmented with a pentachlorophenol‐mineralizing bacterium

Colores

Schmidt

2005

Enviro Toxic and Chemistry

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Specific physiological groups can be used to evaluate the recovery of soil microbial communities following disturbance. In this study, soil was contaminated with pentachlorophenol (PCP) to assess the resiliency of microorganisms responsible for carbon and nitrogen cycling. Methane fluxes were monitored in soil microcosms to evaluate the effects of contamination and augmentation on microbial populations involved in carbon cycling. The addition of a PCP‐mineralizing bacterium, Sphingomonas chlorophenolica strain RA2, enhanced the recovery of methane‐oxidizing capacity relative to uninoculated treatments when soil was contaminated with low concentrations of PCP (10 and 50 μg/g soil, ppm). At the highest level of PCP contamination tested (300 ppm), there was no recovery of methane‐oxidizing capacity whether or not the PCP‐mineralizing bacterium was added to soil. The nitrogencycling capacity of contaminated and augmented soil was tested by measuring nitrification potentials. The addition of PCP resulted in a concentration‐dependent reduction in nitrification rates. After three months of incubation, all augmented soils had nitrification rates equivalent to the uncontaminated control, and the uninoculated soils contaminated with 100 and 300 ppm PCP still were impaired in their nitrification potentials. These results indicate that biological removal of a contaminant has the potential to restore microbially mediated processes to levels observed prior to contamination.

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Effects of toluene on microbially-mediated processes involved in the soil nitrogen cycle

Cited by 14 publications

References 28 publications

Amino acid abundance and proteolytic potential in North American soils

Amino acid abundance and proteolytic potential in North American soils

Evidence for Differential Effects of 2,4,6-Trinitrotoluene and Other Munitions Compounds on Specific Subpopulations of Soil Microbial Communities

Recovery of microbially mediated processes in soil augmented with a pentachlorophenol‐mineralizing bacterium

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