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Kasia Debosz - One of the best experts on this subject based on the ideXlab platform.
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effects and risk assessment of linear alkylbenzene sulfonates in agricultural Soil 2 effects on Soil Microbiology as influenced by sewage sludge and incubation time
2001Co-Authors: Lars Elsgaard, Soren O Petersen, Kasia DeboszAbstract:The anionic surfactant linear alkylbenzene sulfonate (LAS) may inhibit Soil microorganisms and may occur in agricultural Soil through the application of sewage sludge. For five microbial parameters (microbial biomass C and the potentials of iron reduction, ammonium oxidation, dehydrogenase activity, and arylsulfatase activity), we compared the effects of aqueous LAS and LAS-spiked sewage sludge added to existing levels of 0, 3, 8, 22, 62, 174, and 488 mg/kg Soil (dry wt) in a Danish sandy agricultural Soil that was incubated for 5 d to eight weeks. Arylsulfatase activity (measured after four weeks of incubation) was rather insensitive to LAS, with an EC10 of 222 and more than 488 mg/kg in Soil samples treated with aqueous LAS and LAS-spiked sewage sludge, respectively. For the other microbial parameters, the short-term effects (approximately one to two weeks) of aqueous LAS were characterized by an EC10 in the range of 3 to 39 mg/kg. Application of LAS via sewage sludge generally reduced the short-term effects for the microbial parameters, and the EC10 for LAS in sludge-amended Soil after approximately one to two weeks of incubation ranged from less than 8 to 102 mg/kg. Recovery potential was seen for most microbial parameters as a result of prolonged incubation, both under conditions of LAS persistence (anaerobic conditions, the iron-reduction test) and LAS depletion (aerobic incubations, all other assays). In conclusion, the short-term inhibitory effects of LAS on Soil Microbiology were decreased in the presence of sewage sludge and by a prolonged (two to eight weeks) laboratory incubation period.
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effects and risk assessment of linear alkylbenzene sulfonates in agricultural Soil 1 short term effects on Soil Microbiology
2001Co-Authors: Lars Elsgaard, Soren O Petersen, Kasia DeboszAbstract:Linear alkylbenzene sulfonates (LAS) may occur in sewage sludge that is applied to agricultural Soil, in which LAS can be inhibitory to biological activity. As a part of a broader risk assessment of LAS in the terrestrial environment, we tested the short-term effects of aqueous LAS on microbial parameters in a sandy agricultural Soil that was incubated for up to 11 d. The assays included 10 microbial Soil parameters; ethylene degradation; potential ammonium oxidation; potential dehydrogenase activity; beta-glucosidase activity; iron reduction; the populations of cellulolytic bacteria, fungi and actinomycetes; the basal Soil respiration; and the phospholipid fatty acid (PLFA) content. Except for beta-glucosidase activity, basal respiration, and total PLFA content, all Soil parameters were sensitive to LAS, with EC10 values in the range of less than 8 to 22 mg/kg dry weight. This probably reflected a similar mode of LAS toxicity, ascribed to cell membrane interactions, and showed that sensitivity to LAS was common for various Soil microorganisms. The extracellular beta-glucosidase activity was rather insensitive to LAS (ECI10, 47 mg/kg dry wt), whereas the basal Soil respiration was not inhibited even at 793 mg/kg dry weight. This was interpreted as a combined response of inhibited and stimulated compartments of the microbial community. The PLFA content, surprisingly, showed no decrease even at 488 mg/kg. In conclusion, LAS inhibited specific microbial activities, although this could not be deduced from the basal respiration or the total PLFA content. The lowest EC10 values for microbial Soil parameters were slightly higher than the predicted no-effect concentrations recently derived for plants and Soil fauna (approximately 5 mg/kg dry wt).
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effects of linear alkylbenzene sulfonates las on Soil Microbiology
2001Co-Authors: Lars Elsgaard, Soren O Petersen, Kasia Debosz, B KristiansenAbstract:The anionic surfactant linear alkylbenzene sulphonate (LAS) may be introduced into terrestrial environments through the application of sewage sludge onto agricultural Soil. We tested the effects of LAS (0, 0.8, 8, 79 and 793 mg LAS per kg dry weight Soil) on three microbial parameters (potential ammonium oxidation, potential dehydrogenase activity and β-glucosidase activity) in a cultivated sandy Soil that was incubated at 15 °C for 5 to 23 days. Ammonium oxidation and dehydrogenase activity were sensitive to LAS with 10% effect concentrations of 12 to 28 mg LAS kg -1 and 31 mg LAS kg -1 , respectively. The β-glucosidase activity was rather insensitive to LAS with 10% effect concentrations of 279 to >793 mg LAS kg -1 . During LAS exposure for 5 to 23 days there was only weak recovery of the ammonium oxidation. The results confirmed and extended a previous study which showed that LAS also inhibited other compartments of the microbial community, notably bacterial iron reduction. Inhibition of Soil microbiological parameters probably resulted from LAS interaction with both Gram-negative and Gram-positive cell types. Overall, however, the 10% effect concentrations observed for LAS interaction with Soil microbiological parameters were not below the predicted no effect concentration of ∼ 5 mg LAS kg -1 that was recently suggested for plants and Soil fauna.
Lars Elsgaard - One of the best experts on this subject based on the ideXlab platform.
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effect of root litter quality on carbon turnover and Soil Microbiology in topSoil and subSoil horizons
2017Co-Authors: Zhi Liang, Lars Elsgaard, Jorgen E OlesenAbstract:Deployment of deep-rooted crops is suggested to contribute to climate change mitigation by stimulating Soil organic carbon (SOC) storage in deep Soil layers where turnover of SOC is generally slower than in topSoil. Yet, there are few systematic studies on underlying mechanisms and how to optimize SOC content through deep-rooted crops. The aims of this study were to investigate the role of root chemical composition on carbon (C) mineralization dynamics in topSoil (20 cm) and subSoil horizons (60 and 300 cm) of a cultivated sandy loam, and to test the influence of root and soluble C input on Soil microbial and enzymatic activities in the different horizons. We firstly analyzed the chemical properties of root fractions from divergent plant species and selected specific samples for an incubation study to measure the turnover of root-derived C in topSoil and subSoils under controlled laboratory conditions at 20 °C during an incubation period of 20 weeks. During the incubation period, Soil respiration (CO2 production rate), enzyme activity (β-glucosidase) and C substrate utilization (MicroRespTM) were measured. Our results substantiated that root-derived C mineralization was significantly higher in topSoil than subSoil horizons. However, notable C mineralization also occurred in the subSoil horizons after a lag period of 2-3 days. The initial C mineralization rate varied greatly among root materials in all three Soil depths, not at least for CO2 production in subSoil horizons. This could be partly related to the root chemical quality, notably the nitrogen (N) content, which suggests that root N facilitated the microbial activity. Overall, the addition of root materials increased enzyme activities in all three Soil depths after incubation for 1, 5 and 20 weeks compared to the initial stage of 2 h after incubation. When the response was tested to added soluble C substrates, i.e., glucose, N-acetyl-D-glucosamine (NADG) and vanillin, it was found that turn-over of at least glucose and NADG was stimulated in the subSoil horizons after longer time incubation with root materials. Specifically, the turnover dynamics of the N-containing substrate NADG supported that the C mineralization potential in deep Soil horizons may generally be limited by low Soil N content.
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effects and risk assessment of linear alkylbenzene sulfonates in agricultural Soil 2 effects on Soil Microbiology as influenced by sewage sludge and incubation time
2001Co-Authors: Lars Elsgaard, Soren O Petersen, Kasia DeboszAbstract:The anionic surfactant linear alkylbenzene sulfonate (LAS) may inhibit Soil microorganisms and may occur in agricultural Soil through the application of sewage sludge. For five microbial parameters (microbial biomass C and the potentials of iron reduction, ammonium oxidation, dehydrogenase activity, and arylsulfatase activity), we compared the effects of aqueous LAS and LAS-spiked sewage sludge added to existing levels of 0, 3, 8, 22, 62, 174, and 488 mg/kg Soil (dry wt) in a Danish sandy agricultural Soil that was incubated for 5 d to eight weeks. Arylsulfatase activity (measured after four weeks of incubation) was rather insensitive to LAS, with an EC10 of 222 and more than 488 mg/kg in Soil samples treated with aqueous LAS and LAS-spiked sewage sludge, respectively. For the other microbial parameters, the short-term effects (approximately one to two weeks) of aqueous LAS were characterized by an EC10 in the range of 3 to 39 mg/kg. Application of LAS via sewage sludge generally reduced the short-term effects for the microbial parameters, and the EC10 for LAS in sludge-amended Soil after approximately one to two weeks of incubation ranged from less than 8 to 102 mg/kg. Recovery potential was seen for most microbial parameters as a result of prolonged incubation, both under conditions of LAS persistence (anaerobic conditions, the iron-reduction test) and LAS depletion (aerobic incubations, all other assays). In conclusion, the short-term inhibitory effects of LAS on Soil Microbiology were decreased in the presence of sewage sludge and by a prolonged (two to eight weeks) laboratory incubation period.
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effects and risk assessment of linear alkylbenzene sulfonates in agricultural Soil 1 short term effects on Soil Microbiology
2001Co-Authors: Lars Elsgaard, Soren O Petersen, Kasia DeboszAbstract:Linear alkylbenzene sulfonates (LAS) may occur in sewage sludge that is applied to agricultural Soil, in which LAS can be inhibitory to biological activity. As a part of a broader risk assessment of LAS in the terrestrial environment, we tested the short-term effects of aqueous LAS on microbial parameters in a sandy agricultural Soil that was incubated for up to 11 d. The assays included 10 microbial Soil parameters; ethylene degradation; potential ammonium oxidation; potential dehydrogenase activity; beta-glucosidase activity; iron reduction; the populations of cellulolytic bacteria, fungi and actinomycetes; the basal Soil respiration; and the phospholipid fatty acid (PLFA) content. Except for beta-glucosidase activity, basal respiration, and total PLFA content, all Soil parameters were sensitive to LAS, with EC10 values in the range of less than 8 to 22 mg/kg dry weight. This probably reflected a similar mode of LAS toxicity, ascribed to cell membrane interactions, and showed that sensitivity to LAS was common for various Soil microorganisms. The extracellular beta-glucosidase activity was rather insensitive to LAS (ECI10, 47 mg/kg dry wt), whereas the basal Soil respiration was not inhibited even at 793 mg/kg dry weight. This was interpreted as a combined response of inhibited and stimulated compartments of the microbial community. The PLFA content, surprisingly, showed no decrease even at 488 mg/kg. In conclusion, LAS inhibited specific microbial activities, although this could not be deduced from the basal respiration or the total PLFA content. The lowest EC10 values for microbial Soil parameters were slightly higher than the predicted no-effect concentrations recently derived for plants and Soil fauna (approximately 5 mg/kg dry wt).
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effects of linear alkylbenzene sulfonates las on Soil Microbiology
2001Co-Authors: Lars Elsgaard, Soren O Petersen, Kasia Debosz, B KristiansenAbstract:The anionic surfactant linear alkylbenzene sulphonate (LAS) may be introduced into terrestrial environments through the application of sewage sludge onto agricultural Soil. We tested the effects of LAS (0, 0.8, 8, 79 and 793 mg LAS per kg dry weight Soil) on three microbial parameters (potential ammonium oxidation, potential dehydrogenase activity and β-glucosidase activity) in a cultivated sandy Soil that was incubated at 15 °C for 5 to 23 days. Ammonium oxidation and dehydrogenase activity were sensitive to LAS with 10% effect concentrations of 12 to 28 mg LAS kg -1 and 31 mg LAS kg -1 , respectively. The β-glucosidase activity was rather insensitive to LAS with 10% effect concentrations of 279 to >793 mg LAS kg -1 . During LAS exposure for 5 to 23 days there was only weak recovery of the ammonium oxidation. The results confirmed and extended a previous study which showed that LAS also inhibited other compartments of the microbial community, notably bacterial iron reduction. Inhibition of Soil microbiological parameters probably resulted from LAS interaction with both Gram-negative and Gram-positive cell types. Overall, however, the 10% effect concentrations observed for LAS interaction with Soil microbiological parameters were not below the predicted no effect concentration of ∼ 5 mg LAS kg -1 that was recently suggested for plants and Soil fauna.
P C Brookes - One of the best experts on this subject based on the ideXlab platform.
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mineralization of native Soil organic matter is not regulated by the size activity or composition of the Soil microbial biomass a new perspective
2008Co-Authors: S J Kemmitt, Anthony G Odonnell, Clare Lanyon, Ian Waite, Q Wen, T M Addiscott, N R A Bird, P C BrookesAbstract:Soil organic matter is extensively humified; some fractions existing for more than 1000 years. The Soil microbial biomass is surrounded by about 50 times its mass of Soil organic matter, but can only metabolize it very slowly. Paradoxically, even if more than 90% of the Soil microbial biomass is killed, the mineralization of Soil organic matter proceeds at the same rate as in an unperturbed Soil. Here we show that Soil organic matter mineralization is independent of microbial biomass size, community structure or specific activity. We suggest that the rate limiting step is governed by abiological processes (which we term the Regulatory Gate hypothesis), which convert non-bioavailable Soil organic matter into bioavailable Soil organic matter, and cannot be affected by the microbial population. This work challenges one of the long held theories in Soil Microbiology proposed by Winogradsky, of the existence of autochthonous and zymogenous microbial populations. This has significant implications for our understanding of carbon mineralization in Soils and the role of Soil micro-organisms in the global carbon cycle. Here we describe experiments designed to determine if the Regulatory Gate operates. We conclude that there is sufficient experimental evidence for it to be offered as a working hypothesis.
Anthony G Odonnell - One of the best experts on this subject based on the ideXlab platform.
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mineralization of native Soil organic matter is not regulated by the size activity or composition of the Soil microbial biomass a new perspective
2008Co-Authors: S J Kemmitt, Anthony G Odonnell, Clare Lanyon, Ian Waite, Q Wen, T M Addiscott, N R A Bird, P C BrookesAbstract:Soil organic matter is extensively humified; some fractions existing for more than 1000 years. The Soil microbial biomass is surrounded by about 50 times its mass of Soil organic matter, but can only metabolize it very slowly. Paradoxically, even if more than 90% of the Soil microbial biomass is killed, the mineralization of Soil organic matter proceeds at the same rate as in an unperturbed Soil. Here we show that Soil organic matter mineralization is independent of microbial biomass size, community structure or specific activity. We suggest that the rate limiting step is governed by abiological processes (which we term the Regulatory Gate hypothesis), which convert non-bioavailable Soil organic matter into bioavailable Soil organic matter, and cannot be affected by the microbial population. This work challenges one of the long held theories in Soil Microbiology proposed by Winogradsky, of the existence of autochthonous and zymogenous microbial populations. This has significant implications for our understanding of carbon mineralization in Soils and the role of Soil micro-organisms in the global carbon cycle. Here we describe experiments designed to determine if the Regulatory Gate operates. We conclude that there is sufficient experimental evidence for it to be offered as a working hypothesis.
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visualization modelling and prediction in Soil Microbiology
2007Co-Authors: Anthony G Odonnell, Iain M Young, Steven Rushton, Mark D F Shirley, John W CrawfordAbstract:The introduction of new approaches for characterizing microbial communities and imaging Soil environments has benefited Soil Microbiology by providing new ways of detecting and locating microorganisms. Consequently, Soil Microbiology is poised to progress from simply cataloguing microbial complexity to becoming a systems science. A systems approach will enable the structures of microbial communities to be characterized and will inform how microbial communities affect Soil function. Systems approaches require accurate analyses of the spatio-temporal properties of the different microenvironments present in Soil. In this Review we advocate the need for the convergence of the experimental and theoretical approaches that are used to characterize and model the development of microbial communities in Soils.
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16s rdna methods in Soil Microbiology
1999Co-Authors: Anthony G Odonnell, Heike E GorresAbstract:With the introduction of molecular methods, the past decade has seen renewed interest in Soil Microbiology. New and exciting molecular technologies and the promise of finally opening the microbial black box in Soil drive much of this interest. Although these pioneering studies have added much to our knowledge of microbial diversity in Soils, it is debatable whether they have as yet advanced our understanding of the relationship between this diversity and Soil processes. Hopefully, over the next few years, the knowledge gained from molecular studies will provide a better understanding of microbial communities in Soils and lead ultimately to improvements in land management and to the exploitation of the genetic resources of Soil.
Sergey Blagodatsky - One of the best experts on this subject based on the ideXlab platform.
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microbial growth and carbon use efficiency in the rhizosphere and root free Soil
2014Co-Authors: Sergey Blagodatsky, Evgenia Blagodatskaya, Trauteheidi Anderson, Yakov KuzyakovAbstract:Plant-microbial interactions alter C and N balance in the rhizosphere and affect the microbial carbon use efficiency (CUE)–the fundamental characteristic of microbial metabolism. Estimation of CUE in microbial hotspots with high dynamics of activity and changes of microbial physiological state from dormancy to activity is a challenge in Soil Microbiology. We analyzed respiratory activity, microbial DNA content and CUE by manipulation the C and nutrients availability in the Soil under Beta vulgaris. All measurements were done in root-free and rhizosphere Soil under steady-state conditions and during microbial growth induced by addition of glucose. Microorganisms in the rhizosphere and root-free Soil differed in their CUE dynamics due to varying time delays between respiration burst and DNA increase. Constant CUE in an exponentially-growing microbial community in rhizosphere demonstrated the balanced growth. In contrast, the CUE in the root-free Soil increased more than three times at the end of exponential growth and was 1.5 times higher than in the rhizosphere. Plants alter the dynamics of microbial CUE by balancing the catabolic and anabolic processes, which were decoupled in the root-free Soil. The effects of N and C availability on CUE in rhizosphere and root-free Soil are discussed.
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Comments on the paper by Kemmitt et al. (2008) ‘Mineralization of native Soil organic matter is not regulated by the size, activity or composition of the Soil microbial biomass – A new perspective’ [Soil Biology & Biochemistry 40, 61–73]: The biology
2009Co-Authors: Yakov Kuzyakov, Evgenia Blagodatskaya, Sergey BlagodatskyAbstract:Abstract Kemmitt et al. (Kemmitt, S.J., Lanyon, C.V., Waite, I.S., Wen, Q., Addiscott, T.M., Bird, N.R.A., O'Donnell, A.G., Brookes, P.C., 2008. Mineralization of native Soil organic matter is not regulated by the size, activity or composition of the Soil microbial biomass – a new perspective. Soil Biology & Biochemistry 40, 61–73) recently proposed the “Regulatory Gate” hypothesis, which states that decomposition of Soil organic matter (SOM) is regulated solely by abiotic factors. Without studying the mechanisms of such regulation, Kemmitt with coauthors challenged the classical Winogradsky theory of Soil Microbiology and questioned the concept of autochtonous and zymogenous microbial populations. In this letter, we revive the significance of microbial activity for SOM decomposition especially for the short-term (hours to weeks) processes and show that the “Regulatory Gate” is (micro)biologically driven. We explain the results of the three experiments in Kemmitt et al. (2008) from a microbiological point of view and suggest that SOM decomposition is mainly regulated by exoenzymes. We criticize the abiotic Regulatory Gate hypothesis based on bottleneck processes and pools limiting the SOM decomposition rate, comparison of constant and changing environmental conditions, as well as the connection between community structure and functions. We explain the results of Kemmitt et al. (2008) according to the properties of Soil microbial community: functional redundancy and inconsistency between the excessive (but largely inactive) pool of total microbial biomass and the real mineralization activity. Finally, we suggest that to gain new perspectives on SOM decomposition and many other biochemical processes, future studies should focus on hot spots of (micro)biological activity (i.e., the rhizosphere, drillosphere, detritosphere, biopores, etc.) rather than on the bulk Soil.