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  • 1
    Electronic Resource
    Electronic Resource
    Humification processes in reclaimed open-cast lignite mine soils
    Amsterdam : Elsevier
    Soil Biology and Biochemistry 25 (1993), S. 1391-1397 
    Details
    ISSN: 0038-0717
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0038-0717(93)90053-E
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  • 2
    Electronic Resource
    Electronic Resource
    Microdetermination of protease activity in humic bands of different sizes after analytical isoelectric focusing (1989)
    Springer
    Biology and fertility of soils 7 (1989), S. 202-206 
    Details
    ISSN: 1432-0789
    Keywords: Humus fractionation ; Isoelectric points ; Humus-enzyme complexes ; Extracellular protease microdetermination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Extracellular benzoyl-l,-argininamide (BAA)-hydrolysing protease was extracted with neutral pyrophosphate from an arable soil and fractionated by membrane ultrafiltration. There were three fractions: A1 (molecular weight 〉 105), AII (molecular weight 104–105), and R (molecular weight 〈 104). Analytical isoelectric focusing (IEF) of the fractions was carried out on polyacrylamide gels with a restricted pH gradient of 4.0 to 5.0. Two extracellular proteases characterized soil extract E, with one peak (Ip 4.44) bound to a large amount of humic matter and the other (Ip 4.06) bound to a small amount of humus. Following ultrafiltration, the humus-enzyme complex of extract E (Ip 4.44) split into the fractions AI, AII, and R, and was displaced at Ip values that depended on the electrophysical properties of bound organic matter, whereas that at Ip 4.06 was completely removed from the extract E and accumulated only into the low-molecular-weight fraction R. High recoveries of absolute activity were obtained after IEF of the whole extract E, and fractions AII and R, but only about 50% was recovered from fraction AI. It appears that humic substances have reversible inhibitory effects on extracellular proteases, since the maximum recoveries of activity were obtained from fractions where high amounts of protease non-active organic matter had been removed by IER IEF was able to fractionate humic molecules and purify humic-protease complexes on the basis of smaller differences in Ip, and even smaller differences of 0.05 pH units. The present results show that BAA hydrolysing proteases were preferentially linked with a specific class of humic molecules with an Ip of close to 4.44.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00709649
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  • 3
    Electronic Resource
    Electronic Resource
    Isoelectric focusing of soil humic substances in the presence of 8M urea (1986)
    Springer
    Biology and fertility of soils 2 (1986), S. 71-75 
    Details
    ISSN: 1432-0789
    Keywords: Humus fractionation ; Isoelectric points ; Molecular size ; Characteristic bands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The isoelectric focusing (IEF) of different-molecular-size humic fractions, either separately or recombined, was carried out in the presence and absence of 8M urea. In the presence of urea, the fractions were recognizable from both their characteristic microheterogeneity and ranges of focalization. Urea caused a slight shift of the bands towards lower pH values. The refocusing of characteristic band of one fraction produced a slight discrepancy in the isoelectric points (0.2–0.3 pH units). However, the maintenance of the banding in 8M urea and the homogeneity of the band under refocusing demonstrated the reliability of the IEF in fractionating structurally different humic substances. Such experiments should provide useful information on the association/dissociation properties of soil organic matter under controlled conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00257582
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  • 4
    Electronic Resource
    Electronic Resource
    Isolation by isoelectric focusing of humic-urease complexes from earthworm (Eisenia fetida)-processed sewage sludges (2000)
    Springer
    Biology and fertility of soils 31 (2000), S. 489-493 
    Details
    ISSN: 1432-0789
    Keywords: Key words Sewage sludge ; Vermicomposting ; Extracellular urease ; Humic substance ; Isoelectric focusing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Vermicomposting is an eco-biotechnological process that transforms energy-rich and complex organic substances into a stabilized humus-like product. In a laboratory experiment, Eisenia fetida (Sav.) earthworms were employed to process putrescible sewage sludges into a high-value biofertilizer, very rich in urease activity and humic-urease complexes (stabilized extracellular enzymes). Extracellular humic-urease complexes were extracted by a single 24-h extraction at 37  °C using neutral pyrophosphate (0.1 M); then, the extracts were dialysed and characterized by means of an analytical isoelectric focusing technique. This technique gave a multiplicity of humic bands enzymatically active, with isoelectric points ranging from 4.8 to 5.6. The results demonstrated that, after an 18-week incubation period, sewage sludge had undergone a biochemical evolution, which caused a doubling of absolute urease activity and a six-fold increase in specific activity (activity with reference to the humic C fraction). The biochemical evolution of the vermicompost was evaluated also from the sharp decrease in pyrophosphate-extractable C and water-soluble C. Stabilization of organic C during vermicomposting and the activity of humic-urease complexes expressed at low pH values are of extreme importance when organic wastes are used in acid soils for biochemical restoration purposes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740000197
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  • 5
    Electronic Resource
    Electronic Resource
    Kinetic parameters of dehydrogenase in the assessment of the response of soil to vermicompost and inorganic fertilisers (2000)
    Springer
    Biology and fertility of soils 32 (2000), S. 479-483 
    Details
    ISSN: 1432-0789
    Keywords: Keywords Vermicompost ; Mineral fertiliser ; Dehydrogenase kinetics ; Soil fertility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Kinetic parameters (V max and K m) of dehydrogenase activity were determined in order to assess the metabolic response of a soil about 1 year after organic and mineral treatments. The soil was planted with maize (Zea mays) and treated with the following fertilisers: organic (vermicompost; VC), mineral (ammonium phosphate and urea), and an organo-mineral mixture. V max, which represents a measurement of the quantity of enzyme, markedly increased in organic and organo-mineral treatments, indicating that the addition of organic matter caused an increase in dehydrogenase in the active microbial biomass. K m, representing enzyme-substrate affinity and/or different sources of the enzymes, was similar in VC-treated soil and control soil, while it doubled in organo-mineral and mineral treatments. These results suggest that the use of VC did not alter the enzyme-substrate affinity, while mineral fertiliser reduced this affinity or changed the composition and activity of soil microbiota. A positive correlation was found between V max, the metabolic index (dehydrogenase/water-soluble carbon ratio), and the soil organic matter content. The kinetic constants of dehydrogenase activity and the metabolic index may be considered valid parameters to monitor the evolution of microbiological activity in soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740000280
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  • 6
    Electronic Resource
    Electronic Resource
    Fractionation of hydrolase-humus complexes by gel chromatography (1985)
    Springer
    Biology and fertility of soils 1 (1985), S. 25-29 
    Details
    ISSN: 1432-0789
    Keywords: Hydrolase-humus complexes ; Fractionation ; Gel chromatography ; Hydrolysing proteases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Purification of soil phosphatase-, urease-, casein- and benzoylarginamide-hydrolysing proteases was obtained by exhaustively ultrafiltering a soil extract using 0.1M pyrophosphate solution at pH 7.1, separating the retained material into fractions of molecular weight higher (AI) and lower (AII) than 105 and eluting the fractions on gel chromatography. Three peaks of phosphatase and urease activity were obtained after gel chromatography of fraction AI on Sephadex G200 using 0.1M pyrophosphate solution as eluant. Only one distinct activity peak was observed when casein- and benzoylarginamide-hydrolysing proteases were assayed in the eluted fractions. Elution diagrams obtained by gel chromatography of fraction AII on Sephadex G100, using a water as eluant, were characterized by one peak each of phosphatase-, casein- and benzoylarginamide-hydrolysing activity and by two peaks of urease activity. Gel chromatography of both AI and AII, generally, but not always, increased specific activity on a C and N basis of derivative fractions. Both proteases showed the highest increase in specific activity due to a marked decrease in organic C and N and an increase in total activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00710967
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  • 7
    Electronic Resource
    Electronic Resource
    Biochemical characterization of biological activity in very young mine soils (1992)
    Springer
    Biology and fertility of soils 13 (1992), S. 25-30 
    Details
    ISSN: 1432-0789
    Keywords: Soil biochemical properties ; Soil respiration ; Soil enzymes ; Reclamation ; Lignite-mine soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A number of biochemical parameters reflecting biological activity (respiration, ATP, enzyme activities) were determined in 0- to 7-year-old lignite mine soils. C (as CO2) and ATP contents and hydrolytic enzyme activities all increased with soil age. The kinetics of CO2 release showed that both labile and recalcitrant C-bearing substrates were mineralized, the mineralization constant of C decreased with soil age, but were always greater than those of native soils. The percentage of N mineralization, which tended to decrease with soil age, resulted in all cases in a predominance of ammoniacal forms. These findings suggest that since organic C and N accumulated with age in these soils, the C and N cycle is established progressively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00337233
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  • 8
    Electronic Resource
    Electronic Resource
    Characterization of the organic fraction of an uncomposted and composted sewage sludge by isoelectric focusing and gel filtration (1992)
    Springer
    Biology and fertility of soils 13 (1992), S. 112-118 
    Details
    ISSN: 1432-0789
    Keywords: Composting ; Isoelectric point ; Low molecular weight organic matter ; Sewage sludge ; Fractionating organic matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Isoelectric focusing was used to characterize the organic matter of composted and uncomposted sewage sludge. The technique was applied to organic matter extracts and to three fractions, obtained by ultrafiltration, with different molecular weights (〈103, 103–104, 〉104). The elution curves of the extracts through Sephadex G-50 revealed a loss in the proportion of organic matter of low molecular weight as composting progressed, together with an enrichment of the high-molecular-weight proportion. Separation into fractions by controlled ultrafiltration proved to be valid, as deduced from the chromatograms obtained by Sephadex G-50 filtration. The extracts of uncomposted sludge showed a greater number of bands with a low isoelectric point than the composted extract, because there were more acidic molecules in the samples that had not undergone humification. The spectrum corresponding to the extract of the 210-day compost showed greater homogeneity with a lower number of bands. A great part of the organic matter extracted with 0.1 M Na4P2O7 at pH 7.1 corresponded to an intermediate molecular weight. The ampholytes at pH 4–6 gave better resolution than those at pH 3.5–10, in the focusing of fractions with the lowest and the greatest molecular weight. A more homogeneous spectrum was observed for the high-molecular-weight fractions from extracts of the 210-day composted sample; in addition, the bands were displaced towards higher isoelectric points, which indicated that the molecules were more condensed, with a minor content of negatively charged groups and a spectrum similar to that of relative fractions of true humic acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00337345
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  • 9
    Electronic Resource
    Electronic Resource
    Monitoring biochemical activity during sewage sludge composting (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 145-150 
    Details
    ISSN: 1432-0789
    Keywords: Sewage sludge ; Composting ; Enzyme activity ; Respiration ; ATP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A sewage sludge with the addition of two woody materials (1 : 2 ratio), tree-pruning chips and vine shoots, to provide structure were composted under controlled conditions of temperature (28°C) and humidity (70% ambient humidity). Hydrolytic enzyme activities [urease, phosphatase, N-benzoil l-argininamide (BBA) hydrolysing protease, casein-hydrolysing protease, ATP, hydrosoluble and hydrolysable polysaccharides] were determined during the aerobic incubation. Samples were taken and incubated under the same conditions in an accelerative bioreactor to test potential C mineralisation by measuring the CO2 evolved. A rapid mineralisation phase (2–3 weeks) was followed by a slow maturation (4–14 weeks) period. The slow phase and the dynamics of substrate decomposition were better indicated by the hydrolytic enzyme activities that were measured. The structuring agents slightly retarded the compositing process with tree prunings having the strongest effect. Hydrolysable polysaccharides and Folin-reactive compounds (proteins, polyphenols) released by the structure-providing lignocellulose material appear to have controlled both the intensity and the length of the maturation phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369417
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  • 10
    Electronic Resource
    Electronic Resource
    Chemical properties, populations of nitrige oxidizers, urease and phosphatase activities in sewage sludge-amended soils (1985)
    Springer
    Plant and soil 84 (1985), S. 79-91 
    Details
    ISSN: 1573-5036
    Keywords: Ammonification ; Groundwater pollution ; Hydrolyzable-N ; Nitrification ; Phosphatase ; Urease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The aim of this work has been to determine the effect of sterilized and non-sterilized, acrobically or anaerobically digested sewage sludges on urease and phosphatase activities, on populations of nitrite oxidizers and on some chemical properties in laboratory conditions and for long incubation periods. Both urease an phosphatase activities were affected when anaerobic sludges were added to the soil. The inhibitory effects on both enzyme activities attributed to the presence of heavy metals were probably masked by the additional source of organic matter both with acrobic and anaerobic sludges. The level of the NO 2 − oxidizer populations was higher in the aerobic than in the anaerobic sludge amended soil. Ammonia-N concentration were increased when the soil received sludges reflecting a higher mineralization rate probably due to a stimulation of the indigencous ammonia producing microorganisms since differences between non-sterilized and sterilized treatments were minimal or absent. Nitrate-N concentrations increased in amended soils and care must be taken to restrict as much as possible the downward movement of nitrate in order to minimize ground-water pollution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02197869
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