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Klaas G J Nierop - One of the best experts on this subject based on the ideXlab platform.
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origin occurrence and fate of extractable lipids in dutch coastal Dune Soils along a ph gradient
Organic Geochemistry, 2005Co-Authors: Klaas G J Nierop, Dennis F W Naafs, Pim F Van BergenAbstract:Total lipid extracts (TLEs) of subSoils from under oak, had been subjected to natural acidification, were analysed to trace the effects of soil pH on their composition. In addition, roots were analysed as being the main source of SOM in the deeper mineral soil horizons. The TLE of the roots comprised largely triterpenoids and steroids that were barely present in the subSoils. Conversely, only small amounts of alkanoic acids, and no alkanols, ω-hydroxyalkanoic acids or α,ω-alkanedioic acids were detected in the root TLE, whereas in soil TLEs these compounds were highly abundant. The compounds are suggested to be derived from hydrolysed suberin, from the previous grass vegetation and most likely illuviated lipids (i.e. immobilised lipids that moved downwards in dissolved form from overlying horizons) from upper, organic matter-rich horizons and oxidation of lipids mediated by microorganisms. In the course of the soil acidification the amounts of TLE increased and within this fraction long-chain (>C20) alkanoic acids, alkanols, ω-hydroxyalkanoic acids and α,ω-alkanedioic acids increased relatively with respect to short chain (
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occurrence and distribution of ester bound lipids in dutch coastal Dune Soils along a ph gradient
Organic Geochemistry, 2003Co-Authors: Klaas G J Nierop, Dennis F W Naafs, J M VerstratenAbstract:The base-hydrolysable fraction of roots and soil organic matter (SOM) in mineral subSoils from oak forests (coastal Dunes, The Netherlands) with a soil pH varying from pH (CaCl2) 6.9 to 3.5 were analysed both quantitatively and qualitatively. Comparison of thermally assisted hydrolysis and methylation (THM) using tetramethylammonium hydroxide (TMAH) with base hydrolysis data confirmed that base hydrolysis is an efficient way of analysing ester-linked compounds in Soils. The compounds released from SOM upon base hydrolysis comprised largely suberin-derived lipids, which were clearly related to the oak vegetation and, in particular, to oak roots. Compared with fresh (fine) roots, which are largely responsible for the input of SOM in the subSoils, unsaturated and epoxy compounds decreased in soil, probably due to oxidation. The amounts of the saponifiable fraction increased upon acidification, whilst hardly any changes were observed in their composition. This accumulation, without significant compositional alteration of ester-bound moieties in acidic Soils, indicates that these chemically labile compounds can be preserved in Soils.
Pim F Van Bergen - One of the best experts on this subject based on the ideXlab platform.
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origin occurrence and fate of extractable lipids in dutch coastal Dune Soils along a ph gradient
Organic Geochemistry, 2005Co-Authors: Klaas G J Nierop, Dennis F W Naafs, Pim F Van BergenAbstract:Total lipid extracts (TLEs) of subSoils from under oak, had been subjected to natural acidification, were analysed to trace the effects of soil pH on their composition. In addition, roots were analysed as being the main source of SOM in the deeper mineral soil horizons. The TLE of the roots comprised largely triterpenoids and steroids that were barely present in the subSoils. Conversely, only small amounts of alkanoic acids, and no alkanols, ω-hydroxyalkanoic acids or α,ω-alkanedioic acids were detected in the root TLE, whereas in soil TLEs these compounds were highly abundant. The compounds are suggested to be derived from hydrolysed suberin, from the previous grass vegetation and most likely illuviated lipids (i.e. immobilised lipids that moved downwards in dissolved form from overlying horizons) from upper, organic matter-rich horizons and oxidation of lipids mediated by microorganisms. In the course of the soil acidification the amounts of TLE increased and within this fraction long-chain (>C20) alkanoic acids, alkanols, ω-hydroxyalkanoic acids and α,ω-alkanedioic acids increased relatively with respect to short chain (
Dennis F W Naafs - One of the best experts on this subject based on the ideXlab platform.
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origin occurrence and fate of extractable lipids in dutch coastal Dune Soils along a ph gradient
Organic Geochemistry, 2005Co-Authors: Klaas G J Nierop, Dennis F W Naafs, Pim F Van BergenAbstract:Total lipid extracts (TLEs) of subSoils from under oak, had been subjected to natural acidification, were analysed to trace the effects of soil pH on their composition. In addition, roots were analysed as being the main source of SOM in the deeper mineral soil horizons. The TLE of the roots comprised largely triterpenoids and steroids that were barely present in the subSoils. Conversely, only small amounts of alkanoic acids, and no alkanols, ω-hydroxyalkanoic acids or α,ω-alkanedioic acids were detected in the root TLE, whereas in soil TLEs these compounds were highly abundant. The compounds are suggested to be derived from hydrolysed suberin, from the previous grass vegetation and most likely illuviated lipids (i.e. immobilised lipids that moved downwards in dissolved form from overlying horizons) from upper, organic matter-rich horizons and oxidation of lipids mediated by microorganisms. In the course of the soil acidification the amounts of TLE increased and within this fraction long-chain (>C20) alkanoic acids, alkanols, ω-hydroxyalkanoic acids and α,ω-alkanedioic acids increased relatively with respect to short chain (
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occurrence and distribution of ester bound lipids in dutch coastal Dune Soils along a ph gradient
Organic Geochemistry, 2003Co-Authors: Klaas G J Nierop, Dennis F W Naafs, J M VerstratenAbstract:The base-hydrolysable fraction of roots and soil organic matter (SOM) in mineral subSoils from oak forests (coastal Dunes, The Netherlands) with a soil pH varying from pH (CaCl2) 6.9 to 3.5 were analysed both quantitatively and qualitatively. Comparison of thermally assisted hydrolysis and methylation (THM) using tetramethylammonium hydroxide (TMAH) with base hydrolysis data confirmed that base hydrolysis is an efficient way of analysing ester-linked compounds in Soils. The compounds released from SOM upon base hydrolysis comprised largely suberin-derived lipids, which were clearly related to the oak vegetation and, in particular, to oak roots. Compared with fresh (fine) roots, which are largely responsible for the input of SOM in the subSoils, unsaturated and epoxy compounds decreased in soil, probably due to oxidation. The amounts of the saponifiable fraction increased upon acidification, whilst hardly any changes were observed in their composition. This accumulation, without significant compositional alteration of ester-bound moieties in acidic Soils, indicates that these chemically labile compounds can be preserved in Soils.
J M Verstraten - One of the best experts on this subject based on the ideXlab platform.
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occurrence and distribution of ester bound lipids in dutch coastal Dune Soils along a ph gradient
Organic Geochemistry, 2003Co-Authors: Klaas G J Nierop, Dennis F W Naafs, J M VerstratenAbstract:The base-hydrolysable fraction of roots and soil organic matter (SOM) in mineral subSoils from oak forests (coastal Dunes, The Netherlands) with a soil pH varying from pH (CaCl2) 6.9 to 3.5 were analysed both quantitatively and qualitatively. Comparison of thermally assisted hydrolysis and methylation (THM) using tetramethylammonium hydroxide (TMAH) with base hydrolysis data confirmed that base hydrolysis is an efficient way of analysing ester-linked compounds in Soils. The compounds released from SOM upon base hydrolysis comprised largely suberin-derived lipids, which were clearly related to the oak vegetation and, in particular, to oak roots. Compared with fresh (fine) roots, which are largely responsible for the input of SOM in the subSoils, unsaturated and epoxy compounds decreased in soil, probably due to oxidation. The amounts of the saponifiable fraction increased upon acidification, whilst hardly any changes were observed in their composition. This accumulation, without significant compositional alteration of ester-bound moieties in acidic Soils, indicates that these chemically labile compounds can be preserved in Soils.
J.w. Woldendorp - One of the best experts on this subject based on the ideXlab platform.
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suppression of hyphal growth of soil borne fungi by Dune Soils from vigorous and declining stands of ammophila arenaria
New Phytologist, 1998Co-Authors: W.f. De Boer, P. J. A. Klein Gunnewiek, J.w. WoldendorpAbstract:A study was carried out to determine whether expansion of marram-grass stands (Ammophila arenaria (L.) Link) on acidic inner Dutch coastal Dunes was caused by suppressiveness of Soils from these stands against three potential pathogenic fungi of marram grass, namely Fusarium culmorum (W. G. Sm.) Sacc., Phoma exigua Desm. and a Ulocladium sp. The suppressiveness of the acidic inner Dune Soils was compared with that of lime-rich Dune Soils from vigorous and declining marram-grass stands. Suppressiveness of the Dune Soils against the saprotrophic fungi Chaetomium globosum Kunze: Fr, Mucor hiemalis Wehmer and Trichoderma harzianum Rifai was also determined. All fungi had been isolated from marram-grass roots. Suppressiveness was determined by comparing the formation of hyphae from potato-dextrose agar discs into (layer method) or on top of (surface method) Dune Soils with that of controls consisting of sterile, acid-washed beach sand. The growth of the three root-infecting fungi was strongly inhibited in all Soils regardless of the method used. Hence, there were no indications that the potential pathogenic fungi were selectively suppressed by the acidic Dune Soils and, consequently, the results did not give any indication for the involvement of a fungal component in the decline of marram grass. Growth of the saprotrophs C. globosum and M. hiemalis was much less inhibited than that of the root-infecting fungi. Growth of T. harzianum was strongly inhibited in alkaline Soils but not in the acid ones. The suppression of fungal growth could be partly or completely eliminated by a microwave treatment, indicating that biological components of the soil were essential to suppressiveness. The suppression of the fungi by colonies of Dune soil micro-organisms on water-agar differed considerably from soil alone. Yet, all methods indicated the occurrence of general suppressiveness against fungi by Dune Soils, irrespective of the origin of the soil samples. This suppressiveness was probably not due to direct competition with other soil micro-organisms for nutrients but to inhibiting compounds produced by the soil micro-organisms. [KEYWORDS: suppressiveness; antagonism; Dune Soils; Ammophila arenaria (L.) Link Plant-parasitic nematodes; coastal foreDunes; l link; vegetation; degeneration; grassland; heathland; organisms;bacteria]
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analysis of ammonia oxidizing bacteria of the beta subdivision of the class proteobacteria in coastal sand Dunes by denaturing gradient gel electrophoresis and sequencing of pcr amplified 16s ribosomal dna fragments
Applied and Environmental Microbiology, 1997Co-Authors: George A Kowalchuk, W.f. De Boer, John R Stephen, James I Prosser, T M Embley, J.w. WoldendorpAbstract:Denaturing gradient gel electrophoresis (DGGE) is a powerful and convenient tool for analyzing the sequence diversity of complex natural microbial populations. DGGE was evaluated for the identification of ammonia oxidizers of the beta subdivision of the Proteobacteria based on the mobility of PCR-amplified 16S rDNA fragments and for the analysis of mixtures of PCR products from this group generated by selective PCR of DNA extracted from coastal sand Dunes. Degenerate PCR primers, CTO189f-GC and CTO654r, incorporating a 59 GC clamp, were designed to amplify a 465-bp 16S rDNA region spanning the V-2 and V-3 variable domains. The primers were tested against a representative selection of clones and cultures encompassing the currently recognized beta-subdivision ammonia oxidizer 16S rDNA sequence diversity. Analysis of these products by DGGE revealed that while many of the sequences could be separated, some which were known to be different migrated similarly in the denaturant system used. The CTO primer pair was used to amplify 16S rDNA sequences from DNA extracted from soil sampled from Dutch coastal Dune locations of differing in pH and distance from the beach. The derived DGGE patterns were reproducible across multiple DNA isolations and PCRs. Ammonia oxidizer-like sequences from different phylogenetic groupings isolated from gene libraries made from the same sand Dune DNA samples but prepared with different primers gave DGGE bands which comigrated with most of the bands detected from the sand Dune samples. Bands from the DGGE gels of environmental samples were excised, reamplified, and directly sequenced, revealing strong similarity or identity of the recovered products to the corresponding regions of library clones. Six of the seven sequenced clusters of beta-subdivision ammonia oxidizers were detected in the Dune systems, and differences in community structure between some sample sites were demonstrated. The most seaward Dune site contained sequences showing affinity with sequence clusters previously isolated only from marine environments and was the only site where sequences relate to Nitrosomonas genes could be detected. Nitrosospira-like sequences were present in all sites, and there was some evidence of differences between Nitrosospira populations in acid and alkaline Dune Soils. Such differences in community structure may affect physiological differences within beta-subdivision ammonia oxidizers, with consequent effects on nitrification rates in response to key environmental factors.
