| 1. |
- Bååth, Erland, et al.
(författare)
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Effect of metal-rich sludge amendments on the soil microbial community
- 1998
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Ingår i: Applied and Environmental Microbiology. - 0099-2240. ; 64:1, s. 238-245
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Tidskriftsartikel (refereegranskat)abstract
- The effects of heavy-metal-containing sewage sludge on the soil microbial community were studied in two agricultural soils of different textures, which had been contaminated separately with three predominantly single metals (Cu, Zn, and Ni) at two different levels more than 20 years ago. We compared three community-based microbiological measurements, namely, phospholipid fatty acid (PLFA) analysis to reveal changes in species composition, the Biolog system to indicate metabolic fingerprints of microbial communities, and the thymidine incorporation technique to measure bacterial community tolerance. In the Luddington soil, bacterial community tolerance increased in all metal treatments compared to an unpolluted-sludge-treated control soil. Community tolerance to specific metals increased the most when the same metal was added to the soil; for example, tolerance to Cu increased most in Cu-polluted treatments. A dose-response effect was also evident. There were also indications of cotolerance to metals whose concentration had not been elevated by the sludge treatment. The PLFA pattern changed in all metal treatments, but the interpretation was complicated by the soil moisture content, which also affected the results. The Biolog measurements indicated similar effects of metals and moisture to the PLFA measurements, but due to high variation between replicates, no significant differences compared to the uncontaminated control were found. In the Lee Valley soil, significant increases in community tolerance were found for the high levels of Cu and Zn, while the PLFA pattern was significantly altered for the soils with high levels of Cu, Ni, and Zn. No effects on the Biolog measurements were found in this soil.
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| 2. |
- Bååth, Erland, et al.
(författare)
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Microbial community-based measurements to estimate heavy metal effects in soil : The use of phospholipid fatty acid patterns and bacterial community tolerance
- 1998
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Ingår i: Ambio: a Journal of Human Environment. - 0044-7447. ; 27:1, s. 58-61
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Tidskriftsartikel (refereegranskat)abstract
- Microbial community-based measurements to detect effects of heavy metals in soils rely on the premise that metal toxicity exerts a selection pressure, which induces a change in the composition of the community. The phospholipid fatty acid (PLFA) composition gives an integrated picture of all living organisms in the soil, and changes in the PLFA pattern of the soil indicate an altered species composition due to, e.g. metal toxicity. An increased bacterial community tolerance to metals also indicates an altered community composition, with tolerant organisms becoming more abundant relative to sensitive organisms. The use of these two techniques is described, and their advantages and disadvantages as monitoring tools are discussed and exemplified by field data and laboratory experiments from different soils.
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| 3. |
- Börjesson, Gunnar, et al.
(författare)
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Microbial oxidation of CH4 at high partial pressures in an organic landfill cover soil under different moisture regimes
- 1998
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Ingår i: FEMS Microbiology Ecology. - 0168-6496. ; 26:3, s. 207-217
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Tidskriftsartikel (refereegranskat)abstract
- The uptake and utilization of CH4 at high concentrations (5-18% vol.) and different soil moistures were followed for samples from a landfill cover soil with a high organic matter content. Measurements of the utilization of CH4 and O2, and production of CO2 indicated that the activity of methanotrophic organisms accounted for most of the O2 respiration. At water saturation, CH4 oxidation rates decreased with time, probably because NH4/+ accumulated. Denitrification rates, estimated based on both N2 and N2O production, were positively related to soil moisture and only slightly influenced by the extent of CH4 oxidation. Total phospholipid fatty acid concentrations increased, and concentrations of phospholipid fatty acids, typical for obligate methanotrophic bacteria (e.g. 16:1ω8 and 18:1ω8), increased in the CH4-amended samples, indicating growth of both type I and type II methanotrophs.
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| 4. |
- Jacobsen, Carsten Suhr, et al.
(författare)
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Inter-laboratory testing of the effect of DNA blocking reagent G2 on DNA extraction from low-biomass clay samples
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Here we show that a commercial blocking reagent (G2) based on modified eukaryotic DNA significantly improved DNA extraction efficiency. We subjected G2 to an inter-laboratory testing, where DNA was extracted from the same clay subsoil using the same batch of kits. The inter-laboratory extraction campaign revealed large variation among the participating laboratories, but the reagent increased the number of PCR-amplified16S rRNA genes recovered from biomass naturally present in the soils by one log unit. An extensive sequencing approach demonstrated that the blocking reagent was free of contaminating DNA, and may therefore also be used in metagenomics studies that require direct sequencing.
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| 5. |
- Lekberg, Ylva, et al.
(författare)
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Fatty acid 16:1ω5 as a proxy for arbuscular mycorrhizal fungal biomass : current challenges and ways forward
- 2022
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Ingår i: Biology and Fertility of Soils. - : Springer Science and Business Media LLC. - 0178-2762 .- 1432-0789. ; 58:8, s. 835-842
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Tidskriftsartikel (refereegranskat)abstract
- Fatty acid biomarkers have emerged as a useful tool to quantify biomass of various microbial groups. Here we focus on the frequent use of the fatty acid 16:1ω5 as a biomarker for arbuscular mycorrhizal (AM) fungi in soils. We highlight some issues with current applications of this method and use several examples from the literature to show that the phospholipid fatty acid (PLFA) 16:1ω5 can occur in high concentrations in soils where actively growing AM fungi are absent. Unless the study includes a control where the contribution of other microbes can be estimated, we advocate for the use of the neutral lipid fatty acid (NLFA) 16:1ω5. This biomarker has higher specificity, is more responsive to shifts in AM fungal biomass, and quantification can be conducted along with PLFA analysis without doubling analytical efforts. We conclude by contrasting various methods used to measure AM fungal biomass in soil and highlight future research needs to optimize fatty acid analyses.
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| 6. |
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