| 1. |
- Boysen, Marianne E., et al.
(författare)
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Effect of the biocontrol yeast Pichia anomala on interactions between Penicillium roqueforti, Penicillium carneum, and Penicillium paneum in moist grain under restricted air supply
- 2000
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Ingår i: Postharvest biology and technology. - : Elsevier. - 0925-5214 .- 1873-2356. ; 19:2, s. 173-179
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Tidskriftsartikel (refereegranskat)abstract
- Penicillium roqueforti was recently reclassified into the three species P. roqueforti, Penicillium carneum, and Penicillium paneum based on differences in ribosomal DNA sequences and secondary metabolites, e.g. mycotoxins. This is the first report on interaction between these closely related mould species under stress conditions. The yeast Pichia anomala (J121) inhibits growth of P. roqueforti in grain stored in malfunctioning airtight storage systems. The ability of P. anomala to inhibit all three species of the P. roqueforti group was examined in separate experiments as well as the competition between the three mould species when co-cultured with or without the yeast in non-sterile wheat grain (a(w) 0.95) under restricted air supply. Mould growth was analysed by dilution plating after 14 days and the individual colonies identified by random amplified polymorphic DNA (RAPD) fingerprinting. When co-culturing the P. roqueforti group in wheat without P. anomala all three species were able to grow to the same extent. Also, when co-culturing all species of the P. roqueforti group together with P. anomala, the growth response of the three species was very similar. Al yeast levels of 10(4) CFU g(-1),grain a pronounced inhibition was observed and at 10(5) CFU g(-1) grain a fungicidal effect was detected, indicating a potentiated effect of P. anomala when co-culturing the three mould species.
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| 2. |
- Börjesson, Thomas S., et al.
(författare)
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Off-odorous compounds produced by molds on oatmeal agar : Identification and relation to other growth characteristics
- 1993
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Ingår i: Journal of Agricultural and Food Chemistry. - Washington : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 41:11, s. 2104-2111
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Tidskriftsartikel (refereegranskat)abstract
- Ten Penicillium and Aspergillus species, four with a strong musty off-odor and six reference fungi without any characteristic odor, were cultivated on oatmeal agar for 5 days in cultivation vessels provided with an inlet and an outlet for air. Samples of volatile metabolites were collected on a porous polymer adsorbent attached to the outlet from day 2 through day 5 after inoculation. Adsorbed compounds were desorbed thermally and analyzed with GC/MS and a combined GC and sensory analysis, the GC sniff technique. Multivariate analysis of GC/MS and fungal odor data revealed strong associations between 6 of 65 volatile compounds and musty off-odor. The GC sniff technique showed that five of these, dimethyl disulfide, 1-octen-3-ol, 2-methylisoborneol, and two C11H18 compounds, had prominent off-odors. In addition, geosmin, 1-methoxy-3-methylbenzene, and methylphenol were produced in large amounts by some off-odorous fungi and contributed to their unpleasant odor. 3-Methylfuran, 2-methyl-1-propanol, and 3-methyl-1-butanol were much more commonly produced than the off-odorous compounds. Both odorous and other volatile metabolites could be detected after 2 days of fungal growth. The production of odorous metabolites was enhanced at the time of sporulation.
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| 3. |
- Hyvonen, R., et al.
(författare)
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The likely impact of elevated [CO2], nitrogen deposition, increased temperature and management on carbon sequestration in temperate and boreal forest ecosystems: a literature review
- 2007
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Ingår i: New Phytologist. - Cambridge : Wiley. - 0028-646X .- 1469-8137. ; 173:3, s. 463-480
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Forskningsöversikt (refereegranskat)abstract
- Temperate and boreal forest ecosystems contain a large part of the carbon stored on land, in the form of both biomass and soil organic matter. Increasing atmospheric [CO2], increasing temperature, elevated nitrogen deposition and intensified management will change this C store. Well documented single-factor responses of net primary production are: higher photosynthetic rate (the main [CO2] response); increasing length of growing season (the main temperature response); and higher leaf-area index (the main N deposition and partly [CO2] response). Soil organic matter will increase with increasing litter input, although priming may decrease the soil C stock initially, but litter quality effects should be minimal (response to [CO2], N deposition, and temperature); will decrease because of increasing temperature; and will increase because of retardation of decomposition with N deposition, although the rate of decomposition of high-quality litter can be increased and that of low-quality litter decreased. Single-factor responses can be misleading because of interactions between factors, in particular those between N and other factors, and indirect effects such as increased N availability from temperature-induced decomposition. In the long term the strength of feedbacks, for example the increasing demand for N from increased growth, will dominate over short-term responses to single factors. However, management has considerable potential for controlling the C store.
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| 4. |
- Jennessen, Jennifer, et al.
(författare)
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Secondary metabolite and mycotoxin production by the Rhizopus microsporus group
- 2005
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 53:5, s. 1833-1840
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Tidskriftsartikel (refereegranskat)abstract
- Fast-growing Zygomycetes, most notably Rhizopus oligosporus, are traditionally used in many food fermentations, for example, for soybean tempeh production. R. oligosporus is considered to belong to the Rhizopus microsporus group. Certain R. microsporus strains have been reported to produce either the pharmaceutically active rhizoxins or the highly toxic rhizonins A and B. In this study was investigated the formation of secondary metabolites by R. microsporus, R. oligosporus, and Rhizopus chinensis grown on a wide range of different semisynthetic and natural substrates. Liquid chromatography, combined with photodiode array detection and high-resolution mass spectrometric techniques, was used to identify secondary metabolites. Growth on maize, brown rice, and Pharma agar gave both the highest amounts and the maximum diversity of rhizoxins and rhizonins. Rhizoxins were produced by all four R. microsporus strains, whereas only one strain produced rhizonins. The six R. oligosporus and four R. chinensis strains investigated did not produce any of these two classes of metabolites.
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| 5. |
- Lindberg, T., et al.
(författare)
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Distribution of15N in the soil-plant system during a four-year field lysimeter study with barley (Hordeum distichum L.) and perennial meadow fescue (Festuca pratensis Huds.)
- 1989
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Ingår i: Plant and Soil. - Dordrecht, Netherlands : Kluwer Academic Publishers. - 0032-079X .- 1573-5036. ; 119:1, s. 25-37
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Tidskriftsartikel (refereegranskat)abstract
- An annual cereal, barley, and a perennial grass ley, meadow fescue, were grown in field lysimeters in Sweden and fertilized with 12 and 20g Ca(NO3)2-N m-2 yr-1, respectively. Isotope-labeled (15N) fertilizer was added during year 1 of the study, whereafter similar amounts of unlabeled N were added during years 2 and 3. The grass ley lysimeters were ploughed after the growing season of year 3 and sown with barley during year 4. The barley harvest in year 1 removed 59% of the added fertilizer N, while the fertilizer N export by two meadow fescue harvests in year 1 was 65%. The labeled N export decreased rapidly after year 1, especially in the barley, but increased slightly after ploughing of the grass ley.The microbial biomass, measured with the chloroform fumigation method, incorporated a maximum of 1.4-1.7% of the labeled N during the first seven weeks after application. Later on, the incorporation stabilized at less than 1% in both cropping systems.The susceptibility of the residual labeled N to mineralization was evaluated three years after application by means of long-term laboratory incubations. The curves of cumulative mineralized N were described by a two-component first-order regression model that differentiated between an available and a more recalcitrant fraction of potentially mineralizable N. There was no difference in the amounts of potentially mineralizable N between the cropping systems. The labeled N comprised 5 and 2% of the amounts of potentially mineralizable N in the available and more recalcitrant fraction, respectively. The mineralization rate constants for the labeled N were almost twice as high as for the total potentially mineralizable N. The available fraction of the total potentially mineralizable N was 12%, while twice that proportion of the labeled N was available.It was concluded that the short-term ley did not differ from the annual crop with respect to the early disposition of the fertilizer N and the behaviour of the residual organic N.
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| 6. |
- Melin, Petter, et al.
(författare)
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Formulation and stabilisation of the biocontrol yeast Pichia anomala
- 2011
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Ingår i: Antonie van Leeuwenhoek. International Journal of General and Molecular Microbiology. - Dordrecht, Netherlands : Springer Netherlands. - 0003-6072 .- 1572-9699. ; 99:1, s. 107-112
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Tidskriftsartikel (refereegranskat)abstract
- The yeast Pichia anomala has antifungal activities and its potential in biocontrol and biopreservation has previously been demonstrated. To practically use an organism in such applications on a larger scale the microbe has to be formulated and stabilised. In this review we give an overview of our experience of formulating and stabilising P. anomala strain J121 in a wider perspective. The stabilisation techniques we have evaluated were liquid formulations, fluidised bed drying, lyophilisation (freeze-drying) and vacuum drying. With all methods tested it was possible to obtain yeast cells with shelf lives of at least a few months and in all cases the biocontrol activity was retained. Fluidised bed drying was dependent on the addition of cottonseed flour as a carrier during the drying process. In liquid formulations a sugar, preferentially trehalose, was a required additive. These two kinds of microbial stabilisation are easily performed and relatively inexpensive but in order to keep the cells viable the biomaterial has to be stored at cool temperatures. However, there is room for optimization, such as improving the growth conditions, or include preconditioning steps to enable the cells to produce more compatible solutes necessary to survive formulation, desiccation and storage. In contrast, lyophilisation and vacuum drying require a lot of energy and are thus expensive. On the other hand, the dried cells were mostly intact after one year of storage at 30A degrees C. Inevitably, the choice of formulation and stabilisation techniques will be dependent also on the intended use.
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| 7. |
- Menichetti, Lorenzo, et al.
(författare)
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Contribution of roots and amendments to soil carbon accumulation within the soil profile in a long-term field experiment in Sweden
- 2015
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Ingår i: Agriculture, Ecosystems & Environment. - : Elsevier. - 0167-8809 .- 1873-2305. ; 200, s. 79-87
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Tidskriftsartikel (refereegranskat)abstract
- The contribution of different C inputs to organic carbon accumulation within the soil profile in the Ultuna long-term continuous soil organic matter experiment, established in 1956, was determined. Until 1999, C3-crops were grown at the site, but since then maize (C4) has been the only crop. The effect of a total of 10 different inorganic nitrogen and organic amendment treatments (4 Mg C ha−1 yr−1) on SOC in topsoil and subsoil after 53 years was evaluated and the contribution from maize roots to SOC after 10 years of cultivation was estimated.Soil organic carbon (SOC) and δ13C signature were measured down to 50 cm depth. The C content in the topsoil (0–20 cm depth) was 1.5% at the start of the experiment. After 53 years of treatments, the average topsoil C content varied between 0.9 and 3.8% of soil dry weight, with the open fallow having the lowest and the peat amended the highest value. Nitrogen seemed to promote C accumulation in the topsoil treatment effects were smaller below 20 cm depth and only two of the amendments (peat and sewage sludge) significantly affected SOC content down to 35 cm depth. Despite this, penetrometer measurements showed significant treatment differences of compaction below 41 cm depth, and although we could not explain these differences this presented some evidence of an initial treatment-induced subsoil differentiation. Ten years of maize growth affected the δ13C of SOC down to 22.5 cm depth, where it varied between −25.16 and −26.33(‰), and an isotopic mass balance calculation suggested that maize C accounted for 4–8% of total SOC in the topsoil. Until less than 2500 years ago the site was a post-glacial sea floor and the 14C data suggest that marine sediment C still dominates the SOC in deeper soil layers. Overall, the results suggest that 53 years of treatments has caused dramatic changes on the stored C in the topsoil in several of the treatments, while the changes in the subsoil is much less dramatic and a small C accumulation in the upper subsoil was found in two of the treatments.The contribution from roots to SOC accumulation was generally equal to or greater than the contribution from amendments. The retention coefficient of root-derived C in the topsoil was on average 0.30 ± 0.09, which is higher than usually reported in the literature for plant residues but confirms previous findings for the same experiment using another approach. This strengthens the conclusion that root-derived SOC contributed more to SOC than above-ground crop residues.
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| 8. |
- Menichetti, Lorenzo, et al.
(författare)
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Increase in soil stable carbon isotope ratio relates to loss of organic carbon : results from five long-term bare fallow experiments
- 2015
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Ingår i: Oecologia. - New York : Springer Verlag. - 0029-8549 .- 1432-1939. ; 177:3, s. 811-821
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Tidskriftsartikel (refereegranskat)abstract
- Changes in the 12C/13C ratio (expressed as δ13C) of soil organic C (SOC) has been observed over long time scales and with depth in soil profiles. The changes are ascribed to the different reaction kinetics of 12C and 13C isotopes and the different isotopic composition of various SOC pool components. However, experimental verification of the subtle isotopic shifts associated with SOC turnover under field conditions is scarce. We determined δ13C and SOC in soil sampled during 1929–2009 in the Ap-horizon of five European long-term bare fallow experiments kept without C inputs for 27–80 years and covering a latitudinal range of 11°. The bare fallow soils lost 33–65 % of their initial SOC content and showed a mean annual δ13C increase of 0.008–0.024 ‰. The 13C enrichment could be related empirically to SOC losses by a Rayleigh distillation equation. A more complex mechanistic relationship was also examined. The overall estimate of the fractionation coefficient (ε) was −1.2 ± 0.3 ‰. This coefficient represents an important input to studies of long-term SOC dynamics in agricultural soils that are based on variations in 13C natural abundance. The variance of ε may be ascribed to site characteristics not disclosed in our study, but the very similar kinetics measured across our five experimental sites suggest that overall site-specific factors (including climate) had a marginal influence and that it may be possible to isolate a general mechanism causing the enrichment, although pre-fallow land use may have some impact on isotope abundance and fractionation.
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| 9. |
- Menichetti, Lorenzo, et al.
(författare)
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Organic amendments affect delta C-13 signature of soil respiration and soil organic C accumulation in a long-term field experiment in Sweden
- 2013
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Ingår i: European Journal of Soil Science. - : Wiley. - 1351-0754 .- 1365-2389. ; 64:5, s. 621-628
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Tidskriftsartikel (refereegranskat)abstract
- The contribution of young and old soil organic carbon (SOC) pools to soil CO2 fluxes and specific respiration rates of these fluxes was determined by using C-13 signatures in the Ultuna long-term continuous soil organic matter experiment (C-SOME). Initiated in 1956, the experiment had a range of treatments amended organically and with mineral nitrogen fertilizer under C-3 cultivation until 1999, and thereafter under C-4 (maize) cultivation. In 2011, soil respiration was measured in situ prior to planting, during growth and after harvest. The contributions from C-4- and C-3-C as well as their specific respiration rates were estimated from C-13 differences in SOC and CO2 fluxes. The contributions from C-4-C sources were further separated into autotrophic and heterotrophic respiration by comparing respiration rates before and after harvest. Between 165 and 385g C-4-Cm-2 accumulated during 10years of maize growth, contributing between 4.9 and 8.1% to the total SOC stock. Although recent C-4-C had an average specific respiration rate that was 8.4-22.6 times greater than C-3-C, total soil respiration was generally equally split between C-3-C and C-4-C. Both pools are therefore important sources of CO2 in the overall C budget, and a crucial factor in accounting for SOC stock change caused by management. Experimental treatments influenced specific respiration rates of C-4 plant material and accumulation of SOC stock, demonstrating how greater SOC accumulation can be favoured by high-quality C inputs.
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| 10. |
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