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| 2. |
- Castoria, Raffaello, et al.
(författare)
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Conversion of the Mycotoxin Patulin to the Less Toxic Desoxypatulinic Acid by the Biocontrol Yeast Rhodosporidium kratochvilovae Strain LS11
- 2011
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 59:21, s. 11571-11578
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Tidskriftsartikel (refereegranskat)abstract
- The infection of stored apples by the fungus Penicillium e., pansum Causes the contamination of fruits and fruit-derived products with the mycotoxin patulin, which is a major issue in food safety Fungal attack can be prevented by beneficial microorganisms, so-called biocontrol agents Previous time-course thin layer chromatography analyses showed that the aerobic incubation of patulin with the biocontrol yeast Rhodosporidium kratochvilovae strain LS11 leads to the disappearance of the mycotoxin spot and the parallel emergence of two new spots, one of which disappears over time In this work, we analyzed the biodegradation of patulin effected by LS11 through HPLC The more stable of the two compounds was purified and characterized by nuclear magnetic resonance as desoxypatulinic acid, whose formation was also quantitated in patulin degradation experiments After R. kratochvilovae LS11 had been incubated m the presence of (13)C-labeled patulin, label was traced to desoxypatulinic acid, thus proving that this compound derives from the metabolization of patulin by the yeast Desoxypatulinic acid was much less toxic than patulin to human lymphocytes and, in contrast to patulin, did not react in vitro with the thiol-bearing tripeptide glutathione The lower toxicity of desoxypatulinic acid is proposed to be a consequence of the hydrolysis of the lactone ring and the loss of functional, groups that react with thiol groups The formation of desoxypatulinic acid from patulin represents a novel biodegradation pathway that is also a detoxification process
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- Jandrić, Petar, et al.
(författare)
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Teaching in the Age of Covid-19
- 2020
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Ingår i: Postdigital Science and Education. - : Springer Science and Business Media LLC. - 2524-4868 .- 2524-485X. ; 2:3, s. 1069-1230
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A collection of 84 author's testimonies and workspace photographs between 18 March and 5 May 2020.
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| 4. |
- Johansson, P M, et al.
(författare)
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Low-temperature isolation of disease-suppressive bacteria and characterization of a distinctive group of pseudomonads
- 2003
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 69:11, s. 6464-6474
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Tidskriftsartikel (refereegranskat)abstract
- The influence of environmental factors during isolation on the composition of potential biocontrol isolates is largely unknown. Bacterial isolates that efficiently suppressed wheat seedling blight caused by Fusarium culmortun were found by isolating psychrotrophic, root-associated bacteria and by screening them in a bioassay that mimicked field conditions. The impact of individual isolation factors on the disease-suppressive index (DSI) of almost 600 isolates was analyzed. The bacteria originated from 135 samples from 62 sites in Sweden and Switzerland. The isolation factors that increased the probability of finding isolates with high DSIs were sampling from arable land, Swiss origin of samples, and origination of isolates from plants belonging to the family Brassicaceae. The colony morphology of the isolates was characterized and compared to DSIs, which led to identification of a uniform morphological group containing 57 highly disease-suppressive isolates. Isolates in this group were identified as Pseudomonas sp.; they were fluorescent on King’s medium B and had characteristic crystalline structures in their colonies. These isolates were morphologically similar to seven strains that had previously been selected for suppression of barley net blotch caused by Drechslera teres. Members of this morphological group grow at 1.5degreesC and produce an antifungal polyketide (2,3-deepoxy-2,3-didehydrorhizoxin [DDR]). They have similar two-dimensional polyacrylamide gel electrophoresis protein profiles, phenotypic characteristics, and in vitro inhibition spectra of pathogens. In summary, in this paper we describe some isolation factors that are important for obtaining disease-suppressive bacteria in our system, and we describe a novel group of biocontrol pseudomonads.
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| 5. |
- Koch, Eckhard, et al.
(författare)
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Evaluation of non-chemical seed treatment methods for the control of Alternaria dauci and A. radicina on carrot seeds
- 2010
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Ingår i: European journal of plant pathology. - : Springer Science and Business Media LLC. - 0929-1873 .- 1573-8469. ; 127:1, s. 99-112
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Tidskriftsartikel (refereegranskat)abstract
- The current study was initiated to evaluate the efficacy of physical methods (hot water, aerated steam, electron treatment) and agents of natural origin (resistance inducers, plant derived products, micro-organisms) as seed treatments of carrots for control of Alternaria dauci and A. radicina. Control of both Alternaria species by seed treatment with the resistance inducers was generally poor. Results were also not satisfactory with most of the formulated commercial micro-organism preparations. Based on the average of five field trials, one of these, BA 2552 (Pseudomonas chlororaphis), provided a low but significant increase in plant stand. Among the experimental micro-organisms, the best results were obtained with Pseudomonas sp. strain MF 416 and Clonostachys rosea strain IK726. A similar level of efficacy was provided by seed treatment with an emulsion (1%) of thyme oil in water. Good and consistent control was generally achieved with the physical methods aerated steam, hot water and electron treatment. Aerated steam treatment was, apart from the thiram-containing chemical standard, the best single treatment, and its performance may at least partially be due to extensive pre-testing, resulting in dosages optimally adapted to the respective seed lot. In some of the experiments the effect of the hot water treatment, which was tested at a fixed, not specifically adapted dosage, was significantly improved when combined with a Pseudomonas sp. MF 416 or C. rosea IK726 treatment. The results are discussed in relation to the outcome of experiments in which the same seed treatment methods and agents were tested in other seed-borne vegetable pathosystems.
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| 6. |
- Oksinska, Malgorzata P., et al.
(författare)
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Colonization of wheat seedlings (Triticum aestivum L.) by strains of Pseudomonas spp. with respect to their nutrient utilization profiles
- 2011
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Ingår i: European journal of soil biology. - : Elsevier BV. - 1164-5563 .- 1778-3615. ; 47:6, s. 364-373
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Tidskriftsartikel (refereegranskat)abstract
- Nutrients that leach out from roots constitute a major source of food for root-colonizing bacteria. The role of specific nutrients in this interaction is unclear. The aim of the present study was to examine whether colonization ability could be attributed to specific nutrient utilization profiles. Twenty fluorescent pseudomonads were tested for colonization ability of 48-h-old wheat seedlings. Analyses of RFLPs of amplified 165 rRNA gene and of BIOLOG GN2 data demonstrated that colonization ability did not associate with any particular RFLP or metabolic group. The best colonizers PPS96, PSR2, PSR21, good colonizer PSR6 and four of ineffective colonizers were identified through 16S sequence analysis as Pseudomonas reactans. The best and good colonizers distinguished themselves from the less efficient colonizers by specifically utilizing: p-hydroxyphenylacetic acid, bromosuccinic acid, benzoic acid, methyl pyruvate. N-acetyl-D-glucosamine, D-trehalose and adonitol. However, there was no specific sole nutrient utilization profile that predicted excellent root colonization ability of wheat, since the best colonizers did not have identical profiles. This work indicates that strains of P. reactans are present in the rhizosphere of oil seed rape and wheat and that some of them are effective colonizers of wheat roots.
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| 7. |
- Oksinska, M. P., et al.
(författare)
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Resistance to oxidation products of caffeic acid is important for efficient colonization of wheat seedlings by Pseudomonas proteolytica strain PSR114
- 2013
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 66, s. 71-80
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Tidskriftsartikel (refereegranskat)abstract
- The interrelationships between plants and rhizosphere bacteria are strongly dependent on the quality and quantity of root exudates. The ability to colonize roots is crucial for pseudomonads to function as biological control agents of root- and soil-borne pathogenic microbes. The multiplication of rhizosphere bacteria is restricted in the presence of simple phenolic compounds, which are components of the resistance mechanisms of plants to pathogens. Caffeic acid is a phenolic compound, which is commonly found in wheat tissues. It is prone to oxidation into o-quinones, which are toxic to microorganisms. The aim of the present study was to determine whether the ability of microorganisms to resist caffeic acid and its oxidation products could play a role in the early colonization of wheat seedlings. Among the fluorescent pseudomonads that we have studied, strain PSR114 is one of the most efficient colonizers of wheat seedlings during the first 48 h after seed germination, and it is particularly resistant to products resulting from the spontaneous oxidation of caffeic acid. This strain was isolated from the rhizosphere of oilseed rape and identified as being closely related to Pseudomonas proteolytica through the analysis of 16S rRNA and rpoB gene sequences. At pH 7.0, this strain grew intensively in the presence of 1.50 mg mL−1 of caffeic acid. Its multiplication was partially reduced in the presence of oxidized caffeic acid at concentrations above 0.21 mg mL−1, and completely inhibited at concentrations above 0.38 mg mL−1. A Tn5 transposon mutant of PSR114 had lower level of resistance to the oxidation products of caffeic acid, as well as reduced capacity to colonize wheat seedlings when compared to the wild type strain. This work demonstrates that resistance to oxidation products of caffeic acid can be important for successful bacterial colonization of wheat seedlings.
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| 10. |
- Schmitt, A., et al.
(författare)
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Evaluation of non-chemical seed treatment methods for the control of Phoma valerianellae on lamb’s lettuce seeds
- 2009
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Ingår i: Journal of Plant Diseases and Protection. - 1861-3829. ; 116:5, s. 200-207
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to identify seed treatment methods for eradicating Phoma valerianellae from lamb’s lettuce seeds in organic vegetable production. Using seeds naturally infested with the pathogen, the effect of three physical methods (hot water, aerated steam, electron treatment) and different agents of natural origin (micro-organisms, plant derived products, resistance inducers) was tested on moist filter paper, in seed trays under controlled conditions and in the field. in an initial screening, none of the tested putative resistance inducers prevented infection by P. valerianellae, while two out of seven formulated micro-organism preparations and six out of 16 experimental microbial strains were effective. When selected agents and the three physical seed treatment methods were compared in blotter and seed tray tests, the physical methods were generally the most effective treatments, while the micro-organism treatments were clearly less efficacious. However, in field experiments with the same seed lots and the same treatments, a statistically significant increase in plant stand was not obtained with any of the treatments. Combinations of the three physical treatment methods with selected non-chemical agents did not perform better than the physical treatments alone. The most effective alternative seed treatments identified in the present study, aerated steam, hot water, electron treatment and thyme oil (0.1%), can be recommended for eradication of P. valerianellae from lamb’s lettuce seeds in organic farming. Because their efficacy was generally as high as that of the chemical fungicide Aatiram (active ingredient thiram), they are also potentially suited for use in conventional vegetable production.
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