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25 results on '"Hestbjerg, Helle"'

1. Ensiling of Willow and Poplar Biomass Is Improved by Ensiling Additives.

Author

Larsen, Søren Ugilt, Hestbjerg, Helle, Jørgensen, Uffe, and Kongsted, Anne Grete

Subjects
LACTIC acid bacteria, FORMIC acid, GROWING season, WILLOWS, BIOMASS
Abstract

Biomass from willow and poplar harvested for feed during the growing season may be preserved by ensiling; however, little research has focused on ensiling of these biomasses. This study focuses on the use of ensiling additives to reduce the pH to around 4.0 to secure stable storage. Lab-scale ensiling experiments were conducted with different willow and poplar clones, shoot ages, and harvest times (June or September). Ensiling without additives often resulted in limited pH reduction. The pH could be reduced in the biomass of both species by adding formic acid, and the required dose to reduce the pH to 4.0 (buffering capacity, BC) ranged significantly between biomass types but was in the range of 2–5 kg formic acid (78%) per ton fresh weight. BC decreased with increasing dry matter (DM) content and decreasing crude protein content. The pH could also be reduced during ensiling by applying molasses and/or lactic acid bacteria, although not sufficiently in poplar. Willow biomass was ensiled effectively at the pilot scale with less than 7% DM loss by adding formic acid or by mixing with grass biomass. Comparable pH results were obtained at the lab scale and pilot scale. The study demonstrates how willow and poplar can be ensiled; however, more research is needed on quality changes during ensiling. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Production of trichothecenes and other secondary metabolites by Fusarium culmorum and F. equiseti on common laboratory media and a soil organic matter agar: An ecological interpretation

Author

Hestbjerg, Helle, Nielsen, Kristian F., Thrane, Ulf, and Elmholt, Susanne

Subjects
Soil biology, Food security, food quality and human health, Post harvest management and techniques, Biodiversity and ecosystem services
Abstract

Fusarium culmorum and F. equiseti were characterized with regard to production of trichothecenes and other secondary metabolites. Results following growth on laboratory media are interpreted with the aim of increasing the understanding of fungal metabolism in the field environment. While trichothecene production was detected for 94 of 102 F. culmorum isolates, only eight of 57 F. equiseti isolates were positive. Profiles of secondary metabolites were compared following growth on Yeast Extract Sucrose agar (YES), Potato Sucrose Agar (PSA) and an agar medium, prepared from Soil Organic Matter (SOM), which was included to simulate growth conditions in soil. SOM supported the production of chrysogine by F. culmorum. The two species utilized the media differently. F. culmorum produced zearalenone (ZEA) on YES, whereas some F. equiseti isolates produced ZEA on PSA. Other F. equiseti isolates produced equisetin. These differences may reflect that F. culmorum depends on a pathogenic life style while F. equiseti has a more saprotrophic mode of existence.

Published
2002

24. A resource-saving method for isolation of <e1>Fusarium</e1> and other fungi from individual soil particles

Author

HESTBJERG, HELLE, ELMHOLT, SUSANNE, THRANE, ULF, and JENSEN, ULLA B.

Abstract

Plating of individual soil particles onto an agar medium, poured into Petri dishes, is a method of studying fungal distribution between microhabitats in soil. The substitution of Petri dishes with well plates reduced both the required amount of agar medium and labour. A microshovel prepared from an injection needle facilitated the handling of individual, small size, soil particles (0·25–0·50 mm). The described method was evaluated in a study of the distribution of Fusarium within two wheat field soils from Ås, Norway, and from Østermarie, Denmark. Four types of organic particles were distinguished: light coloured root pieces, dark coloured root pieces, straw pieces, and miscellaneous organic pieces. The dominating species were F. culmorum, F. oxysporum and F. avenaceum. Aspects on the value of the method with regard to fungal substrate preference are discussed.

Published
1999

25. Detection and estimation of conidial abundance of <e1>Penicillium verrucosum</e1> in soil by dilution plating on a selective and diagnostic agar medium (DYSG)

Author

ELMHOLT, SUSANNE, LABOURIAU, RODRIGO, HESTBJERG, HELLE, and NIELSEN, JØRGEN M.

Abstract

Penicillium verrucosum is one of the main producers of ochratoxin A (OA) in agricultural commodities. To forecast the risk of OA contamination, there is a need to improve our knowledge on the ecology of P. verrucosum in the field. Dilution plating on ‘dichloran yeast extract sucrose 18% glycerol agar’ (DYSG) offers a simple and very sensitive method of detecting P. verrucosum propagules in soil. The properties of DYSG are illustrated in a suspension mixture experiment and confirmed in a soil mixture experiment. In the latter, P. verrucosum could be detected in conidial concentrations below 200 colony forming units (cfu) g−1 soil even when it constituted no more than 0·3% of the cfu. Furthermore, the DYSG method can be used to estimate the abundance of P. verrucosum propagules in soil with good precision. In some of the analysed cases, however, it was necessary to use appropriate mathematical models to treat results with high numbers of cfu on the Petri dishes.

Published
1999

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