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Pascault N.,University of Burgundy | Nicolardot B.,French National Institute for Agricultural Research | Nicolardot B.,University of Burgundy | Bastian F.,University of Burgundy | And 3 more authors.
Microbial Ecology | Year: 2010

The effect of the location of wheat residues (soil surface vs. incorporated in soil) on their decomposition and on soil bacterial communities was investigated by the means of a field experiment. Bacterial-automated ribosomal intergenic spacer analysis of DNA extracts from residues, detritusphere (soil adjacent to residues), and bulk soil evidenced that residues constitute the zone of maximal changes in bacterial composition. However, the location of the residues influenced greatly their decomposition and the dynamics of the colonizing bacterial communities. Sequencing of 16S rRNA gene in DNA extracts from the residues at the early, middle, and late stages of degradation confirmed the difference of composition of the bacterial community according to the location. Bacteria belonging to the γ-subgroup of proteobacteria were stimulated when residues were incorporated whereas the α-subgroup was stimulated when residues were left at the soil surface. Moreover, Actinobacteria were more represented when residues were left at the soil surface. According to the ecological attributes of the populations identified, our results suggested that climatic fluctuations at the soil surface select populations harboring enhanced catabolic and/or survival capacities whereas residues characteristics likely constitute the main determinant of the composition of the bacterial community colonizing incorporated residues. © 2010 Springer Science+Business Media, LLC. Source

Devincenzi T.,French National Institute for Agricultural Research | Devincenzi T.,Federal University of Rio Grande do Sul | Delfosse O.,CNRS Agricultural Resources Fragmentation and Environment | Andueza D.,French National Institute for Agricultural Research | And 2 more authors.
Food Chemistry | Year: 2014

This study investigated the dose-dependent response in lamb meat of stable nitrogen isotope ratio to the dietary proportion of legumes, and the ability of the nitrogen isotope signature of the meat to authenticate meat produced from legume-rich diets. Four groups of nine male Romane lambs grazing a cocksfoot pasture were supplemented with different levels of fresh alfalfa forage to obtain four dietary proportions of alfalfa (0%, 25%, 50% and 75%) for 98 days on average before slaughter (groups L0, L25, L50 and L75). We measured the stable nitrogen isotope ratio in the forages and in the longissimus thoracis muscle. The δ15N value of the meat decreased linearly with the dietary proportion of alfalfa. The distribution of the δ15N values of the meat discriminated all the L0 lambs from the L75 lambs, and gave a correct classification score of 85.3% comparing lambs that ate alfalfa with those that did not. © 2013 Elsevier B.V. All rights reserved. Source

Thiebeau P.,CNRS Agricultural Resources Fragmentation and Environment | Beaudoin N.,French National Institute for Agricultural Research | Justes E.,French National Institute for Agricultural Research | Allirand J.-M.,French National Institute for Agricultural Research | Lemaire G.,French National Institute for Agricultural Research
European Journal of Agronomy | Year: 2011

Storage of carbohydrates in roots is important for lucerne survival and regrowth rate, begins during initial growth. This study examined whether variation in radiation use efficiency (RUE) and shoot:root partitioning (Pshoot) occurring for various types of lucerne canopy, including seedling crops and regrowths in various seasons, was significant or not. Seedling and regrowth crops were monitored for four sowing dates in fully irrigated experiments on chalky soils in north-eastern France for three years. Pshoot was calculated as the ratio between increments in aerial dry matter (ADM) and total dry matter (TDM) for successive crop measurements. Leaf Area Index (LAI) was regressed against cumulative thermal time (CTh) using a 5°C base temperature, which provided the best fit (R2=0.98). The increase in LAI was exponential up to 0.7m2 of green leaves per m2 of soil (350CTh) and then became linear for seedling crops, but was linear for regrowths. During spring and summer, the slope of the linear phase of LAI increase was almost constant for all the seedling growths (0.011-0.014CTh-1) except the last summer sowing, but was significantly variable (from 0.007 to 0.025CTh-1) for regrowths. The RUE based on ADM and TDM (RUEa and RUEt, respectively) reached a linear phase for seedling growths when ADM exceeded 1.0tDMha-1. RUEa was equal to 1.72gDMMJ-1 irrespective of sowing date, while RUEt was higher at 2.28 and 2.84DMMJ-1 for canopies from spring and summer sowings, respectively. The RUE of seedling crops always exceeded those of regrowth crops present at the same period. Hence seedling crops of lucerne were slower to establish their LAI than regrowths, but used cumulative intercepted radiation as efficiently as the latter. The seedling Pshoot varied slightly according to crop age and season unlike the regrowth Pshoot which decreased significantly vs. CTh5 (-8.9×10-4CTh-1; R2=0.66); while the ratio was also influenced by the daylength of the period. The Pshoot of seedling and regrowth canopies evolved very differently with respect to CTh, the former remaining quite stable and the latter declining. This suggests a change in plant behaviour between seedling and regrowth crops, probably triggered by crop defoliation. © 2011 Elsevier B.V. Source

Keplinger T.,ETH Zurich | Keplinger T.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Konnerth J.,University of Natural Resources and Life Sciences, Vienna | Aguie-Beghin V.,CNRS Agricultural Resources Fragmentation and Environment | And 6 more authors.
Plant Methods | Year: 2014

Background: Besides classical utilization of wood and paper, lignocellulosic biomass has become increasingly important with regard to biorefinery, biofuel production and novel biomaterials. For these new applications the macromolecular assembly of cell walls is of utmost importance and therefore further insights into the arrangement of the molecules on the nanolevel have to be gained. Cell wall recalcitrance against enzymatic degradation is one of the key issues, since an efficient degradation of lignocellulosic plant material is probably the most crucial step in plant conversion to energy. A limiting factor for in-depth analysis is that high resolution characterization techniques provide structural but hardly chemical information (e.g. Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM)), while chemical characterization leads to a disassembly of the cell wall components or does not reach the required nanoscale resolution (Fourier Tranform Infrared Spectroscopy (FT-IR), Raman Spectroscopy).Results: Here we use for the first time Scanning Near-Field Optical Microscopy (SNOM in reflection mode) on secondary plant cell walls and reveal a segmented circumferential nanostructure. This pattern in the 100 nm range was found in the secondary cell walls of a softwood (spruce), a hardwood (beech) and a grass (bamboo) and is thus concluded to be consistent among various plant species. As the nanostructural pattern is not visible in classical AFM height and phase images it is proven that the contrast is not due to changes in surfaces topography, but due to differences in the molecular structure.Conclusions: Comparative analysis of model substances of casted cellulose nanocrystals and spin coated lignin indicate, that the SNOM signal is clearly influenced by changes in lignin distribution or composition. Therefore and based on the known interaction of lignin and visible light (e.g. fluorescence and resonance effects), we assume the elucidated nanoscale structure to reflect variations in lignification within the secondary cell wall. © 2014 Keplinger et al.; licensee BioMed Central Ltd. Source

Jbilou F.,University of Lyon | Joly C.,University of Lyon | Galland S.,University of Lyon | Belard L.,Pole Europeen de Plasturgie | And 5 more authors.
Polymer Testing | Year: 2013

Plasticised corn flour/poly(butylene succinate-co-butylene adipate) (PBSA) materials were prepared by extrusion and injection in order to study the impact of PBSA ratio on their physicochemical properties and biodegradability. Scanning electron microscopy observations showed that corn flour and PBSA are incompatible. Three types of morphology have been observed: (i) starch dispersed in a PBSA matrix, (ii) a "co-continuous-like" morphology of starch and PBSA, and (iii) PBSA dispersed in a starch matrix. As expected, the extent of plasticised corn flour starch hydrolysis by amylolytic enzymes decreased when the amount of PBSA increased. Addition of a lipase to hydrolyse PBSA ester bonds enhanced enzymatic hydrolysis of starch by amylolytic enzymes in materials where PBSA formed a continuous phase. This suggests that PBSA formed a barrier restricting the access of amylolytic enzymes to starch. This was consistent with aerobic and anaerobic biodegradation assays, which also showed lower biodegradability of materials containing a majority of PBSA. © 2013 Elsevier Ltd. All rights reserved. Source

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