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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.


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.


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.


Amougou N.,CNRS Agricultural Resources Fragmentation and Environment | Bertrand I.,CNRS Agricultural Resources Fragmentation and Environment | Cadoux S.,French National Institute for Agricultural Research | Recous S.,CNRS Agricultural Resources Fragmentation and Environment
GCB Bioenergy | Year: 2012

Energy crops are currently promoted as potential sources of alternative energy that can help mitigate the climate change caused by greenhouse gases (GHGs). The perennial crop Miscanthus × giganteus is considered promising due to its high potential for biomass production under conditions of low input. However, to assess its potential for GHG mitigation, a better quantification of the crop's contribution to soil organic matter recycling under various management systems is needed. The aim of this work was to study the effect of abscised leaves on carbon (C) and nitrogen (N) recycling in a Miscanthus plantation. The dynamics of senescent leaf fall, the rate of leaf decomposition (using a litter bag approach) and the leaf accumulation at the soil surface were tracked over two 1-year periods under field conditions in Northern France. The fallen leaves represented an average yearly input of 1.40 Mg C ha -1 and 16 kg N ha -1. The abscised leaves lost approximately 54% of their initial mass in 1 year due to decomposition; the remaining mass, accumulated as a mulch layer at the soil surface, was equivalent to 7 Mg dry matter (DM) ha -1 5 years after planting. Based on the estimated annual leaf-C recycling rate and a stabilization rate of 35% of the added C, the annual contribution of the senescent leaves to the soil C was estimated to be approximately 0.50 Mg C ha -1yr -1 or 10 Mg C ha -1 total over the 20-year lifespan of a Miscanthus crop. This finding suggested that for Miscanthus, the abscised leaves contribute more to the soil C accumulation than do the rhizomes or roots. In contrast, the recycling of the leaf N to the soil was less than for the other N fluxes, particularly for those involving the transfer of N from the tops of the plant to the rhizome. © 2012 Blackwell Publishing Ltd.


Piutti S.,CNRS Agronomy and Environment Laboratory | Slezack-Deschaumes S.,CNRS Agronomy and Environment Laboratory | Niknahad-Gharmakher H.,CNRS Agricultural Resources Fragmentation and Environment | Niknahad-Gharmakher H.,Gorgan University of Agricultural Sciences and Natural Resources | And 3 more authors.
European Journal of Soil Biology | Year: 2015

A laboratory incubation experiment was performed to examine the changes of soil microbial communities possessing arylsulfatase (ARS) activity. Different plant residues were incorporated into soils, and the resulting changes in the density and ARS activity of these communities relative to the sulfate content were studied. Mustard, fescue and wheat plant residues with different biochemical compositions and carbon (C):sulfur (S) ratios ranging from 60 to 486 were tested. Soil lacking residues was included as a control. Among the tested residues, mustard was the most labile and the most rapidly mineralized, leading to a significant 67% increase in the soil microbial biomass C (SMBC) compared with the control. The incorporation of mustard into soil induced a significant shift in the balance of microbes possessing ARS activity (ie. ratio bacteria:fungi) with an increase in the bacterial component producing ARS (ARS-B) but no change in ARS activity. A principal component analysis revealed clear differences between the soil samples according to both the nature of the residues incorporated and the duration of incubation. The correlation coefficients between the different variables showed that the ARS-B:ARS-F ratio was strongly correlated with the soil sulfate content (r = 0.81, p < 0.05). However, ARS activity was more closely correlated with ARS-F density than with ARS-B density (r = 0.63, p < 0.05 and r = 0.29, p < 0.1, respectively). The relative stability of the soil ARS activity, regardless of the nature of the residues incorporated was likely due to non-limiting S conditions for microbial growth in the soil used in this study. © 2015 Elsevier Masson SAS.


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.


Bag R.,CNRS Agricultural Resources Fragmentation and Environment | Beaugrand J.,CNRS Agricultural Resources Fragmentation and Environment | Dole P.,CNRS Agricultural Resources Fragmentation and Environment | Kurek B.,CNRS Agricultural Resources Fragmentation and Environment
Holzforschung | Year: 2011

The aim of this study was to determine the effect of removing extractives from the woody core of hemp (chènevotte) on the chain mobility of hemicelluloses and lignins, which can react during technological transformation such as defibering and/or composite materials production. Extractives are molecules with low molecular weight, which are present in the cell wall matrix and can be readily removed by solvents. In the present paper, the nature and amounts of extractives, removed under different conditions and with solvents of different polarities, were determined. The mobility and structural relaxations of lignins and hemicelluloses were studied in situ by dynamic mechanical analysis and dielectric analysis under controlled moisture content. Extractions at low temperature led to rigidification of lignins and plasticizing of hemicelluloses, probably due to local changes by the selective removal of molecules interacting with the polymers. Probably, the accessibility of hemicelluloses to plasticizing water was increased at controlled humidity. In contrast, hot extractions including water induced rigidification of the hemicelluloses and plasticizing of lignins. This could be related to a combination of molecule extractions and chemical modifications of both polymers. This interpretation is supported by the variation of activation energy for relaxation of hemicelluloses. It can be concluded that each type of extraction has a clear specific effect on the relaxation properties of the amorphous cell wall polymers. © by Walter de Gruyter Berlin New York.


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.


Le Ngoc Huyen T.,CNRS Laboratory of Technology and Innovation | Remond C.,CNRS Agricultural Resources Fragmentation and Environment | Dheilly R.M.,CNRS Laboratory of Technology and Innovation | Chabbert B.,CNRS Agricultural Resources Fragmentation and Environment
Bioresource Technology | Year: 2010

The chemical composition of the whole aerial biomass and isolated organs of Miscanthus x giganteus was examined for saccharification into fermentable sugars at early and late harvesting dates. Delayed harvest was mainly related to increased amounts of cell wall and ester-linked phenolic acids. Addition of an enzyme cocktail (cellulases, β-glucosidase and xylanase) resulted in similar enzyme digestibilities at the two harvesting dates, ranging from 11-13% and 8-9% of the cellulose and arabinoxylan, respectively. However, the internodes, leaves and sheaths varied in cell wall content and composition and gave rise to different saccharification yields with internodes being the most recalcitrant organs. Non-cell wall fraction was estimated as the amount of material extracted by neutral detergent solution, and accounted for 23% of the whole aerial biomass harvested at an early date. However, saccharification yields from the miscanthus biomass did not change after soluble fraction removal. An ammonia pretreatment improved enzyme efficiency on early-harvested miscanthus, to a greater extent than on late-harvested biomass. This trend was confirmed for two different years of harvesting. © 2010 Elsevier Ltd.


Rakotoarivonina H.,University of Reims Champagne Ardenne | Rakotoarivonina H.,CNRS Agricultural Resources Fragmentation and Environment | Hermant B.,University of Reims Champagne Ardenne | Hermant B.,CNRS Agricultural Resources Fragmentation and Environment | And 4 more authors.
Enzyme and Microbial Technology | Year: 2015

This study aimed to characterise the parameters governing the non-specific adsorption of a xylanase from Thermobacillus xylanilyticus (Tx-Xyn11) onto lignin isolated from maize stems. Such adsorption may be due to hydrophobic interactions between Tx-Xyn11 and lignin. Our strategy was to mutate hydrophobic residues present on the surface of Tx- Xyn11 into non-hydrophobic residues. Three mutants (P1, P2, and P3) with altered hydrophobic regions were produced and characterised. The thermostability of the P1 mutant was largely decreased compared with the thermostable Tx-Xyn11. The rate of adsorbed enzyme onto lignin was reduced to a similar extent for the P1 and P2 mutants, whereas the adsorption of the P3 mutant was less affected compared with that of Tx-Xyn11. When considered separately, the hydrophobic residues did not affect xylanase adsorption onto lignin. The addition of Tween 20 also led to the decreased adsorption of Tx-Xyn11 onto lignin. These results suggest that hydrophobic interactions are a key parameter in the interaction of Tx-Xyn11 with isolated lignin. © 2015 Elsevier Inc.

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