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The objective of this work is to demonstrate the effect of operational drying parameters on thephysicochemical and techno-functional properties of lactose-hydrolyzed milk powder (LHMP).LHMP showed water content superior to the control regardless of drying conditions, which is adirect result of the difficulties encountered in drying the product. For a lab-scale spray dryer,the LHMP produced at θair,in ¼ 145°C and mCM ¼ 1.0 kg · h−1 was the only sample that met allstipulated quality parameters: water content 93,particle sizes similar to control, and complete rehydration.

This review presents the advances made concerning the ability of peptides to bestow particular functional properties on various matrices including foods. We focus on systems ranging from model solutions in which peptides are rationally designed to orient their structure and to form hydrogels to mixtures of peptides in complex food matrices. In the latter case, peptides are an integral part of food formulations due to their production in situ or their addition as an ingredient. Examples of complex matrices such as food products, where mixes of peptides are present as hydrolysates with various physico-chemical properties, focus on the ability of peptides to modulate the texture of foods and their functional properties, including solubility, gelation and even emulsifying and foaming properties. Attempts have been made to establish relationships between the physico-chemical and structural characteristics of peptides and their functional properties.

Distillation process of aromatic plants produces a considerable amount of solid residues, which are rich in secondary metabolites known as bioactive compounds. In this context, residues from hydrodistillation of selected aromatic plants such as Mentha piperita L., Cymbopogon citratus Stapf and Eucalyptus camaldulensis Dehnh, have been studied for their total polyphenol content using Folin-Ciocalteu Reagent (FCR) method, total flavonoid content using aluminium chlorid (AlCl3) and antioxidant properties were determined as DPPH radical-scavenging ability (IC50). The anti-termite activity was evaluated by a direct non-choice test. The higher antioxidant activity (IC50 = 0.20 mg/ml) and polyphenols content (224.32 mg GAE/g of dried extract) were showed with E. camaldulensis aqueous extract. However, M. piperita and C. citratus ethanolic extracts showed higher flavonoid content (190.99 and 185.19 mg QE/g of dried extract). The most active extract against termite Reticulitermes flavipes was E. camaldulensis ethanolic extract presenting toxicity at 5% and 10% w/w as concentrations. All these data showed that strategic extraction of residues from hydrodistillation can provide interesting bioactive compounds as novel anti-termite agents in plants protection and allow to give an added-value to aromatic plants.

Tigernut tubers (Cyperus esculentus) are used for the production of vegetable milk, commonly known as &ldquo, Horchata de chufa&rdquo, in Spain. The presence of starch in the tuber limits the yield of the milk, since this carbohydrate gelatinizes during the pasteurization of the milk and leads to the considerable solidification of this drink. The present work aims to improve the yields and extraction practice of the milk by an in situ hydrolysis of starch, using exogenous amylases of industrial or vegetable origin. The obtained results show that sprouting improves the extraction yields of tigernut milk, which goes from 50% to about 70%. This improvement in milk yield corresponds to a hydrolysis of about 35% of the starch in the tuber. The use of exogenous amylases leads to starch hydrolysis rates of 45% and 70%, respectively, for amylolytic extracts from sprouted tigernut tubers and amylase, with the corollary of a natural increase in the sweetness of milk. This technical approach makes it possible to produce a naturally sweetened tigernut milk which easily lends itself to pasteurization without a significant increase in viscosity.

Lignocellulose-derived hydrolyzates typically display a high degree of variation depending on applied biomass source material as well as process conditions. Consequently, this typically results in variable composition such as different sugar concentrations as well as degree and the presence of inhibitors formed during hydrolysis. These key obstacles commonly limit its efficient use as a carbon source for biotechnological conversion. The gram-negative soil bacterium Pseudomonas putida KT2440 is a promising candidate for a future lignocellulose-based biotechnology process due to its robustness and versatile metabolism. Recently, P. putida KT2440_xylAB which was able to metabolize the hemicellulose (HC) sugars, xylose and arabinose, was developed and characterized. Building on this, the intent of the study was to evaluate different lignocellulose hydrolyzates as platform substrates for P. putida KT2440 as a model organism for a bio-based economy. Firstly, hydrolyzates of different origins were evaluated as potential carbon sources by cultivation experiments and determination of cell growth and sugar consumption. Secondly, the content of major toxic substances in cellulose and HC hydrolyzates was determined and their inhibitory effect on bacterial growth was characterized. Thirdly, fed-batch bioreactor cultivations with hydrolyzate as the carbon source were characterized and a diauxic-like growth behavior with regard to different sugars was revealed. In this context, a feeding strategy to overcome the diauxic-like growth behavior preventing accumulation of sugars is proposed and presented. Results obtained in this study represent a first step and proof-of-concept toward establishing lignocellulose hydrolyzates as platform substrates for a bio-based economy., publishedVersion

The conformational itineraries taken by carbohydrate residues in the catalytic subsite of retaining glycoside hydrolases (GHs), harness the link between substrate conformation and reactivity. GHs’ active sites may be described as a combination of subsites dedicated to the binding of individual sugar residues and to catalysis. The three-dimensional structure of GH:carbohydrate complexes has demonstrated that carbohydrate ring conformation changes in an ordered manner during catalysis. Here we demonstrate in silico that a link exists between subsite binding dynamics and substrate specificity for β-galactosidases from clan GH-A families GH1, GH2, GH35, GH42 and GH59. Different oligosaccharides were docked in the active site of reference β-galactosidase structures using Vina-Carb. Subsequent molecular dynamics (MD) simulations revealed that these enzymes favor a high degree of flexibility and ring distortion of the substrate the lytic subsite −1. Although the β-galactosidase families examined are structurally and mechanistically related, distinct patterns of ring distortion were unveiled for the different families. For β-galactosidases, three different family-dependent reaction itineraries (1S3 → 4H3‡ → 4C1, 1,4B → 4H3/ 4E‡ → 4C1, and 1S5 → 4E/ 4H5‡ → 4C1) were identified, all compatible with the antiperiplanar lone pair hypothesis (ALPH) for the hydrolysis of β-glycosides. This comparative study reveals the fuzzy character of the changes in carbohydrate ring geometry prior to carbohydrate hydrolysis.

In solid-state anaerobic digestion, so-called ss-AD, biogas production is inhibited at high total solids contents. Such inhibition is likely caused by a slow diffusion of dissolved reaction intermediates that locally accumulate. In this study, we investigated the effect of H2 and CO2 partial pressure on ss-AD. Partial pressure of H2 and/or CO2 was artificially fixed, from 0 to 1 557mbars for H2 and from 0 to 427mbars for CO2. High partial pressure of H2 showed a significant effect on methanogenesis, while CO2 had no impact. At high [Formula: see text] , the overall substrate degradation decreased with no accumulation of metabolites from acidogenic bacteria, indicating that the hydrolytic activity was specifically impacted. Interestingly, such inhibition did not occur when CO2 was added with H2. This result suggests that CO2 gas transfer is probably a key factor in ss-AD from biomass.

The present study investigated proteolysis combined with heat treatment to make hen Egg White (EW) an efficient emulsifier. EW was hydrolyzed by protease (Thermoase®) at various Enzyme Concentrations (EC) (w/w, 0.1%, 0.2%, 0.4%, 0.8%), followed by heating at 90°C for 8 min. Results showed that optimal emulsifying ability and stability, determined by measurement of emulsion turbidity, were obtained when EC was 0.4%, followed by heat treatment at 90°C. The hydrolysate thus prepared had higher emulsifying ability and stability than either native egg white (nEW) or small molecular weight EW peptides (Runpep®), close to the properties of Egg Yolk (EY) which was a reference as a food emulsifier. Surface hydrophobicity (H0) was found to be linearly related to the emulsifying activity and stability of hydrolyzed egg white proteins.

Few reports describe the effect of lactose hydrolysis on the properties of milk powder during production and storage. Hence, the aim of this study was to evaluate the effects of five different levels of enzymatic lactose hydrolysis during the production and storage of milk powder. As the lactose hydrolysis rate increased, adhesion to the drying chamber also increased, due to higher levels of particle agglomeration. Additionally, more brown powder was obtained when the lactose hydrolysis rate was increased, which in turn negatively affected rehydration ability. Using Raman spectroscopy, crystallization of the lactose residues in various samples was assessed over 6 weeks of accelerated aging at a room temperature environment with 75.5% of air moisture. Products with 25% or greater lactose hydrolysis showed no signs of crystallization, in contrast to the non-hydrolyzed sample.

Gowe is a traditional Beninese fermented red sorghum beverage made from a blend of malted and precooked nonmalted flour. The main objective of this work was to evaluate the degradation of starch during the production of gowe and to characterise the organic acid and sugar profiles of the product obtained using starter cultures. Inoculation was performed with strains of Lactobacillus fermentum or Weissella confusa and of Kluyveromyces marxianus or Pichia anomala used singly or in combination. Size exclusion chromatography revealed that starch was hydrolysed into high molecular weight dextrins (DP over 35), oligosaccharides and glucose, mainly due to the malting and precooking steps. Glucose was the main free sugar, and lactic acid was the main organic acid. The choice of the inoculation strain directly influenced the acidity but also indirectly the sugar content of the resulting gowe and will thus affect consumer acceptability. (Resume d'auteur)

Sub-critical water is widely accepted as an environmentally benign solvent, for extraction but also as a catalytic medium therefore has the potential to support processing of multiple components found in biomass. The manuscript demonstrates the versatility of sub-critical water as a generic medium to support hydrolysis of rice bran (carbohydrates) and sunflower oil (lipid substrates), substrates that possess very different physio-chemically properties within a continuous flow process configuration. Response surface methodologies (RSM) were used to assist modelling the multiple process parameters that impact sub-critical water mediate hydrolysis of sunflower oil. Successful validation, of the models illustrate that 100% FFA yield would be achieved at temperature 385 °C; pressure 20 MPa; residence time of 35 min; oil to water ratio 1:1.8 (v/v) represents 65% water. Experiments conducted under these conditions yielded 93.5%, thereby confirming the utility of the RSM as a tool to assist in process development.

The Arkométha ® process is a system treating organic wastes in several sectors working at high solid concentration and being temperature phased. The present work focuses on the performances of the different phases of the process in treating agricultural wastes. In a first time, the hydrolysis sector has been studied. The most influent parameters have been identified (temperature and retention time), using design of experience. They have been tested afterwards at a pilot scale in order to assess the influence on solubilization and later methane production. Then, tests have been conducted at the lab scale in continuous mode using serial reactors. The methanogenic compartment, composed by two to three sectors has been studied highlighting the efficiency of each sector. The effect of temperature has also been studied, with a strong impact. The two compartments being used in series enabled the study of the complete process. This allowed highlighting some risks linked with certain temperatures combinations. On the other hand, a comparison with a single step reactor has been made. Beside the analysis of the relative performances of each compartment, a major result of this work lies in the distinction between hydrolysis and solubilization. Eventually, we showed that the gain brought by the hydrolysis compartment is not only related to solubilization of organic matter, but also in the increase in kinetics in the downwards sectors. Interestingly, while temperature has a major role in solubilization, it is of less importance in improving the degradation kinetics, where the retention time becomes of higher importance., Le procédé Arkométha® est un système de digestion anaérobie de rejets organiques fonctionnant en voie épaisse et comprenant plusieurs compartiments phasés en température. Ce travail s’est intéressé aux performances des différentes phases du procédé pour le traitement de résidus agricoles. Dans un premier temps, le compartiment d’hydrolyse a été étudié. Les paramètres les plus influents ont été identifiés (température et durée de l’hydrolyse) à l’aide d’un plan d’expérience. Ils ont ensuite été testés sur un pilote afin d’évaluer leur influence sur la solubilisation et la production de méthane ultérieure. Des tests ont alors été conduits à l’échelle laboratoire en mode continu au moyen de réacteurs en séries. Le compartiment méthanogène, constitué de deux à trois secteurs, a été étudié en mettant en évidence l’efficacité de chaque secteur. L’effet de la température a ici également été étudié, avec un impact important. Les deux compartiments ont été mis en série permettant l’étude du procédé complet. Ceci a permis de mettre en lumière certains risques liés à des combinaisons de température peu favorables. Par ailleurs, une comparaison avec un procédé mono-étape a été effectuée. Outre l’étude des performances de chaque compartiment et l’analyse de leur articulation, un résultat intéressant de ce travail réside dans l’affinement de la notion d’hydrolyse dans le cadre de la méthanisation en voie épaisse, communément confondue avec la solubilisation. En effet, nous avons montré que le gain apporté par l’utilisation d’un réacteur séquencé avec un compartiment dédié à l’hydrolyse ne réside pas dans l’amélioration de la solubilisation, mais dans l’augmentation conséquente de la cinétique de méthanisation dans les étapes suivantes. De façon intéressante, alors que la température joue un rôle primordial dans la solubilisation de la matière organique, elle est relativement peu influente pour l’amélioration de la cinétique de dégradation, où le temps de séjour devient prépondérant.

Titanium dioxide is a ceramic material which is widely used as a white pigment and catalyst. In the present work the precipitation of TiO2 by the thermal hydrolysis of titanium oxysulphate was studied in terms of the homogeneous precipitation and the coating of capsules. Experimental work and simulations have been done to describe the precipitation in 0.1 M aqueous solutions while in some experiments sulphuric acid was added to increase the reaction time. In the experimental part of this work, gravimetric and spectroscopic measurements were performed to determine the time-dependent precipitation of the material and particle size measurements to characterize the time-dependent size distribution of the precipitated particles. In the theoretical part different mechanisms of the precipitation process like nucleation, growth and agglomeration were considered using semi-empirical equations. For the transfer of the effects of the individual particle scale to the whole population of particles population balance equations (PBEs), one for the colloidal and one for the deposited phase, were used. Finally, the theoretical results were compared to the experimental ones and the limitations of the model were discussed.

Milk fat is considered to be the main limiting component of the kinetics of dairy wastewater anaerobic digestion. The objective of this work was to give a better understanding of the nonelucidated anaerobic degradation steps of milk fat. For that purpose, the kinetics of fat degradation was quantified in comparison with other milk components (lactose, proteins), regarding the milk fat polluting load and structure [globular (native state), triglycerides]. This work confirms that milk fat is degraded after a lag phase of several days, with a maximal degradation rate 2 to 5 times less than the degradation rate of the other milk components. It was shown that (1) the structure of the fat does not influence the limits of its anaerobic degradation; (2) the lag phase before biogas production is mainly due to unsaturated free fatty acids (FFA); and (3) conversion to biogas occurs at a lower rate for saturated than for unsaturated FFA. Therefore, the prehydrolysis of fat, which increases the instantaneous concentration of unsaturated FFA, sharply increases the length of the lag phase with no significant change in the maximal biogas production rate. To reduce the delay imposed in the biogas production, it is necessary to reduce the concentration of unsaturated FFA.

Ferulic acid is one of the major phenolic acids in plants and can be found esterified to plant cell wall components, but also as long-chain n-alkyl and steryl esters. Microbial feruloyl esterases may play a role in the bioavailability of phenolic acids during human and animal digestion. It is therefore of interest if feruloyl esterases are capable of hydrolyzing nonpolar ferulic acid esters. A series of n-alkyl ferulates with increasing lipophilicity were enzymatically synthesized, and the kinetic constants of their hydrolysis by four feruloyl esterases and a lipase as control were determined. A decrease in k(m) and k(cat), could be observed with decreased substrate polarity for all of the feruloyl esterases. Only one feruloyl esterase and the control lipase showed hydrolytic activity toward octadecyl ferulate. These results led to the conclusion that lipophilic ferulates are poor substrates for known feruloyl esterases and more specific esterases/lipases need to be identified.

Quercoresinosides A and B (1 and 2), two new lignans, were isolated from a toasted Quercus petraea heartwood extract along with a known compound, 3-methoxy-4-hydroxyphenol 1-O-β-d-(6′-O-galloyl)glucopyranoside (3). The purification protocol was based on a taste-guided approach that sought to reveal new bitter compounds released from oak wood into wines and spirits. HRMS and NMR data were used to establish that compounds 1 and 2 are lignan derivatives bearing a glucosyl unit and a galloyl unit at the same positions. Hydrolysis of these compounds showed that they could be distinguished by the absolute configuration of their respective lyoniresinol genin as determined by chiral LC-HRMS in comparison with (+)- and (−)-lyoniresinol standards. Sensory analyses were performed in a non-oaked wine on the pure compounds 1–3. The three molecules exhibited a bitter taste at 2 mg/L that was particularly intense for compounds 2 and 3. Finally, LC-HRMS demonstrated the occurrence of compounds 1–3 in oaked wine and brandy, which supports the hypothesis of their contributions to the increase in bitterness during oak aging.

Introduction. Dans un monde qui cherche à se défaire de sa dépendance à la pétrochimie, le concept de bioraffinage de la biomasse forestière est de plus en plus étudié. Dans une recherche de valorisation maximale des composants de cette biomasse, la transformation de fibres de cellulose en nanocellulose séduit de plus en plus l’industrie papetière par sa haute valeur ajoutée.Littérature. Le concept de bioraffinage forestier intégré vise l’adaptation des usines de pâte à papier en bioraffineries où un maximum de coproduits sont valorisés. Au départ de la cellulose contenue dans la pâte, deux types de nanocellulose peuvent être obtenus en déstructurant les fibres selon différents moyens. Comme elle génère des coproduits valorisables, l’hydrolyse enzymatique constitue un moyen de production de nanocellulose mais doit néanmoins être combinée à des traitements mécaniques. La production de nanocellulose au départ de pâte à papier chimique est une étape de fin de chaine qui peut même s’envisager sans modifier le fonctionnement des usines actuelles. La viabilité économique de cette production et la taille du marché potentiel sont l’objet d’études récentes qui s’avèrent encourageantes.Conclusions. La nanocellulose est un biomatériau d’avenir dont le domaine d’application ne cesse de grandir. La cellulose contenue dans la pâte à papier peut servir de matière première à la production de nanocellulose à l’aide de prétraitements enzymatiques générateurs de coproduits valorisables. Cette production peut s’intégrer dans une usine chimique classique de pâte et constituer ainsi un élargissement de la gamme de produits proposés par l’industrie papetière., Enzymatic hydrolysis to produce nanocellulose in an integrated forest biorefinery strategy. A reviewIntroduction. In a world that seeks to break free from petrochemicals, the concept of forest biomass biorefinery is increasingly being studied as a way to maximize the value of the components of this biomass. Due to the high added value expected when transforming cellulose fibers into nanocellulose, this technology is highly attractive to the pulp and paper industrial world.Literature. The concept of integrated forest biorefinery is to adapt existing pulp mills so as to maximize the value of the co-products. Through the use of various methods, two types of nanocellulose may be obtained from the cellulose in the pulp. Due to its production of valuable byproducts, enzymatic hydrolysis is an interesting method to use for this purpose, but it must be combined with mechanical post-treatments. The production of nanocellulose from chemical pulp takes place in the final step of pulp production, and could be implemented without modifying the existing mills. The economic viability of this mode of production and the potential market size are the subject of recent studies that appear encouraging.Conclusions. Nanocellulose is a promising biomaterial whose field of application continues to grow. Cellulose in wood pulp can be used as a raw material for the production of nanocellulose using enzymatic pre-treatments that generate valuable co-products. This process can be integrated into a conventional chemical pulp mill and constitutes a broadening of the products available to the pulp and paper industry.

Research on the hydrolysis step of the AD became more important with the increased use of recalcitrant waste products such as manure, sewage sludge and agricultural biomass for biogas production. Hydrolysis is often the rate limiting step of the overall AD. Hydrolysis enhancement is one of the required steps to optimise biogas production. Despite the progress to overcome the limitations of hydrolysis, inhibition of hydrolysis is still poorly researched. Humic acid-like molecules (HA) are one of the inhibitors of the anaerobic hydrolysis and their effect on the overall AD process is generally overlooked. In this thesis, the HA inhibition on anaerobic digestion of cellulosic material and mitigation strategies, using cation and enzyme addition, to overcome the inhibition were investigated. In addition, the microbial community dynamics during AD in the presence and absence of HA were examined. In this scope, in Chapter 2, we reviewed the literature and pinpointed the urgent need for comprehensive studies on the role of hydrolytic microorganisms and environmental factors that effects their abundance within biogas plants. Consequently, the hydrolysis mechanism and involved hydrolytic enzymes were discussed. The overall discussion showed that a holistic approach, including microbiological and engineering studies should be chosen to disclose the role of hydrolytic microbes within biogas reactors. In Chapter 3 and, Chapter 4 the effect of HA on anaerobic cellulose hydrolysis and methanogenesis, in batch wise incubations is reported, respectively. Our results showed that pulse addition of 5 g L-1 HA caused a 50 % decrease in hydrolysis rate of anaerobic cellulose degradation (Chapter 3). Moreover, VFA accumulation was observed in the presence of HA during the anaerobic cellulose degradation, which indicated the possible inhibition of HA on methanogenesis. Based on the results of Chapter 3, pure cultures of methanogens and a mixed culture were tested to study the vulnerability of methanogenesis to HA inhibition. Hydrogenotrophic methanogenesis in pure cultures was inhibited by more than 75% in the presence of 1 g L-1 HA whereas, acetoclastic methanogenesis by Methanosaeta concilii was only slightly affected by HA up to 3 g L-1. When methanogenic granular sludge was incubated with HA, the specific methanogenic activity tests showed less inhibition, when compared to the pure cultures of methanogens. HA inhibition was also observed during long-term CSTR operation at an HRT of 20 days, 35°C and a mixture of cellulose and xylan as a subtrate (Chapter 6). 8 g L-1 HA inhibited the hydrolysis efficiency of the cellulose and xylan digestion by 40 % and concomitantly reduced the methane yields. Mitigation of the HA inhibition is required to increase the hydrolysis efficiency and methane yields of cellulosic biomass digestion. Therefore, two different strategies were tested for their potential use as mitigation agents, viz. addition of cations such as, calcium magnesium and iron (Chapter 3 and Chapter 6) and addition of hydrolytic enzymes (Chapter 6). Addition of magnesium, calcium and iron salts mitigated the HA inhibition and hydrolysis efficiencies reached up to 75, 65 and 72%, respectively, compared to the control groups in the batch wise incubations (Chapter 3). However, in long term CSTR operations, calcium addition did not show a positive effect on hydrolysis inhibition. On the other hand, enzyme addition helped to reverse the negative effect of HA. The microbial communities involved in AD were also studied. Chapter 5 and Chapter 6 dealt with microbial community analyses with 16S rRNA next generation sequencing. In Chapter 5, five replicate reactors were monitored during the start-up period. Transient feeding strategy was used to acclimatise anaerobic sludge to efficient cellulose and xylan degradation. During the experiment, Bacteriodales, Clostridiales and Anaerolineales became dominant bacterial populations while, Methanobacteriaceae and Methanospirillaceae were the dominant archaeal populations within the reactors. In Chapter 6, the microbial population dynamics in the presence and absence of HA were monitored. Microbiological analyses showed that the abundance of hydrolytic/fermentative bacterial groups such as Clostridiales, Bacteroidales and Anaerolineales was significantly lowered by the presence of HA. HA also affected the archaeal populations. Mostly hydrogenotrophic methanogens were negatively affected by HA. In conclusion, this thesis confirms that HA inhibit the hydrolysis and methanogenesis within both batch incubations and CSTR systems. Microbial populations were also affected by HA. Therefore, hydrolytic enzyme addition can be an option to mitigate HA inhibition and enhance hydrolysis and methanogenesis during conversion of biomass to biogas. In deze thesis is het remmende effect van HZ (humus zuren) op de anaerobe vergisting van (hemi)cellulose onderzocht. Ook is er gekeken naar het effect van HZ op hydrolyse bevorderende strategieën als toevoeging van kationen of enzymen. Daarnaast is het effect van HZ op de microbiologische populatie dynamica onderzocht.

A novel treatment chain for low strength domestic sewage includes low temperature anaerobic treatment as the main process. It can improve the energy efficiency of sewage treatment compared with conventional aerobic sewage treatment. A combination of an Upflow Anaerobic Sludge Blanket reactor and a sludge digester, a UASB-digester system, was proven to be one of the successful anaerobic systems to challenge temperatures as low as 10°C and organic matter concentrations in the range of 382 and 1054 mg chemical oxygen demand (COD)/l. The UASB is operated at low sewage temperature (10°C) and high loading rate. The produced non-stabilised sludge in the UASB is recirculated over the mesophilic digester (35°C) to convert organic solids to methane gas and produce anaerobic biomass fed back into the UASB reactor, where it converts dissolved COD at the low temperature of the waste water. The effect of sludge recirculation rate and sludge transfer point on the performance of a UASB-digester treating domestic sewage at 15 ˚C was studied in this research. The results show increased total COD removal efficiency when increasing the sludge recirculation rate from 1% to 2.6% of the influent flow rate. Methane gas production increases with the sludge recirculation rate, in the range of 1 to 12.5% of the influent flow rate. A higher sludge transfer point results in an increased suspended COD removal efficiency and a higher VSS concentration of the UASB sludge bed. Co-digestion was applied for improving soluble COD removal efficiency of a UASB-digester system, operated at low temperatures and treating domestic sewage with a high dissolved/suspended COD ratio. Glucose was chosen as a model co-substrate and added to the sludge digester to produce additional methanogenic biomass, which was continuously recycled to inoculate the UASB reactor. Methane production in the UASB reactor almost doubles and soluble COD removal efficiency equals the biodegradability of the influent dissolved COD, due to a twofold increase in methanogenic capacity, when applying co-digestion 16% of influent organic loading rate. Therefore, co-digestion is a suitable approach to support a UASB-digester for treatment of low temperature domestic sewage. A pilot scale UASB-digester (130 + 50 L) was studied to treat domestic wastewater at temperatures of 10-20°C at an HRT of 6 h in the UASB reactor and 15 h in the digester. The results show a stable COD removal efficiency of 60 ± 4.6% during the operation at 12.5 to 20°C. COD removal efficiency decreases to 51.5 ± 5.5% at 10°C. The decreased COD removal efficiency is attributed to an increased influent COD load, leading to insufficient methanogenic capacity of the UASB reactor at such low temperature. Suspended COD removal efficiency was 76.0 ± 9.1% at 10-20°C. The effluent COD concentration is 90 ± 23 mg/L at temperatures between 12.5 and 20°C, while soluble COD removal efficiency fluctuates due to variation in the influent COD concentration. 80% of the influent biodegradable COD is recovered as methane gas (including dissolved methane). Low temperature (10-25°C) hydrolysis after applying a short pre-hydrolysis at 35°C was studied compared with those without the pre-hydrolysis. Batch experiments were executed using cellulose and tributyrin as model substrates for carbohydrates and lipids. Low temperature anaerobic hydrolysis rate constants increase by a factor 1.5 - 10 after applying a short anaerobic pre-hydrolysis at 35°C. The hydrolytic activity of the supernatant collected from the digestate after batch digestion of cellulose and tributyrin at 35°C was higher than that of the supernatants collected from the low temperature (≤ 25°C) digestates. The observed hydrolysis in the UASB of a UASB-digester system, treating domestic sewage at low temperatures (10-20°C) is in line with the elevated hydrolytic activity of mesophilic supernatant. Effects of temperature and temperature shocks on specific methanogenic activity (SMA), and acetate affinity of the digester sludge were studied. Digester sludge from a UASB (12.5°C)-digester (35°C) system, was fed with acetate at constant temperatures of 10-35°C and at varying temperatures from 35°C to 25, to 15 to 10°C. The results show no lag phase in methane production rate when applying temperature shocks of 35°C to 25, 15, and 10°C. The temperature dependency of the SMA of the digester sludge after the temperature shocks was similar to the one at constant temperatures. Acetate affinity of the digester sludge was high at the applied temperatures (10-35°C). Latter is consistent with the finding of no VFA in the effluent of the UASB-digester, treating low strength, and low temperature (12.5°C) domestic wastewater. The UASB-digester system to treat low strength, low temperature domestic sewage was provided with a proof-of-principle, and its essential underlying anaerobic processes were sufficiently elucidated to make the technology ready for further scaling up and demonstration in practice.

Xanthene-1,9-dione-3,4-dihydro-6-methylsulfonyl (1), the main product of sulcotrione phototransformation on plant leaves, was slowly hydrolyzed into 2-hydroxy-4-methylsulfonylbenzoic acid (2) and 1,3-cyclohexanedione (3) in aqueous solution. Interestingly, the rate of hydrolysis was significantly enhanced in the presence of roots of monocotyledonous plants, while the same treatment showed adverse effects on broadleaf weeds. Root growth enhancement varied according to the plant species and concentrations of compound 2, as shown with Zea mays roots. Compound 2 is a derivative of salicylic acid that is known to be a plant signaling messenger. Compound 2 was, therefore, able to mimic some known effects of this phytohormone. This work showed that a pesticide like sulcotrione was transformed into a compound exhibiting a positive impact on plant growth. This study exemplified a rarely reported situation where chemical and biological chain reactions transformed a xenobiotic into a compound exhibiting potential beneficial effects.

MgO kristallisiert im Kochsalzgitter und hat üblicherweise die Mg(100) Ebene an der Oberfläche. Die Mg(111) Ebene besteht aus alternierenden Monoschichten von Sauerstoffanionen und Magnesiumkationen und hat große katalytische Aktivität beispielsweise bei der Claisen-Schmidt-Kondensation. Die bis jetzt bekannten Herstellungsmethoden für MgO(111) Oberflächen waren aufwendig oder uneffektiv. Bei der neuen Herstellungsmethode für (111) Nanoflächen wird eine Mischung von Wasser und Methanol zu einer Lösung von Magnesiummethylat in Methanol mit einer stoichiometrische Menge von 4-Nitro- oder 4-Methoxybenzylalkohol zugegeben und unter überkritischen Bedingungen auf 265 Grad C erhitzt. Nach Ablassen des Lösungsmitteldampfes entsteht ein weißes Pulver, das bei 500 Grad C kalziniert wird. Mehrere transmissionselektronenmikroskopische Bilder zeigen die Strukturen der MgO Nanoplättchen.

The aim of this research was to improve our understanding of the mechanism of glucovanillin hydrolysis by [bêta]-D-t-glucosidase activity in vanilla beans by studying their senescence, freezing and traditional curing. A batch of green pods from Madagascar was ripened at 30°C until fruits turned black; another batch was frozen for few days at -18°C and defrosted at 35°C for 24 h and a third batch was cured using traditional methods. During treatments, samples were analysed for the yield of glucovanillin hydrolysis, and [bêta]-glucosidase activity was measured. Cellular structures were also examined by light and transmission electron microscopy. Green fruits had a low yield of glucovanillin hydrolysis (95%), no measurable [bêta]-glucosidase activity and complete cellular degradation. Similar results were observed in beans after defrosting. During curing, beans had a medium yield of glucovanillin hydrolysis (

Marine microbiologists commonly assay lipase activities by using a synthetic fluorescent analog, 4-methylumbelliferyl (MUF)-oleate. The technique is convenient, but it is considered to be unspecific because of the structure of this analog. This study reports the design of a new specific and sensitive lipase assay based on the use of a radiolabeled triglyceride, [ 3 H]triolein. Free fatty acids (FFA) resulting from its hydrolysis are isolated as a function of time in a one-step liquid-liquid extraction and then radioassayed. MUF-oleate and [ 3 H]triolein techniques were compared by measuring lipase activities at similar substrate concentrations along a trophic gradient in the Southwest Lagoon of New Caledonia, near Nouméa. Hydrolysis rates decreased from the nearshore station to the offshore station and showed similar trends regardless of the technique used. Rates decreased from 5.83 to 0.88 nmol of FFA · liter −1 · h −1 and from 0.76 to 0.23 nmol of 3 H-FFA · liter −1 · h −1 , respectively. These results appeared to be consistent with bacterial production results, which also decreased similarly (from 0.59 to 0.26μ g of C · liter −1 · h −1 ). However, the ratio of MUF-oleate activities to [ 3 H]triolein activities, which was constant at the offshore stations (3.8 ± 0.1), gradually increased at the nearshore stations (from 4.1 to 7.6). This result shows that the two assays respond in different ways to changes in environmental conditions and validates the need to set up more specific enzymatic assays.

Food products are complex matrices. They contain molecules from several families that interact with each other to generate specific structures and functionalities. These molecules may include proteins and peptides resulting from protein hydrolysis, e.g. in cheese. It is still difficult to establish a clear relationship between a pool of peptides and their techno-functionalities such as emulsifying, foaming, gelling or even texture properties within a complex matrix. Among the data usually known, there is the degree of hydrolysis that provides information about the average size of the peptides formed. A high degree of hydrolysis induces the production of a pool of small-size peptides (less than 20 amino acids). Advances in identification methods have made the identification of peptides present in food products possible. The size, charge, hydropathy index and isoelectric point of the peptide, as well as its secondary structure, can be calculated on the basis of the peptide sequence. The aim of this study was to determine which physicochemical and structural characteristics of peptides are involved in the cheese stretchability. This work is a re-evaluation, using multivariate exploratory analysis, of the experimental data obtained from a former study (Sadat-Mekmene et al., 2013) in which one typical functionality criterion of Swiss-type cheese (stretchability) was measured and peptides were identified. This methodology, based on Principal Component Analysis and Correspondence Analysis, is one way to establish a relationship between peptide characteristics and their techno-functional property within a complex dairy matrix. This statistical approach showed that the peptides predominantly involved in cheese stretchability were a mixture of both hydrophobic and hydrophilic peptides and that they are large enough to interact with each other and with native proteins. This approach could be applied to better understand the impact of peptides on various food matrices and food techno-functionalities.

International audience; Oomycetes are microorganisms that are distantly related to true fungi and many members of this phylum are major plant pathogens. Oomycetes express proteins that are able to interact with plant cell wall polysaccharides, such as cellulose. This interaction is thought to be mediated by carbohydrate-binding modules that are classified into CBM family 1 in the CAZy database. In this study, the two CBMs (1-1 and 1-2) that form part of the cell wall glycoprotein, CBEL, from Phytophthora parasitica have been submitted to detailed characterization, first to better quantify their interaction with cellulose and second to determine whether these CBMs can be useful for biotechnological applications, such as biomass hydrolysis. A variety of biophysical techniques were used to study the interaction of the CBMs with various substrates and the data obtained indicate that CBEL's CBM1-1 exhibits much greater cellulose binding ability than CBM1-2. Engineering of the family 11 xylanase from Talaromyces versatilis (TvXynB), an enzyme that naturally bears a fungal family 1 CBM, has produced two variants. The first one lacks its native CBM, whereas the second contains the CBEL CBM1-1. The study of these enzymes has revealed that wild type TvXynB binds to cellulose, via its CBM1, and that the substitution of its CBM by oomycetal CBM1-1 does not affect its activity on wheat straw. However, intriguingly the addition of CBEL during the hydrolysis of wheat straw actually potentiates the action of TvXynB variant lacking a CBM1. This suggests that the potentiating effect of CBM1-1 might not require the formation of a covalent linkage to TvXynB.

The influence of temperature and organic load on the anaerobic digestion of primary sludge was studied in the range of 28-60°C with organic loads ranging from 2 to 8.5gCOD.L-1.j-1. The work was carried out from a mesophilic inoculum with prior adaptation. The incubation was conducted in 10-L perfectly mixed thermo-regulated digesters which were fed fed daily. Results showed that the daily production of methane was more influenced by the load than by temperature. The performances obtained at 28°, 37° and 49°C were found similar but slightly reduced at 55°C. The digester operated at 60°C with the highest load quickly led to acid inhibition resulting in a drastic drop of methane production. The rise in temperature lead to an accumulation of ammonium NH4+ in the digesters as well as soluble COD (measured after filtration to 0.45 microns). These variations suggested a change in the balance of biodegradation pathway. The effect of temperature on the acceleration of hydrolysis / acidogenesis phases was more acute than on the acetogenic and methanogenic phases, thereby leading to the accumulation of intermediate metabolites., L’influence de la température et de la charge organique sur la méthanisation des boues primaires de station d’épuration a été étudiée dans la plage de 28 à 60°C pour une charge organique allant de 2 à 8.5gDCO.L-1.j-1. Les travaux ont été réalisés à partir d’un inoculum mésophile, préalablement adapté. L’incubation des boues a été conduite dans des digesteurs thermostatés parfaitement agités de 10L alimentés quotidiennement. Les résultats révèlent que la production journalière de méthane est davantage influencée par la charge que par la température. Les performances épuratoires obtenues à 28°, 37° et 49°C s’avèrent similaires. Elles sont légèrement moins bonnes à 55°C, et le digesteur opéré à 60°C avec la charge la plus élevée a rapidement conduit à une inhibition acide avec arrêt de production de méthane. L’élévation de température conduit à une accumulation d’ammonium NH4+ dans les digesteurs, ainsi que de la DCO soluble (après filtration à 0,45µm). Ces variations suggèrent une modification des équilibres de biodégradation. L’effet de la température sur d’accélération des phases hydrolyse / acidogenèse s’avère plus accentué que sur les phases d’acétogenèse et de méthanisation, conduisant ainsi à l’accumulation de métabolites intermédiaires.

Background Sugar cane internodes can be divided diagonally into four fractions, of which the two innermost ones are the least recalcitrant pith and the moderately accessible pith-rind interface. These fractions differ in enzymatic hydrolyzability due to structural differences. In general, cellulose hydrolysis in plants is hindered by its physical interaction with hemicellulose and lignin. Lignin is believed to be linked covalently to hemicellulose through hydroxycinnamic acids, forming a compact matrix around the polysaccharides. Acetyl xylan esterase and three feruloyl esterases were evaluated for their potential to fragment the lignocellulosic network in sugar cane and to indirectly increase the accessibility of cellulose. Results The hydrolyzability of the pith and pith-rind interface fractions of a low-lignin-containing sugar cane clone (H58) was compared to that of a reference cultivar (RC). Acetyl xylan esterase enhanced the rate and overall yield of cellulose and xylan hydrolysis in all four substrates. Of the three feruloyl esterases tested, only TsFaeC was capable of releasing p-coumaric acid, while AnFaeA and NcFaeD released ferulic acid from both the pith and interface fractions. Ferulic acid release was higher from the less recalcitrant clone (H58)/fraction (pith), whereas more p-coumaric acid was released from the clone (RC)/fraction (interface) with a higher lignin content. In addition, a compositional analysis of the four fractions revealed that p-coumaroyl content correlated with lignin, while feruloyl content correlated with arabinose content, suggesting different esterification patterns of these two hydroxycinnamic acids. Despite the extensive release of phenolic acids, feruloyl esterases only moderately promoted enzyme access to cellulose or xylan. Conclusions Acetyl xylan esterase TrAXE was more efficient in enhancing the overall saccharification of sugar cane, compared to the feruloyl esterases AnFaeA, TsFaeC, and NcFaeD. The hydroxycinnamic acid composition of sugar cane fractions and the hydrolysis data together suggest that feruloyl groups are more likely to decorate xylan, while p-coumaroyl groups are rather linked to lignin. The three different feruloyl esterases had distinct product profiles on non-pretreated sugar cane substrate, indicating that sugar cane pith could function as a possible natural substrate for feruloyl esterase activity measurements. Hydrolysis data suggest that TsFaeC was able to release p-coumaroyl groups esterifying lignin. Electronic supplementary material The online version of this article (doi:10.1186/s13068-014-0153-3) contains supplementary material, which is available to authorized users.

The coastal northern Adriatic Sea receives pulsed inputs of riverine nutrients, causing phytoplankton blooms and seasonally sustained dissolved organic carbon (DOC) accumulation—hypothesized to cause episodes of massive mucilage. The underlying mechanisms regulating P and C cycles and their coupling are unclear. Extensive biogeochemical parameters, processes and community composition were measured in a 64-day mesocosms deployed off Piran, Slovenia. We followed the temporal trends of C and P fluxes in P-enriched (P +) and unenriched (P −) mesocosms. An intense diatom bloom developed then crashed; however, substantial primary production was maintained throughout, supported by tightly coupled P regeneration by bacteria and phytoplankton. Results provide novel insights on post-bloom C and P dynamics and mechanisms. 1) Post-bloom DOC accumulation to 186 μM remained elevated despite high bacterial carbon demand. Presumably, a large part of DOC accumulated due to the bacterial ectohydrolytic processing of primary productivity that adventitiously generated slow-to-degrade DOC; 2) bacteria heavily colonized post-bloom diatom aggregates, rendering them microscale hotspots of P regeneration due to locally intense bacterial ectohydrolase activities; 3) P i turnover was rapid thus suggesting high P flux through the DOP pool (dissolved organic phosphorus) turnover; 4) Alpha - and Gamma-proteobacteria dominated the bacterial communities despite great differences of C and P pools and fluxes in both mesocosms. However, minor taxa showed dramatic changes in community compositions. Major OTUs were presumably generalists adapted to diverse productivity regimes.We suggest that variation in bacterial ectohydrolase activities on aggregates, regulating the rates of POM → DOM transition as well as dissolved polymer hydrolysis, could become a bottleneck in P regeneration. This could be another regulatory step, in addition to APase, in the microbial regulation of P cycle and the coupling between C and P cycles.

BACKGROUND/OBJECTIVES: To ascertain if the form of dietary nitrogen (free amino acids (AA), small peptides, or intact protein) affects the endogenous nitrogen containing substances lost from the upper digestive tract of humans. SUBJECTS/METHODS: Digesta were collected via a naso-ileal tube from the terminal ileum of 16 adult humans in a single parallel study following an acute feeding regimen. Subjects were given an iso-nitrogenous and isocaloric test meal containing 150 g of casein (CAS) (n¼6), enzyme-hydrolyzed casein (HCAS) (n¼5) or crystalline AA (n¼5) dissolved in 550 ml of water, as the sole sources of nitrogen.RESULTS: The mean concentrations and flows of total nitrogen, protein nitrogen, and soluble protein nitrogen passing the terminal ileum were significantly higher (P o0.01) for the CAS and HCAS test-meal groups compared to the AA meal group. Dietary CAS and HCAS had a considerable influence on digesta mucin concentrations and flows compared to free AA (þ41%). Only 3–4% of the total nitrogen remained unidentified.CONCLUSIONS: The form of dietary nitrogen (protein, small peptides or free AA) had an acute effect upon the secretion or reabsorption of endogenous proteins in the small intestine of healthy humans, as evident from significant differences in both the quantity and composition of the proteins found in digesta at the end of the ileum.

International audience; This work combines physical and biochemical analyses to scrutinize liquefaction and saccharification of complex lignocellulose materials. A multilevel analysis (macroscopic: rheology, microscopic: particle size and morphology and molecular: sugar product) was conducted at the lab-scale with three matrices: microcrystalline cellulose (MCC), Whatman paper (WP) and extruded paper-pulp (PP). A methodology to determine on-line viscosity is proposed and validated using the concept of Metzner and Otto (1957) and Rieger and Novak's (1973). The substrate suspensions exhibited a shear-thinning behaviour with respect to the power law. A structured rheological model was established to account for the suspension viscosity as a function of shear rate and substrate concentration. The critical volume fractions indicate the transition between diluted, semi-diluted and concentrated regimes. The enzymatic hydrolysis was performed with various solid contents: MCC 273.6 gdm/L, WP 56.0 gdm/L, PP 35.1 gdm/L. During hydrolysis, the suspension viscosity decreased rapidly. The fibre diameter decreased two fold within 2 h of starting hydrolysis whereas limited bioconversion was obtained (10-15%).

The fate of a racemic lactic acid polymer (PLA50) was investigated by allowing parallelepiped plates of PLA50 to age in liquid medium containing a mixed culture of Fusarium moniliforme and Pseudomonas putida at 30°C. Microbial activity was monitored by measuring pH, lactic acid formation by high-performance liquid chromatography, and esterase activity in supernatant. Degradation of the plates was monitored by weighing, size exclusion chromatography, and visual examination. Under the selected conditions, pH increased up to 8, whereas it remained constant in the microorganism-free control. No significant lactic acid formation or esterase activity was detected in the supernatant during the experimental period (32 weeks). For the first 17 weeks, the water absorption rate of the plates was the same in both the microbial and the control media. Subsequently, plates absorbed more water in microbial than in control media. Typical surface/center differential degradation of plates was observed until 17 weeks, but it reduced progressively. At 32 weeks, specimens appeared completely disintegrated in the microbial medium. PLA50 plates were also buried in the soil for 8 weeks. After recovery, plates were allowed to degrade 8 weeks under controlled conditions. Scanning electron microscopy of these plates showed the development of some filamentous fungi at the surface and into the bulk of plates. Five fungal strains were isolated which appeared to be able to assimilate PLA50 oligomers in mixed cultures. It was assumed that PLA50 plates had been first degraded by chemical hydrolysis, followed by the bioassimilation of degradation by-products in both experiments. © 1996 John Wiley & Sons. Inc.

The microbial deconstruction of the plant cell wall is a key biological process that is of increasing importance with the development of a sustainable biofuel industry. The glycoside hydrolase families GH5 (PaMan5A) and GH26 (PaMan26A) endo-β-1,4-mannanases from the coprophilic ascomycete Podospora anserina contribute to the enzymatic degradation of lignocellulosic biomass. In this study, P. anserina mannanases were further subjected to detailed comparative analysis of their substrate specificities, active site organization, and transglycosylation capacity. Although PaMan5A displays a classical mode of action, PaMan26A revealed an atypical hydrolysis pattern with the release of mannotetraose and mannose from mannopentaose resulting from a predominant binding mode involving the -4 subsite. The crystal structures of PaMan5A and PaMan26A were solved at 1.4 and 2.85 Å resolution, respectively. Analysis of the PaMan26A structure supported strong interaction with substrate at the -4 subsite mediated by two aromatic residues Trp-244 and Trp-245. The PaMan26A structure appended to its family 35 carbohydrate binding module revealed a short and proline-rich rigid linker that anchored together the catalytic and the binding modules.

It has been claimed that the inorganic pyrophosphatase (PPase) of the plant vacuolar membrane transports K+ in addition to H+ in intact vacuoles (Davies, J. M., Poole, R. J., Rea, P. A., and Sanders, D.(1992) Proc. Natl. Acad. Sci. U. S. A. 89, 11701-11705). Since this was not confirmed using the purified and reconstituted PPase consisting of a 75-kDa polypeptide (Sato, M. H., Kasahara, M., Ishii, N., Homareda, H., Matsui, H., and Yoshida, M. (1994) J. Biol. Chem. 269, 6725-6728), these authors proposed that K+ transport by the PPase is dependent on its association with other membrane components lost during purification. We have examined the hypothesis of K+ translocation by the PPase using native vacuolar membrane vesicles from Vitis vinifera suspension cells, multilabeled with fluorescent probes for K+, H+, and membrane potential. This material contained a high proportion of right-side-out, tightly sealed vesicles, exhibiting high PPase activity which was strongly stimulated by uncouplers and K+. Proton pumping occurred in response to pyrophosphate addition in the absence of K+. No K+ incorporation into the vesicles could be observed after PPase energization in the presence of K+, although H+ transport was highly stimulated. The hydrolytic activity was stimulated by a protonophore and by a H+/K+ exchanger but not by the K+ ionophore valinomycin. No evidence could be obtained supporting the operation of an endogenous K+/H+ exchanger capable to dissipate the putative active K+ flux generated by the PPase. We conclude that PPase in native vacuolar membrane vesicles does not transport K+.

International audience; Enzymatic and chemical modifications of soy protein isolate (SPI) were studied in order to improve SPI properties for their use as wall material for α-tocopherol microencapsulation by spray-drying. The structural modifications of SPI by enzymatic hydrolysis and/or N-acylation were carried out in aqueous media without any use of organic solvent neither surfactant. Emulsions from aqueous solutions of native or modified SPI and hydrophobic α-tocopherol, were prepared and spray-dried to produce α-tocopherol microparticles. The effect of protein modifications and the influence of the core/shell ratio on both emulsion and microparticle properties were characterized. The obtained results demonstrated that oil-in-water emulsions prepared with modified proteins had lower droplet size (0.5–0.9 μm) and viscosity (3.6–14.8 mPa⋅s) compared to those prepared with native proteins (1.1 μm and 15.0 mPa⋅s respectively). Efficiency of oil retention decreased after protein hydrolysis from 79.7 to 38.9%, but the grafting of hydrophobic chain by acylation improved efficiency of α-tocopherol retention up to 94.8%. Moreover, higher emulsion viscosity, particle size and process efficiency were observed with the increase of α-tocopherol amount.

The hydrolysis of native milk fat globules by three microbial lipase preparations, two sn-1,3 specific and one non-specific, exhibiting variable level of an annex phospholipase activity was investigated. The reaction kinetics, the evolution of supramolecular structure and the interfacial properties of hydrolyzed fat globules were monitored. The hydrolytic efficiency of the three enzymes preparations was lower for the natural emulsion than for a model emulsion based on homogenized milk fat. Therefore, it indicated a limited accessibility of the enzymes to the natural emulsion. The hydrolysis was preceded by a lag time, the duration of which was negatively correlated to the annex phospholipase activity. Pre-hydrolysis of membrane components with protease or phospholipase modulated the observed lag times. The sn-1,3 specific lipases triggered an accumulation of sn-2 monoglycerides with a limited destabilization of the natural emulsion structure while the non specific lipase, which generated fatty acids as major hydrolytic products, induced a significant destabilization of the emulsion. Our results suggest that the specificity of lipase contributes to diversify the structure and interfacial reactivity of natural milk fat-based emulsions, and consequently their functional and nutritional values.

Fusarium verticillioides secretes enzymes (secretome), some of which might be potentially useful for saccharification of lignocellulosic biomass since supplementation of commercial cellulases from Trichoderma reesei with the F. verticillioides secretome improved the enzymatic release of glucose, xylose and arabinose from wheat straw by 24%, 88% and 68%, respectively. Determination of enzymatic activities revealed a broad range of hemicellulases and pectinases poorly represented in commercial cocktails. Proteomics approaches identified 57 proteins potentially involved in lignocellulose breakdown among a total of 166 secreted proteins. This analysis highlighted the presence of carbohydrate-active enzymes (CAZymes) targeting pectin (from glycoside hydrolase families GH5, GH27, GH28, GH43, GH51, GH54, GH62, GH88 and GH93, polysaccharide lyase family PL4 and carbohydrate esterase family CE8) and hemicelluloses (from glycoside hydrolase families GH3, GH10, GH11, GH30, GH39, GH43 and GH67). These data provide a first step towards the identification of candidates to supplement T. reesei enzyme preparations for lignocellulose hydrolysis.

Complexation reactions of titanium tetrae- thoxide (Ti(OEt)4) and titanium tetra-n-butoxide (Ti(OBu n )4) with 3-pentenoic acid (PA) and allylacetoacetate (AAA), in a 1:1 M ratio, were studied in ethanol solution at room tem- perature. 13 C-NMR and FTIR spectra showed that all PA and AAA completely reacted with both titanium alkoxides. Hy- dridosilane compounds such as triethoxysilane and trieth- ylsilane were added to titanium chelate complexes in a 1:1 M ratio. The investigation of products by 13 C- and 29 Si- NMR and FTIR showed additions of -SiH to the CAC double bond. The hydrolysis of titanium-PA and AAA complexes, by water in 1 : 4 ratios, resulted in released PA in an amount of 10% and AAA of 20%. The stability of hydrolyzed products was investigated by 13 C-NMR, 29 Si

Tryptic digest of caseinomacropeptide (e-terminal part of x-caseln) was separated into 2 fractions by ultrafiltration membrane (eut-off point 3 000 Da). Both fractions strongly stimulated, in a dose-response-dependent manner, Lactococcus lactis subsp lactis CNRZ 1076 growth in reconstituted skim milk. Growth rates were 2-fold higher than that observed in the control culture., Stimulation de la croissance de Laetococeus laetis subsp laetis par l'hydrolysat trypsique du caséinomacropeptide. L'hydrolysat trypsique du caséinomacropeptide (fraction Cterminale de la caséine K) a été séparé en 2 fractions par ultrafiltration sur membrane ayant un seuil de coupure de 3 000 Da. Ces 2 fractions stimulent fortement la croissance de Lactococcus lactis subsp lactis CNRZ 1076 en milieu lait écrémé selon un effet dont l'intensité dépend de la dose utilisée. Le taux de croissance cellulaire est multiplié par deux par rapport à celui observé sur le lait témoin.

New micro-composites containing different proportions of zirconium oxide in aromatic polyamide have been prepared via a sol-gel process. Poly(phenyleneterephthalamide) chains with carbonyl chloride end groups were synthesized by reacting a mixture of p- and m-phenylene diamines with terephthaloyl chloride. The chain ends were endcapped with aminophenyltrimethoxysilane. Appropriate amount of zirconium propoxide solution (82.3 wt.%) in propanol was mixed in the polymer solution and then a stoichiometric amount of water was added to the mixture to carry out the hydrolysis of methoxy and propxy groups. Hybrid materials using different proportions of zirconium propoxide in the organic polymer were thus prepared. Thin films cast from this material were transparent, yellow in color and tough. A gradual increase in the tensile strength was observed with increase in the zirconia content (up to 10%). The tensile modulus of the hybrid mixture was in the range of 2.7 to 4.0 GPa at 25°C. The values of the tensile strength varied from 163 to 203 MPa at 25°C. The maximum strain at the break point initially increased but then decreased with further addition of zirconia. The glass transition temperature determined from the maxima of the tan δ data using dynamic mechanical thermal analysis increased with increase in the zirconia content. The thermal decomposition temperature of the hybrid material measured through thermogravimeteric analysis was around 450°C.

Ti(OEt)4 reacts at room temperature with a maximum of 1.33 mol equiv of methacrylic acid. This ratio is retained in the primary hydrolysis product Ti6O4(OEt)8(OMc)8 (OMc= OOC-C(Me)=CH2), which was characterized by an X-ray structure analysis. The monoclinic lattice parameters (space group P21/c) are a= 1412.0 (3), b= 1710.1 (1), c= 1501.9 (2) pm, beta107.458 (7)x, and V= 3479 *10exp(6) pm exp(3). Zr(OPr exp(n))4 reacts at room temperature with a maximum of about 2 equiv of methacrylic acid, and both ÄZr-(OPr exp(n))3(OMc)Ün and ÄZr(OPr exp(n))2(OMc)2Ün were isolated. While the bismethacrylate compound is hydrolyzed to give ÄZrO(OMc)2Ün, the monomethacrylate only reacts with 1.33 equiv of water to yield a compound of the composition ÄZr3O3(OH)(OPr exp(n))2(OMc)3Ün.

Iron(II)-containing SiO2 gels can be prepared by the hydrolysis and condensation of tetramethoxysilane in methanolic solutions of iron(II) chloride. These gels show an absorption at 1000 nm indicating the presence of iron(II). In opposition to that, iron(II) cannot be introduced into organically modified gels of the 3-glycidyloxypropyltrimethoxysilane type. Vanadium(IV) can be incorporated into both gels. Unlike the SiO2 gels, the organically modified gels are compact and elastic. The spectra of the vanadium(IV)-containing gels show a characteristic absorption at about 800 nm. In some cases these gels change theirs colours with time, presumably due to the exchange of ligands in the coordination sphere of vanadium.

Crystals of the Lewis-acid-base adduct MeInCi 2 · H 2 N t Bu (I) are formed, when dimethylbis(t-butylamino)silane is allowed to hydrolyze in the presence of methylindium dichloride. I crystallizes in the orthorhombic, acentric space group P 2 1 2 1 2 1 with cell dimensions a 1544.6(3), b 1071.4(2), c 628.6(1) pm and Z = 4. The X-ray structure determination ( R = 0.041) reveals I to be a polymer in the solid state, the molecules being held together by NH ⋯ Cl interactions, forming an one-dimensional chain structure. The indium atom has a four-fold, tetrahedral coordination. Remarkable intramolecular distances are: N-In 221 pm (very short), In-C(1) 214 pm and NC(2) 154 pm (both elongated) and In-Cl 240 pm. The Lewis acidity of the indium atom in I is compared with that of the tin atom in Me 2 Si(N t Bu) 2 Sn · H 2 N t Bu (II) and found to be much higher on the basis of the structural data.

International audience; We isolated the non-hydrolysable macromolecular organic fraction (insoluble fraction resistant to drastic laboratory hydrolyses) from a temperate, loamy, forest soil (Lacadée, France) and from the soil of an adjacent plot cleared 35 years ago and continuously cropped with maize. The quantitative, morphological (light, scanning and transmission electron microscopy) and isotopic (bulk δ13C, individual compound δ13C and radiocarbon dating) features of these two non-hydrolysable fractions were determined and compared. It appeared that: (i) extensive degradation of the non-hydrolysable material inherited from the forest soil occurred upon cropping, revealing that its resistance to drastic laboratory hydrolyses is not paralleled by a great resistance to natural biodegradation triggered by change in land use; (ii) only small inputs of maize-derived compounds occurred in the non-hydrolysable fraction of the cultivated soil so that, in spite of extensive degradation, the forest-inherited carbon still predominates; (iii) the non-hydrolysable fractions of both soils comprise the same components (wood debris, spores, pollen, and, predominantly, granular organic aggregates), which correlate with the previously identified chemical components (charcoal, aliphatic lipid components and melanoidin-like components); (iv) the non-hydrolysable fraction of the cropped soil shows a greater contribution of aliphatic moieties, reflecting differential degradation of the components of the non-hydrolysable material inherited from the forest soil; (v) this degradation resulted in enrichment in the oldest components; and (vi) no relationship is observed, in the two Lacadée soils, between resistance to drastic laboratory hydrolyses, on the one hand, and stability towards biodegradation in situ, on the other. These observations, added to recent ones on other types of soils, suggest that such a conspicuous uncoupling between non-hydrolysable and stable carbon is probably a general feature of organic matter in soil as opposed to sedimentary organic matter.

To suppress the reactivity of nanoscaled non-oxidic powders of titanium nitride (TiN) and silicon carbonitride (SiCN) against hydrolysis and oxidation, chemical surface modification with nitrogen-containing surfactants was investigated. Among these surfactants, long-chain primary amines, ethylenediamines, guanidines, nitriles, isocyanates, and succinimides were examined. Thermogravimetry, elemental analysis, and behavior against the water-vapor adsorption of the modified particles were used as methods to estimate the protective capacity of the organic coating material. The best results were obtained by using the long-chain amines and octadecylisocyanate, which were indicated by a significant shift of the powder oxidation toward the higher temperatures and an increase of the particle hydrophobicity. A long-chain succinimide was found to be the most effective in dispersing nanoscaled TiN in organic media. Preparation of a stable aqueous dispersion without significant changes in the elemental composition of the powder was achieved by the application of an ionic surfactant to the surface-modified particles.

Chain-length selectivity profiles of seven lipases (EC 3.1.1.3) have been determined by multiple substrate competition for three reactions at 30 and 50°C: hydrolysis and synthesis of fatty acid methyl esters and acyl transfer between fatty acid ethyl esters and methyl esters. All acyl chains were even-numbered and saturated. Chain-length specificity profiles depended on the enzyme and the reaction considered, due to the combined influence of enzyme and substrate properties. Changing temperature had a significant influence on substrate specificity for esterification only. The results led to the selection of Candida deformans lipase for the selective hydrolysis of short-chain (C8, C10) esters in an equimolar mixture of C8-C18 methyl esters in the presence of various methanol concentrations. The reaction resulted in a long-chain-enriched methyl ester and a short-chain-enriched fatty acid fractions, respectively, consisting of 96% C12-C18 and 68% C8-C10 in a given example. (Resume d'auteur)

In this paper, the relation between the hydrolysis rate of dissolved polymer substrates and sludge concentration was investigated in two ways, viz. by laboratory experiments and by computer simulations. In the simulations, the hydrolysis of dissolved polymer components was regarded as a general depolymerisation process in which the bonds of the parent molecule break randomly until only monomer and dimer components remain. The results illustrate that for the hydrolysis of dissolved polymer substrates the enzyme activity is the rate-limiting factor. Moreover, a general depolymerisation process can describe the enzymatic hydrolysis of these components.

The formation of volatile compounds from precursors or through chemical rearrangement during heat treatment of bacuri pulp at fruit natural pH were studied using simultaneous distillation/extraction (SDE) technique. An increase of the quantities of oxygenated and hydrocarbon terpenes and, to a lesser degree, aldehydes, was observed after SDE at pH 3, relative to the other extraction methods used, SDE at neutral pH and solid phase extraction (SPE). More particularly, linalool, linalool furanoxides, [alpha]-terpineol, hotrienol, nerol oxide, nerol, and geraniol were isolated in more important quantities after the first treatment than after the others. These results can be partially explained by the hydrolysis of glycosidically bound compounds previously identified in bacuri. Other pathways such as polyol rearrangements were also involved. The formation of linalool and [alpha]-terpineol was probably the result of the rearrangement of 2,6-dimethyloct-1-ene-3,7-diol. Moreover, it was assumed that oxidation reactions occurred during SDE at pH 3; more particularly, linalool pyranoxides partially resulted from nonenzymatic oxidation of linalool. When SDE was performed at pH 3, an increase of furfural and 4-methoxy-2,5-dimethyl-3(2H)-furanone was noticed. The modifications of the concentration of aliphatic aldehydes, known as lipid oxidation compounds, and of fatty acid esters were in good agreement with the observed decrease of palmitic and linoleic acid concentrations during this treatment. Moreover, important amounts of 2-acetyl-1-pyrroline were found in the SDE extract recovered at pH 7.

A mathematical description of the surface related hydrolysis kinetics for spherical particles in a batch digestion is presented as well as a verification of this model with particulate starch as a substrate. Three substrates containing starch with different particle size distributions (PSD) were used. Two were obtained from fresh potatoes by wet sieving and for the third substrate a commercially available starch was used. The substrates were batch digested at 30°C with granular sludge as inoculum and the hydrolysis efficiency was measured and fitted with the model. The results revealed that the hydrolysis rates for the three substrates were equal, viz. 0.4±0.1 g starch/m2/hour. Moreover, for the commercial starch not only the hydrolysis efficiency but also the changes within the PSD of the starch was determined several times with the use of light microscopy and image analysis. The obtained experimental PSD showed good similarity with the theoretical PSD from model calculations. This shows that thesurface of the particulate substrate is the key factor for the hydrolysis process.

The effect of the sludge retention time (SRT) between 3 and 15 days, on hydrolysis, acidification and methanogenesis of domestic sewage was researched by simulating a sludge bed segment of an upflow anaerobic sludge bed (UASB) system as a completely stirred tank reactor (CSTR). The CSTR systems were fed with primary sludge (settled solids of domestic sewage) as the influent at 25°C. The study revealed that an SRT≤8 days resulted in acidogenic conditions with negligible biogas production, whereas an SRT>8 days resulted in methanogenic conditions. The hydrolysis of lipids and carbohydrates increased with increasing SRT, whereas protein hydrolysis only occurred under methanogenic conditions. Approximately 20 and 60% of the particulate biopolymers are hydrolysed under acidogenic and methanogenic conditions, respectively. Hydrolysis was found to be the rate-limiting step for the conversion of carbohydrates. Under acidogenic conditions, acidification was the rate-limiting step for conversion of lipids, while both hydrolysis and acidification were limiting for the conversion of proteins. Under methanogenic conditions, hydrolysis was the rate-limiting step in the whole digestion process. None of the main components of primary sludge followed first order kinetics with respect to hydrolysis. The dewaterability of the sludges from the CSTRs operated under acidogenic conditions deteriorated, whereas the dewaterability of the methanogenic sludge improved in comparison with the dewaterability of the raw primary sludge.