Integrated “omics” approaches to investigate the chemical aspects of symbiosis in termites and potential application in ligno-cellulosic use.

Scientific conference (2010, May 05)

Cellulosic bioethanol could be one of the solutions to satisfy the increasing demand in renewable energy. The most limitative problem is the efficiency of cellulose transformation into fermentable sugars ... [more ▼]

Cellulosic bioethanol could be one of the solutions to satisfy the increasing demand in renewable energy. The most limitative problem is the efficiency of cellulose transformation into fermentable sugars. Investigations to select new glycosyl hydrolases are an interesting approach that constitutes a potential opportunity to improve the valorization of lignocellulosic materials. Three major types of glycosyl hydolases are generally produced by organism’s that are able to efficiently use cellulosic compounds: the endoglucanases, the exoglucanases/cellobiohydrolases and the β-glucosidases. In the ability to transform lignocellulosic materials by animals, symbioses are generally observed with a range of micro-organisms including bacteria, protists and/or fungi that largely (or completely) contribute to the production of the needed enzymatic complexes. In termites, such active enzymes are produced in the insect digestive tract, by the termite insect itself or by symbiotic organisms. Within lower termites gut, such as in our model Reticulitermes santonensis (Feytaud), protists and bacteria are associated and involved in a complex symbiotic system. To investigate the respective role of the insect and different groups of symbionts, multidisciplinary “omics” approaches were here developed including proteomics (ESI-LC-MS-MS, 2D-Dige gel coupled with MALDI-TOF mass spectrometry for protein identification), genomics (with a metagenomic approach based on large cDNA bank construction), metabolomics (LC-MS stragety for carbohydrate degradation product characterization). Moreover, microorganism isolation was used to investigate and characterize glycosyl hydrolases diversity and activity in R. santonensis. The integration of this broad range of “omics” techniques allowed characterizing the role of symbionts in insects in a fundamental approach and to invtigate the chemical ecology of xylophagous insects but also corresponding to an efficient way to promote the selection of efficient enzymatic activities to potentially produce biofuels based on the use of existing lignocellulosic materials. [less ▲]

Study of thermomyces ianuginosa lipase in the presence of tributyrylglycerol and water

in Biophysical Journal (2009), 96(12), 4814-4825

The Thermomyces lanuginosa lipase has been extensively studied in industrial and biotechnological research because of its potential for triacylglycerol transformation. This protein is known to catalyze ... [more ▼]

The Thermomyces lanuginosa lipase has been extensively studied in industrial and biotechnological research because of its potential for triacylglycerol transformation. This protein is known to catalyze both hydrolysis at high water contents and transesterification in quasi-anhydrous conditions. Here, we investigated the Thermomyces lanuginosa lipase structure in solution in the presence of a tributyrin aggregate using 30 ns molecular-dynamics simulations. The water content of the active-site groove was modified between the runs to focus on the protein-water molecule interactions and their implications for protein structure and protein-lipid interactions. The simulations confirmed the high plasticity of the lid fragment and showed that lipid molecules also bind to a secondary pocket beside the lid. Together, these results strongly suggest that the lid plays a role in the anchoring of the protein to the aggregate. The simulations also revealed the existence of a polar channel that connects the active-site groove to the outside solvent. At the inner extremity of this channel, a tyrosine makes hydrogen bonds with residues interacting with the catalytic triad. This system could function as a pipe (polar channel) controlled by a valve (the tyrosine) that could regulate the water content of the active site. [less ▲]

Interesterification of rapeseed oil with anhydrous milk fat and its stearin fraction

Poster (2009)

Rapeseed oil (RO) (a choice source of unsaturation-rich residues) was used in the present study to enrich anhydrous milk fat (AMF) with unsaturated C18 fatty acids (FA) (oleic, linoleic and linolenic ... [more ▼]

Rapeseed oil (RO) (a choice source of unsaturation-rich residues) was used in the present study to enrich anhydrous milk fat (AMF) with unsaturated C18 fatty acids (FA) (oleic, linoleic and linolenic acids). Comparatively, one “harder” fraction of AMF underwent the same reaction. The physico-chemical properties modifications induced by the reaction were followed. The compositional changes are reported in this first part and the consequent physical modifications are presented in a second part. [less ▲]

Enrichment of Anhydrous Milk Fat in Polyunsatured Fatty Acid Residues

Poster (2009)

Lipozyme TL IM was used in a solvent-free batch, microaqueous system for enzymatic interesterification of anhydrous milkfat (AMF) with linseed oil (LO) in binary blends and with rapeseed oil (RO) in one ... [more ▼]

Lipozyme TL IM was used in a solvent-free batch, microaqueous system for enzymatic interesterification of anhydrous milkfat (AMF) with linseed oil (LO) in binary blends and with rapeseed oil (RO) in one ternary blend. [less ▲]

Interesterification of anhydrous milk fat rapeseed and/or linseed oil: oxidative stability

Poster (2009)

Interesterification of rapeseed oil with anhydrous milk fat and its stearin fraction. II. Modifications of melting properties

in Groupement Consultatif International de Recherche sur le Colza (2009), 25

Chemical and/or physical modification of oils and fats are commonly used by food industry to widen their range of applications (1,2). Lipase-catalysed interesterification of anhydrous milk fat (AMF) and ... [more ▼]

Chemical and/or physical modification of oils and fats are commonly used by food industry to widen their range of applications (1,2). Lipase-catalysed interesterification of anhydrous milk fat (AMF) and various vegetable oils is now a well documented procedure (3-7). The purpose of this technique is to produce original structured fats with properties different from a simple blending, that may be used as spreads or introduced into pastry. The new fats contain higher amounts of polyunsaturated fatty acids (PUFA) than butter, which provides health benefits (8,9). To our knowledge only a few authors associated AMF fractionation with blending and interesterification (10,11), although this combination may be used to increase the ratio of vegetable oil in blends and thus the PUFA content of the product. The compositional changes occurring during the lipase-catalysed interesterification of AMF/rapeseed oil (RO) and AMF stearin fraction (AMFSF)/RO blends were described in the first part of this study. In the present and second part are reported the resulting changes in physical properties, especially the melting behaviour through solid fat content (SFC), dropping point (DP) and fusion profiles by differential scanning calorimetry (DSC). [less ▲]

Isolation and biomass production of a Saccharomyces cerevisiae strain binding copper and zinc ions

in Applied Biochemistry and Biotechnology (2009), 157(1),

Effets pré- et/ou probiotiques de levure métabolisant des ions minéraux sur les performances et fonctions immunes d’animaux de rente

Report (2008)

Enrichment of anhydrous milk fat in polyunsaturated fatty acid residues from linseed and rapeseed oils through enzymatic interesterification

in Journal of Agricultural and Food Chemistry (2008), 56(5), 1757-1765

Lipozyme TL IM was used in a solvent-free batch and microaqueous system for enzymatic interesterification of anhydrous milkfat (AMF) with linseed oil (LO) in binary blends and with rapeseed oil (RO) in ... [more ▼]

Lipozyme TL IM was used in a solvent-free batch and microaqueous system for enzymatic interesterification of anhydrous milkfat (AMF) with linseed oil (LO) in binary blends and with rapeseed oil (RO) in one ternary blend. The aim was to obtain and characterize physicochemically fats enriched with unsaturated C-18 fatty acids (oleic, linoleic, and, especially, linolenic acids) from natural vegetable oils. Binary blends of AMF/LO 100/0, 90/10, 80/20, 70/30, and 60/40 (w/w) were interesterified. The change in triacylglycerol (TAG) profiles showed that quasi-equilibrium conditions were reached after 4-6 h of reaction. Free fatty acid contents < 1%. The decrease in solid fat content and in dropping point temperature obtained with increasing content of LO and interesterification resulted in good plastic properties for the products originating from the blends 70/30 and 60/40. This was confirmed by textural measurements. Melting profiles determined by differential scanning calorimetry showed complete disappearance of low-melting TAGs from LO and the formation of intermediary species with a lower melting temperature. Oxidative stability of the interesterified products was diminished with increasing LO content, resulting in low oxidation induction times. A ternary blend composed of AMF/RO/LO 70/20/10 gave satisfactory rheological and oxidative properties, fulfilling the requirements for a marketable spread and, moreover, offering increased potential health benefits due to the enriched content in polyunsatured fatty acid residues. [less ▲]

Enrichment of anhydrous milk fat in polyunsatured fatty acid residues from linseed and rapeseed oil through enzymatic interesterification

Poster (2007)

The interesterification, or ester exchange, between two fats leads to the rearrangement of acyl moieties in both. The use of a sn-1,3-specific lipase confines the exchange of fatty acid residues to the sn ... [more ▼]

The interesterification, or ester exchange, between two fats leads to the rearrangement of acyl moieties in both. The use of a sn-1,3-specific lipase confines the exchange of fatty acid residues to the sn-1 and sn-3 positions of triacylglycerides (TAG), generating products with characteristics that cannot be obtained through a chemical process or a blending. Such reactions require mild conditions with no solvent needed and they yield no unhealthful trans fatty acids, justifying the stepped-up interest of enzymatic interesterification for the production of margarines and other food fats. The aim of this work was to use enzymatic interesterification to enrich anhydrous milk fat (AMF) with unsaturated fatty acid C18 residues from linseed oil (LO) and eventually from rapeseed oil (RO) through some binary blends and one ternary blend. For that, the 1,3-specific lipase from Thermomyces lanuginosa (Lipozyme TL IM) was used in solvent-free batch and micro-aqueous reactions and fat blends with different mass ratios were tested. The evolution of TAG profiles, of interesterification degre (ID) and of free fatty acids (FFA), was followed along the reactions. Determination of dropping points (DP) and solid fat contents (SFC) enabled a rheological characterization of the products. The end products were also characterized for their oxidative stability and their textural properties. [less ▲]