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The effects of temperature, reaction time, and substrate concentration on the incorporation of decanoic acid (DA) and alpha-linolenic acid (ALA), into cocoa butter, were compared, using an immobilized enzyme derived from Rhizomucor miehei. All variables had an effect on incorporation of DA and ALA into cocoa butter but effects were not equivalent for the two fatty acids. Thus, DA was not an adequate model fatty acid for the incorporation of ALA into cocoa butter. The highest ALA incorporation achieved was 77.3±1.3. Samples with ALA incorporated were prepared as “pure” and “blends”, and these exceeded the milk and dark chocolate Canadian Food and Drug Regulation guidelines for products making omega-3 fatty acid content claims. The highest %TAG content, 97.3±1.0%, was achieved for the 11.9wt% “blend” sample. Differential scanning calorimetry suggested that both “pure” and “blend” samples contained mainly form IV and V, with much smaller quantities of form II polymorphs.

The yeast Saccharomyces cerevisiae is a major chemical production platform in the biotechnological industry. It is also increasingly being used as a whole cell biosensor. One method of developing such whole cell biosensors in yeast is by exploiting its mating pathway, which is normally induced by secreted pheromones leading to downstream expression of various genes. Functional expression of different recognition elements or receptors and their coupling to the yeast mating pathway can enable sensing of a variety of ligands. In this work, we have engineered a yeast strain to functionally express a heterologous human olfactory receptor gene which can be coupled to the pheromone signaling pathway, allowing yeast to detect medium chain length fatty acids, alcohols and aldehydes for the first time. Functionally expressing heterologous olfactory receptors in yeast is a challenging task because no definitive method exists on how to express such receptors on the yeast cell surface and couple them to the downstream signaling pathway. We explore in this work how the yeast cell can selectively respond to two activating ligands via two different receptors. We also demonstrate in this work that a synthetic transcription factor can substitute for the native transcription factor in the yeast mating pathway. We believe our biosensor will not only have various uses as a versatile sensor but also aid in the design of synthetic genetic circuits.

L'utilisation de biohuiles comme carburants provenant de la transformation de différents types de biomasse (lignocellulosique, huile végétale, algue,...) est une alternative intéressante aux produits pétroliers développée depuis quelques années par l'Union Européenne. Cependant, le taux d'oxygène de ces biohuiles doit être fortement réduit avant leur introduction dans le pool carburant.Afin de modéliser ces huiles, différents composés oxygénés modèles ont été utilisés (acide décanoïque, décanal, phénol) seuls ou en mélange. Leur désoxygénation a été étudiée à 340 °C et sous 4 MPa, à la fois sur catalyseurs sulfures supportés sur alumine (Mo, CoMo, NiMo), et sur catalyseurs massiques de type NiMoS.Dans ces conditions, la désoxygénation de l'acide décanoïque conduit à la formation d'hydrocarbures en C10 et en C9, ces derniers étant majoritaires sur catalyseurs promus (CoMo et NiMo). La désoxygénation du phénol conduit à la formation d'aromatiques et de naphtènes, ces derniers étant majoritaires quel que soit le catalyseur utilisé. Un fort effet inhibiteur de l'acide sur la désoxygénation du phénol a été mis en évidence, attribué à un phénomène de compétition à l'adsorption en faveur de l'acide.Afin de s'affranchir de l'effet de support, des catalyseurs massiques constitués exclusivement de phases NiMoS ont été synthétisés en présence de différents agents (liquide ionique, formamide, eau). Leurs activités et sélectivités ont été mesurées en désoxygénation de l'acide décanoïque et du phénol. Sur ces deux composés, le solide formé dans l'eau a montré les meilleures activités. / Using bio-oil as engine fuels coming from conversion of biomass (lignocellulosic, vegetable oils, microalgae) is an interesting alternative to petroleum-based products depeloped over the last few years by the European Union. However, oxygen concentrations observed in bio-oil need to be sharply reduced before their introduction in the fuel pool.In order to model bio-oils, the effect of various oxygenates compounds was studied (decanoic acid, decanal and phenol) alone or in a mixture. Their deoxygenation was performed at 340 °C under 4 MPa over sulfided supported catalysts (Mo/Al2O3, CoMo/Al2O3, NiMo/Al2O3) and on bulk catalysts (NiMoS).Under these operating conditions, the deoxygenation of decanoic acid involved production of C10 and C9 hydrocarbons, the latter being the major products obtained on promoted catalysts (CoMo and NiMo). Phenol deoxygenation led to the production of aromatic and naphthenes, the latter being the major products whatever the catalyst used. A strong inhibiting effect of acid on the transformation of phenol was highlighted, assigned to a competitive adsorption in favour of the acid.In order to break out support effect, bulk catalysts formed exclusively by NiMoS phase were synthesized in presence of differents agents (ionic liquid, formamide, water). Activity and selectivity of these catalysts were measured in deoxygenation of two oxygenated model compounds (decanoic acid and phenol). For both oxygenated model compounds, the catalyst synthesized in water presented the highest activity.