Arnaud Muller-Feuga

Cultivated microalgae and the carotenoid fucoxanthin from Odontella aurita as potent anti-proliferative agents in bronchopulmonary and epithelial cell lines

The antiproliferative activities of several extracts from cultivated microalgae in France have been studied against bronchopulmonary and epithelial cell lines, respectively (A549, NSCLC-N6 and SRA 01/04). The algal extracts, of Diatomae (Odontella aurita, Chaetoseros sp.), as well as of Haptophyceae: Isochrisys aff. galbana, appeared as the most active among all the assayed species, expressing a broad spectrum of in vitro antiproliferative activity of well-differentiated pathologic cells such as NSCLC-N6 by terminal differentiation. Bio-guided fractionation of the above referred extracts, led us to the isolation, of the carotenoid fucoxanthin. Fucoxanthin has been structurally determined, through modern spectral means and has been studied separately for its activities.

Comparison of artificial light photobioreactors and other production systems using Porphyridium cruentum

A new type of preparative photobioreactor for high quality production of microalgae is developed for hatchery-nursery of marine animals, as well as for fine chemicals extraction. Of modular conception, two artificial light photobioreactors in plastic and stainless steel are designed so as to provide strictly controlled conditions in an attempt to increase quality and diminish cost prices. They are assessed for production of Porphyridum cruentum and compared to conventional transparent tanks and solar photobioreactors. The concentration and productivity obtained are ten-fold higher than with hatchery tanks, which leads to a significant drop in cost price of biomass. Comparison is also made with a 10 m2 solar photobioreactor operated in the south of France, for which biomass cost price is half that of 1.5 m2 artificial light photobioreactor. Extrapolations erasing size discrepancy show that the cost price of the two technologies are not very different.

Growth as a function of rationing : a model applicable to fish and microalgae

Abstract Since food transformation obeys the same rules in both plant and animal kingdoms, data describing that of fish and microalgae, selected for their aquatic habitat and simple physiology, have been analyzed. It appears that three conditions must be observed in both cases: (i) fasting provokes weight loss, (ii) maximum growth is achieved with a feed ration known as saturation, and decreases beyond that; (iii) between rations of maintenance and of saturation, there is an optimal ration providing maximum transformation yield. Transformation models available in the literature were analyzed with respect to the mathematical constraints resulting from these rules. A three-parameter function to verify them was proposed, then applied to a few experimental series available for fish ( Oncorhynchus nerka ) and microalgae ( Porphyridium cruentum ). The satisfactory nature of the adjustments obtained suggests that the model is applicable to other cases, which are discussed.

Lagrangian trajectory model for turbulent swirling flow in an annular cell: comparison with residence time distribution measurements

Abstract Knowledge of the flow field can be very useful for reactor design and optimization. Data concerning the displacement and trajectories of reactive elements are of primary interest for a better understanding of process running. Results can be deduced from computational fluid dynamics or experimental measurements. However, numerical simulation is difficult to achieve for complex flow such as swirling decaying flow, and trajectories need to be calculated on the basis of velocity field measurements. This problem can be simplified by using a Lagrangian formulation, in which case the only major difficulty is to express the influence of turbulence on calculated trajectories. Velocity fluctuations can be considered as pure random functions or related to turbulence correlations. These two methods were used to calculate trajectories of elementary fluid particles in a swirling decaying flow on the basis of hydrodynamic characteristics obtained by particle image velocimetry (PIV) studies. Trajectory dispersion was then compared with experimental results obtained by PIV measurements of the instantaneous flow field. This comparison shows the great dependence of velocity fluctuation (and thus of trajectories) on spatial correlations. Finally, the correct mathematical formulation of velocity fluctuation was checked by using the trajectory calculation algorithm to determine residence time distribution (RTD). A comparison with experimental RTD confirmed the efficiency of the method for determining trajectories in swirling decaying flow.