International audienceThe ability of selected lactic acid bacteria to carry out malolactic fermentation depends on the level of numerous wine characteristics. A Hadamard's experimental matrix was used to determine the main effects of 11 physico-chemical factors on malolactic activity of three Leuconostoc œnos strains and one Lactobacillus plantarum strain. Ethanol had the greatest inhibitory effect on the achievement of malolactic fermentation for all Leuc. œnos strains. An inhibitory effect of the L-malic acid was also found in the operating conditions. These strains show different degrees of sensitivity to pH. One of these strains was inhibited by SO2. Malolactic activity of the Lact. plantarum strain is mainly affected by a low pH, and this strain is often less efficient than Leuc. œnos strains. This methodology could be used for the selection of strains for malolactic starters. Further work is in progress using factorial design in order to determine the interactions between influential factors
International audienceA simple staining procedure, associated with image analysis, was used to discriminate two zones (the filamentous zones and the compacted cores) in aggregates of fungal biomass according to their accessibility for an agent of the medium. The application of the method to batch fermentations of Schizophyllum commune showed a higher proportion of loosely entangled particles (clumps) and thinner filamentous outer zones obtained at a high agitation speed (500 rpm) compared to low agitation speeds (120-200 rpm)
International audienceA colour image processing algorithm is presented to identify and measure morphological features of mycelial aggregates in biomass stained with crystal violet to discriminate filamentous regions and compacted cores. The method improves the accuracy and allows automation of the previous monochrome procedure (Durant et al., 1994). It has been applied to the characterisation of aggregates from a shake-flask culture of Fomes fomentarius (Basidiomycete) presenting extended filamentous outer zones. The area of the whole pellet, core, and annular regions of each pellet were measured. The convex area ratio and annular fullness were estimated and means of each samples were calculated
International audience9-hydroxyl derivative of ellipticine, compound of current interest known for its antitumor activity, shows a degradation in a reverse-phase column during High-Performance Liquid Chromatography analyses. In this paper, a chemical explanation of this phenomenon is proposed with the help of a degradation mechanism previously plubished, to understand the appearance of additionnal peaks corresponding to other products
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