Résumé
background: Lactic acid (LA) is a carboxylic acid widely used as preservative, acidulant, and/or flavouring in food industry; it is also used as a raw material for the production of lactate ester, propylene glycol, 2,3-pentanedione, propanoic acid, acrylic acid and acetaldehyde. In recent years, the demand for LA production has dramatically increased due to its application as a monomer for poly-lactic acid synthesis, a biodegradable polymer used as a plastic in many industrial applications. LA can be produced either by fermentation or chemical synthesis; the former route has received considerable interest, due to environmental concerns and the limited nature of petrochemical feedstocks; thus, 90% of LA produced worldwide is obtained by fermentation, this process comprises the bioconversion of a sugar solution (carbohydrates) into LA in the presence of a microorganism. Objectives: This work is aimed at studying the effect of pH control and culture media composition on the LA production using renewable sources from the agroindustry sector. Methods: A Lactobacillus brevis strain is used to perform lab scale experiments under aerobic and anaerobic conditions, using three different culture media compositions: a high nutritional content medium (MRS), as a reference, a low nutritional content medium with glucose as the only carbon source (GM), and a potential low nutritional content medium with cassava flour as carbon source (HY1). results: The higher LA production is accomplished under anaerobic conditions, 17.6 ± 0.1, 12.6 ± 0.2 y 13.6 ± 0.2 g LA/L, for MRS, GM and HY1 medium, respectively. The effect of pH on LA biosynthesis in a 5L bioreactor is also studied using the HY1 medium. For a fermentation time of 120 h, the highest LA concentration obtained was 24.3 ± 0.7g LA/L, productivity 0.20 g/L/h, YP/S 0.32g LA/g syrup, at pH 6.5...
Sujets)
Levilactobacillus brevis , Acide lactiqueRésumé
TMAA (Tamarind methacrylic acid) cation exchanger resin was synthesized, based on locally available polysaccharide Tamarind Kernel powder. The resin was characterized by FTIR and elemental analysis. The resin was found to be stable in acidic as well as in basic medium. Physicochemical properties of the resin were examined. The total cation exchange capacity was measured and effect of pH and metal ion concentration on ion exchange capacity were studied. The distribution coefficients at different pH were also studied using batch equilibration method. The developed column technique has been used for the binary separation of Cu+2/Zn+2, Cu+2/Pb+2, Cu+2/Cd+2 and waste water treatment.