ABSTRACT
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...
Subject(s)
Levilactobacillus brevis , Lactic AcidABSTRACT
El licopeno es un carotenoide de elevado poder antioxidante que se obtiene a partir de fuentes naturales especialmente frutas y vegetales; también puede ser producido mediante el cultivo de microoganismos. En el presente artículo se estudia la síntesis de licopeno a partir del cultivo sumergido de Clavibacter michiganeses sub. michiganenses. Se considera el diseño de medios de cultivo y la separación, cuantificación y caracterización del carotenoide. Con el fin de establecer los niveles más apropiados para los factores de estudio (fuente de carbono, fuente de nitrógeno y sales), se programa un diseño de factor único; para el estudio de optimización se emplea un diseño central compuesto (33), cuya variable respuesta es la concentración de producto. El ajuste estadístico de los resultados experimentales muestra valores de fuente de carbono (glucosa: 7.5 g/L), nitrógeno (peptona: 10g/L y extracto de levadura: 10 g/L) y sales (cloruro de sodio: 10 g/L y fosfato dipotásico: 1 g/L), como constituyentes del medio de cultivo para lograr la mayor concentración de pigmento (2.85 mg carotenos/mL).