ABSTRACT
Lactic acid purification was directly done from fermentation utilizing a fluidized bed column refilled with a strong anionic exchange resin. The purpose of this work was to study the influence of two important design parameters, bed-diameter (D) and bed-height (H), in the lactic acid binding and elution capacity of the matrix. By changing the settled bed height from 2.5 to 5 cm for each diameter of column analyzed it was possible to obtain an 50% increase in the binding capacity of the resin in all experiments. This fact was attributed to a higher contact time between the culture broth and the anionic resin produced by the increase of back mixing and lactic acid residence time.
Subject(s)
Bioreactors , Lactic Acid/metabolism , Adsorption , Algorithms , Anion Exchange Resins , Bacteriological Techniques , Culture Media , Fermentation , Lactic Acid/isolation & purification , Lacticaseibacillus casei/metabolism , Resins, SyntheticABSTRACT
A two-stage two-stream chemostat system and a two-stage two-stream immobilized upflow packed-bed reactor system were used for the study of lactic acid production by Lactobacillus casei subsp casei. A mixing ratio of D12/D2 = 0.5 (D = dilution rate) resulted in optimum production, making it possible to generate continuously a broth with high lactic acid concentration (48 g l-1) and with a lowered overall content of initial yeast extract (5 g l-1), half the concentration supplied in the one-step process. In the two-stage chemostat system, with the first stage at pH 5.5 and 37 degrees C and a second stage at pH 6.0, a temperature change from 40 degrees C to 45 degrees C in the second stage resulted in a 100% substrate consumption at an overall dilution rate of 0.05 h-1. To increase the cell mass in the system, an adhesive strain of L. casei was used to inoculate two packed-bed reactors, which operated with two mixed feedstock streams at the optimal conditions found above. Lactic acid fermentation started after a lag period of cell growth over foam glass particles. No significant amount of free cells, compared with those adhering to the glass foam, was observed during continuous lactic acid production. The extreme values, 57.5 g l-1 for lactic acid concentration and 9.72 g l-1 h-1 for the volumetric productivity, in upflow packed-bed reactors were higher than those obtained for free cells (48 g l-1 and 2.42 g l-1 h-1) respectively and the highest overall L(+)-lactic acid purity (96.8%) was obtained in the two-chemostat system as compared with the immobilized-cell reactors (93%).
Subject(s)
Bioreactors/microbiology , Industrial Microbiology/methods , Lactic Acid/biosynthesis , Lacticaseibacillus casei/metabolism , Biomass , Cells, Immobilized/metabolism , Culture Media/chemistry , Fermentation , Glucose/metabolism , Hot Temperature , Hydrogen-Ion Concentration , Lacticaseibacillus casei/growth & developmentABSTRACT
A cylindrical upflow filter packed with non-reticulated polyurethane foam, seeded with anaerobic sewage sludge and geared to biological treatment of dairy industrial wastewater, was used to determine the biomass content of the biofilm and suspended flora. This microflora is responsible for the conversion to methane and carbon dioxide of most of organic matter in wastewater. The methanogenic process reduces the COD of liquid wastes in more than 83% when operate at organic loading rate of 6 Kg COD/m3/d. Sequential sampling showed that biomass could be determined by measurement of volatile solids of each filter section. Those solids are related to filter geometry an produce accumulation of flocs (0.7g/l) in the bottom zone corresponding to liquid inlet.
Subject(s)
Bacteria, Anaerobic , Biomass , Filtration/instrumentation , Industrial Microbiology/instrumentation , Environment, ControlledABSTRACT
A cylindrical upflow filter packed with non-reticulated polyurethane foam, seeded with anaerobic sewage sludge and geared to biological treatment of dairy industrial wastewater, was used to determine the biomass content of the biofilm and suspended flora. This microflora is responsible for the conversion to methane and carbon dioxide of most of organic matter in wastewater. The methanogenic process reduces the COD of liquid wastes in more than 83
when operate at organic loading rate of 6 Kg COD/m3/d. Sequential sampling showed that biomass could be determined by measurement of volatile solids of each filter section. Those solids are related to filter geometry an produce accumulation of flocs (0.7g/l) in the bottom zone corresponding to liquid inlet.
ABSTRACT
A cylindrical upflow filter packed with non-reticulated polyurethane foam, seeded with anaerobic sewage sludge and geared to biological treatment of dairy industrial wastewater, was used to determine the biomass content of the biofilm and suspended flora. This microflora is responsible for the conversion to methane and carbon dioxide of most of organic matter in wastewater. The methanogenic process reduces the COD of liquid wastes in more than 83
when operate at organic loading rate of 6 Kg COD/m3/d. Sequential sampling showed that biomass could be determined by measurement of volatile solids of each filter section. Those solids are related to filter geometry an produce accumulation of flocs (0.7g/l) in the bottom zone corresponding to liquid inlet.
ABSTRACT
Se realizaron estudios sobre levaduras del género Kluyveromyces (K. fragilis 507, K. lactis 29 y K. lactis 10), que crecen en lactosa como única fuente de carbono, ya que poseen el sistema enzimático para la utilización de este azucar. Se determinó la actividad de ß-galactosidasa en medios con glucosa y con lactosa, en cultivos de estas tres cepas en fase log. Al agregar entre ) y 12% v/v de etanol a células tratadas con tolueno, no se observó inhibición enzimática para la cepa K. lactis 10 que tenía la mayor actividad enzimática (704,4 Unidades). Como existe la posibilidad de utilizar industrialmente suero concentrado 4 veces como sustrato que contenga lactosa, se realizaron ensayos de fermentación a 30 C las tres cepas, en medios que contenían inicialmente 16,5 y 24,5% de lactosa. Al cabo de 48 h la lactosa residual fue prácticamente cero, lográndose concentraciones de etanol directo entre 7,60 y 10,10% v/v. Es de esperar que la velocidad de fermentación de un disacárido como lactosa, esté relacionada con la velocidad de hidrólisis del mismo azúcar, por lo que cepas con una mayor velocidad enzimática hidrolítica debieran poseer mayor velocidad de fermentación. En este caso no se observó tal comportamiento, por cuanto cepas con actividad enzimática tan distinta como K. lactis 10 (704,4 U) y K lactis 29(189,7 U) no presentaron mayores diferencias en la producción de etanol a partir de lactosa
Subject(s)
beta-Galactosidase/metabolism , Ethanol/metabolism , Kluyveromyces/enzymology , Lactose/metabolism , Fungal Proteins/metabolism , Species Specificity , Fermentation , Kluyveromyces/metabolismABSTRACT
Se realizaron estudios sobre levaduras del género Kluyveromyces (K. fragilis 507, K. lactis 29 y K. lactis 10), que crecen en lactosa como única fuente de carbono, ya que poseen el sistema enzimático para la utilización de este azucar. Se determinó la actividad de ß-galactosidasa en medios con glucosa y con lactosa, en cultivos de estas tres cepas en fase log. Al agregar entre ) y 12% v/v de etanol a células tratadas con tolueno, no se observó inhibición enzimática para la cepa K. lactis 10 que tenía la mayor actividad enzimática (704,4 Unidades). Como existe la posibilidad de utilizar industrialmente suero concentrado 4 veces como sustrato que contenga lactosa, se realizaron ensayos de fermentación a 30 C las tres cepas, en medios que contenían inicialmente 16,5 y 24,5% de lactosa. Al cabo de 48 h la lactosa residual fue prácticamente cero, lográndose concentraciones de etanol directo entre 7,60 y 10,10% v/v. Es de esperar que la velocidad de fermentación de un disacárido como lactosa, esté relacionada con la velocidad de hidrólisis del mismo azúcar, por lo que cepas con una mayor velocidad enzimática hidrolítica debieran poseer mayor velocidad de fermentación. En este caso no se observó tal comportamiento, por cuanto cepas con actividad enzimática tan distinta como K. lactis 10 (704,4 U) y K lactis 29(189,7 U) no presentaron mayores diferencias en la producción de etanol a partir de lactosa (AU)
Subject(s)
Comparative Study , Ethanol/metabolism , beta-Galactosidase/metabolism , Fungal Proteins/metabolism , Lactose/metabolism , Kluyveromyces/enzymology , Kluyveromyces/metabolism , Fermentation , Species SpecificityABSTRACT
We investigated the behavior of yeast of the genus Kluyveromyces (K. fragilis 507, K. lactis 29 and K. lactis 10), which grow on lactose as sole carbon source, since they possess an enzyme system for the utilization of this sugar. We determined the beta-galactosidase activity of these strains, grown in the logarithmic phase in media containing glucose and lactose. On addition of 0 to 12% v/v ethanol to cells treated with toluene, we did not observe inhibition of the enzyme in strain 10 of Kluyveromyces lactis, which showed the greatest activity (704.4 Units). Since there exist the possibility of industrial utilization of concentrated whey (4 times), we performed fermentation tests of the three strains, at 30 C, in media containing initial lactose concentrations of 16.5 and 24.5%. After 48 h the residual lactose concentration was practically zero, and the ethanol concentrations had reached 7.60 and 10.10% v/v. It might be expected that the rate of fermentation of a disaccharide such as lactose would be related to the rate of hydrolysis of the sugar, so that strains having a higher rate of enzymatic hydrolysis should show a higher fermentation rate. However, we did not observe such behavior, as strains of Kluyveromyces having enzymatic activities as different as K. lactis 10 (704.4 U) and K. lactis 29 (189.7 U) did not show any great difference in the production of ethanol from lactose.
Subject(s)
Ethanol/metabolism , Fungal Proteins/metabolism , Kluyveromyces/enzymology , Lactose/metabolism , beta-Galactosidase/metabolism , Fermentation , Kluyveromyces/metabolism , Species SpecificityABSTRACT
We investigated the behavior of yeast of the genus Kluyveromyces (K. fragilis 507, K. lactis 29 and K. lactis 10), which grow on lactose as sole carbon source, since they possess an enzyme system for the utilization of this sugar. We determined the beta-galactosidase activity of these strains, grown in the logarithmic phase in media containing glucose and lactose. On addition of 0 to 12
v/v ethanol to cells treated with toluene, we did not observe inhibition of the enzyme in strain 10 of Kluyveromyces lactis, which showed the greatest activity (704.4 Units). Since there exist the possibility of industrial utilization of concentrated whey (4 times), we performed fermentation tests of the three strains, at 30 C, in media containing initial lactose concentrations of 16.5 and 24.5
. After 48 h the residual lactose concentration was practically zero, and the ethanol concentrations had reached 7.60 and 10.10
v/v. It might be expected that the rate of fermentation of a disaccharide such as lactose would be related to the rate of hydrolysis of the sugar, so that strains having a higher rate of enzymatic hydrolysis should show a higher fermentation rate. However, we did not observe such behavior, as strains of Kluyveromyces having enzymatic activities as different as K. lactis 10 (704.4 U) and K. lactis 29 (189.7 U) did not show any great difference in the production of ethanol from lactose.
