Production of dextransucrase, dextran and fructose from sucrose using Leuconostoc mesenteroides NRRL B512(f)

Abstract

The production of dextransucrase, dextran and fructose by sucrose fermentation using Leuconostoc mesenteroides NRRL-B512(F) was studied in batch operation in a bioreactor with total working volume of 1.5 dm 3 . The effect of temperature (20 to 40 • C), pH (5.5 and 6.7) and sucrose concentration (10 to 120 g/l) on process performance was studied. The optimum conditions for dextran and fructose production were T = 35 • C and pH = 5.5.Cell growth is not inhibited by high sucrose concentrations; however, for sucrose concentration higher than 40 g/dm 3 separation of products from cells is difficult.Biomass (X), enzyme (E), dextran (D), fructose (F) and sucrose (S) rate equations were considered in order to derive a simple fermentation kinetic model from batch experimental data. The logistic equation provided a reasonable description for cell concentration, X. The Luedeking and Piret equation was used to describe the enzyme production rate, by considering only the growth associated term. The concentrations of products (dextran and fructose) were reasonably described by a first order kinetic law with respect to both substrate and enzyme concentrations; the substrate, S was consumed for cell growth and for dextran and fructose production.Model parameters µ m and X o were calculated from cell growth as a function of time. The yield Y E/X were calculated from X max and E max and Y X/S was estimated from X max and the sucrose consumed by the bacteria. The remaining parameter k was obtained by fitting the experimental data of substrate, dextran and fructose concentrations versus time.

Scale up of dextran production from a mutant of Pediococcus pentosaceus (SPAm) using optimized medium in a bioreactor

“…On comparison of dextran and sucrose concentration profiles in the bioreactor, it was found that the dextran concentration peaked after the commencement of sucrose consumption. In bioreactor, the enzyme activity (10.9 U/ml) and the cell optical density both, reached maximum at 14h, which is in agreement with the report of growth associated biosynthesis of dextransucrase (Santos et al, 2000;Rodrigues et al, 2003, Michelena et al, 2003. Oxygen is known to have positive effects on the growth of certain strains of L. mesenteroides (Veljkovic et al 1992).…”

Microbial Dextran-Hydrolyzing Enzymes: Fundamentals and Applications

“…The most extensively studied dextransucrase from the commercially important strains NRRL B-512 and B-512F of L. mesenteroides synthesizes a soluble linear ␣-1,6-linked dextran with about 5% randomly distributed ␣-1,3-branched linkages of up to 50 to 100 residues (168,176,191). The long branches are important factors for properties of the dextran (209).…”

Locticacid bacteria: funcionality, polysaccharides, therapeutic potencial and applications in food

“…Mesenteroides y Leuconostoc mesenteroides subsp. Dextranicum producen dextranas en rendimientos elevados, usando la enzima extracelular dextrana-sacarasa durante el metabolismo de la sacarosa [73,92].…”

“…Los lactobacilos son comúnmente empleados como starters en la manufacturación de productos lácteos, siendo el caso del Lactobacillus rhamnosus ssp que es una especie productora de EPS con potencial probiótico [25,63,12]. Otras especies con potencial de producción de EPS son los Lactococcus lactis spp [113,12,36]; Leuconostoc spp., Leuconostoc fructosum, Leuconostoc mesenteroides spp [6,92,42,12]; Pediococcus acidilactici var [100] y Proponibacterium como Propionibacterium freudenreichii spp [47,75,107,35,60], los cuales son de interés por sus efectos estimulantes sobre probióticos y por ser, también, productores de vitamina B12 [107].…”