Strategies for the production of high-content fructo-oligosaccharides through the removal of small saccharides by co-culture or successive fermentation with yeast

Abstract

Fructo-oligosaccharides (FOS) obtained by fermentation of sucrose may be purified at large-scale by continuous chromatography (Simulated Moving Bed: SMB). In order to improve the efficiency of the subsequent SMB purification, the optimization of the fermentative broth composition in salts and sugars was investigated. Fermentations conducted at reduced amount of salts, using Aureobasidium pullulans whole cells, yielded 0.63 ± 0.03 g of FOS per gram of initial sucrose. Additionally, a microbial treatment was proposed to reduce the amount of small saccharides in the mixture. Two approaches were evaluated, namely a co-culture of A. pullulans with Saccharomyces cerevisiae; and a two-step fermentation in which FOS were first synthesized by A. pullulans and then the small saccharides were metabolized by S. cerevisiae. Assays were performed in 100mL shaken flasks and further scaled-up to a 3 L working volume bioreactor. Fermentations in two-step were found to be more efficient than the co-culture ones. FOS were obtained with a purity of 81.6 ± 0.8% (w/w), on a dry weight basis, after the second-step fermentation with S. cerevisiae. The sucrose amount was reduced from 13.5 to 5.4% in total sugars, which suggests that FOS from this culture broth will be more efficiently separated by SMB.

Removal of Small-Molecular Byproducts from Crude Fructo-Oligosaccharide Preparations by Fermentation Using the Endospore-Forming Probiotic Bacillus coagulans

“…Microbial treatment is an increasingly attractive solution for the purification and enrichment of oligosaccharides from a crude preparation [23,32,35,[58][59][60]. Most previous studies involved sequential fermentation (or co-fermentation) with yeast such as S. cerevisae, K. lactis, and Pichia pastoris to remove the small sugars, increasing the purity and content of oligosaccharides.…”

“…For example, glucose oxidase has been used to convert the glucose into gluconic acid and hydrogen peroxide [31,32], whereas the use of glucose isomerase to convert glucose into fructose was not effective [33,34]. The microbial treatment of crude FOS preparations has also been considered, using species such as Saccharomyces cerevisiae and Kluyveromyces lactis, which prefer monosaccharides and disaccharides as carbon sources and convert them into ethanol and carbon dioxide, but the ethanol then needs to be removed [23,35]. It would be more efficient to convert the unwanted monosaccharides and disaccharides directly into valuable co-products using more suitable microorganisms.…”

Optimal control for fermentative production of fructo-oligosaccharides in fed-batch bioreactor

“…biomass concentration (g X L −1 ) X min minimal biomass concentration (g X L −1 ) Y F/G biomass yield coefficient from fructose/glucose (g F/G .g − i constant penalty parameters final-time condition purification of FOS, industrially performed by simulated-movingbed chromatography [10]. Different strategies have been applied for the reduction of the glucose in the fermentation mixture [11].…”

A one-step bioprocess for production of high-content fructo-oligosaccharides from inulin by yeast

“…The presence of glucose, fructose, and sucrose decreases the prebiotic activity of the products. To obtain high content FOS, several techniques have been employed to remove the non-prebiotic sugars from the FOS mixtures, which include ultra and nanofiltration, activated charcoal systems, microbial treatment, and ion-exchange chromatography (Crittenden, & Playne, 2002;Nobre, 5 Suvarov, & De Weireld, 2014;Nobre, Teixeira, & Rodrigues, 2012;Nobre et al, 2016;Pinelo, Jonsson, & Meyer, 2009). The purity of FOS can reach up to 95% by using these purification techniques, but they are costly.…”

“…Glucose oxidase together with β-D-fructofuranosidase could improve FOS content up to 98%, but the sugar composition in the FOS was significantly different from that produced by fructosyltransferase/furanosidases (Yun, Lee, & Song, 1994). Nobre et al (2016) used a two-step fermentation to remove the non-prebiotic sugars and they obtained the FOS with a purity of 81.6%, in which FOS were synthesized by Aureobasidium pullulans and the small saccharides were metabolized by Saccharomyces cerevisiae. Although these strategies significantly improved the purity of FOS, simple and low-cost processes for high-content FOS production remain to be established.…”