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Co-immobilized β-galactosidase and Saccharomyces cerevisiae cells for the simultaneous synthesis and purification of galacto-oligosaccharides

Aburto, Carla, Guerrero, Cecilia, Vera, Carlos, Wilson, Lorena, Illanes, Andrés
Enzyme and microbial technology 2018 v.118 pp. 102-108
Aspergillus oryzae, Saccharomyces cerevisiae, aeration, beta-galactosidase, biochemical pathways, calcium alginate, crosslinking, ethanol, galactooligosaccharides, lactose, yeasts
Simultaneous synthesis and purification (SSP) of galacto-oligosaccharides (GOS) from lactose was conducted using a combi-biocatalyst formed by crosslinked enzyme aggregates of Aspergillus oryzae β-galactosidase and Saccharomyces cerevisiae cells co-immobilized by entrapment in calcium alginate gel particles. Product yield obtained with the combi-biocatalyst was similar than obtained with the soluble enzyme (23.3%), having a final purity of 25.7%. During the simultaneous process, ethyl-β-galactoside was produced from the ethanol generated as a metabolic product of yeast cells, but ethyl-β-galactoside was considerably decreased at high aeration (4 vvm). The combi-biocatalyst can be recovered and reused but its performance is limited by the reduction of the metabolic capacity of the cells. In this way, a process was developed for the SSP of GOS from lactose, obtaining a comparable product yield and higher specific productivity than in a conventional synthesis.