Enrichment and evaluation of galacto-oligosaccharides produced by whole cell treatment of sugar reaction mixture.

A process was developed for enrichment of galacto-oligosaccharides (GOS), synthesized from a whole cell driven system, from a sugar reaction mixture (SRM) containing non prebiotic sugars (monosaccharides and disaccharides) as impurities. SRM containing 38% (w/w of total carbohydrates) of GOS was enriched by 7 and 27%, attaining a purity of 45 and 65% respectively using Saccharomyces cerevisiae followed by Kluyveromyces lactis var. lactis treatment. The two cell types could be recycled for consecutive 12 and 10 cycles respectively. The microbial purified GOS (MPG) was characterized by mass spectrometry and quantitated by HPLC. MPG was further evaluated for its prebiotic potential on Lactobacillus acidophilus, Lactobacillus amylovorus, Lactobacillus brevis, Lactobacillus plantarum, Lactobacillus casei Shirota and Saccharomyces boulardii. The growth profile and colony forming units were determined and compared with the profiles obtained on glucose, used as a control. MPG was efficiently utilized by L. acidophilus and L. plantarum which showed antimicrobial activity with zone of lysis (12 and 10 mm) against Escherichia coli and Citrobacter (14 and 9 mm) respectively and performed better than Vivinal (commercial GOS), fructo-oligosaccharides and inulin. The synergistic effect of the MPG with L. acidophilus and L. plantarum was found to be most effective against pathogens as compared to other tested commercial oligosaccharides.