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Formation of galacto‐oligosaccharides during lactose hydrolysis by a novel β‐galactosidase from the moderately thermophilic fungus Talaromyces thermophilus
Author(s) -
Nakkharat Phimchanok,
Kulbe Klaus D.,
Yamabhai Montarop,
Haltrich Dietmar
Publication year - 2006
Publication title -
biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.144
H-Index - 84
eISSN - 1860-7314
pISSN - 1860-6768
DOI - 10.1002/biot.200600013
Subject(s) - lactose , chemistry , hydrolysis , thermophile , yield (engineering) , mesophile , food science , chromatography , biochemistry , enzyme , biology , materials science , bacteria , metallurgy , genetics
Discontinuous and continuous processes of lactose hydrolysis and concomitant galacto‐oligosaccharide (GalOS) formation were studied. To this end a wide experimental range of the main variables was evaluated, including the initial lactose concentration, the degree of lactose conversion, the pH value and the temperature for discontinuous transformations, while the initial lactose concentration and the feed rate were varied for the continuous process. For both processes a high‐initial lactose concentration proved to be advantageous for the formation of GalOS. The maximum amount of GalOS (100 g/L, corresponding to a yield of approximately 50% based on the initially employed lactose) was obtained after 8 h of incubation when using 200 g/L lactose as substrate and 90% lactose hydrolysis was observed. GalOS productivity in the continuous process (g/L·h) was enhanced by an increase of the flow rate. The maximum GalOS productivity of 70 g/L·h was obtained at a flow rate of 24 mL/h when using a reactor with a total working volume of 21 mL. As was evident from these experiments, this β‐galactosidase from a moderately thermophilic fungus showed a strong transgalactosylation activity and can be used for the formation of GalOS, sugars that are of considerable interest for functional food applications because of their presumed healthpromoting effects.