Background:
β-galactosidases are enzymes that are utilized to hydrolyze lactose into galactose and glucose, and
are is widely used in the food industry.
Objective:
We describe the recombinant expression of an unstudied, heterodimeric β-galactosidase originating from Lactobacillus brevis ATCC 367 in Escherichia coli. Furthermore, six different constructs, in which the two protein subunits were
fused with different peptide linkers.
Method:
The heterodimeric subunits of the β-galactosidase were cloned in expressed in various expression constructs, by
using either two vectors for the independent expression of each subunit, or using a single Duet vector for the co-expression
of the two subunits.
Results:
The co-expression in two independent expression vectors only resulted in low β-galactosidase activities, whereas
the co-expression in a single Duet vector of the independent and fused subunits increased the β-galactosidase activity significantly. The recombinant β-galactosidase showed comparable hydrolyzing properties towards lactose, N-acetyllactosamine,
and pNP-β-D-galactoside.
Conclusion:
The usability of the recombinant L. brevis β-galactosidase was further demonstrated by the hydrolysis of
human, bovine, and goat milk samples. The herein presented fused β-galactosidase constructs may be of interest for
analytical research as well as in food- and biotechnological applications.