Lactic acid bacteria from healthy breast-fed infants were
isolated and screened for β-galactosidase production in
MRS broth. Among 49 isolates that exhibited the yellow
clear zone on MRS agar supplemented with bromocresol
blue, the isolate CM33 was selected as being the highest
β-galactosidase producer and was identified as Lactobacillus
fermentum based on its morphological characteristics and
16S rDNA nucleotide sequence. L. fermentum CM33 exhibited
a good survival rate under the simulated stomach
passage model, comparable to known probiotic strains L.
gallinarum JCM2011 and L. agilis JCM1187. L. fermentum
CM33 was antagonistic to pathogenic bacteria Listeria monocytogenes,
Escherichia coli 0157:H7, Salmonella typhi, and
Salmonella enteriditis, using the well diffusion method. In
addition, the selected lactobacilli exhibited a high growth
rate when cultivated in modified MRS containing commercial
galactooligosaccharide (GOS) as a sole carbon source,
as well as in glucose. A preliminary study on the enzymatic
synthesis of oligosaccharide using crude β-galactosidase revealed
the capability for oligosaccharide synthesis by the
transgalactosylation activity.