Table 4.
The β-galactosidase activity of several probiotic strains (modified from [46]).
| Probiotic Strains | β-Galactosidase Activity Level |
|---|---|
| Bifidobacterium lactis W52 | ++++ |
| Bifidobacterium lactis W51 | +++ |
| Lactobacillus acidophilus W22 | +++++ |
| Lactobacillus acidophilus W70 | +++++ |
| Lactobacillus brevis W78 | + |
| Lactobacillus casei W20 | + |
| Lactobacillus casei W79 | ++ |
| Lactobacillus plantarum W21 | + |
| Lactobacillus rhamnosus W71 | + |
| Lactobacillus salivarius W24 | +++++ |
| Lactococcus lactis W19 | + |
| Streptococcus thermophilus W69 | +++++ |
Measurement of β-galactosidase enzymatic activity was performed, as described by Miller [47], by spectrophotometric measurement (405 nm) of the formation of the yellow chromophore ο-nitrophenol (ONP) as the hydrolytic product of the action of β-galactosidase on the colourless substrate o-nitrophenyl-β-galactoside. Higher levels of ONP indicate greater amounts of β-galactosidase released from the bacterial cells (+ to +++++).