Adhesion stability
Adhesion characterization may be an important quality-control
method for assessing the surface structure of probiotic bacteria and
related gut barrier effects. In several studies, adhesion was related
to a shortening of duration of diarrhea, immunogenic effects, competitive
exclusion, and other health effects (2, 5, 10–12).
Adhesion of probiotic strains is variable. Adhesion in different
in vitro models varies even within the same strain and differences
between strains can be significant (13–15). Adhesion
of some common probiotic strains was studied by using a
human colon carcinoma cell line (Caco-2) and human ileostomy
glycoproteins as in vitro models for intestinal epithelium and
mucus, respectively (Figure 3). Of 6 probiotic strains tested,
only Lactobacillus johnsonii LJ-1 and Lactobacillus GG were adhesive in both models. The most adhesive strain to Caco-2
cells [Lactobacillus casei (Fyos)] adhered poorly to ileostomy
glycoproteins, indicating that the surface properties needed for
adhesion to epithelial cells and mucus may be different. Therefore,
possible changes in adhesion stability should be examined
by using more than one model.
Some reports on the stability of adhesion properties are available
in the literature. Elo et al (16) tested the stability of Lactobacillus
GG from different production lots and products by comparing
the original strain with cultures used for a longer period in
industrial processes. Only slight variation in adhesion properties
was observed. However, a more significant drop was reported in
the adhesion properties of a culture that had been maintained in
MRS broth for 3.5 y with a weekly transfer. Lactobacillus GG isolated from the fecal samples of subjects consuming a fermented
whey drink containing Lactobacillus GG had adherence
properties equal to those of the original strain (16; Table 1).
With use of the human intestinal mucus glycoprotein adhesion
model, the adhesion properties of Lactobacillus GG were studied
by using different production lots as well as the strain recovered
from feces. The adhesion tests were conducted as described
earlier (6). The production lots included the original Lactobacillus
GG (ATCC 53103; a gift from SL Gorbach, Tufts University,
Boston), a Lactobacillus GG pharmaceutical grade starter culture
(Valio Ltd, Helsinki), a Lactobacillus GG starter culture
provided by Valio Ltd, and frozen samples of freeze-dried production
lots 1089 (Valio Ltd, 1987) and WA IV (Valio Ltd,
1987). In addition, a fecal isolate of Lactobacillus GG recovered after consumption of a whey drink containing Lactobacillus GG
was studied.