Chemistry Reference
In-Depth Information
et al., 1997). It appears that ingested RS acts as a metabolic substrate to create an
optimal environment for
B. lactis
. Thus, RS can enhance the apoptotic response
to DNA damage initiated by carcinogens in the colon of rats, which may lead to a
reduction of the colorectal cancer risk.
Human fecal pH-controlled batch cultures showed that RS induces an ecologi-
cal shift in the colonic microbiota by inducing
Bifidobacterium
spp. (Lesmes et al.,
2008). A possible mechanism by which the
B. lactis
in combination with RS enhanced
AARGC may be through the immunomodulating properties of probiotic bacteria
(Perdigón et al., 2003).
Lactobacillus
also activated different immune receptors and
induced a different cytokine profile (such as tumor necrosis factor-α, interferon-α,
and interleukin-10) that promote immune responses in BALB/c mice (Perdigón et
al., 2001; Dogi et al., 2008).
Lactobacillus casei, L. delbrueckii
ssp.
bulgaricus,
and
L.acidophilus
enhanced the immunoglobulin G
1
(IgG
1
) response favoring Th2 bal-
ance, while
L. acidophilus
also increased the IgG
2a
response inducing Th1 balance
(Perdigón et al., 2001). The main immune cells activated after oral
L. casei
admin-
istration were those of the innate immune response, with an increase in the specific
markers of these cells (CD-206 and TLR-2), but with no changes in the number of T
cells (Galdeano and Perdigón 2006).
RS was successfully used as symbiotic in ice cream containing 1 percent RS
with free and encapsulated
L. casei
(Lc-01) and
B. lactis
(Bb-12) (Homayouni et al.,
2008). Crittenden et al. (2001) screened 40 probiotic
Bifidobacterium
strains using an
in vitro
screening regimen to find that
B. lactis
Lafti B94 possesses all the required
characteristics to complement HACS in a synbiotic yogurt.
Bifidobacterium lactis
Laftitrade mark B94 was genetically closely related to the
B. lactis
type strain (DSM
10140), and to the commercial strains
B. lactis
Bb-12 and
B. lactis
DS 920. These
strains produced the same pulse field gel electrophoresis patterns when the chromo-
somal DNA was cut using a restriction enzyme. However,
B. lactis
Laftitrade B94
was the only one of these isolates that could hydrolyze and utilize HACS. It survived
well in an
in vitro
gastrointestinal model, grew well at temperatures up to 45°C, and
grew to a high cell yield in laboratory-scale fermentations.
B. lactis
Laftitrade B94
survived without substantial loss of viability in synbiotic yogurt containing HACS
during storage at 4°C for 6 weeks. Thus, the strain appeared to possess technological
properties suitable for yogurt manufacture.
6.5 ColoNIC CEll hEAlTh
Prebiotics may exert their cancer protective effects via modulation of fermenta-
tive events, possibly by increasing SCFA production or by altering gut microbiota
toward a more beneficial composition. Butyrate and, to a lesser degree, propionate
are substrates for the aerobic energy metabolism (Jacobasch et al., 1999). In normal
cells, butyrate induces proliferation at the crypt base, while inhibiting proliferation
at the crypt surface. In neoplastic cells, butyrate inhibits DNA synthesis and arrests
cell growth in the G
1
phase of the cell cycle. Butyrate is associated with induction of
