Lactosucrose (4^G-β-D-galactosylsucrose) was fermented in vitro by bifidobacteria and lactobacilli, and to a limited degree by the Bacteroides fragilis group, clostridia, eubacteria, and enterobacteriaceae. The effects of dietary lactosucrose on the fecal flora and fecal metabolites were studied in eight healthy volunteers (20-23 years of age) who ingested 3 g of lactosucrose/day for 7 days followed by 6 g of lactosucrose/day for 7 consecutive days. During lactosucrose intake, the counts of bifidobacteria were increased significantly (p< 0.001), whereas the counts of clostridia, including Clostridium perfringens, and bacteroidaceae were decreased significantly (p<0.05) compared with the values before the intake. The total bacterial counts were decreased significantly (p< 0.05) on day 14 during the intake. The frequency of occurrence of lecithinase-negative clostridia was decreased significantly (p<0.05) when compared with the values before and after the intake. No detectable changes occurred in the counts of other organisms throughout the experimental periods. Fecal concentrations of ammonia, sulfide, phenol, ethylphenol, skatol and indole were decreased significantly (p< 0.05) during lactosucrose intake. Acetic acid and lactic acid were increased significantly (p< 0.05) during the intake. Fecal enzyme activity of β-glucuronidase was decreased significantly (p< 0.05) on day 14 of the intake. Serum very low density lipoprotein (VLDL) was increased significantly (p< 0.01) on day 14 during the intake. Mean fecal pH values decreased from 6.3 to 5.9, and mean water content increased 3.6% during the intake. Fecal weight was increased slightly during the intake. The results obtained showed that the effective dose of lactosucrose for all healthy adults is 3 g/day.

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We measured the antitumor activity of Bifidobacterium infantis (B. infantis). We used mainly a cell wall preparation (WPG) based upon preliminary experiments (Cancer Res. 45: 1300-1307, 1985). First, we evaluated the antitumor effects of WPG on peritoneal and thoracic tumor-bearing animals, using mouse Ehrlich carcinoma and Meth A fibrosarcoma, as well as rat MADB 106 mammary tumor. More frequent, earlier onset and dose-related injections of WPG were more effective in these tumor-bearing animals. Cell kinetic studies revealed that WPG induced polymorphonuclear cells (PMNs) followed by macrophages at the injection cavity. In addition, WPG directly activated these cells to inhibit the growth of tumor cells in in vitro assays. These results suggest that the bifidobacterial cell wall, WPG induces and activates nonspecific phagocytes (PMNs and macrophages) in situ to reject growing tumor cells in peritoneal and thoracic cavity of animals.

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Bifidobacteria are harbored in the intestine of specific animals and humans at different ages. In this study, we examined the immune responses affected by Bifidobacterium longum and B. animalis, focusing upon the cytokines produced by mouse peritoneal cells. Both B. longum and B. animalis induced the expression of IL-1β, IL-6, IL-10 and TNF-α mRNA in mouse peritoneal cells, as determined by RTPCR. The amount of IL-6 secreted by thioglycollate-induced peritoneal exudate cells (TG-PEC) in the presence of these bacteria were similarly augmented, as shown by ELISA. More TNF-α was induced in B. longum than in B. animalis. A difference in the level of TNF production was also suggested from the in vivo tumor suppression test using TNF-sensitive Meth A tumors, although both species of bacteria profoundly suppressed the tumor incidence and tumor growth. Taken together, both B. longum and B. animalis promote the induction and/or secretion of inflammatory cytokines (IL-6 and TNF-α) in mouse peritoneal cells. However, the level of TNF-α production induced by B. animalis was lower than that by B. longum.

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We investigated the effects of oral administration of undigestible oligo- and polysaccharides to rats on microbial fermentation products and fecal enzyme activities. The fecal pH values were decreased by feeding diet containing arabinogalactan (AG), kestose (Kes) and nystose (Nys). The fecal moisture was significantly increased by feeding polydextrose (PD), xylooligosaccharide (XO), glucuronosyl xylooligosaccharide (GXO), citrus pectin (CP) and apple pectin (AP) diet. Oligo- and polysaccharides in the diet resulted in a decrease in fecal β-glucosidase, β-glucuronidase and urease activities measured at a constant pH (7.2). PD-containing diet, exceptionally, increased fecal β-glucosidase activity three- to fourfold. Furthermore, fecal enzyme activities were assayed at the fecal pH to assume their actual activities in the colon. These activities were distinctly altered; particularly, β-glucosidase activity in rats fed PD increased and all of the enzyme activities assayed in rats fed Kes and Nys were significantly decreased. These results suggest that the actual enzyme activities of intestinal bacteria should be assayed not at their optimal pHs, but at intestinal pHs. The effects of ten oligo- and polysaccharides on the intestinal environment are discussed in connection with the reduction in the incidence of colon cancer by daily intake of the saccharide.

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