New prebiotic blend of polydextrose and galacto-oligosaccharides has a bifidogenic effect in young infants.

OBJECTIVE: The aim of the study was to evaluate the effect of infant formula with polydextrose (PDX) and galacto-oligosaccharides (GOS) on fecal microbiota and secretory IgA (sIgA). MATERIALS AND METHODS: In the present double-blind, randomized study, term infants received control (Enfamil Lipil) or the same formula with PDX/GOS (4 g/L, 1:1 ratio; PDX/GOS) for 60 days; a reference breast-fed group was included. Formula intake, tolerance, and stool characteristics were collected via electronic diary and analyzed by repeated measures analysis of variance. Anthropometric measurements and stool samples were obtained at baseline and after 30 and 60 days of feeding. Fecal sIgA was measured by enzyme-linked immunosorbent assay and fecal bacteria by fluorescent in situ hybridization and quantitative real-time polymerase chain reaction (qPCR); both were analyzed by Wilcoxon rank sum test. RESULTS: Two hundred thirty infants completed the study. Infants consuming PDX/GOS had softer stools than control at all times (P < 0.001). Using qPCR, counts in PDX/GOS were closer to the breast-fed group, tended to be higher than control for total bifidobacteria (P = 0.069) and Bifidobacterium longum (P = 0.057) at 30 days, and were significantly higher for total bifidobacteria and B longum at 60 days and B infantis at 30 days (P = 0.002). No significant differences were detected between PDX/GOS and control in changes from baseline to 30 or 60 days for sIgA or total bifidobacteria by fluorescent in situ hybridization or qPCR; however, significantly higher changes from baseline were detected between PDX/GOS and control for B infantis at 30 days and B longum at 60 days (P ≤ 0.035). CONCLUSIONS: Infant formula with PDX/GOS produces soft stools and a bifidogenic effect closer to breast milk than formula without PDX/GOS.

Polydextrose enrichment of infant formula demonstrates prebiotic characteristics by altering intestinal microbiota, organic acid concentrations, and cytokine expression in suckling piglets.

Oligosaccharides, the 3rd-most abundant component in human milk, are virtually absent from infant formulas and from the cow milk on which most are based. In breast-fed infants, human milk oligosaccharides (HMO) act as both receptor analogs, interfering with pathogen adhesion, and as prebiotics, stimulating the growth of certain commensal bacteria (e.g. bifidobacteria) and supporting the innate immunity. To further align the functional properties of infant formula with those of human milk, polydextrose (PDX) is proposed as a substitute for HMO. To determine the prebiotic functionality of PDX, 1-d-old pigs were fed a cow milk-based formula supplemented with increasing concentrations of PDX (0, 1.7, 4.3, 8.5, or 17 g/L) for 18 d (n = 13). Additional reference groups included pigs sampled at d 0 and sow-reared pigs sampled at d 18 (n = 12). Ileal Lactobacilli CFU, but not Bifidobacteria, increased linearly with increasing PDX (P = 0.02). The propionic acid concentration in digesta linearly increased with the PDX level (P = 0.045) and lactic acid increased linearly by 5-fold with increasing PDX (P = 0.001). Accordingly, digesta pH decreased linearly (P < 0.05) as PDX increased, with a maximal reduction approaching 0.5 pH units in pigs fed 17 g/L. Expression of TNFα, IL-1ß, and IL-8 showed a negative quadratic pattern in response to PDX supplementation, declining at intermediate concentrations and rebounding at higher concentrations of PDX. In summary, PDX enrichment of infant formula resulted in a prebiotic effect by increasing ileal lactobacilli and propionic and lactic acid concentrations and decreasing pH with associated alterations in ileal cytokine expression.

Addition of polydextrose and galactooligosaccharide to formula does not affect bacterial translocation in the neonatal piglet.

OBJECTIVES: The aim of the study was to determine the effect of polydextrose (PDX) and galactooligosaccharide (GOS) on bacterial translocation (BT) in neonatal piglets. MATERIALS AND METHODS: Piglets (n = 36) were randomized 12 hours after birth to receive total enteral nutrition (TEN) as formula; TEN + GOS (4 g/L), TEN + PDX (4 g/L), or TEN + GOS + PDX (2 g/L each) for 7 days or were supported by total parenteral nutrition (TPN) as a positive control for BT (n = 8). Blood, spleen, liver, and mesenteric lymph node (MLN) samples were cultured for aerobic and anaerobic bacteria. Colon microbiota 16S rDNA was measured by polymerase chain reaction. Myeloperoxidase activity and tumor necrosis factor-α expression were measured in ileum and ascending colon. RESULTS: Among the enterally fed groups, no difference was seen in the Lactobacillus and Bacteroides 16S rDNA copies per gram of colonic contents, yet total bacterial levels were lower (P < 0.05) in the TEN + GOS group compared with TEN alone. Bacteria were detected in the blood, liver spleen, and MLN of TPN piglets. In contrast, bacterial counts were predominantly detected in the MLN of TEN piglets, at much lower levels than in TPN, and levels were not affected by GOS and PDX addition. TPN piglets had elevated (P < 0.05) ileal myeloperoxidase activity and a trend in elevated ascending colon tumor necrosis factor-α expression (P = 0.1). CONCLUSIONS: PDX and GOS added to formula do not induce BT in healthy piglets. Low levels of bacteria in MLN of healthy neonatal piglets may reflect mucosal sampling rather than pathological BT.

Molecular ecological analysis of fecal bacterial populations from term infants fed formula supplemented with selected blends of prebiotics.

Supplementation of infant formulas with prebiotic ingredients continues the effort to mimic functional properties of human milk. In this double-blind, controlled, 28-day study, healthy term infants received control formula (control group; n = 25) or control formula supplemented with polydextrose (PDX) and galactooligosaccharide (GOS) (4 g/liter) (PG4 group; n = 27) or with PDX, GOS, and lactulose (LOS) (either 4 g/liter [PGL4 group; n = 27] or 8 g/liter [PGL8 group; n = 25]). A parallel breast-fed group (BF group) (n = 30) was included. Stool characteristics, formula tolerance, and adverse events were monitored. Fecal bacterial subpopulations were evaluated by culture-based selective enumeration (Enterobacteriaceae), quantitative real-time PCR (Clostridium clusters I, XI, and XIV, Lactobacillus, and Bifidobacterium), and fluorescence in situ hybridization (FISH) (Bifidobacterium). Fecal bacterial community profiles were examined by using 16S rRNA gene PCR-denaturing gradient gel electrophoresis. The daily stool consistency was significantly softer or looser in the BF group than in all of the groups that received formula. The formulas were well tolerated, and the incidences of adverse events did not differ among feeding groups. Few significant changes in bacterial subpopulations were observed at any time point. The bacterial communities were stable; individual profiles tended to cluster by subject rather than by group. Post hoc analysis, however, demonstrated that the bacterial community profiles for subjects in the BF, PG4, PGL4, and PGL8 groups that first received formula at a younger age were less stable than the profiles for subjects in the same groups that received formula at an older age, but there was no difference for the control group. These data indicate that formulas containing PDX, GOS, and LOS blends are more likely to influence gut microbes when administration is begun in early infancy and justify further investigation of the age-related effects of these blends on fecal microbiota.

Development and evaluation of a reflective solar disinfection pouch for treatment of drinking water.

A second-generation solar disinfection (SODIS) system (pouch) was constructed from food-grade, commercially available packaging materials selected to fully transmit and amplify the antimicrobial properties of sunlight. Depending upon the season, water source, and challenge organism, culturable bacteria were reduced between 3.5 and 5.5 log cycles. The system was also capable of reducing the background presumptive coliform population in nonsterile river water below the level of detection. Similar experiments conducted with a model virus, the F-specific RNA bacteriophage MS2, indicated that the pouch was slightly less efficient, reducing viable plaques by 3.5 log units in comparison to a 5.0 log reduction of enterotoxigenic Escherichia coli O18:H11 within the same time period. These results suggest that water of poor microbiological quality can be improved by using a freely available resource (sunlight) and a specifically designed plastic pouch constructed of food-grade packaging materials.

Identification and characterization of novel surface proteins in Lactobacillus johnsonii and Lactobacillus gasseri.

We have identified and sequenced the genes encoding the aggregation-promoting factor (APF) protein from six different strains of Lactobacillus johnsonii and Lactobacillus gasseri. Both species harbor two apf genes, apf1 and apf2, which are in the same orientation and encode proteins of 257 to 326 amino acids. Multiple alignments of the deduced amino acid sequences of these apf genes demonstrate a very strong sequence conservation of all of the genes with the exception of their central regions. Northern blot analysis showed that both genes are transcribed, reaching their maximum expression during the exponential phase. Primer extension analysis revealed that apf1 and apf2 harbor a putative promoter sequence that is conserved in all of the genes. Western blot analysis of the LiCl cell extracts showed that APF proteins are located on the cell surface. Intact cells of L. johnsonii revealed the typical cell wall architecture of S-layer-carrying gram-positive eubacteria, which could be selectively removed with LiCl treatment. In addition, the amino acid composition, physical properties, and genetic organization were found to be quite similar to those of S-layer proteins. These results suggest that APF is a novel surface protein of the Lactobacillus acidophilus B-homology group which might belong to an S-layer-like family.