Lactose/Sucrose/D-Glucose Assay Kit

Background: Prebiotic dietary fibers change the intestinal microbiome favorably and provide a health benefit to the host. Objectives: Polylactose is a novel fiber, synthesized by extrusion of lactose. We evaluated its prebiotic activity by determining its fermentability, effect on the microbiota, and effects on adiposity and liver lipids in a diet-induced obesity animal model. Methods: Male Wistar rats (4-5 wk old) were fed normal-fat (NF, 25% fat energy) or high-fat (HF, 51% fat energy) diets containing different fibers (6% fiber of interest and 3% cellulose, by weight), including cellulose (NFC and HFC, negative and positive controls, respectively), polylactose (HFPL), lactose matched to residual lactose in the HFPL diet, and 2 established prebiotic fibers: polydextrose (HFPD) and fructooligosaccharide (HFFOS). After 10 wk of feeding, organs were harvested and cecal contents collected. Results: HFPL animals had greater cecum weight (3 times greater than HFC) and lower cecal pH (∼1 pH unit lower than HFC) than all other groups, suggesting that polylactose is more fermentable than other prebiotic fibers (HFPD, HFFOS; P < 0.05). HFPL animals also had increased taxonomic abundance of the probiotic species Bifidobacterium in the cecum relative to all other groups (P < 0.05). Epididymal fat pad weight was significantly decreased in the HFPL group (29% decrease compared with HFC) compared with all other HF groups (P < 0.05) and did not differ from the NFC group. Liver lipids and cholesterol were reduced in HFPL animals when compared with HFC animals (P < 0.05). Conclusions: Polylactose is a fermentable fiber that elicits a beneficial change in the gut microbiota as well as reducing adiposity in rats fed HF diets. These effects of polylactose were greater than those of 2 established prebiotics, fructooligosaccharide and polydextrose, suggesting that polylactose is a potent prebiotic.

In this study, a food-grade cell surface display host/vector system for Lactobacillus casei was constructed. The food-grade host L. casei Q-5 was a lactose-deficient derivative of L. casei ATCC 334 obtained by plasmid elimination. The food-grade cell surface display vector was constructed based on safe DNA elements from lactic acid bacteria containing the following: pSH71 replicon from Lactococcus lactis, lactose metabolism genes from L. casei ATCC 334 as complementation markers, and surface layer protein gene from Lactobacillus acidophilus ATCC 4356 for cell surface display. The feasibility of the new host/vector system was verified by the expression of green fluorescent protein (GFP) on L. casei. Laser scanning confocal microscopy and immunofluorescence analysis using anti-GFP antibody confirmed that GFP was anchored on the surface of the recombinant cells. The stability of recombinant L. casei cells in artificial gastrointestinal conditions was verified, which is beneficial for oral vaccination applications. These results indicate that the food-grade host/vector system can be an excellent antigen delivery vehicle in oral vaccine construction.

Soluble dietary fiber is a growing food ingredient market. Twin-screw extrusion of lactose with an acid catalyst has been reported as a way to polymerize lactose to oligomers which are indigestible and analyze as dietary fiber. Lactose was dry blended with citric acid at two different concentrations, 1 and 2%. Glucose was added to raw mixes at 0, 10, or 20% (w/w). Samples with 2% citric acid yielded a higher concentration of indigestible oligosaccharides (52.3–59.8%, w/w) than 1% citric acid samples (37.1–49.9%). Glucose did not affect the yield. Glucose addition was beneficial and reduced the motor torque and specific mechanical energy of the extruder, and extruded products were lighter in color. The generated oligomers had a degree of polymerization that ranged from 3 to 5, as determined by mass spectrometry. Testing if the oligomers confer a beneficial effect (to be classified as dietary fiber), is still required.