Consumption of antimicrobial manuka honey does not significantly perturb the microbiota in the hind gut of mice.

The aim of this study was to test the hypothesis that consuming manuka honey, which contains antimicrobial methylglyoxal, may affect the gut microbiota. We undertook a mouse feeding study to investigate whether dietary manuka honey supplementation altered microbial numbers and their production of organic acid products from carbohydrate fermentation, which are markers of gut microbiota function. The caecum of C57BL/6 mice fed a diet supplemented with antimicrobial UMF® 20+ manuka honey at 2.2 g/kg animal did not show any significantly changed concentrations of microbial short chain fatty acids as measured by gas chromatography, except for increased formate and lowered succinate organic acid concentrations, compared to mice fed a control diet. There was no change in succinate-producing Bacteroidetes numbers, or honey-utilising Bifidobacteria, nor any other microbes measured by real time quantitative PCR. These results suggest that, despite the antimicrobial activity of the original honey, consumption of manuka honey only mildly affects substrate metabolism by the gut microbiota.

The effect of cell immobilization on the antibacterial activity of Lactobacillus reuteri DPC16 cells during passage through a simulated gastrointestinal tract system.

Cell immobilization has the ability to influence the survival and functional characteristics of probiotic bacterial strains in harsh environments. This study investigated the effect of cell immobilization and passage through a simulated gastrointestinal tract (GI) on the antibacterial activity of Lactobacillus reuteri DPC16. Antibacterial activity, reuterin production and diol dehydratase activity were assayed in recovered isolates of L. reuteri that had been immobilized in Ca alginate-skim milk, and incubated in simulated GI fluids. Among all the recovered isolates tested, any that had undergone immobilization followed by immediate recovery of the cells without subsequent incubation in any fluids demonstrated the highest reuterin production, antimicrobial activity and diol dehydratase enzyme activity. L. reuteri DPC16 cells that had been immobilized, incubated in simulated GI fluids, and subsequently recovered from the beads often showed some loss of antimicrobial activity compared to the immobilized cells. The data confirm that the process of immobilization of L. reuteri in Ca alginate-skim milk, rather than the passage through simulated GI fluids, resulted in enhanced antibacterial activity. This is attributed to increased diol dehydratase activity, resulting in increased reuterin production.

Functional properties of free and encapsulated Lactobacillus reuteri DPC16 during and after passage through a simulated gastrointestinal tract.

Lactobacillus reuteri DPC16 is a probiotic bacterium that has strong antimicrobial activities on pathogens, mainly due to its ability to produce reuterin, an antimicrobial compound. The objective of this study was to examine the ability of an encapsulation technique to protect the functional properties of cells of L. reuteri DPC16 during passage through a simulated GI tract. The functional properties of the cells were studied before and after passage through the tract. An alginate-skim milk encapsulation system was used to deliver the probiotic bacterium through the simulated GI tract, allowing for the release of the cells into the simulated colonic fluid. The cells were then isolated and cultured. The recovered cells showed no diminution in functional properties, including their growth kinetics, ability to adhere to epithelial cells and ability to inhibit the adhesion of E. coli to epithelial cells. The bacteriostatic and bactericidal properties of the recovered cells against some pathogens were significantly greater (P < 0.05) than those of the original cells. Production of reuterin by the recovered cells was significantly greater than that of the original cells when cultured in MRS medium in the absence of its metabolic precursor, glycerol. The results demonstrate significant consequences for the application of the encapsulation technique to protect and/or enhance the functional properties of the probiotic cells.

Influence of bovine lactoferrin on selected probiotic bacteria and intestinal pathogens.

This study investigated the effects of bovine lactoferrin (BLf) on the growth of different groups of bacteria in vitro. BLf showed a significant inhibitory effect on the growth of selected pathogens but not probiotics. BLf, in combination with probiotics, has the potential to influence the composition of the gut microflora via inhibition of intestinal pathogens with no significant effect on probiotic bacteria.

Evaluation of the cytoprotective effects of bovine lactoferrin against intestinal toxins using cellular model systems.

Lactoferrin is an iron-binding glycoprotein that exhibits a range of health benefits including immune regulation and disease prevention derived from its structural properties. The present study employed immune cell models and a colon epithelial cell model to investigate the protective effects of bovine lactoferrin (BLf) on both immune cells and colon epithelium cells. BLf caused significant reduction of faecal genotoxin-induced DNA damage in HT29 cells, and down-regulation of lipopolysaccharide (LPS)-induced macrophage cell stress and endotoxic response, in an infection status.

The impact of performing spirometry on shunting across a patent foramen ovale.

Transient changes in intrathoracic pressure can alter left and right intra-atrial pressures, and may provoke shunting of blood across a patent foramen ovale (PFO). Spirometry causes a transient rise and subsequent fall in intrathoracic pressure that, if performed following a dive on compressed air, could raise the risk of decompression illness by arterialisation of venous bubbles across a PFO. To assess whether spirometry can provoke right-to-left shunting across a patent foramen ovale, a subject with a known PFO, previously identified by bubble contrast transthoracic echocardiography, where shunting was only evident on performing a Valsalva manoeuvre, underwent re-examination whilst performing spirometry. Right-to-left shunting was not evident at rest, but was provoked by performing spirometry. If spirometry is to be performed within two hours of surfacing, this should be regarded as a potential risk for decompression illness.

Biofilm reactors for industrial bioconversion processes: employing potential of enhanced reaction rates.

This article describes the use of biofilm reactors for the production of various chemicals by fermentation and wastewater treatment. Biofilm formation is a natural process where microbial cells attach to the support (adsorbent) or form flocs/aggregates (also called granules) without use of chemicals and form thick layers of cells known as "biofilms." As a result of biofilm formation, cell densities in the reactor increase and cell concentrations as high as 74 gL(-1) can be achieved. The reactor configurations can be as simple as a batch reactor, continuous stirred tank reactor (CSTR), packed bed reactor (PBR), fluidized bed reactor (FBR), airlift reactor (ALR), upflow anaerobic sludge blanket (UASB) reactor, or any other suitable configuration. In UASB granular biofilm particles are used. This article demonstrates that reactor productivities in these reactors have been superior to any other reactor types. This article describes production of ethanol, butanol, lactic acid, acetic acid/vinegar, succinic acid, and fumaric acid in addition to wastewater treatment in the biofilm reactors. As the title suggests, biofilm reactors have high potential to be employed in biotechnology/bioconversion industry for viable economic reasons. In this article, various reactor types have been compared for the above bioconversion processes.

Exopolysaccharide and extracellular metabolite production by Lactobacillus delbrueckii subsp. bulgaricus, grown on lactose in continuous culture.

Lactobacillus delbrueckii subsp. bulgaricus NCFB 2483, when grown on lactose in continuous culture, showed increasing specific yields and volumetric productivities of exopolysaccharide (EPS) with increasing dilution rate. Specific and volumetric productivities of lactate and galactose, as extracellular metabolites, increased in response to the incremental changes in the dilution rate up to 0.4 h(-1). Elevated Y(p/s) values determined for EPS (0.025 g EPS x g lactose(-1)) at the dilution rates of 0.3 h(-1)-0.4 h(-1), relative to those determined at lower dilution rates, suggest a diversion of carbon flux towards EPS being associated with the higher rates of growth.

Exopolysaccharides from lactic acid bacteria: perspectives and challenges.

Some lactic acid bacteria (LAB) secrete a polysaccharide polymer. This extracellular polysaccharide, or "exopolysaccharide" (EPS), is economically important because it can impart functional effects to foods and confer beneficial health effects. LAB have a "Generally Recognized As Safe" (GRAS) classification and are likely candidates for the production of functional EPSs. Current challenges are to improve the productivity of EPSs from LAB and to produce EPSs of a structure and size that impart the desired functionality. The engineering of improvements in these properties will depend on a deep understanding of the EPS biosynthetic metabolism and of how the structure of EPSs relates to a functional effect when incorporated into a food matrix.