Gaining insight into microbial physiology in the large intestine: a special role for stable isotopes.

The importance of the human large intestine for nutrition, health, and disease, is becoming increasingly realized. There are numerous indications of a distinct role for the gut in such important issues as immune disorders and obesity-linked diseases. Research on this long-neglected organ, which is colonized by a myriad of bacteria, is a rapidly growing field that is currently providing fascinating new insights into the processes going on in the colon, and their relevance for the human host.

High-fat diet, muscular lipotoxicity and insulin resistance.

A high dietary fat intake and low physical activity characterize the current Western lifestyle. Dietary fatty acids do not stimulate their own oxidation and a surplus of fat is stored in white adipose tissue, liver, heart and muscle. In these organs intracellular lipids serve as a rapidly-available energy source during, for example, physical activity.

Spatial and temporal expression of Lactobacillus plantarum genes in the gastrointestinal tracts of mice.

Lactobacillus plantarum is a common inhabitant of mammalian gastrointestinal tracts, and L. plantarum strain WCFS1 is a human isolate with a known genome sequence. L.

Expression of Aspergillus hemoglobin domain activities in Aspergillus oryzae grown on solid substrates improves growth rate and enzyme production.

DNA fragments coding for hemoglobin domains (HBD) were isolated from Aspergillus oryzae and Aspergillus niger. The HBD activities were expressed in A. oryzae by introduction of HBD gene fragments under the control of the promoter of the constitutively expressed gpdA gene.

Towards understanding molecular modes of probiotic action.

The possibility that certain microorganisms might be beneficial to human health is highlighted by the numerous consumer products containing probiotic bacteria. Probiotics are typically administered in food that, following entry into the gastro-intestinal tract, results in measurable health-promoting effects. Although there is a growing list of health benefits provided by the consumption of probiotics, their precise mechanisms of action remain largely unknown.

Beyond diversity: functional microbiomics of the human colon.

Molecular tools have revealed wide microbial diversity in the human alimentary tract. Most intestinal microorganisms have not been cultured and the in situ functions of distinct groups of the intestinal microbiota are largely unknown but pivotal to understanding the role of these microorganisms in health and disease. Promising strategies to gain more insight into the functionality of the complex microbial communities in the human alimentary tract, including fermentation processes in the colon, are discussed.

Dietary fructooligosaccharides affect intestinal barrier function in healthy men.

In contrast to most expectations, we showed previously that dietary fructooligosaccharides (FOS) stimulate intestinal colonization and translocation of invasive Salmonella enteritidis in rats. Even before infection, FOS increased the cytotoxicity of fecal water, mucin excretion, and intestinal permeability. In the present study, we tested whether FOS has these effects in humans.

Influence of glutamate on growth, sporulation, and spore properties of Bacillus cereus ATCC 14579 in defined medium.

A chemically defined medium in combination with an airlift fermentor system was used to study the growth and sporulation of Bacillus cereus ATCC 14579. The medium contained six amino acids and lactate as the main carbon sources. The amino acids were depleted during exponential growth, while lactate was metabolized mainly during stationary phase.

Dietary fructooligosaccharides increase intestinal permeability in rats.

We showed previously that fructooligosaccharides (FOS) decrease the resistance to salmonella infection in rats. However, the mechanism responsible for this effect is unclear. Therefore, we examined whether dietary FOS affects intestinal permeability before and after infection with Salmonella enterica serovar Enteritidis.

Scaling behavior of delayed demixing, rheology, and microstructure of emulsions flocculated by depletion and bridging.

This paper describes an experimental comparison of microstructure, rheology, and demixing of bridging- and depletion-flocculated oil-in-water emulsions. Confocal scanning laser microscopy imaging showed that bridging-flocculated emulsions were heterogeneous over larger length scales than depletion-flocculated emulsions. As a consequence, G' as determined from diffusing wave spectroscopy (DWS) corresponded well with G' as measured macroscopically for the depletion-flocculated emulsions, but this correspondence was not found for the bridging-flocculated emulsions.

Genome data mining of lactic acid bacteria: the impact of bioinformatics.

Lactic acid bacteria (LAB) have been widely used in food fermentations and, more recently, as probiotics in health-promoting food products. Genome sequencing and functional genomics studies of a variety of LAB are now rapidly providing insights into their diversity and evolution and revealing the molecular basis for important traits such as flavor formation, sugar metabolism, stress response, adaptation and interactions. Bioinformatics plays a key role in handling, integrating and analyzing the flood of 'omics' data being generated.

Post-genomics of lactic acid bacteria and other food-grade bacteria to discover gut functionality.

Recent years have seen an explosion in the number of complete or almost complete genomic sequences of lactic acid bacteria and other food-grade bacteria that are used in functional foods to increase the health of the consumer. These have been instrumental in the development of functional, comparative and other post-genomics approaches that provide the possibility to detect, unravel and understand their functionality in the human intestinal tract. In conjunction with other high-throughput approaches, these advances can be exploited in the functional food innovation cycle for developing new or designed probiotic and other bacterial products that impact gut health.

Engineering metabolic highways in Lactococci and other lactic acid bacteria.

Lactic acid bacteria (LAB) are widely used in industrial food fermentations and are receiving increased attention for use as cell factories for the production of food and pharmaceutical products. Glycolytic conversion of sugars into lactic acid is the main metabolic highway in these Gram-positive bacteria and Lactococcus lactis has become the model organism because of its small genome, genetic accessibility and simple metabolism. Here we discuss the metabolic engineering of L.

Diarrhea caused by enterotoxigenic Escherichia coli infection of humans is inhibited by dietary calcium.

Background & Aims: In several rat infection experiments, we have shown that dietary calcium inhibits intestinal colonization and translocation of invasive salmonella. The aim of the present study was to find out whether calcium is also protective against enterotoxigenic Escherichia coli (ETEC) infection. This was first tested in our rat model and subsequently verified in a human infection study.

Dietary fructo-oligosaccharides dose-dependently increase translocation of salmonella in rats.

Prebiotics, such as fructo-oligosaccharides (FOS), stimulate the protective gut microflora, resulting in an increased production of organic acids. This may result in increased luminal killing of acid-sensitive pathogens. However, host defense against invasive pathogens, like salmonella, also depends on the barrier function of the intestinal mucosa.

The effect of oral temperature on the temperature perception of liquids and semisolids in the mouth.

This work examined the influence of oral temperature on oral perception of temperature in liquids and semisolids. A panel of 20 adults assessed the temperature of water, custard dessert and mayonnaise. Oral temperatures were manipulated by 5-s mouth rinses of 10, 35 and 55 degrees C performed prior to assessments, which resulted in oral temperatures of 27, 35 and 43 degrees C, respectively.

Hyperhomocysteinemia and risk of vascular disease in women.

Plasma levels of total homocysteine (tHcy), a possible risk factor for vascular disease, are generally lower in women than in men and lower in premenopausal women than in postmenopausal women. This article reviews studies that have investigated associations of hyperhomocysteinemia with risk of vascular disease among women or that compared risk by stratum of gender or menopausal status. Seven out of 12 epidemiological studies that included both men and women found hyperhomocysteinemia to be a stronger risk factor in women than in men.

Pyruvate flux distribution in NADH-oxidase-overproducing Lactococcus lactis strain as a function of culture conditions.

The influence of growth conditions on product formation from glucose by Lactococcus lactis strain NZ9800 engineered for NADH-oxidase overproduction was examined. In aerobic batch cultures, a large production of acetoin and diacetyl was found at acidic pH under pH-unregulated conditions. However, pyruvate flux was mainly driven towards lactate production when these cells were grown under strictly pH-controlled conditions.