Live-cell imaging tool optimization to study gene expression levels and dynamics in single cells of Bacillus cereus.

Single-cell methods are a powerful application in microbial research to study the molecular mechanism underlying phenotypic heterogeneity and cell-to-cell variability. Here, we describe the optimization and application of single-cell time-lapse fluorescence microscopy for the food spoilage bacterium Bacillus cereus specifically. This technique is useful to study cellular development and adaptation, gene expression, protein localization, protein mobility, and cell-to-cell communication over time at the single-cell level.

Substantial Differences between Organ and Muscle Specific Tracer Incorporation Rates in a Lactating Dairy Cow.

We aimed to produce intrinsically L-[1-(13)C]phenylalanine labeled milk and beef for subsequent use in human nutrition research. The collection of the various organ tissues after slaughter allowed for us to gain insight into the dynamics of tissue protein turnover in vivo in a lactating dairy cow. One lactating dairy cow received a constant infusion of L-[1-(13)C]phenylalanine (450 µmol/min) for 96 h.

Multifactorial diversity sustains microbial community stability.

Maintenance of a high degree of biodiversity in homogeneous environments is poorly understood. A complex cheese starter culture with a long history of use was characterized as a model system to study simple microbial communities. Eight distinct genetic lineages were identified, encompassing two species: Lactococcus lactis and Leuconostoc mesenteroides.

Ethanol metabolism and its effects on the intestinal epithelial barrier.

Ethanol is widely consumed and is associated with an increasing global health burden. Several reviews have addressed the effects of ethanol and its oxidative metabolite, acetaldehyde, on the gastrointestinal (GI) tract, focusing on carcinogenic effects or alcoholic liver disease. However, both the oxidative and the nonoxidative metabolites of ethanol can affect the epithelial barrier of the small and large intestines, thereby contributing to GI and liver diseases.

Virulence aspects of Listeria monocytogenes LO28 high pressure-resistant variants.

High pressure treatment is a novel food processing approach for reducing pathogens in foods and food ingredients. However, relatively little is known about the pathogenic potential of organisms that survive the treatment. Twelve previously isolated and characterized variants of Listeria monocytogenes LO28 obtained after a high pressure treatment were assessed for their virulence potential and antibiotic susceptibility.

Fatty acid ethyl esters induce intestinal epithelial barrier dysfunction via a reactive oxygen species-dependent mechanism in a three-dimensional cell culture model.

Background & Aims: Evidence is accumulating that ethanol and its oxidative metabolite, acetaldehyde, can disrupt intestinal epithelial integrity, an important factor contributing to ethanol-induced liver injury. However, ethanol can also be metabolized non-oxidatively generating phosphatidylethanol and fatty acid ethyl esters (FAEEs). This study aims to investigate the effects of FAEEs on barrier function, and to explore the role of oxidative stress as possible mechanism.

Sporulation environment of emetic toxin-producing Bacillus cereus strains determines spore size, heat resistance and germination capacity.

Aim: Heat resistance, germination and outgrowth capacity of Bacillus cereus spores in processed foods are major factors in causing the emetic type of gastrointestinal disease. In this study, we aim to identify the impact of different sporulation conditions on spore properties of emetic toxin-producing B. cereus strains.

Relatively high-protein or 'low-carb' energy-restricted diets for body weight loss and body weight maintenance?

Background: 'Low-carb' diets have been suggested to be effective in body weight (BW) management. However, these diets are relatively high in protein as well.

Objective: To unravel whether body-weight loss and weight-maintenance depends on the high-protein or the 'low-carb' component of the diet.

The journey of resveratrol from yeast to human.

The natural polyphenolic compound resveratrol was first discovered in the 1940s. In the recent years, this compound received renewed interest as several findings implicated resveratrol as a potent SIRT1 activator capable of mimicking the effects of calorie restriction, and regulating longevity in lower organisms. Given the worldwide increase in age-related metabolic diseases the beneficial effects of resveratrol on metabolism and healthy aging in humans are currently a topic of intense investigation.

Genome-wide transcriptional profiling of the cell envelope stress response and the role of LisRK and CesRK in Listeria monocytogenes.

The Gram-positive bacterium Listeria monocytogenes is widely distributed in the environment and capable of causing food-borne infections in susceptible individuals. In this study, we investigated the cell envelope stress response in L. monocytogenes.

Diversity in biofilm formation and production of curli fimbriae and cellulose of Salmonella Typhimurium strains of different origin in high and low nutrient medium.

The biofilm forming behavior of 51 Salmonella Typhimurium strains was determined in Tryptone Soya Broth (TSB) and 20 times diluted TSB (1/20TSB) at 25°C and 37°C. The results indicated that biofilm forming behavior is influenced by environmental conditions and associated with the origin of the strains. Clinical, outbreak-associated and retail product isolates showed dense biofilm formation in both media at 25°C, and in TSB also at 37°C.

Calorie restriction-like effects of 30 days of resveratrol supplementation on energy metabolism and metabolic profile in obese humans.

Resveratrol is a natural compound that affects energy metabolism and mitochondrial function and serves as a calorie restriction mimetic, at least in animal models of obesity. Here, we treated 11 healthy, obese men with placebo and 150 mg/day resveratrol (resVida) in a randomized double-blind crossover study for 30 days. Resveratrol significantly reduced sleeping and resting metabolic rate.

Leucine as a pharmaconutrient to prevent and treat sarcopenia and type 2 diabetes.

Amino acids function as precursors for de novo protein synthesis. In addition, however, they play a key role as nutritional signals that regulate multiple cellular processes. There is ample in vitro and in vivo evidence showing that muscle tissue responds to increases in amino acid availability via signal transduction pathways that are also regulated by insulin, glucagon, growth hormone, and insulin growth factor 1.

The production of intrinsically labeled milk and meat protein is feasible and provides functional tools for human nutrition research.

Administration of labeled, free amino acids does not allow direct assessment of in vivo dietary protein digestion and absorption kinetics. Consequently, dietary protein sources with labeled amino acids incorporated within their protein matrix are required. The aim of the present study was to produce intrinsically L-[1-(13)C]phenylalanine-labeled milk and meat protein that would permit in vivo assessment of postprandial protein digestion and absorption kinetics in humans.

Isolation of highly heat-resistant Listeria monocytogenes variants by use of a kinetic modeling-based sampling scheme.

Stable high-hydrostatic-pressure (HHP)-resistant Listeria monocytogenes LO28 variants were previously isolated and characterized. These HHP variants were also more resistant to heat. In addition, nonlinear heat inactivation kinetics pointed toward the existence of heat-resistant variants, although these could not be isolated so far.

Clostridial spore germination versus bacilli: genome mining and current insights.

Bacilli and clostridia share the characteristic of forming metabolically inactive endospores. Spores are highly resistant to adverse environmental conditions including heat, and their ubiquitous presence in nature makes them inevitable contaminants of foods and food ingredients. Spores can germinate under favourable conditions, and the following outgrowth can lead to food spoilage and foodborne illness.

Differential effects of saturated versus unsaturated dietary fatty acids on weight gain and myocellular lipid profiles in mice.

Objective: In conditions of continuous high-fat (HF) intake, the degree of saturation of the fatty acids (FAs) in the diet might have a crucial role in the onset of obesity and its metabolic complications. In particular, the FA composition of the diet might influence the storage form of lipids inside skeletal muscle. The aim of the present study was to examine whether the FA composition of HF diets differentially affects weight gain and accumulation of myocellular triacylglycerol (TAG) and diacylglycerol (DAG).

Mixed species biofilms of Listeria monocytogenes and Lactobacillus plantarum show enhanced resistance to benzalkonium chloride and peracetic acid.

We investigated the formation of single and mixed species biofilms of Listeria monocytogenes strains EGD-e and LR-991, with Lactobacillus plantarum WCFS1 as secondary species, and their resistance to the disinfectants benzalkonium chloride and peracetic acid. Modulation of growth, biofilm formation, and biofilm composition was achieved by addition of manganese sulfate and/or glucose to the BHI medium. Composition analyses of the mixed species biofilms using plate counts and fluorescence microscopy with dual fluorophores showed that mixed species biofilms were formed in BHI (total count, 8-9 log₁₀ cfu/well) and that they contained 1-2 log₁₀ cfu/well more L.

Changes in body fat percentage during body weight stable conditions of increased daily protein intake vs. control.

Objective: The objective of this study was to examine if increased protein intake vs. control influences body fat percentage during stable body weight.

Design: Body composition was assessed before and after a 3-month isoenergetic dietary intervention of 2MJ/d supplements exchanged with 2MJ/d of habitual ad libitum energy intake.

Protein intake induced an increase in exercise stimulated fat oxidation during stable body weight.

Background: Protein-rich weight-loss diets spare fat-free mass at the cost of fat mass. The objective was to examine if there is a change in stimulated fat oxidation related to protein intake during stable body weight.

Methods: Subjects' (BMI 22±2kg/m(2), age 25±8 years) maximal fat oxidation (Fat(max)) was assessed during a graded bicycle test, before and after a 3-month dietary-intervention of 2MJ/day supplements exchanged with 2MJ/d of habitual energy intake.

HrcA and DnaK are important for static and continuous-flow biofilm formation and disinfectant resistance in Listeria monocytogenes.

The food-borne pathogen Listeria monocytogenes is able to form biofilms in food processing environments. Since biofilms are generally difficult to eradicate during clean-up procedures, they pose a major risk for the food industry. Stress resistance mechanisms involved in L.

Comparative analysis of Bacillus weihenstephanensis KBAB4 spores obtained at different temperatures.

The impact of Bacillus weihenstephanensis KBAB4 sporulation temperature history was assessed on spore heat resistance, germination and outgrowth capacity at a temperature range from 7 to 30 degrees C. Sporulation rate and efficiency decreased at low temperature, as cells sporulated at 12, 20 and 30 degrees C with approximately 99% efficiency, whereas at 7 degrees C and 10 degrees C, a maximum 15% of sporulation was reached. Spores formed at 30 degrees C showed the highest wet heat resistance at 95 degrees C, with spores formed at 7 and 10 degrees C displaying only survival of 15min exposure at 70 degrees C, indicating their low level heat resistance.

Germinant receptor diversity and germination responses of four strains of the Bacillus cereus group.

Four strains of the Bacillus cereus group were compared for their germinant receptor composition and spore germination capacity. Phylogenetic analysis of the germinant receptor encoding operons of the enterotoxic strains B. cereus ATCC 14579 and ATCC 10987, the emetic strain AH187, and the psychrotolerant strain Bacillus weihenstephanensis KBAB4, indicated a core group of five germinant receptor operons to be present in the four strains, with each strain containing one to three additional receptors.

Dependence of continuous-flow biofilm formation by Listeria monocytogenes EGD-e on SOS response factor YneA.

Listeria monocytogenes was previously shown to form biofilms composed of a network of knitted chains under continuous-flow conditions. Here we show that the SOS response is activated under these conditions and that deletion of its regulon member yneA results in diminished biofilm formation under continuous-flow conditions.

The SOS response of Listeria monocytogenes is involved in stress resistance and mutagenesis.

The SOS response is a conserved pathway that is activated under certain stress conditions and is regulated by the repressor LexA and the activator RecA. The food-borne pathogen Listeria monocytogenes contains RecA and LexA homologues, but their roles in Listeria have not been established. In this study, we identified the SOS regulon in L.