Pyroelectric Effect Enables Simple and Rapid Evaluation of Biofilm Formation.

Biofilms are detrimental to human life and industrial processes due to potential infections, contaminations, and deterioration. Therefore, the evaluation of microbial capability to form biofilms is of fundamental importance for assessing how different environmental factors may affect their vitality. Nowadays, the approaches used for biofilm evaluation are still poor in reliability and rapidity and often provide contradictory results. Here, we present what we call biofilm electrostatic test (BET) as a simple, rapid, and highly reproducible tool for evaluating in vitro the ability of bacteria to form biofilms through electrostatic interaction with a pyroelectrified carrier. The results show how the BET is able to produce viable biofilms with a density 6-fold higher than that on the control, after just 2 h incubation. The BET could pave the way to a rapid standardization of the evaluation of bacterial resistance among biofilm-producing microorganisms. In fact, due to its simplicity and cost-effectiveness, it is well suited for a rapid and easy implementation in a microbiology laboratory.

Antibacterial and antioxidant properties of grape stem extract applied as disinfectant in fresh leafy vegetables.

In the present study total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity and antimicrobial properties of grape (Vitis vinifera var. Red Globe) stem extract is reported. Also, the identification of main phenolic compounds was carried out by UPLC-PAD analysis. TPC and TFC of extract were 37.25 g GAE kg-1 and 98.07 g QE kg-1, respectively. Extract showed an antioxidant capacity of 132.60 and 317 g TE kg-1 for DPPH and ABTS radical scavenging capacity, respectively. The main phenolic compounds identified were rutin, gallic acid, chlorogenic acid, caffeic acid, catechin and ferulic acid. Extract inhibited the growth of Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica subsp. enterica serovar Typhimurium, and Escherichia coli O157: H7 at MIC range 16-18 g L-1. Extract affected the different phases of bacterial growth. In addition, application of Extract (25 g L-1) as a sanitizer was effective to reduce the populations of all bacteria inoculated in lettuce (0.859-1.884 log reduction) and spinach (0.843-2.605 log reduction). This study emphasizes the potential of grape processing byproducts as an emergent and attractive source of bioactive compounds with antioxidant properties and antimicrobial activity against important foodborne pathogens. The study demonstrated that stem extract could be used to control the presence of human pathogenic bacteria in fresh leafy vegetables.

Effects of different dairy products on postprandial lipemia.

BACKGROUND AND AIM: To evaluate the effects on postprandial lipemia (PPL), of three fat rich meals, with similar composition but different physical structure (liquid, semisolid and solid). METHODS AND RESULTS: Eight type 2 diabetic patients of both genders (6M/2F), age 51+/-9 yrs (M+/-SD), BMI 29+/-3 kg/m2, with fasting plasma glucose levels 145+/-24 mg/dL, cholesterol 200+/-38 mg/dL and triglyceride 110+/-45 mg/dL. Participants consumed in the morning, after a 12-hour fast and at 1-week intervals, three test meals with similar volume and composition [protein 36 g, lipid 30 g, carbohydrate 115 g, energy 3556 kJ (850 Kcal)] but with the main source of fat represented by foods with different physical structure (milk, mozzarella-cheese, butter). Each patient underwent gastric emptying measurements by echography; plasma FFA, triglycerides, glucose and insulin were evaluated at baseline and every hour for six hours after each meal. Fasting plasma glucose, cholesterol and triglyceride concentrations were similar at the baseline of the three test meals. Average increases in postprandial plasma triglyceride levels after butter (88+/-8 mg/dL) and mozzarella-cheese (104+/-56 mg/dL) were not different than after milk (98+/-53 mg/dL). The plasma triglyceride peak was also similar after the three test meals but peak time after butter (315+/-42 min; p<0.01) and mozzarella-cheese (277+/-31 min; p<0.02) was significantly delayed compared to milk (225+/-28 min). Gastric emptying rate was similar after butter and milk (14+/-2, 13+/-6 mL/h) and significantly faster after mozzarella-cheese (18+/-5 mL/h; p<0.03). CONCLUSIONS: While the physical structure of fat-rich foods has no major effect on postprandial plasma triglyceride concentrations, it is able to influence the timing of triglyceride peak; gastric emptying time does not play a major role in modulating the postprandial response of triglycerides and glucose.

Antioxidant effect of red wine anthocyanins in normal and catalase-inactive human erythrocytes.

Previous studies reported that aged red wine, but not novel red wine or white wine protects human red blood cells from oxidative damage induced in vitro by H(2)O(2.) Here, we demonstrate that the beneficial properties of aged red wine are due, at least in part, to the presence of anthocyanins. We firstly measured the "antioxidant power" of an Italian red wine (Taurasi, Avellino) and that of its anthocyanin fractions by using Ferric Reducing Antioxidant Power Assay. Subsequently, we demonstrate that fractions containing anthocyanins lower ROS (reactive oxygen species) and methemoglobin production in human erythrocytes treated with H(2)O(2.) Finally, we reported that the protective effects of anthocyanins were also confirmed in an experimental model in which RBCs were deprived of catalase activity by treatment with 4 mM sodium azide. The results obtained clearly demonstrate that red wine anthocyanins protect human RBCs from oxidative stress.

A thermophilic alcohol dehydrogenase from Bacillus acidocaldarius not reactive towards ketones.

An NAD-dependent alcohol-aldehyde oxidoreductase was purified to homogeneity and characterized from cell extracts of the thermophilic microorganism Bacillus acidocaldarius. The 500-fold purified homogeneous enzyme had a molecular mass of 154 kDa, as shown by gel filtration and glycerol gradient centrifugation. On sodium dodecyl sulfate polyacrylamide gel electrophoresis the protein showed one band of 38 kDa, indicating that the enzyme is a tetramer composed of subunits of identical molecular weight. Ethanol was the best substrate with the highest kcat/Km values, and the enzyme showed a substrate specificity that included linear, secondary and cyclic alcohols, as well as anisaldehyde, but it was not active on ketones. The protein contains eight zinc atoms per tetramer, four of which are removed by chelating agents with a concomitant loss of thermal stability. Circular dichroism spectra and determination of the NH2-terminal sequence allowed structural and homology comparison with other alcohol dehydrogenases from animal and bacterial sources.

Identification of a high-molecular-weight cadmium-binding protein in copper-resistant Bacillus acidocaldarius cells.

Bacillus acidocaldarius grown in the presence of Cu++ was capable of accumulating the metal in the form of a protease-sensitive high molecular weight (HMW) moiety whose formation was inhibited by actinomycin D. Only cells preadapted in Cu++ were able to grow in a Cd(++)-containing medium. A cell-free extract from cadmium-stressed cells was fractionated by gel-permeation chromatography. The majority of cadmium was found associated with a HMW protein fraction which was further purified by anion exchange chromatography and high-performance liquid chromatography. The molecular weight of the purified protein was estimated to be 23,000 by SDS-PAGE. Amino acid analysis showed a low cysteine content and an abundance of aspartate and glutamate. It is likely that the cadmium-binding protein is an essential component of the mechanism mediating recovery from heavy metal toxicity.