Effect of controlled extracellular oxidation–reduction potential on microbial metabolism and proteolysis in buckwheat sourdough

The aim of this study was to keep constant the extracellular oxidation–reduction potential (ORP) and to observe the microbial activity changes in gluten-free (GF) sourdough fermentations with lactic acid bacteria (Weissella cibaria, Pediococcus pentosaceus and coculture of both microorganisms). ORP (E_h7) was held constant at ca. +350 and ?300 mV by gas sparging with air and N₂/H₂, respectively, to achieve oxidizing or reducing conditions during buckwheat sourdough fermentations. Microbial metabolism, free thiols, proteolysis and volatile compounds were monitored. Oxidizing conditions increased the acidification rate of W. cibaria and mixed culture (mix), which contains P. pentosaceus and W. cibaria. Reducing conditions exhibited a slow acidification rate and low microbial cell density upon fermentation. Oxidizing conditions changed lactic to acetic acid ratio of W. cibaria and mix culture from 7.9 ± 1.3 and 16.0 ± 0.6 (control conditions) to 0.5 ± 0.1 and 1.2 ± 0.2 (oxidizing conditions). A release of glucose and fructose was observed by W. cibaria and P. pentosaceus under oxidizing conditions. Free thiols content was increased by reducing conditions in fermentations with P. pentosaceus. Free amino nitrogen and free amino acid content were highly increased by reducing conditions in fermentations with W. cibaria. Free amino acid release was mainly influenced by low ORP and low pH values. Extracellular redox potential changes exhibited profile modifications of volatile compounds. Oxidizing conditions promoted a higher variety in volatile compounds as compared to the profile obtained under reducing conditions. It has been demonstrated that the extracellular ORP control has an influence on the microbial activity in buckwheat sourdoughs. Oxidizing and reducing conditions can influence the microbial activity differently and thus the final quality of GF sourdough. This is a new alternative approach for GF sourdough production and it could provide an improvement of raw materials, which can be used for GF bread production.     

5'-Nuclease PCR for quantitative event-specific detection of the genetically modified Mon810 MaisGard maize

Genetically modified maize is grown extensively in the world today. MaisGard (Monsanto, Yieldgard in the USA) is a genetically modified maize harbouring the Mon810 transformation event. European Community legislation requires that genetically modified organisms (GMOs) be approved before they are placed on the market. Labelling is required when more than 1% of any ingredient of a food originates from a GMO. There is consequently a need for specific, quantitative methods for detection of genetically modified foods. We have determined the DNA sequence of the 5'-flanking region of the Mon810 insert using ligation mediated PCR. A primer probe set overlapping the junction was designed and used in a quantitative, event-specific Taqman 5'-nuclease assay. Mon810 DNA was quantified relative to endogenous maize zein gene DNA. The results were expressed as the percentage of genetically modified Mon810 maize DNA relative to the total content of maize DNA.     

Flavonoid Analyses and Antimicrobial Activity of Various Parts of Phaleria macrocarpa (Scheff.) Boerl Fruit

Phaleria macrocarpa (Scheff.) Boerl (Thymelaceae) is commonly known as 'Crown of God', 'Mahkota Dewa', and 'Pau'. It originates from Papua Island, Indonesia and it grows in tropical areas. Empirically, it is potent in treating the hypertensive, diabetic, cancer and diuretic patients. It has a long history of ethnopharmacological usage, and the lack of information about its biological activities led us to investigate the possible biological activities by characterisation of flavonoids and antimicrobial activity of various part of P. macrocarpa against pathogenic bacteria and fungi. The results showed that kaempferol, myricetin, naringin, and rutin were the major flavonoids present in the pericarp while naringin and quercetin were found in the mesocarp and seed. Furthermore, the antibacterial activity of different parts of P. macrocarpa fruit showed a weak ability to moderate antibacterial activity against pathogenic tested bacteria (inhibition range: 0.93-2.17 cm) at concentration of 0.3 mg/disc. The anti fungi activity was only found in seed extract against Aspergillus niger (1.87 cm) at concentration of 0.3 mg/well. From the results obtained, P. macrocarpa fruit could be considered as a natural antimicrobial source due to the presence of flavonoid compounds.     

Simulated sunlight action spectra for inactivation of MS2 and PRD1 bacteriophages in clear water

Action spectra for simulated sunlight were measured in clear water for two viruses: PRD1, a double-stranded DNA bacteriophage, and MS2, a single-stranded RNA bacteriophage. Viruses were diluted into phosphate buffered saline (20 mM PBS, pH 7.5) and exposed for 22 h to simulated sunlight either directly or through one of six glass filters with 50% cutoff wavelengths ranging from 280 to 350 nm. Virus survival was measured using the double agar layer plaque method. Both UVA (320-400 nm) and UVB (280-320 nm) light were found to contribute to PRD1 inactivation, while only UVB inactivated MS2. A computational model was developed for interpreting these action spectra with 3-nm resolution. Using these methods, we provide detailed estimates of the sensitivity of MS2 and PRD1 to photoinactivation from 285 to 345 nm. The resulting sensitivity coefficients can be combined with solar spectra to estimate inactivation rates in clear water under different sunlight conditions. This approach will be useful for modeling the inactivation of viruses and other microorganisms in sunlit natural and engineered systems.     

Contribution of the NADH-oxidase (Nox) to the aerobic life of Lactobacillus sanfranciscensis DSM20451T

Lactobacillus sanfranciscensis is the key bacterium in traditional sourdough fermentation. The molecular background of its oxygen tolerance was investigated by comparison of wild type and NADH-oxidase (Nox) knock out mutants. The nox gene of L. sanfranciscensis DSM20451^T coding for a NADH-oxidase (Nox) was inactivated by single crossover integration to yield strain L. sanfranciscensis DSM20451Δnox. By inactivation of the native NADH-oxidase gene, it was ensured that besides fructose, O₂ can react as an electron acceptor. In aerated cultures the mutant strain was only able to grow in MRS media supplemented with fructose as electron acceptor, whereas the wild type strain showed a fructose independent growth response. The use of oxygen as an external electron acceptor enables L. sanfranciscensis to shift from acetyl-phosphate into the acetate branch and gain an additionally ATP, while the reduced cofactors were regenerated by Nox-activity. In aerated cultures the wild type strain formed a fermentation ratio of lactate to acetate of 1.09 in MRS supplemented with fructose after 24 h of fermentation, while the mutant strain formed a fermentation ratio of 3.05. Additionally, L. sanfranciscensis showed manganese-dependent growth response in aerated cultures, the final OD and growth velocity was increased in media supplemented with manganese. The expression of two predicted Mn²⁺/Fe²⁺ transporters MntH1 and MntH2 in L. sanfranciscensis DSM20451^T was verified by amplification of a 318 bp fragment of MntH1 and a 239 bp fragment of MntH2 from cDNA library obtained from aerobically, exponentially growing cells of L. sanfranciscensis DSM20451^T in MRS. Moreover, the mutant strain DSM20451Δnox was more sensitive to the superoxide generating agent paraquat and showed inhibition of growth on diamide-treated MRS-plates without fructose supplementation.     

Well shaped Mn₃O₄ nano-octahedra with anomalous magnetic behavior and enhanced photodecomposition properties

Very uniform and well shaped Mn₃O₄ nano‐octahedra are synthesized using a simple hydrothermal method under the help of polyethylene glycol (PEG200) as a reductant and shape‐directing agent. The nano‐octahedra formation mechanism is monitored. The shape and crystal orientation of the nanoparticles is reconstructed by scanning electron microscopy and electron tomography, which reveals that the nano‐octahedra only selectively expose {101} facets at the external surfaces. The magnetic testing demonstrates that the Mn₃O₄ nano‐octahedra exhibit anomalous magnetic properties: the Mn₃O₄ nano‐octahedra around 150 nm show a similar Curie temperature and blocking temperature to Mn₃O₄ nanoparticles with 10 nm size because of the vertical axis of [001] plane and the exposed {101} facets. With these Mn₃O₄ nano‐octahedra as a catalyst, the photodecomposition of rhodamine B is evaluated and it is found that the photodecomposition activity of Mn₃O₄ nano‐octahedra is much superior to that of commercial Mn₃O₄ powders. The anomalous magnetic properties and high superior photodecomposition activity of well shaped Mn₃O₄ nano‐octahedra should be related to the special shape of the nanoparticles and the abundantly exposed {101} facets at the external surfaces. Therefore, the shape preference can largely broaden the application of the Mn₃O₄ nano‐octahedra.     

Untersuchungen zur Enzymaktivität in keimreduzierten Industriegewürzen

A range of decontaminated spices of industrial use have been examinated for their enzymes (catalase, peroxidase, amylase, lipase activity). The genuine enzymes remain fully active in irradiated spices, whereas the microbial load is clearly reduced. In contrast steam treated spices no longer demonstrate enzyme activities. Steam treatment offers e.g. black pepper without lipase activity, which can no longer cause fat deterioration. Low microbial load in combination with clearly detectable enzyme activity in spices is an indication for irradiation, whereas, reduced microbial contamination combined with enzyme inactivation indicate steam treatment of raw material.     

Behavioral and physiological changes in Daphnia magna when exposed to nanoparticle suspensions (titanium dioxide, nano-C60, and C60HxC70Hx)

Little is known aboutthe impact manufactured nanoparticles will have on aquatic organisms. Previously, we demonstrated that toxicity differs with nanoparticle type and preparation and observed behavioral changes upon exposure to the more lethal nanoparticle suspensions. In this experiment, we quantified these behavioral and physiological responses of Daphnia magna at sublethal nanoparticle concentrations. Titanium dioxide (TiO2) and fullerenes (nano-C60) were chosen for their potential use in technology. Other studies suggest that addition of functional groups to particles can affect their toxicity to cell cultures, but it is unknown if the same is true at the whole organism level. Therefore, a fullerene derivative, C60HxC70Hx, was also used to examine how functional groups affect Daphnia response. Using a high-speed camera, we quantified several behavior and physiological parameters including hopping frequency, feeding appendage and postabdominal curling movement, and heart rate. Nano-C60 was the only suspension to cause a significant change in heart rate. Exposure to both nano-C60 and C60HxC70Hx suspensions caused hopping frequency and appendage movement to increase. These results are associated with increased risk of predation and reproductive decline. They indicate that certain nanoparticle types may have impacts on population and food web dynamics in aquatic systems.     

Case Study: Numerical Simulations of Debris Flow below Sto?e, Slovenia

In November 2000 a landslide–debris flow with a volume of 1.2×106?m3 slid down from Sto?e Mountain in NW Slovenia. It partly or totally destroyed 23 buildings in the village of Log pod Mangartom and killed 7 people. As landslides of the same or even greater initial mass could endanger the village in the future, numerical simulations of these possible events were carried out. A hazard map of the area, and the most effective protection measures were determined in detail. A one-dimensional model DEBRIF1D, developed from a dam-break flow model, was used for simulations along the canyon in the upper part of the reach. Downstream, in the region of the village, two two-dimensional models were used: a newly developed PCFLOW2D, and a commercial model FLO-2D. The three models were calibrated by field measurements. A special feature of the DEBRIF1D model enables direct computation of the initial hydrograph. Validity of the quadratic equation expressing the resistance was roughly confirmed by field measurements, and a comparison of the accuracy and applicability of the three models is given.     

PAS-positive substances in endometrial cells during the course of irregular bleeding

Cytologic smears of the endometrium in 81 cases of irregular bleeding were analysed for carbohydrates by the modified PAS method after Hotchkiss (1948). The positive issue of the cytochemical reaction was determined semiquantitatively. The intensity of reaction was numerically scored fy differentiating positivity in cells. Statistical analysis of data and the testing of the significance of differences have shown that are statistically highly significant differences in the intensity of reaction between the group of the secretion phase on the one hand and, on the other, the group of the proliferation phase, glandular cystic hyperplasia, and glandular hyperplasia. It has also been found that differences in the intensity of reaction between the group of the proliferation phase and the group of glandular cystic hyperplasia, as well as between the group of glandular cystic hyperplasia and glandular hyperplasia were only accidental.