Study of the antimicrobial activities of Solanum indicum ssp. distichum (Schumach. and Thonning 1827) fruits (“gnangnan” berries) from a tropical humid zone (Côte d’Ivoire)

The antibacterial activity of both aqueous and ethanolic extracts of Solanum indicum ssp. distichum (Schumach. and Thonning, 1872) fruits was investigated. These extracts were evaluated for antibacterialactivity against two Gram positive (Listeria innocua LRGIA 01 and Staphylococcus aureus CNRZ3) and two Gram negative (Escherichia coli industrial strain and Pseudomonas aeruginosa ATCC 15742) strains. Thisevaluation was performed by following their growth by a spectrophotometric method in Brain Heart Infusion broth. L. innocua LRGIA01growth was completely inhibited by 0.04 g.mL-1 of aqueous extract of Solanumindicum berries, while a dose-dependent inhibition by 0.04 g.mL-1 and 0.1 g.mL-1 ethanolic extracts was observed. Conversely, the inhibitory activity of ethanolic extract on P. aeruginosa ATCC 15742 growth, was higher than that of aqueous extract. E. coli industrial strain and S. aureus CNRZ 3 growth were inhibited by 0.1 mg.mL-1 ethanolic extract but not by 0.04 mg.mL-1 ethanolic or aqueous extracts. These results suggest that different classes of compounds are likely responsible for the antibacterial activities. The high inhibitory activity of aqueous and ethanolic extracts on L. innocua LRGIA01 and P. aeruginosa ATCC 15742 strains, respectively calls for further studies to identify the antibacterial compounds present in Solanum indicum berriesand their mechanisms of action

Biopreservation of chocolate mousse with Lactobacillus helveticus 2/20: Microbial Challenge Test

Probiotic bacteria are used for food biopreservation because their metabolic products might contribute to ensuring food microbiological safety and/or increase its shelf life without the addition of chemical preservatives. Moreover, biopreserved foods are excellent vehicles for the delivery of probiotic bacteria. The aim of the study was to investigate the potential of chocolate mousse food matrix for the delivery of the probiotic strain Lactobacillus helveticus 2/20 (Lb. helveticus 2/20) and to investigate its capacity to inhibit the growth of two foodborne pathogenic bacteria (Staphylococcus aureus and Escherichia coli). Therefore, the populations of free or encapsulated in calcium alginate Lb. helveticus 2/20 cells and/or of each pathogen (used to voluntarily contaminate each sample) were monitored both in complex nutrient medium (MRS broth) and in chocolate mousse under refrigeration conditions and at room temperature. Lb. helveticus 2/20 alone in free or encapsulated state effectively inhibited the growth of Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 in chocolate mousse when stored at 20 ± 2 °C. Practically no viable unwanted bacteria were identified on the 7th day from the beginning of the process. High viable Lb. helveticus 2/20 cell populations were maintained during storage under refrigerated conditions (4 ± 2 °C) and at room temperature. Chocolate mousse is thus a promising food matrix to deliver probiotic Lb. helveticus 2/20 cells, which could also protect it from contamination by unwanted bacteria

Microscopic origin of random telegraph noise fluctuations in aggressively scaled RRAM and its impact on read disturb variability

Random telegraph noise (RTN) is an important intrinsic phenomenon of any logic or memory device that is indicative of the reliability and stochastic variability in its performance. In the context of the resistive random access memory (RRAM), RTN becomes a key criterion that determines the read disturb immunity and memory window between the low (LRS) and high resistance states (HRS). With the drive towards ultra-low power memory (low reset current) and aggressive scaling to 10 × 10 nm2 area, contribution of RTN is significantly enhanced by every trap (vacancy) in the dielectric. The underlying mechanisms governing RTN in RRAM are yet to be fully understood. In this study, we aim to decode the role of conductance fluctuations caused by oxygen vacancy transport and inelastic electron trapping and detrapping processes. The influence of resistance state (LRS, shallow and deep HRS), reset depth and reset stop voltage (VRESET-STOP) on the conductance variability is also investigated. © 2013 IEEE

Antimicrobial activity of camel milk casein and its hydrolysates

The aim of this study was to evaluate the antimicrobial activity of camel caseins and their hydrolysates by gastrointestinal proteolytic enzymes against 3 Gram-positive and 2 Gram-negative bacterial strains. Camel caseins (CN) were hydrolysed by successive action of pepsin and pancreatin. Hydrolysis of CN was checked by electrophoresis and gel filtration chromatography (GFC). Both techniques showed that CN was hydrolysed into peptides. Among the tested bacteria, a decrease of 19.3%±0.02 of E. coli XL1 blue cells growth was observed in the presence of undigested camel casein at a concentration of 20 mg ml−1. After successive hydrolyses by pepsin and pancreatin, camel milk casein hydrolysates still exhibited anti-bacterial activity against E. coli XL1 blue strain (19.73±0.01% growth inhibition under the same conditions). Gram-positive strain growth was not affected by intact camel CN, while, at the same concentration (20 mg ml–1), their hydrolysates slightly inhibited the growth of these bacteria. This suggests that antibacterial peptidic fragments of caseins were generated by pepsin and pancreatin

New Insights of the Switching Process in GeAsTe Ovonic Threshold Switching (OTS) Selectors

Experimental evidence and analysis in this work provide new insights into the fast switching process in GeAsTe ovonic threshold switching (OTS) selectors. For the first time, the full switching-OFF process, covering the defect cluster shrinking and rupture stages, can be measured and characterized. Two distinct switch-OFF mechanisms and their dependence on the total impedance of the selector and resistor (1S1Rs) circuit are identified. The impact of series resistance value on the switching process, the 1S1Rs operation, and the underlying mechanisms can be explained by the dynamic resistance of OTS that is induced by the transition of defect clusters. This research sheds new light on OTS switching mechanism and its impact on 1S1Rs operation

Glutathione Transferase from Trichoderma virens Enhances Cadmium Tolerance without Enhancing Its Accumulation in Transgenic Nicotiana tabacum

BACKGROUND: Cadmium (Cd) is a major heavy metal pollutant which is highly toxic to plants and animals. Vast agricultural areas worldwide are contaminated with Cd. Plants take up Cd and through the food chain it reaches humans and causes toxicity. It is ideal to develop plants tolerant to Cd, without enhanced accumulation in the edible parts for human consumption. Glutathione transferases (GST) are a family of multifunctional enzymes known to have important roles in combating oxidative stresses induced by various heavy metals including Cd. Some GSTs are also known to function as glutathione peroxidases. Overexpression/heterologous expression of GSTs is expected to result in plants tolerant to heavy metals such as Cd. RESULTS: Here, we report cloning of a glutathione transferase gene from Trichoderma virens, a biocontrol fungus and introducing it into Nicotiana tabacum plants by Agrobacterium-mediated gene transfer. Transgenic nature of the plants was confirmed by Southern blot hybridization and expression by reverse transcription PCR. Transgene (TvGST) showed single gene Mendelian inheritance. When transgenic plants expressing TvGST gene were exposed to different concentrations of Cd, they were found to be more tolerant compared to wild type plants, with transgenic plants showing lower levels of lipid peroxidation. Levels of different antioxidant enzymes such as glutathione transferase, superoxide dismutase, ascorbate peroxidase, guiacol peroxidase and catalase showed enhanced levels in transgenic plants expressing TvGST compared to control plants, when exposed to Cd. Cadmium accumulation in the plant biomass in transgenic plants were similar or lower than wild-type plants. CONCLUSION: The results of the present study suggest that transgenic tobacco plants expressing a Trichoderma virens GST are more tolerant to Cd, without enhancing its accumulation in the plant biomass. It should be possible to extend the present results to crop plants for developing Cd tolerance and in limiting Cd availability in the food chain

Feeding habits of Mysis relicta — an overview

Mysis relicta has been recognized as an important component of many limnetic food webs. The first approach to studying the feeding habits of M. relicta was the analysis of stomach contents. Assumptions regarding stomach content analysis have been tested and seasonal feeding estimates of M. relicta have been reported recently. Laboratory grazing and/or predation experiments have recently been completed using M. relicta primarily from Lakes Michigan and Tahoe. Mysis relicta is concluded to be opportunistic, capable of utilizing a variety of food resources. It may play an important role in structuring limnetic food webs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42916/1/10750_2004_Article_BF00008103.pd