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High-voltage pulsed electric fields (PEF) and pulsed discharge plasmas have received a great deal of attention in the fields of biochemistry, medicine, agriculture and food industry. The destruction phenomenon of cell membranes has been confirmed by PEF and discharge plasma, and it can be used for inactivating microorganisms and extracting cell contents. In recent years, it has been reported that PEF changes the activity of proteins such as enzymes. This review describes how PEF and pulsed discharge plasma function in enzyme activity change and permeabilization in food processing. It is thought that PEF affects the three-dimensional structure of proteins, and research is underway. Here, we will introduce the latest research results on the mechanism of enzyme activity change by PEF. In addition, we will introduce the latest research on changes in cell permeability using shock waves caused by the pulsed discharge plasma. [ABSTRACT FROM AUTHOR]

Microbial biosynthesis of hydrocarbon from CO2 reduction driven by electron uptake process from the cathodic electrode has gained intensive attention in terms of potential industrial application. However, a lack of a model system for detailed studies on the mechanism of the CO2 reduction hinders the improvement in efficiency for microbial electrosynthesis. Here, we examined the mechanism of microbial CO2 reduction at the cathode by a well‐described microbe for extracellular electron uptake, Shewanella oneidensis MR‐1, capable of reducing gaseous CO2 to produce formic acid. Using whole‐cell electrochemical assay, we observed stable cathodic current production at −0.65 V vs Ag/AgCl KCl sat. associated with the introduction of CO2. The observed cathodic current was enhanced by the addition of 4 μM riboflavin, which specifically accelerates the electron uptake process of MR‐1 by the interaction to its outer‐membrane c‐type cytochromes. The significant impact of an uncoupler agent and a mutant strain of MR‐1 lacking sole F‐type ATPase suggested the importance of proton import to the cytoplasm for the cathodic CO2 reduction. The present data suggest that MR‐1 potentially serves as a model system for microbial electrosynthesis from CO2. [ABSTRACT FROM AUTHOR]

Extracellular electron transfer (EET) via cell‐bound redox enzymes and/or redox shuttles is extensively studied in environmental bacteria. Meanwhile, EET capable pathogens have been identified in the human gut. However, other EET‐capable bacterial niches where possible biofilm infections are prominent have scarcely been explored. Herein, we electrochemically characterized human oral biofilm pathogens, Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis, to examine their EET capability. Both strains showed current production with the electrode poised at +0.4 V vs. a standard hydrogen electrode, which was associated with a decrease in electron‐donor concentration, coupled with the appearance of oxidative peaks in differential pulse (DP) and cyclic voltammograms (CV). Addition of antibiotics that suppress the biosynthesis of membrane or protein showed a significant current decrease, demonstrating that current production reflects the cellular activity in these pathogens. DPV‐ and CV‐based kinetic analyses supported by transmission electron microscopy of the cells stained for transition metals suggest a potential EET mechanism associated with the presence of redox enzymes on the cell membrane. These results could be the basis to reevaluate human oral pathogens from an electroactive point of view. The identified electrochemical activity of the two strains can be an effective test for assessing the impact of antibacterial compounds on the pathogen cellular activity on an electrode. [ABSTRACT FROM AUTHOR]

Oil production by microalgae is investigated as a possible solution to sustain the petroleum shortage. Some microalgae such as Botryococcus braunii have the advantage of being able to produce a high amount of hydrocarbon without requiring arable lands to grow on. Also, hydrocarbons extracted from B. braunii are suitable for the cosmetic industry, as they are long-chain hydrocarbons similar to squalene. As such, B. braunii oil might generate a high profit. However, harvesting hydrocarbon from microalgae cultures is difficult. Here we show an innovative way of collecting hydrocarbon from algae culture using high voltage electric discharges (HVED). Botryococcus braunii form a matrix full of hydrocarbons allowing many cells to stick together as microcolonies. When the energy applied is too high, hydrocarbons are destroyed; and when the energy is to low, algae culture stays unchanged. But when energy applied is just sufficient (near 625 J mL−1), cells leave colonies and sink to the bottom of the samples, while hydrocarbons remain unaffected and float to the surface of the samples. Such a phenomenon allows us to harvest the matrices of colonies which are empty of cells, suitable as a biomass for biofuel production. [ABSTRACT FROM AUTHOR]

Pulsed electric fields (PEFs) are applied as physical stimuli for DNA/drug delivery, cancer therapy, gene transformation, and microorganism eradication. Meanwhile, calcium electrotransfer offers an interesting approach to treat cancer, as it induces cell death easier in malignant cells than in normal cells. Here, we study the spatial and temporal cellular responses to 10 μs duration PEFs; by observing real-time, the uptake of extracellular calcium through the cell membrane. The experimental setup consisted of an inverted fluorescence microscope equipped with a color high-speed framing camera and a specifically designed miniaturized pulsed power system. The setup allowed us to accurately observe the permeabilization of HeLa S3 cells during application of various levels of PEFs ranging from 0.27 to 1.80 kV/cm. The low electric field experiments confirmed the threshold value of transmembrane potential (TMP). The high electric field observations enabled us to retrieve the entire spatial variation of the permeabilization angle (θ). The temporal observations proved that after a minimal permeabilization of the cell membrane, the ionic diffusion was the prevailing mechanism of the delivery to the cell cytoplasm. The observations suggest 0.45 kV/cm and 100 pulses at 1 kHz as an optimal condition to achieve full calcium concentration in the cell cytoplasm. The results offer precise levels of electric fields to control release of the extracellular calcium to the cell cytoplasm for inducing minimally invasive cancer calcium electroporation, an interesting affordable method to treat cancer patients with minimum side effects. [ABSTRACT FROM AUTHOR]

Biofuel production as a sustainable source of green energy is considered a promising complement to petroleum in order to prevent environmental problems such as global warming. In this regard, microalgae can be one of the best options, since other plant resources may be used for human consumption and utilizing them for producing biofuel may cause an increase in their price. However, there are several challenges to extract oil from microalgae, e.g., high energy consumption, chemical solvents, and algae culture destruction, which should be addressed by new approaches. In this paper, we suggest nanosecond pulse electric field as a physical method for hydrocarbon extraction from microalgae. Botryococcus braunii with high hydrocarbon production potential was used as the microalga model. To obtain an effective extraction, nsPEFs with 87.5-kV/cm electric field, 200-ns pulse duration, 0.3-J/pulse energy, 1-Hz pulse repetition frequency, and 1–50 pulses were applied. Microscopic observations with image processing and chemical assessments were performed for analyzing the samples, understanding the extraction mechanisms, and comparing the outcomes. According to the results, 50 pulses with 16.7-J/mL energy consumption were sufficient for oil extraction, showing that the pulsed power approach can be used as an appropriate physical method for extracting oil from Botryococcus braunii. [ABSTRACT FROM AUTHOR]

Background: Recent understanding that specific algae have high hydrocarbon production potential has attracted considerable attention. Botryococcus braunii is a microalga with an extracellular hydrocarbon matrix, which makes it an appropriate green energy source. Results: This study focuses on extracting oil from the microalgae matrix rather than the cells, eliminating the need for an excessive electric field to create electro-permeabilization. In such a way, technical limitations due to high extraction energy and cost can be overcome. Here, nanosecond pulsed electric fields (nsPEF) with 80 ns duration and 20-65 kV/cm electric fields were applied. To understand the extraction mechanism, the structure of the algae was accurately studied under fluorescence microscope; extraction was quantified using image analysis; quality of extraction was examined by thin-layer chromatography (TLC); and the cell/matrix separation was observed real-time under a microscope during nsPEF application. Furthermore, optimization was carried out by screening values of electric fields, pulse repetition frequencies, and energy spent. Conclusions: The results offer a novel method applicable for fast and continues hydrocarbon extraction process at low energy cost. [ABSTRACT FROM AUTHOR]

Aims: This article shows the effect of nanosecond pulsed electric field (nsPEF) on Escherichia coli, which could imply a durable change in protein expressions and then impacted the phenotype of surviving bacteria that might lead to increase pathogenicity. Methods and Results: The effects of nsPEF on E. coli viability and membrane permeabilization were investigated. One log10 reduction in bacterial counts was achieved at field strength of 107 V m-1 with a train of 500 successive pulses of 60 9 109 s. Incubation of germs after treatment with propidium iodide showed that membrane permeabilization was reversible. Possible protein changes of surviving bacteria were checked to assess potential phenotypical changes using two-dimensional electrophoresis. In our study, after 40 generations, only UniProt #P39187 was up-regulated with P ≤ 0·05 compared with the control and corresponded to the uncharacterized protein YtfJ. Antibiograms were used to check whether or not the pattern of cultivable bacteria after nsPEF deliveries changed. Conclusions: The results tend to show that nsPEFs are able to inactivate bacteria and have probably no serious impact in E. coli protein patterns. Significance and Impact of the Study: The use of nsPEF is a safe promising new nonthermal method for bacterial inactivation in the food processing and environmental industry. [ABSTRACT FROM AUTHOR]

Background: Bacillus Calmette-Guerin (BCG) is the most effective treatment for non-muscle invasive bladder cancer. However, a failure in the initial response or relapse within the first five years of treatment has been observed in 20% of patients. We have previously observed that in vivo administration of an inhibitor of nitric oxide improved the response to BCG of bladder tumor bearing mice. It was described that this effect was due to a replacement of tumor tissue by collagen depots. The aim of the present work was to clarify the mechanism involved in this process. Methodology/Principal Findings: We demonstrated that BCG induces NIH-3T3 fibroblast proliferation by activating the MAPK and PI3K signaling pathways and also differentiation determined by alpha-smooth muscle actin (alpha-SMA) expression. In vivo, intratumoral inoculation of BCG also increased alpha-SMA and collagen expression. Oral administration of L-NAME enhanced the pro-fibrotic effect of BCG. Peritoneal macrophages obtained from MB49 tumor-bearing mice treated in vivo with combined treatment of BCG with L-NAME also enhanced fibroblast proliferation. We observed that FGF-2 is one of the factors released by BCG-activated macrophages that is able to induce fibroblast proliferation. The involvement of FGF-2 was evidenced using an anti-FGF2 antibody. At the same time, this macrophage population improved wound healing rate in normal mice and FGF-2 expression was also increased in these wounds. Conclusions/Significance: Our findings suggest that fibroblasts are targeted by BCG both directly and through activated macrophages in an immunotherapy context of a bladder murine model. We also described, for the first time, that FGF-2 is involved in a dialog between fibroblasts and macrophages induced after BCG treatment. The fact that L-NAME administration improves the BCG effect on fibroblasts, NO inhibition, might represent a new approach to add to the conventional BCG therapy. [ABSTRACT FROM AUTHOR]

Disinfection and sterilization against cold-tolerant microorganisms are very important for enhancing food safety and hygiene management under refrigeration conditions. We isolated Exiguobacterium sp. and Pantoea sp. from an immersion solution of packed tofu and evaluated their growth properties and sensitivities to various bactericidal methods. These microorganisms were classified as psychrotrophic bacteria, according to their ability to grow at 4 °C, with an optimum growth temperature of 30 °C. Exiguobacterium sp. and Pantoea sp. were more sensitive to heat and sodium hypochlorite than Escherichia coli (E. coli). Exiguobacterium sp. was sensitive to acetic acid and citric acid, while Pantoea sp. was relatively insensitive and E. coli was insensitive to these organic acids. All microorganisms used in this study were resistant to sodium hydroxide solution (pH 8.00). Exiguobacterium sp. showed resistance to ozonated water and UV; therefore, particular attention should be paid to the contamination of this microorganism in food factories. Both Exiguobacterium sp. and Pantoea sp. were inactivated by pulsed electric field (PEF) treatment that did not cause lethal damage to E. coli. The results obtained in this study suggest that the bactericidal methods targeting the fragile cell membrane with high permeability are effective for the inactivation of cold-tolerant microorganisms. [ABSTRACT FROM AUTHOR]

Pulsed electric fields (PEFs), which are generated by pulsed power technologies, are being tested for their applicability in food processing through protein conformational change and the poration of cell membranes. In this article, enzyme activity change and the permeabilization of agricultural products using pulsed power technologies are reviewed as novel, nonthermal food processes. Compact pulsed power systems have been developed with repetitive operation and moderate output power for application in food processing. Firstly, the compact pulsed power systems for the enzyme activity change and permeabilization are outlined. Exposure to electric fields affects hydrogen bonds in the secondary and tertiary structures of proteins; as a result, the protein conformation is induced to be changed. The conformational change induces an activity change in enzymes such as α-amylase and peroxidase. Secondly, the conformational change in proteins and the induced protein functional change are reviewed. The permeabilization of agricultural products is caused through the poration of cell membranes by applying PEFs produced by pulsed discharges. The permeabilization of cell membranes can be used for the extraction of nutrients and health-promoting agents such as polyphenols and vitamins. The electrical poration can also be used as a pre-treatment for food drying and blanching processes. Finally, the permeabilization of cell membranes and its applications in food processing are reviewed. [ABSTRACT FROM AUTHOR]

The authors report a pregnancy in a 34 year old patient who previously experienced a myocardial infarction. The pregnancy ended at 39 weeks in the birth of a healthy girl weighting 3040 g, by cesarean section under epidural anesthesia. A review of the literature revealed 33 similar cases, 16 of which were adequately documented. [ABSTRACT FROM AUTHOR]

Cover Feature: Electrochemical Characterization of Current-Producing Human Oral Pathogens by Whole-Cell Electrochemistry (ChemElectroChem 9/2020) Keywords: Aggregatibacter actinomycetemcomitans; cyclic voltammetry; differential pulse voltammetry; extracellular electron transfer; Porphyromonas gingivalis EN Aggregatibacter actinomycetemcomitans cyclic voltammetry differential pulse voltammetry extracellular electron transfer Porphyromonas gingivalis 1954 1954 1 05/18/20 20200504 NES 200504 B The Cover Feature b illustrates the current production capability, that is, electron transport from the cell inside to the extracellular electrode surface in two periodontal pathogens. Aggregatibacter actinomycetemcomitans, cyclic voltammetry, differential pulse voltammetry, extracellular electron transfer, Porphyromonas gingivalis. [Extracted from the article]