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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 .

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.

Additional file 1. Additional materials and methods and results; including Figures S1 to S7 and Table S1.

Once pathogens form a biofilm, they become more tolerant to drugs and quicker to recover from physical removal than planktonic cells. Because such robustness of a biofilm is associated with the active metabolism of its constituent microbes, establishment of a direct assay quantifying biofilm's metabolic activity is important for developing antibiofilm substrates and techniques. Current production capability via extracellular electron transport (EET) was recently found in Gram-positive pathogens, which we hypothesized to correlate with the metabolic activity of their biofilm. Here, we identified current production from the biofilm of oral pathogen Streptococcus mutans that enables the electrochemical assessments of their metabolic activity in situ which conventionally require gene insertion for a fluorescent protein expression. Single-potential amperometry (SA) showed that S. mutans produced an anodic current and formed a biofilm within 8 h on a +0.4 V electrode vs a standard hydrogen electrode (SHE) in the presence of the electron donor glucose. Current production was significantly decreased by the addition of a metabolic inhibitor Triclosan. Furthermore, the anabolic activity of a single cell using high-resolution mass spectroscopy revealed that higher current production resulted in a higher metabolic fixation of an atomically labeled nitrogen 15N. These results demonstrate that current production in S. mutans reflects its metabolic activity. Given electrochemical impedance spectroscopy (EIS) helps quantifying the bacterial cell adhesion on the electrode, combination of EIS and SA could be a novel assay for EET capable pathogens for quantifying their time-dependent metabolic activity, cellular electrode coverage and physiological response to antibiofilm compounds.

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 × 10−9 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.

Using various prototype of nanosecond pulsed electric field (nsPEF), eradication of microorganisms that are pathogens in industrial and domestic water was investigated. This matter becomes a societal issue since new European administrative constraints are coming out such as the legislation named REACH and the biocide directive. This legislation tries to limit the use of chemicals able to eradicate microorganisms. One of the different ways to eliminate micro-organisms such as bacteria consists in the delivery of pulsed electric fields (PEF). Nanosecond pulsed electric field (nsPEF) may be an interesting alternative with a lower energy cost when compared with ms or μs PEF technologies. However, only few insights are available that report a gain in cost and in efficiency as well. The aim of this study is to show that a strong decontamination in a reservoir can be obtained by using a derivated flow. A mathematical model (algorithm), using a language C program was developed to predict the effectiveness of the flow decontamination through a bypass. The work carried out has been to compare this theoretical model with laboratory tests. Efficiency and speediness of bacteria destruction was drastically improved and energy cost reduced thanks to optimization of flow parameter and improvement of generator performance., Les effets des champs électriques pulsés (CEP) sur les microorganismes ont été montrés depuis Sale et Hamilton. L'une des premières applications en a été l'électroporation cellulaire pour permettre la transfection de plasmides à travers la membrane plasmique. Il s'agit de la principale méthode de transfert de gènes. Un autre champ d'application est la décontamination de nourriture liquide. Mais la technologie capable de donner ces résultats en termes de décontamination requièrt, pour un champ électrique de faible amplitude, l'utilisation d'impulsions de longues durées provoquant une grande consommation énergétique. Ceci a été montré pour la décontamination du lait, des jus de fruits et du vin. Le mécanisme par lequel les CEP avec une durée milliseconde (ms) ou microseconde (µs) agissent est bien décrit et intervient sur la bicouche lipidique. Le but de cette thèse est d'étudier les possibilités d'utilisation des champs électriques pulsés nanosecondes (nsCEP) pour décontaminer de l'eau de procédés industriels. Un générateur d'impulsions haute tension associé à un applicateur constitué de deux électrodes planes permettent de générer un champ électrique homogène dans l'eau. Ce dispositif a d'abord été éprouvé en batch puis en flux sur des suspensions bactériennes (Escherichia coli BL21(DE3) et Legionella pneumophila sérogroupe 1) cultivées en laboratoire. L'utilisation de générateurs de plus en plus performants et l'optimisation des conditions de flux ont permis d'améliorer drastiquement le rendement énergétique de décontamination et la vitesse globale de traitement. Il a également été montré qu'il est possible de déterminer par le calcul, la vitesse de décontamination d'un tel système, à partir des caractéristiques des générateurs et des paramètres de fluidiques. Si ce travail n'a pas permis la réalisation d'un prototype d'échelle industrielle, les grandes lignes permettant le passage du procédé de l'échelle laboratoire à l'échelle industrielle ont été données.

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.

Using various prototype of nanosecond pulsed electric field (nsPEF), eradication of microorganisms that are pathogens in industrial and domestic water was investigated. This matter becomes a societal issue since new European administrative constraints are coming out such as the legislation named REACH and the biocide directive. This legislation tries to limit the use of chemicals able to eradicate microorganisms. One of the different ways to eliminate micro-organisms such as bacteria consists in the delivery of pulsed electric fields (PEF). Nanosecond pulsed electric field (nsPEF) may be an interesting alternative with a lower energy cost when compared with ms or μs PEF technologies. However, only few insights are available that report a gain in cost and in efficiency as well. The aim of this study is to show that a strong decontamination in a reservoir can be obtained by using a derivated flow. A mathematical model (algorithm), using a language C program was developed to predict the effectiveness of the flow decontamination through a bypass. The work carried out has been to compare this theoretical model with laboratory tests. Efficiency and speediness of bacteria destruction was drastically improved and energy cost reduced thanks to optimization of flow parameter and improvement of generator performance., Les effets des champs électriques pulsés (CEP) sur les microorganismes ont été montrés depuis Sale et Hamilton. L'une des premières applications en a été l'électroporation cellulaire pour permettre la transfection de plasmides à travers la membrane plasmique. Il s'agit de la principale méthode de transfert de gènes. Un autre champ d'application est la décontamination de nourriture liquide. Mais la technologie capable de donner ces résultats en termes de décontamination requièrt, pour un champ électrique de faible amplitude, l'utilisation d'impulsions de longues durées provoquant une grande consommation énergétique. Ceci a été montré pour la décontamination du lait, des jus de fruits et du vin. Le mécanisme par lequel les CEP avec une durée milliseconde (ms) ou microseconde (µs) agissent est bien décrit et intervient sur la bicouche lipidique. Le but de cette thèse est d'étudier les possibilités d'utilisation des champs électriques pulsés nanosecondes (nsCEP) pour décontaminer de l'eau de procédés industriels. Un générateur d'impulsions haute tension associé à un applicateur constitué de deux électrodes planes permettent de générer un champ électrique homogène dans l'eau. Ce dispositif a d'abord été éprouvé en batch puis en flux sur des suspensions bactériennes (Escherichia coli BL21(DE3) et Legionella pneumophila sérogroupe 1) cultivées en laboratoire. L'utilisation de générateurs de plus en plus performants et l'optimisation des conditions de flux ont permis d'améliorer drastiquement le rendement énergétique de décontamination et la vitesse globale de traitement. Il a également été montré qu'il est possible de déterminer par le calcul, la vitesse de décontamination d'un tel système, à partir des caractéristiques des générateurs et des paramètres de fluidiques. Si ce travail n'a pas permis la réalisation d'un prototype d'échelle industrielle, les grandes lignes permettant le passage du procédé de l'échelle laboratoire à l'échelle industrielle ont été données.