We propose a control unit intended for light stimulation of optical nerves (LiSON), which is an optoelectronic-based visual prosthesis. The device is composed of an image sensor array to capture the scene and a miniaturized laser array to stimulate the neural cells forming the optic nerve. The adopted optical stimulation technique is intended to avoid the signal overlapping caused by conventional direct stimulation pathways, and thus improve the image quality. The presented control unit consists of averaging and subtracting the received optical data to reproduce the behavior of bipolar cells, followed by a voltage-controlled oscillator acting as ganglion cells used to transform the signal in a pulse train. The control unit prototype contains an image sensor of 9 × 9 pixels array to validate the operation principles of the proposed system. The chip was fabricated in 0.13 µm CMOS standard technology, and the measurements meet the expectation.

Many research groups tried to develop visual prosthesis in order to restore sight for the blindness. However, the results obtained in very limited and the use these devices by the blinds is marginal. This amounts to the technique of stimulation. To do so, new device has been developed based on light stimulation and stimulate optic nerve. This prosthesis is powered by inductive way using coil. In this paper, we propose a second generation of visual prosthesis based on photovoltaic pixel to power the chip and to capture the scene. So, the vision system is studied. we developed essentially the anatomophysiology of the retina, the optic nerve and the cortex. Each layer of the retina has been modeled and essentially the layers of the information pretreatment. A novel visual prosthesis design has been obtained: autonomy and wireless visual prosthesis.

The directed synthesis of non-centrosymmetric copper (II) bromo-complex has been achieved through the use of homochiral organic molecule. Reaction containing (S)-(-)-3-aminoquinuclidine, CuBr2, HBr and H2O were subjected to mild hydrothermal conditions, resulting in the growth of single crystals of [(S)-C7H16N2][CuBr4]. The compound crystallizes in the non polar space group P2(1)2(1)2(1)(No. 19), which exhibits the enantiomorphic crystal class 222 (D-2). In the crystal structure, the tetrabromocuprate(II) anion is connected to three organic cations through N-H center dot center dot center dot Br hydrogen bonds to form cation-anion-cation molecular units, which are held together by means of offset face-to-face interactions to give one-dimensional chains. DSC measurements indicated that the compound [(S)-C7H16N2][CuBr4] underwent a reversible phase transition at 80 degrees C. [(S)-C7H16N2][CuBr4] is more than 1.2 times as efficient as KDP in second harmonic generation; making it a potentially attractive material for non-linear optical applications. The synthesized product was also screened for in vitro antioxidant and antimicrobial activities, while showing favorable antioxidant activities against DPPH as well as the discoloration of beta-carotene. (C) 2018 Elsevier B.V. All rights reserved.

Enterobacter cloacae C3 strain was isolated from a soil contaminated by natural-gas condensate in Sfax City, Tunisia. This strain was selected for further studies based on its high surface activities. The physicochemical properties and stability of produced biosurfactants were investigated. Biosurfactants from E. cloacae C3 strain are able to reduce the surface tension of Landy medium from 65 to 32 mN/m. The produced biosurfactants were identified as lipopeptides using thin layer chromatography (TLC) technique. Acid precipitated lipopeptides have critical micelle concentration of 100 mg/l. They showed good emulsification activities against different hydrocarbon substrates in comparison with chemical surfactants Tween 80 and SDS, and they were effective in a wide range of temperature and pH. Good performance of diesel oil solubilization was exhibited by lipopeptides C3 at extreme environmental conditions, which is essential for enhancing oil recovery. The degradation of diesel oil (2.0%, v/v) in mineral-salts medium reached a maximum value of 48% after about 15 days of incubation, in the presence of 0.1% (w/v) lipopeptides. These results suggest the importance of lipopeptides C3 production for application in bioremediation of environments polluted with various hydrocarbons. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

In the wake of an increased attention on the eco-friendly biopesticidal products and the rising market requirements for organic agents, lipopeptides compounds have been described as biological control agents which improve the overall health growth and development of plants. Nevertheless, their high production cost constitue the major flaw in their wide use to control plant diseases. The present article aims to formulate an economic media for lipopeptides production by Bacillus mojavensis A21 for application as natural fungicides for plant disease treatment. We herein demonstrated the suitability of the potato waste, as low cost substrate, for lipopeptides production. Moreover, sea water  was found to be a good mineral salts sources. In the second part of this study, we investigate the inhibitory activity of A21 lipopeptides against the phtopathogenic Fusarium sp. The in vitro test showed a minimal inhibitory concentration of about 0.3 mg/ml. The microscopic examination, of the treated Fusarium revealed an excessive lysis of the mycelia ultrastructure with destructed spores. The in vivo antagonist activity was confirmed towards the infected potato tubers. A21 lipopeptides are effective in decreasing by about 78.26% and 60.68% when applied as preventive and curative treatments, respectively, as compared to the untreated tubers.

This work concerns the study of the enhancement of surfactin and fengycin production by B. mojavensis A21 and application of the produced product in diesel biodegradation. The influences of the culture medium and cells immobilization were studied. The highest lipopeptides production was achieved after 72 hours of incubation in a culture medium containing 30 g/L glucose as carbon source and a combination of yeast extract (1 g/L) and glutamic acid (5 g/L) as nitrogen sources with initial pH 7.0 at 30°C and 90% volumetric aeration. The study of primary metabolites production showed mainly the production of acetoin, with a maximum production after 24 h of strain growth. The use of immobilized cells seemed to be a promising method for improving lipopeptides productivity. In fact, the synthesis of both lipopeptides, mainly fengycin, was greatly enhanced by the immobilization of A21 cells. An increase of diesel degradation capacity of approximately 20, 27, and 40% in the presence of 0.5, 1, and 2 g/L of produced lipopeptides, respectively, was observed. Considering these properties, B. mojavensis A21 strain producing a lipopeptide mixture, containing both surfactin and fengycin, may be considered as a potential candidate for future use in bioremediation and crop protection.

Bacillus methylotrophicus DCS1 strain was isolated from diesel contaminated soil and screened for its ability to produce biosurfactants; it was found effective for the production of surface active molecules. The structural characterization of the isolated lipopeptides was studied by a variety of analytical techniques. The organic extract of DCS1 lipopeptides was fractionated by silica gel column chromatography (60Mesh). Fractions containing lipopeptides were collected and identified by tandem mass spectrometry MALDI-TOF-MS and MALDI-TOF MS2. The crude biosurfactants contains a mixture of homologous lipopeptides with molecular weights between 1016 and 1556Da. Mass spectrometry analysis of partially purified lipopeptides revealed that it contains different isoforms belonging to three families: surfactin, iturin and fengycin. To identify lipopeptides isoforms, MALDI-TOF MS2 was used and ions representing characteristic fragmentations were detected. The mass spectrometry characterization revealed the presence of four variants of surfactin lipopeptides, four variants of pumilacidin that differ according to the β-hydroxy fatty acid chain length as well as the type of amino acid at position 7, five variants of iturin A/mycosubtilin varying in the β-amino fatty acid chain length from C12 to C16, C16 iturin C1, five isoforms of bacillomycin D varying in the β-amino fatty acid chain length from C14 to C18, and six fengycin isoforms that differ according to the length of the β-hydroxy fatty acid side chain as well as the amino acid at position 6. The capacity of B. methylotrohicus DCS1 strain to produce many lipopeptides isoforms belonging to different families and having a structural diversity is a very interesting characteristic that allows them to be used in various fields of biotechnological applications.

The present work aims to investigate the antioxidant and antimicrobial activities as well as the potential of DCS1 lipopeptides produced by Bacillus methylotrophicus DCS1 strain at inhibition and disruption of biofilm formation.

This article presents a new design of the visual prosthesis based on the optical stimulation. The aim of this work is to seek an architecture of image acquisition, by using a simple treatment and without recourse to extensive treatment of a processor, and to provide an outlook on the image quality acquired by the patient. To do so, we have proposed two architectures of image processing, which have tested with different images. Simulation results demonstrate that the patient can recognize objects and the projection of targets, read letters (scale 20/200 and 20/100) and identify faces and scenes.

Lipopeptides constitute a structurally diverse group of metabolites produced by various bacterial and fungal genera. In the past decades, research on lipopeptides has been fueled by their surfactant activities. However, natural functions of lipopeptides compounds have received considerably less attention. The aim of this study was to isolate and identify the lipopeptides from Bacillus amyloliquefaciens An6, and further evaluate their biological activities. An6 lipopeptides were detected by PCR using degenerated primers and MALDI‐TOF‐MS. An6 strain was found to produce surfactin, fengycin, and bacillomycin. Following their purification, the in vitro antioxidant activity of An6 lipopeptides was studied through different assays. The scavenging effect on 1,1‐diphenyl‐2‐picrylhydrazyl radicals at a dosage of 0.75 mg/mL was 81%. Its reducing power was concentration‐dependant and reached a maximum of 1.07 at 2.5 mg/mL. Moreover, they showed a strong inhibition of β‐carotene bleaching. An6 lipopeptides mixture was also found to display significant antimicrobial activity against several Gram‐positive, Gram‐negative bacteria, and fungal strains. An6 lipopeptides were insensitive to proteolytic enzymes, stable between pH 4.0 and 12.0, and resistant to high temperature. Our results provided enough evidence proving that An6 lipopeptides could be used as functional‐food components.

Since the end of the 20th century, the efforts regarding the environment protection have been increasingly intensified. As most of surfactants used at present arise from the chemical industry, the search for new biological surfactants or biosurfactants of microbial origin with lesser side effects is of great interest. Neutral lipids, glycolipids, phospholipids, lipopolysaccharides and lipopeptides are listed among biosurfactants. Lipopeptides synthetized by microorganisms, in particular those of the genus Bacillus, are the most promising, because of their excellent interfacial properties and their biological activities. Surfactines, fengycines and iturines are the main families of biosurfactants produced by the genus through a ribosome-independent mechanism. Considering their potentialities and their harmlessness, lipopeptides have been used in various fields such as environment petroleum industry and agronomy. The application of lipopeptides in the foodprocessing and pharmaceutical industries should be improved. This review is a synthesis of the knowledge acquired, until now, on the biosurfactants produced by the genus Bacillus. We have focused on the structure of lipopeptides, their mode of synthesis as well as their biological activities and their potential applications.

Six biosurfactant-producing bacteria were isolated from hydrocarbon contaminated soils in Sfax, Tunisia. Isolates were screened for biosurfactant production by different conventional methods including hemolytic activity, surface tension reduction, drop-collapsing and oil displacement tests. All these screening tests show that all the isolates behave differently. Among the isolated bacteria, DCS1 strain was selected for further studies based on its highest activities and it was identified as Bacillus methylotrophicus DCS1. This strain was found to be a potent producer of biosurfactant when cultivated in mineral-salts medium supplemented with diesel oil (2 %, v/v) as a sole carbon source. Physicochemical properties and stability of biosurfactants synthesized by B. methylotrophicus DCS1 were investigated. The produced biosurfactants DCS1, from Landy medium, possess high surface activity that could lower the surface tension of water to a value of 31 from 72 mN m−1 and have a critical micelle concentration (CMC) of 100 mg L−1. Compared with SDS and Tween 80, biosurfactants showed excellent emulsification activities against different hydrocarbon substrates and high solubilization efficiency towards diesel oil. Biosurfactants DCS1 showed good stability in a wide range of temperature, pH and salinity. These results suggested that biosurfactants produced by B. methylotrophicus DCS1 could be an alternative to chemically synthesized surfactants for use in bioremediation processes to enhance the solubility of hydrophobic compounds.

The aim of the present study was to evaluate the acute and sub-chronic toxicity of lipopeptides mixture produced by Bacillus mojavensis A21 as well as their in vitro anticoagulant activity. A21 lipopeptides was given to mice at single dose from 75 mg to 1000 mg/kg body weight (bw). The median lethal dose (LD50) of A21 lipopeptides was about 550 mg/kg bw. Sub-chronic toxicity study for 28 days was done by daily oral administration of A21 lipopeptides at doses of 40 and 400 mg/kg bw in rats. Results showed that A21 lipopeptides did not cause any change in body weights and they did not produce any marked alterations in the hematological blood parameters including hematocrit concentration, hemoglobin level, white and red cells count. However, the platelets level decreased significantly compared to control value. Moreover, no significant differences in the serum biochemical characteristics were observed for rats treated by the lowest dose. In contrast, a little enhancement of alanine-aminotransferase (ALT) activity and decrease in total cholesterol were observed with the highest dose. A21 lipopeptides were also found to cause a prolongation of the thrombin time (TT), the prothrombin time (PT) and the activated partial thromboplastin time (APTT). Overall, A21 lipopeptides may be very promising compounds for therapeutic purposes.

This study focuses on the isolation and characterisation of a peptide with bacteriocin-like properties from Bacillus amyloliquefaciens An6. Incubation conditions were optimised, and the effects of the incubation period and of carbon and nitrogen sources were investigated. The produced bacteriocin was partially purified with ammonium sulphate precipitation, dialysis and ultrafiltration and was then biochemically characterised. Maximum bacteriocin production was achieved after 48h of incubation in a culture medium containing 20g/L starch and 10g/L yeast extract, with an initial pH 8.0 at 30°C under continuous agitation at 200rpm. The bacteriocin was sequentially purified and its molecular weight was determined to be 11kDa by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The bacteriocin was relatively heat-resistant and was not sensitive to acid and alkaline conditions (pH 4.0-10.0). Its inhibitory activity was sensitive to proteinase K but was resistant to the proteolytic action of alcalase, trypsin, chymotrypsin and pepsin. In conclusion, bacteriocin An6, owing its wide spectrum of activity as well as its high tolerance to acidic and alkaline pH values, temperature and proteases shows great potential for use as a food biopreservative.

•Lipopeptides from B. mojavensis A21, exhibits strong in vitro antioxidant activity.•A21 lipopeptides were effective in accelerating the wound healing activity.•A21 lipopeptides should be an attractive candidate for a successful treatment of wounds which appear to be related to their significant antioxidant potential.

The strain Bacillus amyloliquefaciens An6 was found to be a potent producer of biosurfactant when cultivated Landy medium. The produced biosurfactant showed high physicochemical properties in terms of the surface activities. It was able to reduce surface tension to less than 30 from 72 mN/m and its critical micelle concentration (CMC) is 100 mg/L The emulsifier produced was found to be an alternative to chemically synthesized surfactants since it shows high solubilization efficiency towards diesel oil (71.54% at 1 g/L), better than SDS and Tween 80. Further, it showed good stability over a wide range of pH, temperature and salinity. It was found that it can enhance the diesel oil degradation efficiency of the An6 strain. Moreover, it was found that it can solubilize diesel more effectively than SDS and Tween 80 and therefore has potential applications in bioremediation. (C) 2015 Elsevier Ltd. All rights reserved.

The study was carried out to examine how the fatty acid compositions of oils (soybean and palm oils) were reflected in the products and their effects on the growing performance of broilers. Feed consumption, body weight, abdominal fat/carcass yield and fatty acid levels of abdominal fat were determined. During treatment (day 0 to 38), the highest growth rate was recorded in control group while the lowest was in broilers fed a ration containing soybean oil. At the end of trial, the carcass fat content was generally higher in all treated groups compared to the control. Fatty acids composition was found to be greatly influenced by the dietary fat. The highest level of poly-unsaturated fatty acid was obtained from the group fed ration contained soybean oil. Consequently, the compositions of fatty acids from these sorts of animal products presented for human consumption was seen to highly alter depending on animal nutrition.

Physico-chemical and mechanical properties of cuttlefish skin gelatin (G), chitosan (C) from shrimp (Penaeus kerathurus) and composite films (G75/C25, G50/C50, G25/C75) plasticized with glycerol were investigated. The results indicated that chitosan film had higher tensile strength and lower elongation at break when compared with the other films. Composite films show no significant difference in tensile strength (TS), thickness and transparency. The structural properties evaluated by FTIR and DSC showed total miscibility between both polymers. DSC scans showed that the increase of chitosan content in the composite films increases the transition temperature (Tg) and enthalpy (ΔHg) of films. The morphology study of gelatin, chitosan and composite films showed a compact and homogenous structure. In addition, gelatin and G75/C25 films demonstrated a high antioxidant activities monitored by β-carotene bleaching, DPPH radical-scavenging and reducing power activities, while films contained chitosan exhibited higher antimicrobial activity against Gram-positive than Gram-negative bacteria.

The in vitro antioxidant activity and the in vivo wound healing performance of the exopolysaccharide EPS22, produced by Pseudomonas stutzeri AS22, were investigated. Antioxidant activity was evaluated by three different tests. The scavenging effect on DPPH radicals at a concentration of 1 mg/ml was 80 ± 1.41%. The reducing power reached a maximum of 1.26 ± 0.02 at 2 mg/ml. Moreover, EPS22 showed good chelating ability and chelated almost 88.5 ± 0.7% of ferrous ions at 0.75 mg/ml. The rheological characterization of EPS22 gel (0.5%) showed a pseudoplastic behavior, high elasticity, good mechanical strength and stability with high water-absorption ability. The application of the EPS22 gel on dermal full-thickness excision wounds in a rat model every two days, enhanced significantly wound healing activity and a total closure was achieved after 12 days of wound induction. Further, histological examination of biopsies showed advanced tissue regeneration, characterized by the presence of well-organized stratum of both derma and epidermis.

An original sodium alginate from Tunisian seaweed (Cystoseira barbata) was purified and characterized by circular dichroism (CD) and ATR-FTIR spectroscopies. ATR-FTIR spectrum of C. barbata sodium alginate (CBSA) showed the characteristic bands of mannuronic (M) and guluronic acids (G). The M/G ratio was estimated by CD (M/G - 0.59) indicating that CBSA was composed of 37% mannuronic acid and 63% guluronic acid. The analysis of viscosity of CBSA showed evidence of pseudoplastic fluid behaviour. The emulsifying capacity of CBSA was evaluated at different concentrations (0.25-3%), temperatures (25-100 degrees C) and pH (3.0-11.0). Compared to most commercial emulsifiers, the emulsion formulated by CBSA was found to be less sensitive to temperature changes and more stable at acidic pH. CBSA was examined for antioxidant properties using various antioxidant assays. CBSA exhibited important DPPH radical-scavenging activity (74% inhibition at a concentration of 0.5 mg/ml) and considerable ferric reducing potential. Effective hydroxyl-radical scavenging activity (82% at a concentration of 5 mg/ml) and potent protection activity against DNA breakage were also recorded for CBSA. However, in the linoleate beta-carotene system, CBSA exerted moderate antioxidant activity (60% at a concentration of 1.5 mg/ml). Therefore, CBSA can be used as a natural ingredient in food industry or in the pharmaceutical field. (C) 2014 Elsevier B.V. All rights reserved.