Bacillus methylotrophicus DCS1: Production of Different Lipopeptide Families, In Vitro Antifungal Activity and Suppression of Fusarium Wilt in Tomato Plants.

The present work aims to quantitatively and qualitatively monitor the production of lipopeptide mixtures by Bacillus methylotrophicus DCS1 strain in Landy medium and to investigate the antifungal activities of DCS1 strain and its produced lipopeptides. The in vitro activities were tested by the direct confrontation and agar well diffusion methods, while the in vivo study was carried out in order to test the efficiency of DCS1 bacterial suspension in the control of Fusarium wilt in tomato plants. Identification of lipopeptides by mass spectrometry (LC/MSD-TOF) showed that lipopeptide isoforms produced during the first 24 h and 48 h of fermentation are identical, belonging to bacillomycin D and fengycins A and B homologues with a difference in the yield of production.

Manufacturing PLA/PCL Blends by Ultrasonic Molding Technology.

Ultrasonic molding (USM) is a good candidate for studying the plasticization of polymer mixtures or other composite materials due to either the little amount of material needed for processing, low waste or the needed low pressure and residence time of the mold. Thus, the novelty of this research is the capability of USM technology to process PLA/PCL blends and their corresponding neat materials, encompassing all the production stages, from raw material to the final specimen. The major findings of the work revealed that the thermal properties of the blends were not affected by the USM process, although the crystallinity degree experienced variations, decreasing for PLA and increasing for PCL, which was attributed to the crystallization rate of each polymer, the high process speed, the short cooling time and the small particle size.

Investigation of halotolerant marine Staphylococcus sp. CO100, as a promising hydrocarbon-degrading and biosurfactant-producing bacterium, under saline conditions.

A halotolerant strain CO100 of Staphylococcus sp. was isolated from contaminated sediments taken from the fishing harbour of Sfax, Tunisia, as an efficient hydrocarbonoclastic candidate. Strain CO100 exhibited a high capacity to break down almost 72% of the aliphatic hydrocarbons contained in crude oil (1%, v/v), used as the sole carbon and energy source, after 20 days of culture, at 100 g/l NaCl, 37 °C and 180 rpm.

Short and ultrashort antimicrobial peptides anchored onto soft commercial contact lenses inhibit bacterial adhesion.

Commercial soft contact lenses were chemically modified to incorporate antibacterial properties. Contact lenses and especially soft contact lenses present a risk of eye microbial infection that eventually may lead to vision loss. This is a significant health issue given the large population of contact lenses wearers worldwide.

Antifungal and antiprotozoal green amino acid-based rhamnolipids: Mode of action, antibiofilm efficiency and selective activity against resistant Candida spp. strains and Acanthamoeba castellanii.

Nowadays, infections caused by fungi and protists constitute a serious problem for public health services. The limited number of treatment options coupled with the increasing number of resistant microorganisms makes necessary the development of new non-toxic antifungal and antiprotozoal agents. Cationic amino acid-based rhamnolipids have been recently prepared by our group and exhibited good antibacterial activity.

Marinobacter maroccanus sp. nov., a moderately halophilic bacterium isolated from a saline soil.

During the taxonomic investigation of exopolymer-producing halophilic bacteria, a rod-shaped, motile, Gram-stain-negative, halophilic bacterium, designated strain N4, was isolated from a saline soil located in northern Morocco. Optimal growth of the isolate was at 30-37 ºC and at pH 7.0-8.

Production, characterization and biotechnological potential of lipopeptide biosurfactants from a novel marine Bacillus stratosphericus strain FLU5.

This work aimed at studying the potential of a new hydrocarbonoclastic marine bacterium, Bacillus stratosphericus FLU5, to produce an efficient surface-active agent BS-FLU5. Biosurfactant production was examined on different carbon sources; using the surface tension measurement and the oil displacement test. Strain FLU5 showed its capacity to produce biosurfactants from all tested substrates, in particular the residual frying oil, which is a cheap renewable carbon source alternative, thus minimizing the high cost of producing those surfactants.

Isolation and characterization of kurstakin and surfactin isoforms produced by Enterobacter cloacae C3 strain.

In this work, the extraction, structural analysis, and identification as well as antimicrobial, anti-adhesive, and antibiofilm activities of lipopeptides produced by Enterobacter cloacae C3 strain were studied. A combination of chromatographic and spectroscopic techniques offers opportunities for a better characterization of the biosurfactant structure. Thin layer chromatography (TLC) and HPLC for amino acid composition determination are used.

Replicability of Ultrasonic Molding for Processing Thin-Wall Polystyrene Plates with a Microchannel.

Ultrasonic molding is a new technology for processing small and micro polymeric components with reasonable cost and energy savings when small and medium batch sizes are required. However, when microcomponents are manufactured, the replicability of different micro features has to be guaranteed. The aim is to investigate the capability of ultrasonic molding technology for processing thin-wall plates of polystyrene with a microchannel, analyzing the filling behavior, the optical transparency, and the dimensional accuracy of the thin plate.

Complete Genome Sequence of Marinobacter flavimaris LMG 23834, Which Is Potentially Useful in Bioremediation.

The complete genome sequence of the halophilic strain LMG 23834 is presented here. The genomic information of this type strain will be useful for taxonomic purposes and for its potential use in bioremediation studies.

Cortical Auditory-Evoked Responses in Preterm Neonates: Revisited by Spectral and Temporal Analyses.

Characteristic preterm EEG patterns of "Delta-brushes" (DBs) have been reported in the temporal cortex following auditory stimuli, but their spatio-temporal dynamics remains elusive. Using 32-electrode EEG recordings and co-registration of electrodes' position to 3D-MRI of age-matched neonates, we explored the cortical auditory-evoked responses (AERs) after 'click' stimuli in 30 healthy neonates aged 30-38 post-menstrual weeks (PMW). (1) We visually identified auditory-evoked DBs within AERs in all the babies between 30 and 33 PMW and a decreasing response rate afterwards.

Interaction of the Lipopeptide Biosurfactant Lichenysin with Phosphatidylcholine Model Membranes.

Lichenysins produced by Bacillus licheniformis are anionic lipopeptide biosurfactants with cytotoxic, antimicrobial, and hemolytic activities that possess enormous potential for chemical and biological applications. Through the use of physical techniques such as differential scanning calorimetry, small- and wide-angle X-ray diffraction, and Fourier-transform infrared spectroscopy as well as molecular dynamics simulations, we report on the interaction of Lichenysin with synthetic phosphatidylcholines differing in hydrocarbon chain length. Lichenysin alters the thermotropic phase behavior of phosphatidylcholines, displaying fluid-phase immiscibility and showing a preferential partitioning into fluid domains.

Structural characterization and identification of cyclic lipopeptides produced by Bacillus methylotrophicus DCS1 strain.

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).

Antioxidant properties, antimicrobial and anti-adhesive activities of DCS1 lipopeptides from Bacillus methylotrophicus DCS1.

Background: 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.

Results: The produced biosurfactants were characterized as lipopeptides molecules by using thin layer chromatography (TLC) and Fourier transform infrared spectroscopy (FT-IR). The DCS1 lipopeptides were assayed for their antioxidant activity through five different tests.

Green Catanionic Gemini Surfactant-Lichenysin Mixture: Improved Surface, Antimicrobial, and Physiological Properties.

Catanionic surfactant mixtures form a wide variety of organized assemblies and aggregates with improved physicochemical and biological properties. The green catanionic mixture NN-Bis(Ncaproylarginine) α,ω-propyldiamide (C(CA)):Lichenysin (molar ratio 8:2) showed antimicrobial synergies against Yersinia enterocolitica, Bacillus subtilis, Escherichia coli O157:H7, and Candida albicans. Flow cytometry and viability studies indicated that this catanionic mixture increases the probability of Y.

Micellization and Antimicrobial Properties of Surface-Active Ionic Liquids Containing Cleavable Carbonate Linkages.

Imidazolium-based ionic liquids (ILs) containing cleavable carbonate linkages, 1-alkyloxycarbonyloxyethyl-3-methylimidazolium chlorides with alkyl chains of 10, 12, and 14 carbon atoms, were synthesized, and their self-assembly behavior and antimicrobial activity were investigated. Differential scanning calorimetry and polarized optical microscopy studies reveal that carbonate-functionalized ILs form stable thermotropic smectic liquid-crystalline phases over a wide range of temperature. The surface activity and aggregation behavior of these new ILs were investigated by tensiometry, conductometry, potentiometry, and spectrofluorimetry.

Lichenysin-geminal amino acid-based surfactants: Synergistic action of an unconventional antimicrobial mixture.

Recently it has been demonstrated that catanionic mixtures of oppositely charged surfactants have improved physicochemical-biological properties compared to the individual components. Isotherms of mixtures of an anionic biosurfactant (lichenysin) and a cationic aminoacid surfactant (C(LA)) indicate a strong interaction suggesting the formation of a new "pseudo-surfactant". The antimicrobial properties of the mixture lichenysin and C(LA) M80:20, indicate a synergistic effect of the components.

New cationic vesicles prepared with double chain surfactants from arginine: Role of the hydrophobic group on the antimicrobial activity and cytotoxicity.

Cationic double chain surfactants have attracted much interest because they can give rise to cationic vesicles that can be used in biomedical applications. Using a simple and economical synthetic approach, we have synthesized four double-chain surfactants with different alkyl chain lengths (LANHCx). The critical aggregation concentration of the double chain surfactants is at least one order of magnitude lower than the CMC of their corresponding single-chain LAM and the solutions prepared with the LANHCx contain stable cationic vesicles.

Kinetic and Structural Aspects of the Permeabilization of Biological and Model Membranes by Lichenysin.

The various lichenysins produced by Bacillus licheniformis are anionic surfactants with interesting properties. Here it is shown that lichenysin caused hemolysis of human erythrocytes, which varied with lichenysin concentration in a sigmoidal manner. The release of K(+) from red blood cells induced by lichenysin preceded the leakage of hemoglobin, and in addition, hemolysis could be impeded by the presence of compounds in the external medium having a size larger than that of PEG 3350, indicating a colloid-osmotic mechanism for hemolysis.

Purification and identification of Bacillus subtilis SPB1 lipopeptide biosurfactant exhibiting antifungal activity against Rhizoctonia bataticola and Rhizoctonia solani.

This study reports the potential of a soil bacterium, Bacillus subtilis strain SPB1, to produce lipopeptide biosurfactants. Firstly, the crude lipopeptide mixture was tested for its inhibitory activity against phytopathogenic fungi. A minimal inhibitory concentration (MIC), an inhibitory concentration at 50% (IC50%), and an inhibitory concentration at 90% (IC90%) values were determined to be 0.

Tryptophan-containing lipopeptide antibiotics derived from polymyxin B with activity against Gram positive and Gram negative bacteria.

Resistance to all known antibiotics is a growing concern worldwide, and has renewed the interest in antimicrobial peptides, a structurally diverse class of amphipathic molecules that essentially act on the bacterial membrane. Propelled by the antimicrobial potential of this compound class, we have designed three new lipopeptides derived from polymyxin B, sp-34, sp-96 and sp-100, with potent antimicrobial activity against both Gram positive and Gram negative bacteria. The three peptides bind with high affinity to lipopolysaccharide as demonstrated by monolayer penetration and dansyl-displacement.

Optimizing the production of the biosurfactant lichenysin and its application in biofilm control.

Aims: Apply response surface methodology (RSM) to develop and optimize an economical medium for lichenysin production, which is a surfactant produced by Bacillus licheniformis and evaluate the application of lichenysin in the prevention and disruption of pathogenic micro-organism biofilm that creates health problems in the food industry and hospitals.

Results: An economical medium containing molasses was optimized to enhance lichenysin production by RSM. A production of 3·2 g l(-1) of lichenysin was achieved with an optimum medium containing 107·82 g l(-1) of molasses, 6·47 g l(-1) of NaNO3 and 9·7 g l(-1) of K2 HPO4 /KH2 PO4 , in which molasses and phosphate salts had a significant effect on biosurfactant production.

In Silico/In Vivo Insights into the Functional and Evolutionary Pathway of Pseudomonas aeruginosa Oleate-Diol Synthase. Discovery of a New Bacterial Di-Heme Cytochrome C Peroxidase Subfamily.

As previously reported, P. aeruginosa genes PA2077 and PA2078 code for 10S-DOX (10S-Dioxygenase) and 7,10-DS (7,10-Diol Synthase) enzymes involved in long-chain fatty acid oxygenation through the recently described oleate-diol synthase pathway. Analysis of the amino acid sequence of both enzymes revealed the presence of two heme-binding motifs (CXXCH) on each protein.

A bioinspired peptide scaffold with high antibiotic activity and low in vivo toxicity.

Bacterial resistance to almost all available antibiotics is an important public health issue. A major goal in antimicrobial drug discovery is the generation of new chemicals capable of killing pathogens with high selectivity, particularly multi-drug-resistant ones. Here we report the design, preparation and activity of new compounds based on a tunable, chemically accessible and upscalable lipopeptide scaffold amenable to suitable hit-to-lead development.

Self-assembly and antimicrobial activity of long-chain amide-functionalized ionic liquids in aqueous solution.

Surface active amide-functionalized ionic liquids (ILs) consisting of a long alkyl chain (C6C14) connected to a polar head group (methylimidazolium or pyridinium cation) via an amide functional group were synthesized and their thermal stability, micellar properties and antimicrobial activity in aqueous solution investigated. The incorporation of an amide group increased the thermal stability of the functionalized ionic liquids compared to simple alkyl chain substituted ionic liquids. The surface activity and aggregation behaviour in aqueous solution of amide-functionalized ionic liquids were examined by tensiometry, conductivity and spectrofluorimetry.