Structure‐Function Relationships of Rhamnolipid and Exopolysacharide Biosurfactants of Pseudomonas aeruginosa as Therapeutic Targets in Cystic Fibrosis Lung Infections

Chronic Pseudomonas aeruginosa lung infection is the cause of much morbidity and most of the mortality in cystic fibrosis (CF) patients. The high prevalence of P. aeruginosa infections in CF is related to the microbe\u27s large genome and mechanisms of adaptation to the CF lung environment, the host immune system and antibiotic resistance. Among a wide range of P. aeruginosa metabolites involved in infection development in CF, the biosurfactant compounds, rhamnolipids (RLs) and exopolysaccharides (EPSs), have important roles in the early stages of P. aeruginosa infection in CF. RLs and EPSs are involved in bacterial adhesion, biofilm formation, antibiotic resistance, and impairment of host immune system pathways, as well as in processes such as biofilm maintenance and the mucoid phenotype of P. aeruginosa, which lead to development of chronic infection. Due to the proposed roles of RLs and EPSs and the importance of prevention and treatment of P. aeruginosa respiratory infections in CF, these compounds are promising targets for patient therapy. In the future, impairment of P. aeruginosa quorum sensing (QS) pathways and modification of host respiratory mucus epithelial membranes should be considered as potential approaches in preventing respiratory infections caused by this microbe in CF patients

Production and characterization of rhamnolipids from Pseudomonas aeruginosa san ai

Production and characterization of rhamnolipid biosurfactant obtained by strain Pseudomonas aeruginosa san ai was investigated. With regard to carbon and nitrogen source several media were tested to enhance production of rhamnolipids. Phosphate-limited proteose peptone-ammonium salt (PPAS) medium supplemented with sun flower oil as a source of carbon and mineral ammonium chloride and peptone as a nitrogen source greatly improved rhamnolipid production, from 0.15 on basic PPAS (C/N ratio 4.0), to 3 g L-1, on optimized PPAS medium (C/N ratio 7.7). Response surface methodology analysis was used for testing effect of three factors: temperature, concentration of carbon and nitrogen source (w/w), in optimized PPAS medium on rhamnolipid production. Isolated rhamnolipids were characterized by IR and ESI-MS. IR spectra confirmed that isolated compound corresponds to rhamnolipid structure, whereas MS indicated that isolated preparation is a mixture of mono-rhamno-mono-lipidic, mono-rhamno-di-lipidic- and dirhamno- di-lipidic congeners

Effects of methyl oleate and tween 80 on the antibiotic productivity and the fatty acid composition of the total lipids of Streptomyces hygroscopicus CH-7

The effects of methyl oleate and Tween 80, hexaene H-85 production stimulators, on the fatty acid composition of the total lipids of S. hygroscopicus CH-7 were investigated. Besides oleic acid in the biomass, an increase of the branched chain fatty acid contents was observed: from 1.6 to 2.1 fold in the medium with methyl oleate and 2.5 - 2.9 in the medium with Tween 80 compared to the base medium. These two additives act differently on the growth of the producing strain and the uptake of valine, an essential nutrient. A decreased proteolytic activity and similar cellular fatty acid profiles indicate that the main effect of the added compounds is to facilitate the excretion of antibiotics to the outer medium, thus increasing biosynthesis

Rachel Touzé avec la participation de Jean-François Belhoste et Serge Pascal, Grilles de fenêtres et d’impostes en fer forgé, du XVe au XVIIIe siècle. Paris, Monum, Editions du Patrimoine, 2006, 288 p. (Albums du Centre de recherche sur les Monuments historiques)

Lacoue-Labarthe Marie-France. Rachel Touzé avec la participation de Jean-François Belhoste et Serge Pascal, Grilles de fenêtres et d’impostes en fer forgé, du XVe au XVIIIe siècle. Paris, Monum, Editions du Patrimoine, 2006, 288 p. (Albums du Centre de recherche sur les Monuments historiques). In: Bulletin Monumental, tome 166, n°4, année 2008. pp. 369-370

Adsorption of Candida rugosa lipase onto alumina: Effect of surface charge

The impact of the surface charge of alumina supports on the adsorption of Candida rugosa lipase was investigated in terms of the zeta potentials of the adsorption partners. The lipase adhered onto alumina with similar efficiency under both repulsive and attractive electrostatic conditions, shifting the zeta potential of the support towards that of the enzyme. The behavior was explained by a heterogeneous distribution of the surface charge of the lipase molecule. Special emphasis in this study was placed on the effect of immobilization on the enzyme kinetics and principal reasons for enzyme immobilization: improvement in stability and potential for reuse. The enzyme affinity was not altered by its adsorption onto alumina, while the Vmax value of the lipase decreased. The thermostability of the adsorbed lipase was improved. A significant potential for reuse was found

Genetic and Proteomic Analyses of a Proteasome-Activating Nucleotidase A Mutant of the Haloarchaeon Haloferax volcanii▿ †

The halophilic archaeon Haloferax volcanii encodes two related proteasome-activating nucleotidase proteins, PanA and PanB, with PanA levels predominant during all phases of growth. In this study, an isogenic panA mutant strain of H. volcanii was generated. The growth rate and cell yield of this mutant strain were lower than those of its parent and plasmid-complemented derivatives. In addition, a consistent and discernible 2.1-fold increase in the number of phosphorylated proteins was detected when the panA gene was disrupted, based on phosphospecific fluorescent staining of proteins separated by 2-dimensional gel electrophoresis. Subsequent enrichment of phosphoproteins by immobilized metal ion and metal oxide affinity chromatography (in parallel and sequentially) followed by tandem mass spectrometry was employed to identify key differences in the proteomes of these strains as well as to add to the restricted numbers of known phosphoproteins within the Archaea. In total, 625 proteins (approximately 15% of the deduced proteome) and 9 phosphosites were identified by these approaches, and 31% (195) of the proteins were identified by multiple phosphoanalytical methods. In agreement with the phosphostaining results, the number of identified proteins that were reproducibly exclusive or notably more abundant in one strain was nearly twofold greater for the panA mutant than for the parental strain. Enriched proteins exclusive to or more abundant in the panA mutant (versus the wild type) included cell division (FtsZ, Cdc48), dihydroxyacetone kinase-linked phosphoenolpyruvate phosphotransferase system (EI, DhaK), and oxidoreductase homologs. Differences in transcriptional regulation and signal transduction proteins were also observed, including those differences (e.g., OsmC and BolA) which suggest that proteasome deficiency caused an up-regulation of stress responses (e.g., OsmC versus BolA). Consistent with this, components of the Fe-S cluster assembly, protein-folding, DNA binding and repair, oxidative and osmotic stress, phosphorus assimilation, and polyphosphate synthesis systems were enriched and identified as unique to the panA mutant. The cumulative proteomic data not only furthered our understanding of the archaeal proteasome system but also facilitated the assembly of the first subproteome map of H. volcanii

Immobilization of Candida rugosa lipase by adsorption onto biosafe meso/macroporous silica and zirconia

Lipase from Candida rugosa was immobilized by adsorption onto laboratory prepared supports, silica SBA-15 and zirconia. The adsorption process was studied as a function of pH in terms of percent of adsorbed lipase, enzyme activity and zeta potential of support and enzyme. Several analytical approaches such as laser Doppler electrophoresis, Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) showed that the lipase was successfully immobilized onto both supports. The zeta-potential data suggest that the adsorption efficiency does not depends on the sign but on the magnitude of the surface charge of adsorption partners, and therefore underline the importance of their dispersion stability. Adsorption to material surface altered enzyme characteristics. nu(max), for the lipase immobilized onto silica and zirconia were 4.8-fold and 3.6-fold lower than that of the free lipase, respectively. The Km showed no alteration of enzyme-substrate affinity on zirconia support, whereas the enzyme immobilized on silica had 3.6 times lower affinity. Thermostability at 60 degrees C of the lipase was improved 12-fold on zirconia and 4-fold on silica. Finally, in examining reusability, the immobilized lipase retained more than 90% of initial activity after eight reuses on both supports. (C) 2014 Elsevier B.V. All rights reserved

Comparative Analysis of Rhamnolipids from Novel Environmental Isolates of Pseudomonas aeruginosa

International audienceA comparative analysis of rhamnolipids from environmental isolates of Pseudomonas aeruginosa was undertaken to evaluate strain-specific rhamnolipid fingerprints obtained under different growth conditions. Environmental isolates of P. aeruginosa produced rhamnolipids on different types of substrates, including cheap and renewable sources like sunflower oil from deep fryers and sunflower oil mill effluent. Rhamnolipids were monitored by high-performance liquid chromatography–electrospray ionization interface mass spectrometry, which allowed fast and reliable identification and quantification of the congeners present. The highest concentration of total rhamnolipids of 3.33 g/l was obtained by the strain P. aeruginosa 67, recovered from petroleum contaminated soil, and strains D1 (1.73 g/l) and D2 (1.70 g/l), recovered from natural microbial consortia originated from mazut-contaminated soil, grown on sunflower oil as a carbon source. Di- to mono-rhamnolipids ratios were in the range of 0.90–5.39 for different media composition and from 1.12 to 4.17 for different producing strains. Rhamnolipid profiles of purified mixtures of all tested strains are similar with chain length from C8–C12, pronounced abundance of Rha–C10–C10 and Rha–Rha–C10–C10 congeners, and a low content of 3-(3-hydroxyalkanoyloxy)-alkanoic acids. Concentrations of major congeners of RLs were found to slightly vary, depending on strain and growth conditions, while variations in minor congeners were more pronounced. Statistically significant increase of critical micelle concentration values was observed with lowering the ratio of total mono- to di-rhamnolipids ratio indicating that mono-rhamnolipids start to form micelles at lower concentration than di-rhamnolipids