9 research outputs found

    Stability of (Bio)Functionalized Porous Aluminum Oxide

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    Porous aluminum oxide (PAO), a nanostructured support for, among others, culturing microorganisms, was chemically modified in order to attach biomolecules that can selectively interact with target bacteria. We present the first comprehensive study of monolayer-modified PAO using conditions that are relevant to microbial growth with a range of functional groups (carboxylic acid, α-hydroxycarboxylic acid, alkyne, alkene, phosphonic acid, and silane). Their stability was initially assessed in phosphate-buffered saline (pH 7.0) at room temperature. The most stable combination (PAO with phosphonic acids) was further studied over a range of physiological pHs (4–8) and temperatures (up to 80 °C). Varying the pH had no significant effect on the stability, but it gradually decreased with increasing temperature. The stability of phosphonic acid-modified PAO surfaces was shown to depend strongly on the other terminal group of the monolayer structure: in general, hydrophilic monolayers were less stable than hydrophobic monolayers. Finally, an alkyne-terminated PAO surface was reacted with an azide-linked mannose derivative. The resulting mannose-presenting PAO surface showed the clearly increased adherence of a mannose-binding bacterium, <i>Lactobacillus plantarum</i>, and also allowed for bacterial outgrowth

    Mucus adhesion and SpaCBA pili gene diversity among <i>L. rhamnosus</i>.

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    <p>Panel (A) shows the genotype and phenotype of all strains. Based on our genomic analysis, pilin and sortase genes were assigned as present (green) or divergent (red). Sequences of corresponding genes were further analyzed using blastx. The sequence identity was shown by an upper triangle superposed to the SOLiD genomic data, where the colour gradient corresponds to the identity percentage to GG pili genes. We also indicated if the strains were tested by immunoblotting analysis (DB), electron microscopy (EM) or <i>in vitro</i> competitive binding assay (AB). Green is for pili positive and red for pili negative. Panel (B) shows the human mucus binding ability (%) of all <i>L. rhamnosus</i> isolates ranked from the lowest to the highest mucus binder.</p

    Pilosotype distribution in our <i>L. rhamnosus</i> collection.

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    <p>The table describes the niches or isolation sources, the number of strains per group and their pilosotype, <i>i.e.</i> the presence of an intact and functional SpaCBA pili cluster as determined in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003683#pgen-1003683-g006" target="_blank">Figure 6</a>. Probiotic strains GG, VIFIT, IDOF, AK-RO and CO-RO were classified as intestinal isolates. The group ‘Others’ contained strains of unspecified origins (clinical specimens) or from minor isolation source (<i>n</i><2), <i>i.e.</i> hip punction or pus.</p

    CRISPR spacer oligotyping and CRISPR-associated protein diversity in <i>L. rhamnosus</i> species.

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    <p>Panel (A) illustrates the genetic organization of the CRISPR system and its associated genes in <i>L. rhamnosus</i> GG. Panel (B) shows the conservation (blue), the partial conservation (grey) or the absence (yellow) of <i>L. rhamnosus</i> GG spacers. The presence (green) or the absence (red) of the <i>cas</i> genes is also indicated in Panel (C). Strains are organized according to their genetic relatedness defined in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003683#pgen-1003683-g001" target="_blank">Figure 1</a>.</p

    API 50CH fermentative profile of <i>L. rhamnosus</i> strains.

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    <p>Fermentation ability is indicated in black for positive, grey for partially positive and white for negative. Strains are organized according to their genetic relatedness as defined in the hierarchical clustering and coloured according to their respective niche/origin (<a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003683#pgen-1003683-g001" target="_blank">Figure 1</a>). Carbohydrates of interest are marked by a red asterisk. Black arrows show fermentative profile shifts among <i>L. rhamnosus</i> strains.</p

    Analysis of genome diversity in <i>L. rhamnosus</i> by mapped SOLiD sequencing.

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    <p>The 100 <i>L. rhamnosus</i> strains were clustered using hierarchical clustering <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003683#pgen.1003683-Sturn1" target="_blank">[78]</a> based on their relative shared gene content with <i>L. rhamnosus</i> GG. Strain names were colour-coded as follows: green for dairy isolates, purple for intestinal isolates, orange for oral isolates, magenta for vaginal isolates and blue for clinical/other isolates. Four main groups or clusters were highlighted and numbered. The <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003683#pgen-1003683-g001" target="_blank">Figure 1</a> also shows the 17 variable chromosomal regions identified in GG, as further detailed in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003683#pgen-1003683-t001" target="_blank">Table 1</a>. Each row corresponds to one strain, and each column shows the genes in these variable regions, colour-coded as follows: blue for present and yellow for absent.</p

    Anthropocentric view of the <i>L. rhamnosus</i> species.

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    <p>The interactions between <i>L. rhamnosus</i> and the human cavities are frequent and occur in various contexts, <i>i.e.</i> consumption of food products (common scenario) or development of bacteremia (rare event). For each niche or isolation source, the strains were grouped according to their geno-phenotype (radar plot). The geno-phenotype is based on the scoring of distinctive genetic and phenotypic traits measured in this study, <i>i.e.</i> gene-content, CRISPR oligotype, bile resistance, pilosotype, sugar group I (dulcitol, D-arabinose and L-fucose), sugar group II (D-saccharose, D-maltose, methyl-α-D-glucopyranoside and D-turanose) and sugar group III(L-rhamnose, L-sorbose, D-ribose and D-lactose). The distinction between the two main geno-phenotypes mostly relies on gene acquisition and loss, point mutations, genetic reorganization that possibly reflect strain adaptation to an ecological niche.</p
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