A study was made of two glucomannans, one isolated by alkaline borate extraction of Sitka spruce wood and the second from black spruce. These were methylated by the Hakomori procedure employing sodium hydride in dimethyl sulfoxide. Considerable experimentation was done to determine the best conditions for methylation and to demonstrate the utility and practicability of analysis by these methods. Some inferences regarding the structure of the glucomannans are drawn from the methylation data. / Science, Faculty of / Chemistry, Department of / Graduate

The structural elucidation of bacterial capsular polysaccharides is traditionally performed by using "wet chemical procedures" but instrumental methods such as nuclear magnetic resonance spectroscopy and novel mass spectrometric techniques are coming into prominence. In this thesis three different mass spectrometric techniques were investigated to establish their applicability for the sequencing of bacterial capsular polysaccharides. These techniques included fast atom bombardment (FAB), desorption chemical ionisation (DCI) and laser desorption ionisation Fourier transform ion cyclotron resonance spectroscopy (LDI-FTICR). The soft ionisation produced by these methods allows sequential loss of individual sugar residues without excess thermal decomposition of the ring. Thus sequencing of oligosaccharides could be achieved. The most common of all these three techniques is FAB which is already considered to be a well established form of soft ionisation, although the exact mechanism of ionisation is unknown. The utilisation of DCI has not been thoroughly exploited in carbohydrate research, due to the non-volatility of oligosaccharides and the possible thermal decomposition of the sample in the source. LDI-FTICR due to the general unavailability of the instrument has only been used for model studies of "shelf carbohydrates". In the course of this work it was found that FAB MS and DCIMS complement each other. The sequence of linear oligosaccharides of up to five sugar units can be deduced from either the native or permethylated sample. If the oligosaccharides investigated were generated by phage-borne enzyme, the total sequence of the native polysaccharide can be established. This was illustrated by the use of FABMS on Klebsiella K44 de-O-acetylated oligosaccharide and the reduced oligosaccharide. The sequence of the polysaccharide was shown to be: [Formula Omitted] The structural elucidation of bacterial capsular polysaccharides is traditionally performed by using "wet chemical procedures" but instrumental methods such as nuclear magnetic resonance spectroscopy and novel mass spectrometric techniques are coming into prominence. In this thesis three different mass spectrometric techniques were investigated to establish their applicability for the sequencing of bacterial capsular polysaccharides. These techniques included fast atom bombardment (FAB), desorption chemical ionisation (DCI) and laser desorption ionisation Fourier transform ion cyclotron resonance spectroscopy (LDI-FTICR). The soft ionisation produced by these methods allows sequential loss of individual sugar residues without excess thermal decomposition of the ring. Thus sequencing of oligosaccharides could be achieved. The most common of all these three techniques is FAB which is already considered to be a well established form of soft ionisation, although the exact mechanism of ionisation is unknown. The utilisation of DCI has not been thoroughly exploited in carbohydrate research, due to the non-volatility of oligosaccharides and the possible thermal decomposition of the sample in the source. LDI-FTICR due to the general unavailability of the instrument has only been used for model studies of "shelf carbohydrates". In the course of this work it was found that FAB MS and DCIMS complement each other. The sequence of linear oligosaccharides of up to five sugar units can be deduced from either the native or permethylated sample. If the oligosaccharides investigated were generated by phage-borne enzyme, the total sequence of the native polysaccharide can be established. This was illustrated by the use of FABMS on Klebsiella K44 de-O-acetylated oligosaccharide and the reduced oligosaccharide. The sequence of the polysaccharide was shown to be: [Formula Omitted] The location of acid-labile pyruvic acid acetal group, like base-labile acetate group, is also difficult to establish chemically. The fragment ions arising from permethylated oligosaccharides were mostly non-reducing end residues. This is due to the stability of oxonium ion formation. However, when an amino sugar was investigated, oxonium ions were not observed. Instead the cleavage took place between the glycosidic oxygen and the reducing end residue. This fragmentation route is in sharp contrast to previously reported spectral data. This may be due to the fact that amino sugars strengthen the glycosidic bond between the oxygen and the carbon-1. LDI-FTICR was investigated for its applicability to a "real" sample. The sequence of the linear Klebsiella K44 de-O-acetylated, phage degraded oligosaccharide was determined from the spectrum. Furthermore, a few positions of linkage were also deduced from ring cleavage fragments. Although linkage positions can be obtained from methylation analysis data, some sugar residues such as deoxyhexoses are more labile than others, thus positions of linkage obtained from LDI-FTICR can be used for confirmation. / Science, Faculty of / Chemistry, Department of / Graduate

Includes bibliographical references. / As part of an international collaborative programme concerned with the elucidation of the molecular structures of capsular polysaccharides (the K-antigen) produced by strains of the bacterial genus Klebsiella, the capsular material of serotype K71 has been investigated, and that of serotypes K36 and K64 re-examined, by novel enzymic and spectroscopic methods. The cultivation and employment of bacteriophages which are capable of cleaving (by specific glycanase action) the isolated, cognate bacterial polysaccharide in vitro has yielded highly significant oligosaccharides. These may represent the repeating unit in the polysaccharide or be derivatives resulting from conversion of uronic acid to the 4,5-unsaturated analogue where, as found for serotype K64, the mode of cleavage is β-elimination not hydrolysis. The oligosaccharides thus generated have proved to be far more amenable to chemical and spectroscopic studies than their parent polymers, thereby facilitating complete characterisation of the molecular structures of the original polysaccharides. Chemical methods applied to these oligosaccharides included specific degradations by periodate oxidation and acid-, alkali- or enzyme- catalysed hydrolysis, products being identified by methylation analysis (involving the extensive use of gas-liquid chromatography coupled to mass spectrometry) and spectroscopic studies (mass and n.m.r.). During the course of these investigations it became apparent that the structures of the intact oligosaccharides (containing six or seven sugar residues) could be determined almost entirely from spectroscopic analysis, chiefly by detailed two-dimensional n.m.r. studies involving the use of high field spectrometers and the application of homo- and heteronuclear shift correlated spectroscopy, the sequence of sugar units being confirmed by mass spectrometric analysis of the permethylated derivatives. Methylation analysis of the oligosaccharides derived from Klebsiella serotype K36 proved that the glucuronic acid residue is linked through 0-2, and not 0-4 as published by others; this finding was corroborated during characterisation of the monomeric oligosaccharide by mass- and n.m.r. spectroscopy. Bacteriophage φ64 was shown to cleave the cognate K64 exopolysaccharide by a β-elimination process; the resulting hex-4-enuronic acid, present as a terminal group in the derived oligosaccharide was fully characterised by hydrogenation and g.l.c.-m.s. of acetylated products, and by detailed n.m.r. studies including long-range heteronuclear experiments. Finally the structure of the heptasaccharide repeating unit of the Klebsiella K71 capsular polysaccharide was established by spectroscopic analysis of the oligosaccharides derived by bacteriophage φ71 cleavage of the polymer; features of the proposed structure were confirmed by chemical degradation studies performed on the native polysaccharide.

No description available.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

No description available.

Le psoriasis est une maladie cutanée multifactorielle qui est caractérisée, entre autres, par l'hyperplasie épidermique, causée par une hyperprolifération et une différenciation anormale des kératinocytes. Plusieurs traitements existent pour soigner la maladie, mais leurs effets secondaires peuvent affecter l'observance des patients. Ainsi, certains, dont les cas sont légers, préfèrent utiliser des crèmes pour soulager leurs symptômes, mais très peu sont adaptées aux peaux psoriasiques. Les extraits de sources marines, dont Aldavineᵀᴹ 5X, un complexe de polysaccharides d'algues (CPA) de la compagnie Lucas Meyer Cosmetics, et ses polysaccharides, le fucane (FUC) et le galactane (GAL), connaissent un intérêt grandissant pour leurs propriétés antiprolifératives contre certains cancers. Puisque le psoriasis comporte aussi un aspect prolifératif, ces extraits pourraient aussi posséder certaines propriétés antipsoriasiques. L'objectif de ce projet est d'évaluer le potentiel antipsoriasique du CPA et des polysaccharides FUC et GAL, individuellement. Les substituts cutanés sains et psoriasiques ont été produits par génie tissulaire selon la méthode d'auto-assemblage, dont certains ont été traités avec le CPA(1 % ou 2 %), FUC (0,25 mg/mL ou 0,5 mg/mL), GAL (0,625 mg/mL ou 1,25 mg/mL) ou du méthotrexate (MTX; 734 μM), servant de contrôle positif. Le MTX, le CPA et les polysaccharides FUC et GAL ont diminué l'épaisseur de l'épiderme vivant des kératinocytes psoriasiques, qui est augmenté dans le psoriasis. Également, la plupart de ces traitements ont régulé l'hyperprolifération et la différenciation anormale des kératinocytes psoriasiques, notamment en diminuant l'expression du Ki-67 et de la kératine 14, des marqueurs dont l'expression est augmentée dans le psoriasis, et en augmentant celle de la loricrine, où l'expression y est diminuée ou nulle. En définitive, le CPA et ses polysaccharides ont un effet antipsoriasique sur des substituts cutanés produits par génie tissulaire, en régulant l'hyperprolifération et la différenciation anormale des kératinocytes. / Psoriasis is a multifactorial skin disease that can be defined, in part, by epidermal hyperplasia, due to hyperproliferation and abnormal differentiation of the keratinocytes. Several treatments are available to manage the disease, but side effects can affect patient compliance. Therefore, patients with mild psoriasis use skincare creams to alleviate their symptoms, but very few are formulated to be suitable for psoriatic skin. Recent interest for marine extracts, such as Aldavineᵀᴹ 5X, a complex of algae polysaccharides (CPA) from the company Lucas Meyer Cosmetics, and its polysaccharides, fucan (FUC) and galactan (GAL), is growing due to their antiproliferative properties against some cancers. Since hyperproliferation is also present in psoriasis, these extracts may also have some antipsoriatic properties. This project aims to determine the antipsoriatic potential of CPA and its polysaccharides FUC and GAL, separately. Healthy and psoriatic skin substitutes were produced by tissue engineering, according to the self-assembly method, some treated with CPA (1 % or 2 %), FUC (0.25 mg/mL or 0.5 mg/mL), GAL (0.625 mg/mL or 1.25 mg/mL) or methotrexate (MTX; 734 μM), used as a reference compound. MTX, CPA, FUC and GAL reduced epidermal thickness of the psoriatic keratinocytes, which is usually increased in psoriasis. Furthermore, most of the treatments regulated the hyperproliferation and abnormal differentiation of psoriatic keratinocytes, notably by reducing the expression of Ki-67 and keratin 14, whose expression is increased in psoriasis, and by promoting the expression of loricrin, whose expression is decreased or absent in the pathology. Ultimately, CPA and its polysaccharides have an antipsoriatic effect on skin substitutes produced by tissue engineering, by regulating hyperproliferation and abnormal differentiation of keratinocytes.

Lai Kin Ming Connie. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 121-141). / Abstracts in English and Chinese. / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Introduction on growth cycle of mushroom --- p.1 / Chapter 1.2 --- Literature review of mushroom biological activities --- p.3 / Chapter 1.2.1 --- Various bioactivities of mushroom --- p.3 / Chapter 1.2.2 --- Components responsible for various bioactivities of mushrooms --- p.3 / Chapter 1.3 --- Mushroom polysaccharides and polysaccharide-protein complexes --- p.5 / Chapter 1.3.1 --- Polysaccharides important for antitumor effects --- p.5 / Chapter 1.3.2 --- Polysaccharide-protein complexes important for antitumor effects --- p.7 / Chapter 1.4 --- Structure-function relationship of antitumor activities of polysaccharides --- p.8 / Chapter 1.4.1 --- Effect of molecular mass --- p.8 / Chapter 1.4.2 --- Effect of linkages --- p.9 / Chapter 1.4.3 --- Effect of degree of branching --- p.9 / Chapter 1.4.4 --- Effect of conformation --- p.10 / Chapter 1.5 --- Immunomodulatory effects of mushroom polysaccharides and polysaccharide-protein complexes --- p.11 / Chapter 1.5.1 --- Immunomodulatory effects of polysaccharides --- p.11 / Chapter 1.5.1.1 --- Bioactive polysaccharides in Lentinus edodes --- p.11 / Chapter 1.5.1.2 --- Bioactive polysaccharides in Ganoderma lucidum --- p.12 / Chapter 1.5.2 --- Immunomodulatory effects of polysaccharide-protein complexes --- p.12 / Chapter 1.5.2.1 --- Bioactive polysaccharide-protein complexes in Trametes versicolor --- p.13 / Chapter 1.5.3 --- Immunotherapeutic effects of mushroom polysaccharides --- p.14 / Chapter 1.6 --- Cell cycle and apoptosis --- p.14 / Chapter 1.6.1 --- Introduction of cell cycle --- p.14 / Chapter 1.6.2 --- Cell cycle regulation --- p.15 / Chapter 1.6.3 --- Antitumor effects through apoptotic gene regulation --- p.17 / Chapter 1.7 --- Mushroom sclerotium with antitumor activity --- p.20 / Chapter 1.7.1 --- Literature review on Pleurotus tuber-regium --- p.20 / Chapter 1.7.2 --- Literature review on Poria cocos --- p.22 / Chapter 1.7.3 --- Literature review on Polyporus rhinocerus --- p.23 / Chapter 1.8 --- Objectives --- p.23 / Chapter Chapter 2. --- Materials and Methods --- p.25 / Chapter 2.1 --- Materials --- p.25 / Chapter 2.1.1 --- Mushroom sclerotia --- p.25 / Chapter 2.1.2 --- Animal Model --- p.25 / Chapter 2.1.3 --- Cell lines --- p.27 / Chapter 2.2 --- Methods --- p.28 / Chapter 2.2.1 --- Extraction Scheme for mushroom sclerotia --- p.28 / Chapter 2.2.1.1 --- Hot water extraction only --- p.28 / Chapter 2.2.1.2 --- Sequential extraction scheme --- p.28 / Chapter 2.2.2 --- Measurement of monosaccharide profile --- p.31 / Chapter 2.2.2.1 --- Acid Depolymerisation --- p.31 / Chapter 2.2.2.2 --- Neutral Sugar Derivatization --- p.31 / Chapter 2.2.2.3 --- Gas Chromatography (GC) --- p.32 / Chapter 2.2.3 --- High Pressure Liquid Chromatography (HPLC) --- p.33 / Chapter 2.2.3.1 --- Size exclusion chromatography --- p.33 / Chapter 2.2.3.2 --- Anion exchange chromatography --- p.34 / Chapter 2.2.4 --- Linkage analysis by methylation --- p.34 / Chapter 2.2.4.1 --- Preparation of partially methylated polysaccharides --- p.34 / Chapter 2.2.4.2 --- Preparation of partially methylated alditol acetates (PMAAs) --- p.37 / Chapter 2.2.4.3 --- Gas chromatography-Mass spectrometry (GC-MS) analysis --- p.37 / Chapter 2.2.5 --- Determination of total sugar by phenol-sulphuric acid Method --- p.38 / Chapter 2.2.6 --- Determination of acidic sugars by measurement of uronic acid content --- p.39 / Chapter 2.2.7 --- Determination of protein content by Lowry-Folin method --- p.40 / Chapter 2.2.8 --- Chemical modification by carboxymethylation --- p.41 / Chapter 2.2.9 --- In vitro antitumor assay --- p.41 / Chapter 2.2.9.1 --- Trypan blue exclusion assay --- p.42 / Chapter 2.2.9.2 --- MTT Assay --- p.42 / Chapter 2.2.10 --- Cell cycle analysis by Flow Cytometry --- p.43 / Chapter 2.2.11 --- In vivo antitumor and immunomodulatory assay --- p.44 / Chapter 2.2.11.1 --- Measurement on tumor growth --- p.44 / Chapter 2.2.11.2 --- Blood sampling for immunostimulatory effects --- p.45 / Chapter 2.2.12 --- Mouse Cytokine Array --- p.45 / Chapter 2.2.13 --- Quantification of Mouse IL-13 by ELISA --- p.46 / Chapter 2.2.14 --- Enumeration of peritoneal cells --- p.47 / Chapter 2.2.15 --- Enumeration of splenocytes --- p.49 / Chapter 2.2.16 --- Statistical methods --- p.50 / Chapter Chapter 3. --- Results and Discussion --- p.51 / Chapter 3.1 --- Yield of crude mushroom sclerotial extracts --- p.51 / Chapter 3.2 --- Chemical composition of crude mushroom sclerotial extracts --- p.57 / Chapter 3.2.1 --- Total carbohydrate content --- p.57 / Chapter 3.2.2 --- Uronic acid content --- p.58 / Chapter 3.2.3 --- Soluble protein content --- p.58 / Chapter 3.3 --- Monosaccharide profiles of mushroom sclerotial extracts by GC --- p.60 / Chapter 3.4 --- Chromatographic analyses of mushroom sclerotial extracts --- p.65 / Chapter 3.4.1 --- Molecular weight profile by size exclusion chromatography (SEC) --- p.65 / Chapter 3.4.2 --- Charge distribution by ion exchange chromatography (IEC) --- p.73 / Chapter 3.5 --- Antitumor effects of mushroom sclerotial extracts from hot water extraction alone --- p.73 / Chapter 3.5.1 --- In vitro antiproliferative study by HL-60 --- p.73 / Chapter 3.5.2 --- In vitro antiproliferative study by MCF-7 --- p.74 / Chapter 3.5.3 --- In vivo antitumor study by BALB/c mice --- p.75 / Chapter 3.6 --- Antitumor effects of extracts from sequential extraction scheme --- p.76 / Chapter 3.6.1 --- In vitro antiproliferative study by HL-60 --- p.76 / Chapter 3.6.2 --- In vitro antiproliferative study by MCF-7 --- p.78 / Chapter 3.6.3 --- In vivo antitumor study by BALB/c mice --- p.80 / Chapter 3.7 --- Comparison of in vitro and in vivo activities of mushroom sclerotial extracts --- p.82 / Chapter 3.8 --- Dose-response relationship of hot water extract from PR on cancer cell lines --- p.85 / Chapter 3.8.1 --- In vitro dose-response antiproliferation of PR-W and PR-HWE on HL-60 --- p.85 / Chapter 3.8.2 --- In vitro dose-response antiproliferation of PR-W on K562 and S180 --- p.88 / Chapter 3.8.3 --- In vivo dose-response relationship of PR-W on S180 --- p.91 / Chapter 3.9 --- Flow cytometric analysis of PR-W on cancer cell lines --- p.92 / Chapter 3.9.1 --- Antiproliferative effect of PR-W on HL-60 --- p.92 / Chapter 3.9.2 --- Antiproliferative effect of PR-W on K562 --- p.95 / Chapter 3.9.3 --- Proposed mechanisms of cell cycle arrest by PR-W --- p.98 / Chapter 3.10 --- Host-mediated antitumor mechanism of PR-W --- p.100 / Chapter 3.10.1 --- Mouse cytokine array --- p.100 / Chapter 3.10.2 --- Quantification of IL-13 by ELISA --- p.105 / Chapter 3.10.3 --- Immunostimulatory effects of PR-W on mice --- p.109 / Chapter 3.11 --- Correlation between antitumor activity and structure of mushroom sclerotial extract from hot water extraction alone --- p.114 / Chapter Chapter 4. --- Conclusions and Future works --- p.118 / List of References --- p.121 / Related Publications --- p.142

Athymic nude mice were employed as the in vivo model to study the detailed mechanism of how the three sclerotial polysaccharides act to inhibit the growth of human xenografted tumors in vivo. Using immunohistochemical staining, it was found that the presence of F4/80 + macrophages was related to the reduction of tumor size of the HL-60 xenograft. mRNA extracted from the spleens were reverse-transcribed to cDNA and detected by real-time PCR so that a variety of genes related to the toll-like receptors being up-regulated or down-regulated due to the injection of mushroom sclerotial polysaccharides were determined. Combining the results from dectin-1 regulation, it was concluded that both hot water-soluble sclerotial polysaccharides, PTRW and PRW, having a structure of polysaccharide-protein complexes were responsible for activating and thus binding to CR3 or toll-like receptors while PRSon with structure of pure beta-glucan was responsible for activating the expression of dectin-1 receptor, which led to the subsequent activation of host immune system in immunopotentiation and antitumor activities. / In the future, further investigation of the detailed structure of mushroom sclerotial polysaccharides is required to explain the immunomodulatory mechanism so that the effective dosage for immunomodulation as well as antitumor effects can be determined. Furthermore, phage display can be applied to find out any novel glucan receptors specific to the mushroom sclerotial polysaccharides. / In vitro antitumor study indicated that PTRW had a significant (p<0.05) inhibitory effect (>40%) on the human monocytic leukemic cells (THP-1) in addition to HL-60 and K562 cells. In vitro immunomodulatory study showed that both PRW and PRSon had significant proliferative effects (p<0.05) on human normal spleen monocyte/macrophage cell, MD. Moreover, PRSon was shown to have a significant increase (p<0.05) in the growth of human natural killer cells, NK-92M1; however, PTRW showed a significant inhibition (p<0.05) on this cell line. / Mushroom sclerotia have a rich source of polysaccharides when compared with fruit bodies. It was previously reported that the polysaccharides from novel mushroom sclerotia, namely, Pleurotus tuber-regium and Polyporus rhinocerus, had potent in vitro and in vivo antitumor effects. In this project, hot water-soluble sclerotial polysaccharides of Pleurotus tuber-regium (PTRW), hot water-soluble and sonication-assisted cold alkali-soluble sclerotial polysaccharides of Polyporus rhinocerus (PRW and PRSon, respectively) were chosen for investigation of their in vivo and in vitro immunomodulatory effects. / Polysaccharides have long been proposed to exert their antitumor and thus immunomodulating functions through glucan receptors and among the four being discovered, Dectin-1 has drawn most attention recently. In the in vivo study, PRSon showed an increase in the expression of Dectin-1 on mice spleen MNCs while PTRW showed an increase in the expression of the previously widely-reported complement receptor (CR3). There was also an increase of Dectin-1 expression on PEC in the mice injected with PRSon. In the in vitro study, the three mushroom sclerotial polysaccharides were incubated with NK-92M1, MD and THP-1 cells. There was a significant increase (p<0.05) of Dectin-1 expression on NK-92MI cells incubated with PTRW. On the other hand, PTRW caused a significant decrease ( p<0.05) of Dectin-1 expression while PRSon showed a significant increase (p<0.05) on THP-1 cells. The cytokine profile of extra-cellular media indicated that the inhibition of THP-1 cells by PTRW should be related to the innate immunity. In the in vitro study, human primary immune cells, CD56+ NK cells were used to incubate with sclerotial polysaccharides and there was a significant stimulation (p<0.05) of their growth when compared with the control. / The in vivo immunomodulatory study was carried out by injecting the abovementioned sclerotial polysaccharides intraperitoneal to 7-8 weeks old healthy male BALB/c mice. The spleens excised from groups injected with PTRW and PRW were found to have significant increase of weight ( p<0.001). Flow cytometric analysis revealed that the NK cell population in spleen mononuclear cells (MNCs) of mice injected with PRW and PRSon was increased when compared with the control. In addition, ail three sclerotial polysaccharides showed a large increase of T helper cell population as well as CD4+/CD8+ ratio in spleen MNCs. On the other hand, the macrophage population in peritoneal exudates cells (PEC) was found to be increased in the groups of mice injected with PTRW and PRW. / Lai, Kin Ming Connie. / Adviser: Cheung Chi Keung. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3412. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 120-137). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Les biofilms ont longtemps été décrits comme des organisations évolutives de microorganismes, attachés à une surface et englués dans une matrice contenant, entre autre, des polysaccharides. En partant de ce constat BioFilm Control a souhaité cribler des microorganismes pour la production d’exopolysaccharides, en utilisant le BioFilm Ring Test® (BRT). Le principe repose sur la coincubation de microorganismes avec des particules magnétiques en microplaque. Les particules sont plus ou moins attirées par un aimant en fonction du stade d’organisation du biofilm. En se formant, il piège, dans sa matrice visqueuse, les particules qui perdent leur mobilité. Celle-ci est révélée par une aimantation qui provoque l’apparition d’un spot (pas de biofilm) ou non (biofilm). Une analyse d’images quantifie ce processus et permet de le standardiser. La démarche a consisté dans un premier temps à vérifier le comportement de microorganismes modèles producteurs de polysaccharides (bactéries et microalgues) avec le BRT. L’étude a été étendue au criblage d’une banque de lactobacilles. Les résultats inattendus ont orienté l’étude vers l’analyse du rôle exact des polysaccharides et plus généralement de l’implication des macromolécules dans la structuration du biofilm. Pour cela, la dégradation séquentielle de chaque famille macromoléculaire a été réalisée via des enzymes dépolymérisantes sur les biofilms de Leuconostoc mesenteroides et Bacillus sp. Au regard des résultats obtenus, l’utilisation du BRT a été étendue à la caractérisation qualitative et quantitative d’enzymes de dégradation de polysaccharides. / Biofilms were described for a long time as evolutionary structures elaborated by microorganisms, fixed on a surface and maintained in a polysaccharidic matrix. From this assessment, BioFilm Control chose to screen microorganisms for their capacity to produce exopolysaccharides (EPS), using theBioFilm Ring Test® (BRT). The principle is the co-incubation of magnetic particles with microbial culture on microplates. The mobility of particles depends on the stage of biofilm formation. During this formation, particles are trapped in the matrix and loose their mobility. Revelation is induced by magnet which causes a spot in the absence of biofilm. The pictures analysis quantifies this phenomenon and standardizes different results. This approach was realised, at first step, by the test of EPS-producing bacteria or microalgae with the BRT. The study was extended to the screening of a lactobacilli collection. Unexpected results guided the research toward the understanding of the role of macromolecules in biofilm structuring. To study their implication, sequential enzymatic degradation has been achieved for each macromolecular family of Leuconostoc mesenteroïdes and Bacillus sp. biofilms. Using the results, BRT was then appreciated as a suitable method to detect and quantify polysaccharide degrading enzymes.