Добірка наукової літератури з теми "Microorganisme extracellulaire"
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Статті в журналах з теми "Microorganisme extracellulaire":
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Park, Jeong-Su, and Jong-Moon Jeong. "Characterization of Extracellular Cholesterol Oxidase Produced from Soil Microorganism." Journal of the Korean Society of Food Science and Nutrition 37, no. 11 (November 28, 2008): 1507–14. http://dx.doi.org/10.3746/jkfn.2008.37.11.1507.
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Pugsley, A. P. "Extracellular enzymes of microorganisms." Annales de l'Institut Pasteur / Microbiologie 139, no. 2 (March 1988): 274. http://dx.doi.org/10.1016/0769-2609(88)90013-0.
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Beeler, Erik, Nicholas Choy, Jonathan Franks, Francis Mulcahy, and Om V. Singh. "Extracellular Synthesis and Characterization of Silver Nanoparticles from Alkaliphilic Pseudomonas sp." Journal of Nanoscience and Nanotechnology 20, no. 3 (March 1, 2020): 1567–77. http://dx.doi.org/10.1166/jnn.2020.16496.
Анотація:
Bio-nanotechnology offers eco-friendly processes for the synthesis of stable nanoparticles (NPs). We hypothesized that microorganisms isolated from the root nodules of leguminous plants would biosynthesize silver (Ag) bio-nanoparticles. Clover root nodules enriched with nutrient broth (NB) produced four distinct colonies on NA plates. Microbial colonies were purified by repeated streaking and designated as SS6, SS7, SS8, and SS9 for identification using 16S rRNA sequencing. Four species of Pseudomonas were identified with a similarity score of over 99% using the EZ Taxon search engine, and tested for extracellular biosynthesis of AgNPs. Microorganism Pseudomonas taiwanensis-SS8 with alkaliphilic growth characteristics reduced the AgNO3 solution into AgNPs in the shortest time period. AgNPs were characterized using UV-Vis spectrophotometry and electron and transmission electron microscopy. A number of physical (i.e., temperature and time) and chemical (i.e., pH and growth media) parameters were optimized. An efficient polydispersal biosynthesis of AgNPs at pH 8–9 after 48 hrs in NB growth medium was observed. In addition, the AgNPs showed antimicrobial properties against 16 commonly occurring pathogenic microorganisms.
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Ortiz, Martha L. "Aproximaciones a la comprensión de la degradación de la lignina." Orinoquia 13, no. 2 (September 1, 2009): 137–44. http://dx.doi.org/10.22579/20112629.208.
Анотація:
Titulo en ingles: Approaches to understanding lignin degradation.RESUMEN: El objetivo de esta revisión es reunir los hallazgos más recientes que aportan a la comprensión de las rutas metabólicas que intervienen en la degradación del biopolímero más recalcitrante del planeta: la lignina. Esta le proporcionó a las plantas resistencia mecánica en sus tejidos para colonizar la tierra y una barrera fisicoquímica ante la infección microbiana. Debido a su naturaleza recalcitrante, la lignina es el precursor principal para la síntesis de la reserva de materia orgánica del suelo, regulando el ciclo del carbono. Adicionalmente, el sistema enzimático extracelular inespecífico que usan los microorganismos para degradar la lignina, ofrece un sinnúmero de moléculas con potencial biotecnológico. Este trabajo pretende estimular la investigación en la degradación de lignina, especialmente en ambientes poco explorados como la Amazorinoquía para el desarrollo de la bioprospección en nuestro país.Palabras clave: Lignina, enzimas, microorganismos, biotecnología.ABSTRACT: This work was aimed at summarising our current knowledge regarding understanding the metabolic routes intervening in lignin degradation, this being the most recalcitrant biopolymer on earth. Lignin provides plant tissues with mechanic resistance for colonising the earth and represents a physicochemical barrier to microbial infection. Lignin is the main precursor for synthesising the reserve of soil organic matter due to its recalcitrant nature, thereby regulating the carbon cycle. The unspecific extracellular enzymatic system used by microorganisms for lignin degradation offers a large number of molecules having biotechnological poten- tial. This work tries to stimulate research into lignin degradation, especially in little-explored environments such as the Amazon-Orinoquía region for developing bioprospecting in Colombia.Key words: Lignin, enzyme, microorganism, biotechnology.
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Bhola, Rahul, Shaily M. Bhola, Brajendra Mishra, and David L. Olson. "Microbiologically influenced corrosion and its mitigation: (A review)." Material Science Research India 7, no. 2 (February 8, 2010): 407–12. http://dx.doi.org/10.13005/msri/070210.
Анотація:
The microbiologically influenced corrosion (MIC) is one of the most common forms of corrosion that results from the presence and activity of microorganisms. The presence of microorganism aids in the formation of a bio film and constitutes various bacterial cells, extracellular polymeric substrates (EPS) and corrosion products. In this paper, a review on the importance of MIC and various ways to mitigate has been introduced; a brief description of the physical, chemical, electrochemical and biological mitigation methods for MIC has been included and EPS formation mechanism, chemical composition, properties and its influence on corrosion has been discussed.
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Filio-Rodríguez, Georgina, Iris Estrada-García, Patricia Arce-Paredes, María M. Moreno-Altamirano, Sergio Islas-Trujillo, M. Dolores Ponce-Regalado, and Oscar Rojas-Espinosa. "In vivo induction of neutrophil extracellular traps by Mycobacterium tuberculosis in a guinea pig model." Innate Immunity 23, no. 7 (September 20, 2017): 625–37. http://dx.doi.org/10.1177/1753425917732406.
Анотація:
In 2004, a novel mechanism of cellular death, called ‘NETosis’, was described in neutrophils. This mechanism, different from necrosis and apoptosis, is characterized by the release of chromatin webs admixed with microbicidal granular proteins and peptides (NETs). NETs trap and kill a variety of microorganisms. Diverse microorganisms, including Mycobacterium tuberculosis, are NET inducers in vitro. The aim of this study was to examine whether M. tuberculosis can also induce NETs in vivo and if the NETs are bactericidal to the microorganism. Guinea pigs were intradermally inoculated with M. tuberculosis H37Rv, and the production of NETs was investigated at several time points thereafter. NETs were detected as early as 30 min post-inoculation and were clearly evident by 4 h post-inoculation. NETs produced in vivo contained DNA, myeloperoxidase, elastase, histones, ROS and acid-fast bacilli. Viable and heat-killed M. tuberculosis, as well as Mycobacterium bovis BCG were efficient NET inducers, as were unilamellar liposomes prepared with lipids from M. tuberculosis. In vitro, guinea pig neutrophils also produced NETs in response to M. tuberculosis. However, neither the in vivo nor the in vitro-produced NETs were able to kill M. tuberculosis. Nevertheless, in vivo, neutrophils might propitiate recruitment and activation of more efficient microbicidal cells.
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El-Registan, G. I., A. L. Mulyukin, Yu A. Nikolaev, N. E. Suzina, V. F. Gal’chenko, and V. I. Duda. "Adaptogenic functions of extracellular autoregulators of microorganisms." Microbiology 75, no. 4 (July 2006): 380–89. http://dx.doi.org/10.1134/s0026261706040035.
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Lemos, Marco F. L., Illyane S. M. Lima, Kaori L. da Fonseca, Hugo R. Monteiro, and Ana C. Esteves. "Extracellular enzymatic activity from tributyltin resistant microorganisms." Current Opinion in Biotechnology 22 (September 2011): S80. http://dx.doi.org/10.1016/j.copbio.2011.05.239.
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Castro, Guillermo R., Adrián O. Stettler, Marcela A. Ferrero, and Faustino Siñeriz. "Selection of an extracellular esterase-producing microorganism." Journal of Industrial Microbiology 10, no. 3-4 (September 1992): 165–68. http://dx.doi.org/10.1007/bf01569761.
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Speziale, Pietro, Carla Renata Arciola, and Giampiero Pietrocola. "Fibronectin and Its Role in Human Infective Diseases." Cells 8, no. 12 (November 26, 2019): 1516. http://dx.doi.org/10.3390/cells8121516.
Анотація:
Fibronectin is a multidomain glycoprotein ubiquitously detected in extracellular fluids and matrices of a variety of animal and human tissues where it functions as a key link between matrices and cells. Fibronectin has also emerged as the target for a large number of microorganisms, particularly bacteria. There are clear indications that the binding of microorganism’ receptors to fibronectin promotes attachment to and infection of host cells. Each bacterium may use different receptors which recognize specific fibronectin domains, mostly the N-terminal domain and the central cell-binding domain. In many cases, fibronectin receptors have actions over and above that of simple adhesion: In fact, adhesion is often the prerequisite for invasion and internalization of microorganisms in the cells of colonized tissues. This review updates the current understanding of fibronectin receptors of several microorganisms with emphasis on their biochemical and structural properties and the role they can play in the onset and progression of host infection diseases. Furthermore, we describe the antigenic profile and discuss the possibility of designing adhesion inhibitors based on the structure of the fibronectin-binding site in the receptor or the receptor-binding site in fibronectin.
Дисертації з теми "Microorganisme extracellulaire":
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Guilhot, Robin. "Écologie des drosophiles et de leurs symbiotes microbiens en conditions naturelles." Electronic Thesis or Diss., Montpellier, SupAgro, 2020. http://www.theses.fr/2020NSAM0007.
Анотація:
Les symbioses et le microbiote sont devenus des sujets d’étude prioritaires, souvent explorés grâce à l’organisme modèle Drosophila. Pourtant, nos connaissances des relations naturelles entre drosophiles et symbiotes microbiens, c’est à dire en dehors du laboratoire, sont fragmentaires. Or, comprendre la coévolution entre hôte et symbiotes microbiens nécessite une fine description des effets des partenaires symbiotiques les uns sur les autres. Dans cette thèse, j’ai étudié de façon empirique les interactions entre drosophiles (Drosophila melanogaster et D. suzukii) et symbiotes extracellulaires (bactéries et levures) avec des souches sauvages et dans des conditions qui reproduisaient la nature. Ma thèse a porté sur les trois questions suivantes : (i) comment les drosophiles acquièrent et conservent-elles ces microorganismes tout au long de leur cycle de vie ; (ii) quels sont les effets de ces microorganismes sur le développement de leurs hôtes ; (iii) comment ces microorganismes interagissent-ils entre eux ? Mes travaux ont révélé que levures et bactéries sont plus que des sources de nourriture (i.e. acquisition des ressources) puisqu’elles influencent également comment la larve alloue ses ressources entre traits d’histoire de vie (i.e. plasticité développementale). L’étude des phases d’acquisition et de transmission des symbiotes microbiens par l’insecte en conditions proches de la nature a montré que ceux-ci sont partiellement acquis de l’environnement, conservés entre différents stades de vie, transmis entre générations et lors de l’accouplement. Par ailleurs, j’ai découvert de substantielles interactions entre symbiotes microbiens affectant leur multiplication et leur transmission entre stades de vie de l’hôte. Mon travail révèle une certaine complexité des interactions naturelles entre drosophiles et leurs symbiotes microbiens. Il démontre non seulement que ces interactions sont durables, mais également qu’elles sont composées d’effets imbriqués, simultanés et invisibles dans les systèmes nécessairement simplifiés des laboratoires. Mes travaux apportent également des pistes pour améliorer le contrôle des populations de D. suzukiiMicrobiota and symbiotic interactions are priority topics that are often explored using the Drosophila model organism. However, existing knowledge of natural relationships, i.e. in situ, between Drosophila flies and microbial symbionts is fragmented. Understanding coevolution between a host and its microbial symbionts requires a detailed understanding of the co-effects between symbiotic partners. In this PhD, I empirically studied the interactions between Drosophila flies (the model organism D. melanogaster and the pest species D. suzukii) and extracellular microbial symbionts (bacteria and yeasts) using wild strains under near-natural conditions. I investigated three main questions: (i) how do Drosophila flies acquire and transmit their microbial symbionts along their life cycle; (ii) how do these microorganisms affect host development; (iii) how do these microorganisms interact? My work revealed that yeasts and bacteria are not simply sources of nutrition (i.e. resource acquisition) for Drosophila but also influence how fly larva allocate resources between different life history traits (i.e. developmental plasticity). Second, the conducted study on microbial acquisition and transmission phenomena under near-natural conditions showed that symbionts are partially acquired from the environment, conserved through different life stages, and transmitted between generations and through mating. Thirdly, I found substantial interactions between microbial symbionts that affect their multiplication and transmission between host generations. These results reveal natural interactions of some complexity between Drosophila flies and their microbial symbionts. This demonstrates not only that these interactions are durable but also composed of nested effects that are simultaneous and invisible in obligatorily simplified laboratory systems. In addition, this work brings new elements likely to improve population control of the pest D. suzukii
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Buchon, Laurent. "Influence de la température sur la physiologie de la croissance et la production d'enzymes exocellulaires chez des bactéries adaptées aux basses températures." Rouen, 2000. http://www.theses.fr/2000ROUES046.
Анотація:
Des bactéries adaptées au froid ont été sélectionnées pour leur capacité à dégrader des polysaccharides naturels. L'influence de la température de croissance, sur la régulation de la production des enzymes exocellulaires, a été étudiée. Nous avons mis en évidence l'existence de cinq profils de régulation qui ne sont corrélés ni a l'origine taxonomique des souches, ni au type d'activité produite. D'autre part, chez une même souche, le profil de production d'une activité donnée peut varier suivant la composition du milieu de culture, notamment en substrat carboné, ainsi qu'en fonction de la présence d'inducteur spécifique. La dépendance des profils de production à l'égard des conditions nutritionnelles, démontre également qu'aucune loi générale ne peut être établie quant à l'influence de la température sur la production des enzymes exocellulaires, chez les bactéries adaptées au froid. Cependant des comportements différents peuvent être observés suivant le groupe thermique des souches. En utilisant la représentation selon Arrhénius, du taux de croissance en fonction de la température, nous avons démontré l'existence d'une température critique de rupture de pente chez toutes les souches psychrotrophes, celle-ci étant absente chez les psychrophiles. Sur la base de ce critère distinctif nous avons établi que, chez les psychrotrophes, la production des enzymes exocellulaires varie de façon discontinue sur l'ensemble de la gamme de températures suboptimales de croissance, ce qui se traduit par l'existence de deux domaines thermiques de production. En revanche chez les psychrophiles la production varie de façon monotone sur la gamme de températures inférieures à l'optimum de croissance. Ces profils pourraient résulter d'adaptation en réponse aux différentes amplitudes de température caractérisant les environnements d'origine des représentants de chacun de ces deux groupes thermiques.
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Ngom, Marie Odile. "Induction and production of specific extracellular lipases from selected microorganisms." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0031/MQ64416.pdf.
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Dusny, Christian [Verfasser]. "Microfluidics enable quantitative physiology of individual microorganisms in controlled extracellular environments / Christian Dusny." Aachen : Shaker, 2015. http://d-nb.info/1080763341/34.
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Kolba, Clifford Andrew. "Intracellular and extracellular acid phosphatase activity in axenically cultured phosphate-deprived achlorophyllous euglena gracilis /." Access Digital Full Text version, 1994. http://pocketknowledge.tc.columbia.edu/home.php/bybib/11714372.
Анотація:
Thesis (Ed.D.)--Teachers College, Columbia University, 1994.Typescript; issued also on microfilm. Sponsor: O. Roger Anderson. Dissertation Committee: Patricia L. Dudley. Includes tables. Includes bibliographical references (leaves 119-129).
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Reid, Vernita Jennilee. "Extracellular acid proteases of wine microorganisms : gene identification, activity characterization and impact on wine." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20322.
Анотація:
Thesis (MSc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: Non-Saccharomyces yeasts of oenological origin have previously been associated with spoilage or regarded as undesired yeasts in wine. However, these yeasts have recently come under investigation for their positive contribution towards wine aroma especially when used in sequential or co-inoculated fermentations with Saccharomyces cerevisiae. These yeasts are also known to secrete a number of enzymes that could be applicable in wine biotechnology. Amongst these enzymes are aspartic proteases. The secreted proteases from some non-Saccharomyces yeast may play a role in protein haze reduction, as demonstrated by some authors, while simultaneously increasing the assimilable nitrogen content of the wine for the utilization and growth of fermentative microorganisms. Moreover, the proteases may have an indirect effect on wine aroma by liberating amino acids that serve as aroma precursors. Although many screenings have been performed detecting protease activity in non-Saccharomyces yeasts, no attempts have been made to characterize these enzymes. This study set out to isolate and characterize genes encoding extracellular aspartic proteases from non-Saccharomyces yeasts. An enzymatic activity screening of a collection of 308 Saccharomyces and non-Saccharomyces yeasts, isolated from grape must, was performed. The aspartic protease-encoding genes of two non- Saccharomyces yeasts, which showed strong extracellular proteolytic activity on plate assays, were isolated and characterized by in silico analysis. The genes were isolated by employing degenerate and inverse PCR. One gene was isolated from Metschnikowia pulcherrima IWBT Y1123 and named MpAPr1. The other putative gene was isolated from Candida apicola IWBT Y1384 and named CaAPr1. The MpAPr1 gene is 1137 bp long, encoding a 378 amino acid putative protein with a predicted molecular weight of 40.1 kDa. The CaAPr1 putative gene is 1101 bp long and encodes a 367 amino acid putative protein with a predicted molecular weight of 39 kDa. These features are typical of extracellular aspartic proteases. The deduced protein sequences showed less than 40% homology to other yeast extracellular aspartic proteases. By heterologous expression of MpAPr1 in S. cerevisiae, it was confirmed that the gene encodes an extracellular acid protease. The expression of MpAPr1 was shown to be induced in media containing proteins as sole nitrogen source and repressed when a preferred nitrogen source was available. The gene was expressed in the presence of casein, bovine serum albumin (BSA) and grape juice proteins and repressed in the presence of ammonium sulphate. Expression was most induced in the presence of grape juice proteins, which was expected since these proteins are present in the natural habitat of the yeast. A genetic screening confirmed the presence of the MpAPr1 gene in 12 other M. pulcherrima strains isolated from grape juice. The extracellular protease activity of the strains was also visualized on plates. As far as we know, this is the first report on the genetic characterization of secreted aspartic proteases from non-Saccharomyces yeasts isolated from grape must and provides the groundwork for further investigations.
AFRIKAANSE OPSOMMING: Nie-Saccharomyces giste is voorheen met wynbederf geassosieer en hul teenwoordigheid in wyn is ongewens. Hierdie giste is onlangs ondersoek vir hulle positiewe bydrae tot wyn aroma, in veral sekwensiële en ko-inokulerings met Saccharomyces cerevisiae. Sommige van die nie-Saccahromyces giste skei ‘n verskeidenhied ensieme af wat moontlik vir die wynmaker van nut kan wees. Een groep van hierdie ensieme is die aspartiese suurproteases. Soos deur sommige navorsers aangetoon word, kan die proteases die vorming van proteïenwaasverlaging, terwyl dit terselfdertyd die assimilerende stikstofinhoud van die wyn vir die gebruik en groei van fermentasie-mikroörganismes verhoog. Die proteases kan moontlik ook ‘n indirekte uitwerking op die aromaprofiel van die wyn hê deur die vrystelling van aminosure wat as aromavoorlopers dien. Alhoewel baie studies gedoen is wat die ekstrasellulêre teenwoordigheid van proteases bevestig in nie-Saccharomyces giste wat van druiwesap/wyn afkoms is, is daar geen dokumentasie oor die genetiese karakterisering van hierdie ensieme beskikbaar nie. Die doel van hierdie studie was om gene wat aspartiese proteases in nie-Saccharomyces giste enkodeer, te isoleer en gedeeltelik te karakteriseer. ‘n Versameling van 308 Saccharomyces en nie-Saccharomyces giste wat uit druiwe sap geïsoleer is, is gesif vir ensiematiese aktiwiteit deur plaattoetse uit te voer. Twee gene wat aspartiese protease enkodeer, is geïsoleer van twee nie-Saccharomyces giste. Dit hetpositief gedurende die aktiwiteitstoetse getoets en is deur in silico–analise gekarakteriseer. Die gene is deur die uitvoering van gedegenereerde en inverse PKR geïdentifiseer. Een geen is vanaf Metschnikowia pulcherrima IWBT Y1123 geïsoleer en is MpAPr1 genoem, terwyl die ander van Candida apicola IWBT Y1384 geïsoleer en CaAPr1 genoem is. Die MpAPr1-geen is 1137 bp lank en enkodeer ‘n proteïen wat uit 378 aminosure bestaan met ‘n voorspelde molekulêre massa van 40.1 kDa. Daar teenoor is die CaAPr1-geen 1101 bp lank en enkodeer vir ‘n proteïen wat uit 367 aminosure met ‘n molekulêre massa van 39 kDa bestaan. Hierdie eienskappe is kenmerkend van aspartiese protease. Die afgeleide proteïenvolgorde het minder as 40% homologie met ander ekstrasellulêre aspartiese proteases vertoon, wat dui op die nuwigheid van hierdie ensieme. Die MpAPr1-geen is heterologies in S. cerevisiae YHUM272 uitgedruk en dit het bevestig dat die geen inderdaad ‘n ekstrasellulêre aspartiese protease enkodeer. Die MpAPr1-geen is uitgedruk in media wat alleenlik proteïen as stikstofbron bevat het, terwyl dit onderdruk is in gevalle waar ‘n verkose stikstofbron beskikbaar was. Die geen is uitgedruk in die teenwoordigheid van kaseïen, BSA en proteïene afkomstig vanaf druiwesap en in die teenwoordigheid van ammoniumsulfaat onderdruk. Die hoogste uitdrukking was in die teenwoordigheid van druifproteïene. Hierdie proteïene is teenwoordig in die natuurlike habitat van die gis en is dus dalk ‘n bekende stikstofbron vir die gis. ‘n Genetiese sifting het die teenwoordigheid van die MpAPr1-geen in 12 ander M. pulcherrima–rasse, wat ook van wynkundige oorsprong is, bevestig. Die aspartiese protease-aktiwiteit van die 12 rasse is ook op agarplate waargeneem. Na ons wete, is dit die eerste verslag oor die genetiese karakterisering van afgeskeide aspartiese proteases van nie- Saccharomyces giste van wynkundige oorsprong en verskaf die grondslag vir verdere ondersoek.
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Kim, Hyun Jung. "The effect of extracellular and surface macromolecules on the deposition of pathogenic microorganisms in saturated porous media." Diss., UC access only, 2009. http://proquest.umi.com/pqdweb?did=1974753331&sid=1&Fmt=7&clientId=48051&RQT=309&VName=PQD.
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Brauge, Thomas. "Étude des exopolysaccharides de la matrice extracellulaire des biofilms de Listeria monocytogenes." Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10151/document.
Анотація:
L’objectif de ces travaux a été d’étudier le rôle des exopolysaccharides dans la formation des biofilms de Listeria monocytogenes et dans leur résistance face à des procédures de nettoyage rencontrées en entreprise dans des circuits fermés. Nous avons montré que l’exopolysaccharide majeur présent dans la matrice extracellulaire des biofilms de L. monocytogenes était de l’acide téichoïque identique à l’acide téichoïque pariétal. Nous avons identifié que sur 93 souches de sérotype 1/2a étudiées la moitié présentaient une mutation sur le gène lmo2550 ce qui pouvait entraîner la non-ramification de l’acide téichoïque avec le résidu N-Acétylglucosamine (GlcNAc). Des mutants de la souche de référence EGD-e inactivés pour les gènes lmo2549 ou lmo2550 intervenant dans la ramification de l’acide teichoïque par le GlcNAc ainsi que des mutants inactivés pour les gènes lmo2537 ou tagO1tagO2 intervenant dans la voie de biosynthèse des acides téichoïques ont été étudiés. Cela nous a permis de montrer que l’absence de GlcNAc sur les acides téichoïques avait modifié les propriétés de surface de L. monocytogenes, diminué l’adhésion à l’acier inoxydable et modifié l’architecture des biofilms de 48h. Par ailleurs, ils étaient plus sensibles à une procédure de nettoyage en circuit fermé avec un détachement plus important, une modification de l’architecture des biofilms et la présence uniquement de cellules viables non cultivables et mortes après passage d’un flux de soude. Le but de ces travaux était de mieux comprendre le rôle de la matrice extracellulaire dans la formation des biofilms de L. monocytogenes pour ensuite trouver le meilleur moyen de l’éradiquer dans l’environnement industrielThe aim of this work was to study the role of exopolysaccharides in the formation of Listeria monocytogenes biofilm and their resistance to cleaning procedure in industry. We showed that the major exopolysaccharide present in the extracellular matrix of L. monocytogenes biofilm was teichoic acid, which was identical at the structure to the parietal teichoic acid. We identified that 50% of 93 strains of 1/2a serotype studied had a mutation in the lmo2550 gene that could lead to non-branching of the teichoic acid with the N-Acetylglucosamine residue (GlcNAc). We therefore examined mutants of EGD-e reference strain which had inactivated lmo2549 or lmo2550 or lmo2537 or tagO1tagO2 genes allowing highlighting the absence of the GlcNAc residue on teichoic acids. The mutation of these genes had changed the L. monocytogenes surface properties, decreased the adhesion to stainless steel and modified the architecture of 48h-biofilms. Furthermore, they were more susceptible to a circuit cleaning procedure with an important detachment, a change in the architecture of the biofilm and the presence of non-cultivable but viable cells and dead cells after passage of the caustic soda flow versus the wild-type EGD-e strain. The aim of this work was to better understand the role of the extracellular matrix in the formation of L. monocytogenes biofilm and then find the procedure to eradicate it in the industrial environment
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Kara, Fadime. "Investigation Of Sodium And Potassium Ions In Relation To Bioflocculation Of Mixed Culture Microorganisms." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608488/index.pdf.
Анотація:
Bioflocculation happens naturally and microorganisms aggregate into flocs during wastewater treatment. It is critical to understand the mechanisms of bioflocculation and its impact on the following solid/liquid separation process
since seperation by settling is one of the key aspects that determine the efficiency and the overall economy of activated sludge systems. Bioflocculation occurs via extracellular polymeric substances (EPS) and cations by creating a matrix to hold various floc components together so the cations become an important part of the floc structure. The main objective of this study is to investigate the effects of monovalent cations specifically potassium and sodium (K and Na) on the bioflocculation, settleability and dewaterability of activated sludge. The particular aim is to grow the mixed culture microorganisms in the presence of specific cation so that the effect of cation on the stimulation of EPS production can be seen. In order to achieve this aim, semi-continuous reactors were separately operated at concentrations of 5, 10, and 20 meq/L of each cation with mixed culture bacteria
and fed with synthetic feed medium representing influent to the activated sludge systems. Also, a control reactor at low cation dose was operated for each reactor set. The effective volume of the reactors was 2 L with 8 days of sludge residence time (SRT) and pH was kept at 7.7±0.3. The activated sludge reactors were operated until the reactors reached steady state and then related analyses were conducted. It was found that addition of potassium and sodium ions at increasing concentrations resulted in increase in total polymer concentration. However, potassium ions promoted the synthesis of both polysaccharide and protein type polymers whereas sodium ions tended to stimulate production of protein type polymers and had an affinity to bind more protein within the floc structure. Sodium sludges had lower hydrophobicity and higher surface charges, so sodium ions led to deterioration in flocculation of sludges. Addition of both these ions decreased the dewaterability, sodium ions had more detrimental effect on dewaterability of sludges compared to potassium ions. The examination of data related to settleability showed that potassium ions led to no drastic deterioration in settling characteristics of the activated sludge but the addition of sodium ions deteriorated the settleability. In addition, it was seen that while the addition of potassium ions to the feed led to a decrease in viscosity, increase in sodium concentration correlated with an increase in viscosity. Finally, the comparison of chemical oxygen demand (COD) removal efficiency of these cations showed that sodium is more efficient in COD removal.
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Wargnies, Marion. "Adaptations métaboliques de Trypanosoma brucei en réponse à des variations des conditions intra- et extracellulaires." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0200/document.
Анотація:
Trypanosoma brucei est un parasite protozoaire responsable de la trypanosomiase humaine africaine. Il présente un cycle de vie complexe alternant entre des hôtes mammifères et un vecteur insecte, la mouche tsé-tsé. Au cours de ce cycle, il rencontre des environnements radicalement distincts auxquels il s’adapte en régulant son métabolisme. Nous avons étudié le métabolisme intermédiaire et énergétique de la forme procyclique évoluant dans le tractus digestif de l’insecte vecteur. Dans cet environnement dépourvu de glucose, la néoglucogenèse est cruciale pour la croissance et la survie des parasites car elle permet la synthèse d’hexoses phosphates et en particulier du glucose 6-phosphate qui alimente plusieurs voies de biosynthèse essentielles. Nos travaux confirment ce flux néoglucogénique alimenté par la proline mais aussi par le glycérol. Nous montrons que le glycérol est une source de carbone efficacement métabolisée et préférentiellement utilisée par la forme procyclique à défaut de la proline et même du glucose pour alimenter son métabolisme intermédiaire. Cette situation qu in’a jamais été décrite auparavant met en évidence la répression du glycérol sur le métabolisme du glucose. Nous montrons également que l’enzyme fructose 1,6-biphosphatase(FBPase), spécifique de la néoglucogenèse, n’est pas essentielle à la survie du parasite en conditions dépourvues de glucose indiquant qu’il existe une alternative à cette enzyme.Toutefois, FBPase joue un rôle important dans la virulence de T. brucei dans l’insecte.De plus, nous avons mis en évidence une autre stratégie d’adaptation de T. brucei basée sur des réarrangements génomiques qui peuvent mener à la synthèse de gènes chimèresTrypanosoma brucei is a protozoan parasite responsible for human African trypanosomiasis. His complex life cycle alternates between mammalian hosts and the insect vector, the tsetsefly. During this cycle, the parasite encounters dissimilar environments and adapts to the sechanging conditions by regulating his metabolism. We have studied intermediate and energetic metabolism of the procyclic form living in the midgut of the insect vector. In this glucose-depleted environment, gluconeogenesis is crucial for growth and viability of the parasites. Indeed, it allows the synthesis of hexoses phosphates and in particular glucose 6-phosphate which feeds several essential biosynthetic pathways. Our work has confirmed the existence of a gluconeogenic flux fed by proline and glycerol. We have shown that glycerol is an efficiently metabolized carbon source and is preferentially used by the procyclic form rather than proline or even glucose. This situation never described before highlights glycerol repression on glucose metabolism. We have also showed that the enzyme fructose 1,6-biphosphatase (FBPase), specific of the gluconeogenesis, is not essential for the viability ofthe parasite in glucose-depleted conditions, suggesting that there is an alternative to this enzyme. However, FBPase plays an important role for virulence of T. brucei in the insect. Moreover, we have showed another adaptation strategy developed by T. brucei which is basedo n genomic rearrangements leading to the synthesis of chimeric genes
Книги з теми "Microorganisme extracellulaire":
1
Chaloupka, J., and Vladimir Krumphanzl, eds. Extracellular Enzymes of Microorganisms. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-1274-1.
2
Jiří, Chaloupka, Krumphanzl V, Československá společnost mikrobiologická při ČSAV., and Mikrobiologický ústav (Československá akademie věd), eds. Extracellular enzymes of microorganisms. New York: Plenum Press, 1987.
3
Chaloupka, J. Extracellular Enzymes of Microorganisms. Springer, 2012.
4
Chaloupka, J. Extracellular Enzymes of Microorganisms. Springer London, Limited, 2012.
5
Microbial extracellular polymeric substances: Characterization, structure, and function. Berlin: Springer, 1999.
6
(Editor), Jost Wingender, Thomas R. Neu (Editor), and Hans-Curt Flemming (Editor), eds. Microbial Extracellular Polymeric Substances: Characterization, Structure and Function. Springer, 1999.
Частини книг з теми "Microorganisme extracellulaire":
1
Priest, Fergus G. "Regulation of Extracellular Enzyme Synthesis in Bacilli." In Extracellular Enzymes of Microorganisms, 3–12. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-1274-1_1.
2
Kučerová, H., and J. Chaloupka. "Stimulation of a Proteinase Synthesis in Bacillus Megaterium by Netropsin." In Extracellular Enzymes of Microorganisms, 85–88. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-1274-1_10.
3
Bawden, M. J., T. Litjens, T. R. Hercus, B. K. May, and W. H. Elliott. "Extracellular Protease Production by B. Amyloliquefaciens." In Extracellular Enzymes of Microorganisms, 89–92. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-1274-1_11.
4
Aronson, Arthur I. "Formation and Properties of a Bacillus Subtilis Protein Protease Inhibitor." In Extracellular Enzymes of Microorganisms, 93–98. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-1274-1_12.
5
Turková, J., M. J. Benes, M. Kühn, V. M. Stepanov, and L. A. Lyublinskaya. "Use of Highly Porous Bead Cellulose with Attached Bacitracin for Affinity Chromatography of a Microbial Proteinase." In Extracellular Enzymes of Microorganisms, 99–103. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-1274-1_13.
6
Vořlšek, Josef, and Kalju Vanatalu. "Saccharomyces Cerevisiae Secretes X-Prolyl-Dipeptidyl (Amino) Peptidase: Electron Cytochemical Study with Statistical Evaluation." In Extracellular Enzymes of Microorganisms, 105–10. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-1274-1_14.
7
Aiba, Shuichi, Yoshiaki Monden, Masatoshi Ohnishi, Ming Zhang, and Jun-ichi Koizumi. "Production of α-Amylase by Bacillus Stearothermophilus (pAT9) and Gene Manipulation to Improve the Stability of the Recombinant Plasmid." In Extracellular Enzymes of Microorganisms, 113–27. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-1274-1_15.
8
Suominen, Ilari, Matti Karp, Jaana Lautamo, Jonathan Knowles, and Pekka Mantsälä. "Thermostable Alpha Amylase of Bacillus Stearothermophilus: Cloning, Expression, and Secretion by Escherichia Coli." In Extracellular Enzymes of Microorganisms, 129–37. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-1274-1_16.
9
Pazlarová, J. "Exocellular Protein and α-Amylase Secretion in Bacillus Subtilis." In Extracellular Enzymes of Microorganisms, 139–42. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-1274-1_17.
10
Jensen, B., J. Olsen, and K. Allermann. "Extracellular Amylase from the Thermophilic Fungus Thermomyces Lanuginosus." In Extracellular Enzymes of Microorganisms, 143–46. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-1274-1_18.
Тези доповідей конференцій з теми "Microorganisme extracellulaire":
1
Bedina Zavec, Apolonija. "Extracellular Vesicles for Cosmetic Applications." In Socratic Lectures 8. University of Lubljana Press, 2023. http://dx.doi.org/10.55295/psl.2023.ii16.
Анотація:
Extracellular vesicles (EVs) are nanosized membrane vesicles that carry membrane and cargo molecules inherited from their parental cells. Excellent delivery capacity, biological origin, and nanosized dimensions support the great potential of EVs as medical and cosmetic active ingredients. Many studies have already reported improved skin conditions by using EVs for skin rejuvenation, scar removal, and anti-pigmentation treatments. In this review, EVs from mesenchymal stem cells, platelets, skin microbiota, and microalgae will be considered. The most promising results come from mesenchymal stem cell (MSC) derived EVs that have impressive antiaging and wound-healing effects on the skin, but their use for medical or cosmetic purposes is not yet allowed in Europe and the United States. Autologous platelet- and extracellular vesicle-rich plasma (PVRP) is well tolerated and capable of rejuvenating the face; intradermal injections and topical applications are currently being considered in clinical and cosmetic dermatology. Symbiotic microorganisms of the human skin have many beneficial effects on the skin, but the presence of bacteria in cosmetic products is restricted; therefore, the preparation of EVs from skin-beneficial microbes is particularly relevant, and there are already many cosmetic products containing lysates from different probiotics on the market. Microalgae can produce many valuable bioactive compounds, antioxidants such as carotenoids are particularly interesting; therefore, microalgae are promising producers of EVs that could be used in cosmetic products. Keywords: Extracellular vesicles; Skin health; Microbiota; Mesenchymal stem cells; Micro-algae
2
Rohova, Maryna, Vladyslav Kovalenko, Volodymyr Tkachenko, Inna Lych, and Iryna Voloshyna. "Green Biosynthesis of Zinc Nanoparticles." In The 9th International Conference on Advanced Materials and Systems. INCDTP - Leather and Footwear Research Institute (ICPI), Bucharest, Romania, 2022. http://dx.doi.org/10.24264/icams-2022.iv.12.
Анотація:
Currently there is a growing need for the development of an environmentally friendly process of synthesis of nanoparticles, during which no toxic chemicals are used. That is why an important area of research in nanotechnology sphere is the synthesis of metal nanoparticles by microorganisms such as bacteria and yeast (detoxification often occurs by reduction of metal ions/formation of metal sulfides). Bacteria are the organism of choice due to their fast growth, high efficiency and low cost. Metal nanoparticles exhibit antimicrobial properties, but the properties of nanoparticles depend on their size and shape, making them specific for different applications. Nevertheless, the desired size and shape of nanoparticles can be obtained by optimizing the synthesis process through manipulating their reaction conditions. Microbial synthesis of nanoparticles is an alternative to chemical and physical methods, as it is non-toxic and biocompatible. Despite the relevance of the application of the “green synthesis” method in the field of nanotechnology, biosynthesis by bacterial organisms has certain disadvantages, such as a high probability of pathogenicity, labour-intensive cultivation, and pollution problems. Ultimately, there is a need to explore more potential microorganisms for the synthesis of metal nanoparticles. The paper provides a review of literature data on the biosynthesis of zinc nanoparticles using lactic acid microorganisms. It was shown that bacteria are capable of synthesizing both extracellular and intracellular nanoparticles in the wavelength range of 315-392 nm. Data on the manifestation of antimicrobial properties by zinc nanoparticles against various gram-positive and gram-negative bacterial microorganisms and micromycetes.
3
Ibragimova, C. M., E. A. Trifonova, E. A. Filipenko, and A. V. Kochetov. "STUDY OF THE ROLE OF EXTRACELLULAR RIBONUCLEASES IN PHYTOPATHOGENESIS IN PLANTS BY THE EXAMPLE OF TRANSGENIC POTATO PLANTS CARRIED WITH THE GENES OF ZRNaseII EXTRACELLULAR RIBONUCLEASIS OF ZINNIA." In The All-Russian Scientific Conference with International Participation and Schools of Young Scientists "Mechanisms of resistance of plants and microorganisms to unfavorable environmental". SIPPB SB RAS, 2018. http://dx.doi.org/10.31255/978-5-94797-319-8-913-916.
4
Lyu, Xidi, Kexi Liao, Zihan Zou, Guoxi He, and Shitao Liu. "Effects of Flow Velocity on Biofilm formation and corrosion behavior of L245 steel in the presence of sulfate reducing bacteria." In International Petroleum Technology Conference. IPTC, 2024. http://dx.doi.org/10.2523/iptc-24640-ms.
Анотація:
Shale gas is a type of unconventional natural gas that is found primarily within reservoir rock sequences dominated by organic-rich shale, and is usually exploited by hydraulic fracturing technology, which typically requires a large amount of water to be injected into the gas well, and when the fracturing process is completed, a portion of the injected water immediately flows back. The fracturing flow-back fluid contains a large number of microorganisms when it enters the surface gathering and transportation system, resulting severe internal corrosion of the pipelines, especially those built during the early exploitation process, using carbon steel like L245 steel[1]. The anoxic environment and large amount of fluid accumulation in the pipeline provide appropriate conditions for the growth and reproduction of microorganisms, which increased the risk of Microbiologically Influenced Corrosion (MIC). MIC is a prevalent form of corrosion instigated by the bioactivity of diverse microorganisms. Representing a substantial challenge in the oil and gas sector, it is estimated that MIC accounts for approximately 40% of all incidents of internal pipeline corrosion[2]. SRB are typically considered the primary culprits in causing MIC, mainly because SRB are often found at the sites of corrosion believed to be associated with MIC[3]. SRB is a general term for a group of bacteria that are widely distributed in anaerobic environments, such as soil, seawater, river water, underground pipes and oil & gas wells where are rich in organic matter and sulfate[4-6]. The presence of SRB will lead to the corrosion of metal pipelines and equipment, moreover, its corrosion products FeS and Fe(OH)2 and the bacteria themselves will cause the blockage of pipelines and formation, and affect the subsequent gas production and development. SRB can use sulfides with valence states above -2 as electron acceptors, including HSO3, S2O32- and element S, to reduce S to a stable -2 valence. SRB is a strict anaerobe, its growth and reproduction are inhibited when exposed to oxygen, but it can survive for a period of time[7]. The theories related to SRB-induced corrosion include cathode depolarization theory[8, 9], metabolite corrosion theory[10-12], concentration difference cell theory[13], Extracellular Electron Transfer (EET) theory[14, 15] and Biocatalytic Cathodic Sulfate Reduction (BCSR) theory[16]. According to the researches of many scholars, factors such as biofilm structure[17, 18], ambient temperature[19], pH level[20], Cl−[21], CO2[22], H2S[23], cathodic protection potential[24, 25] and magnetic field[26] all can affect the corrosion behavior of SRB. In oil and natural gas pipeline, the flow of medium is complicated, and the influence of flow conditions on corrosion behavior of SRB cannot be ignored. The change of flow regime and flow velocity can affect the mass transfer in the pipeline, and thus affect the biochemical reaction process[27]. Furthermore, the change of shear stress can affect the formation, breakage, detachment and spalling of the biofilm attached to the pipeline and lead to the change of the state of the pipe wall and the corrosion state and potential, shear stress can even affect the transport, transfer and reaction rates of materials under the biofilm[28]. It is generally believed that the flow of the medium is not conducive to the adhesion of microbial cells on the pipelines’ surface and the formation of biofilm. On the one hand, polarization agents such as H and H2O in the fluid can rapidly diffuse to the electrode surface and improve the reaction rate of cathode. On the other hand, higher flow velocity can make the anodized ions leave the metal surface quickly, improve the anodic dissolution rate, and also affect the formation of the corrosion product film or destroy the product film that has been generated[29]. Some scholars have also found that under low Reynolds number, the biofilm formed on the inner wall of pipeline has a high content of active bacteria, while under high Reynolds number, the biofilm has a high content of extracellular polymeric substance (EPS)[30]. Scholars have made a lot of contributions to the study of SRB-induced corrosion and MIC, but there are few researches focus on the influence of hydraulic conditions on SRB corrosion. In particular, the variation of metal surface and SRB corrosion rate at different flow velocities, the influence of fluid flow on corrosion characteristics and the underlying corrosion mechanism have not been reported.
5
Khair, Nedaa Kamalalden. "Activity of Antibiotic Producing Bacteria Isolated from Rhizosphere Soil Region of Different Medicinal Plants." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0093.
Анотація:
The rhizosphere soil of medicinal plants is rich in microorganisms that develop antibiotics as natural mechanism of protection against other microbes that live in their vicinity. The present study aims to explore the production of antibacterial agents from rhizosphere soil bacteria of 11 medicinal plants and determine their activity against Gram-negative (Pseudomonas aeruginosa, Escherichia coli) and Gram-positive (Bacillus cereus, Staphylococcus aureus) bacteria. Soil samples were collected and used to isolate antibiotic producing bacteria (APB). Those isolates (108) were first tested using Cross-streak method against test bacteria. Then, isolates that showed a positive antibacterial effect (12) were tested by antibiotic susceptibility test (AST) of their cell free supernatant (CFS) and their extracellular and intracellular secondary metabolites extraction which gave positive results. Staphylococcus aureus found to be the most sensitive test bacteria with inhibitory zones ranging from 13.5 - 19 mm. Moreover, combinatorial effect of isolates CFS with two organic acids (3% Acetic acid and 0.4 mg/ml Acetylsalicylic acid), two commercial antibiotics (0.016 mg/ml Augmentin and 0.128 mg/ml Doxycycline), and two pure antibiotics (10 mcg/disk Penicillin and 25mcg/disk Carbenicillin) was in vitro evaluated using AST. The combinations of CFS-carbenicillin showed a marked synergistic activity against all test bacteria. The presence of possible antibacterial agents as acetic acid, lactic acid and citric acid in CFS of APB was confirmed by HPLC analysis. Ultimately, in vitro antibacterial study for rhizosphere soil bacteria in this work suggests the possibility of using these bacterial metabolites in clinical infections caused by selected test bacteria, especially when they combine with antibiotics or organic acids.
Звіти організацій з теми "Microorganisme extracellulaire":
1
Wilson, Charles, and Edo Chalutz. Biological Control of Postharvest Diseases of Citrus and Deciduous Fruit. United States Department of Agriculture, September 1991. http://dx.doi.org/10.32747/1991.7603518.bard.
Анотація:
The objectives of this research were to develop control measures of postharvest diseases of citrus and deciduous fruits by using naturally-occurring, non-antibiotic-producing antagonists; study the mode of action of effective antagonists and optimize their application methods. Several antagonists were found against a variety of diseases of fruits and vegetables. One particularly effective yeast antagonist (US-7) was chosen for more in-depth studies. This antagonist outcompetes rot pathogens at the wound site for nutrients and space; it is better adapted than the pathogen to extreme environmental conditions such as temperature, humidity and osmotic changes, and is relatively resistant to common postharvest fungicides. Our data suggests that other modes of action may also be involved. These are induction of host resistance by the antagonists or its products, and direct interaction between the antagonists and the pathogen with the possible involvement of an extracellular material and/or cell wall degrading enzymes produced by the antagonist. However, these interactions were not fully elucidated. The antagonistic activity of US-7 and other biocontrol agents isolated, was enhanced by calcium salts. While the mode of action is not known, the addition of these salts had a significant effect both in laboratory experiments and in large-scale tests. Compatibility of the yeast antagonist with present packinghouse treatments and procedures was determined. An integrated control procedure was developed, utilizing the antagonists together with ultra-low dosages of fungicides and activity-enhancing additives. This cooperative research resulted in numerous publications describing the antagonistic agents. their mode of action and possible commercial application. Patents were developed from this research and a commercial company is pursuing the licensing of these patents and the testing of the procedure on a commercial scale. Our research findings have expanded the potential for using non-antibiotic-producing antagonistic microorganisms in the control of postharvest diseases of fruits and vegetables; thus meeting a critical need to find alternatives to the use of synthetic fungicides on food products.
2
Gurevitz, Michael, William A. Catterall, and Dalia Gordon. face of interaction of anti-insect selective toxins with receptor site-3 on voltage-gated sodium channels as a platform for design of novel selective insecticides. United States Department of Agriculture, December 2013. http://dx.doi.org/10.32747/2013.7699857.bard.
Анотація:
Voltage-gated sodium channels (Navs) play a pivotal role in excitability and are a prime target of insecticides like pyrethroids. Yet, these insecticides are non-specific due to conservation of Navs in animals, raising risks to the environment and humans. Moreover, insecticide overuse leads to resistance buildup among insect pests, which increases misuse and risks. This sad reality demands novel, more selective, insect killers whose alternative use would avoid or reduce this pressure. As highly selective insect toxins exist in venomous animals, why not exploit this gift of nature and harness them in insect pest control? Many of these peptide toxins target Navs, and since their direct use via transformed crop plants or mediator microorganisms is problematic in public opinion, we focus on the elucidation of their receptor binding sites with the incentive of raising knowledge for design of toxin peptide mimetics. This approach is preferred nowadays by agro-industries in terms of future production expenses and public concern. However, characterization of a non-continuous epitope, that is the channel receptor binding site for such toxins, requires a suitable experimental system. We have established such a system within more than a decade and reached the stage where we employ a number of different insect-selective toxins for the identification of their receptor sites on Navs. Among these toxins we wish to focus on those that bind at receptor site-3 and inhibit Nav inactivation because: (1) We established efficient experimental systems for production and manipulation of site-3 toxins from scorpions and sea anemones. These peptides vary in size and structure but compete for site-3 on insect Navs. Moreover, these toxins exhibit synergism with pyrethroids and with other channel ligands; (2) We determined their bioactive surfaces towards insect and mammalian receptors (see list of publications); (3) We found that despite the similar mode of action on channel inactivation, the preference of the toxins for insect and mammalian channel subtypes varies greatly, which can direct us to structural features in the basis of selectivity; (4) We have identified by channel loop swapping and point mutagenesis extracellular segments of the Navinvolved with receptor site-3. On this basis and using channel scanning mutagenesis, neurotoxin binding, electrophysiological analyses, and structural data we offer: (i) To identify the residues that form receptor site-3 at insect and mammalian Navs; (ii) To identify by comparative analysis differences at site-3 that dictate selectivity toward various Navs; (iii) To exploit the known toxin structures and bioactive surfaces for modeling their docking at the insect and mammalian channel receptors. The results of this study will enable rational design of novel anti-insect peptide mimetics with minimized risks to human health and to the environment. We anticipate that the release of receptor site-3 molecular details would initiate a worldwide effort to design peptide mimetics for that site. This will establish new strategies in insect pest control using alternative insecticides and the combined use of compounds that interact allosterically leading to increased efficiency and reduced risks to humans or resistance buildup among insect pests.