Determination of minimum inhibitory concentrations of sophorolipids against selected halotolerant and moderately halophilic bacteria, and extremely halophilic archaea isolated from salt samples and salted skins / R. D. Ashby in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIX, N° 8 (08/2024)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIX, N° 8 (08/2024) . - p. 339-348 Titre : Determination of minimum inhibitory concentrations of sophorolipids against selected halotolerant and moderately halophilic bacteria, and extremely halophilic archaea isolated from salt samples and salted skins Type de document : texte imprimé Auteurs : R. D. Ashby, Auteur ; Meral Birbir, Auteur ; P. Yilmaz, Auteur ; J. Msanne, Auteur ; Antonio Ventosa, Auteur ; E. Yilmaz, Auteur Année de publication : 2024 Article en page(s) : p. 339-348 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Antimicrobiens Archées Les archées ou Archaea, "originel, primitif", anciennement appelés archéobactéries, sont des microorganismes unicellulaires procaryotes, c'est-à-dire des êtres vivants constitués d'une cellule unique qui ne comprend ni noyau ni organites, à l'instar des bactéries. D'apparence souvent semblable à ces dernières, les archées ont longtemps été considérées comme des bactéries extrêmophiles particulières, jusqu'à ce que les recherches phylogénétiques sur les procaryotes, commencées en 1965, aboutissent, avec les travaux de Carl Woese et George E. Fox, à la publication en 1977 d'un arbre phylogénétique fondé sur les séquences des gènes d'ARN ribosomique des organismes étudiés, arbre dans lequel les procaryotes étaient scindés en deux domaines distincts, celui des bactéries et celui des archées. (Wikipedia) Bactéries Concentration minimale inhibitrice (antimicrobiens) En microbiologie, la concentration minimale inhibitrice (CMI) est la plus faible concentration d'un produit chimique, généralement un médicament, qui empêche la croissance visible d'une ou de plusieurs bactéries. La CMI dépend du micro-organisme considéré, de l'être humain affecté (in vivo uniquement) et de l'antibiotique lui-même. La CMI est déterminée en préparant des solutions du produit chimique in vitro à diverses concentrations croissantes, en incubant les solutions avec des groupes séparés de bactéries en culture et en mesurant les résultats en utilisant une méthode de dilution standardisée (agar ou microdilution). Les résultats se classent ensuite comme "sensible", "intermédiaire" ou "résistant" à un antimicrobien particulier en utilisant un point d'arrêt. Les points d'arrêt sont des valeurs convenues, publiées dans les directives d'un organisme de référence, comme le US Clinical and Laboratory Standards Institute (CLSI), la British Society for Antimicrobial Chemotherapy (BSAC) ou le Comité européen sur les tests de sensibilité aux antimicrobiens (EUCAST). On a pu constater des écarts importants au niveau des points d'arrêt de divers pays européens au fil des ans, et entre ceux de l'EUCAST et du CLSI. Alors que la CMI est la concentration la plus faible d'un agent antibactérien nécessaire pour inhiber la croissance visible, la concentration bactéricide minimale (CBM) est la concentration minimale d'un agent antibactérien qui entraîne la mort bactérienne. Plus la CMI est proche de la CBM, plus le composé est bactéricide. La première étape de la découverte d'un médicament est souvent le dépistage d'un médicament candidat de banque de données pour les CMI contre les bactéries d'intérêt. En tant que tels, les CMI sont généralement le point de départ pour de plus grandes évaluations précliniques de nouveaux agents antimicrobiens. Le but de la mesure de la concentration minimale inhibitrice est de s'assurer que les antibiotiques sont choisis efficacement pour augmenter le succès du traitement. (Wikipedia) Cuirs et peaux -- Conservation Peaux salées Sels de sodium Sophorolipides Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Sophorolipids (SLs) are fungal/yeast glycolipids that possess antimicrobial activity. In this study, three different SL mixtures were produced by microbial fermentation from oleic acid (SL-o), palmitic acid (SL-p), and stearic acid (SL-s), and tested for their antimicrobial activity against various halotolerant and moderately halophilic bacteria, and against extremely halophilic archaea that were isolated from salt and salted skin samples, as well as bacterial and extremely halophilic archaeal reference strains. The minimum inhibitory concentrations (MICs) of each of the SLs against known halotolerant and halophilic microorganisms were determined by the broth microdilution test method using resazurin dye. The extremely halophilic archaeal strains were most susceptible to the antimicrobial action of the tested SLs with MIC values as low as 3.42 μg/mL. Conversely, the endospore-forming halotolerant test strains, although susceptible to SLs, showed MIC values as high as 109.38 μg/mL. The SL-o, SL-p, and SL-s each exhibited broad-spectrum activity, demonstrating growth-inhibition against ten salt-associated bacterial strains and three archaeal strains possessing proteolytic activity, lipolytic activity, or both properties. In addition, each of the SLs showed growth-inhibition against three bacterial reference strains and two extremely halophilic archaeal reference strains. The findings from this study suggest that SL-o, SL-p, and SL-s might be utilized as potential antimicrobial agents together with salt, contributing to the preservation of the leather industry’s salted skins and hides. Note de contenu : - Materials - Production, isolation, purification, and analysis of sophorolipids - Inoculation procedure for test microorganisms - Preparation of resazurin solution - Determination of MICs of sophorolipid solutions and ethanol against test strains - Table 1 : Diacetylated lactone distribution for the sophorolipids used in this study produced from palmitic acid (SL-p), stearic acid (SL-s), and oleic acid (SL-o) according to their hydroxy fatty acid content - Table 2 : MIC values of SL-o, SL-p, SL-s (μg/mL) and ethanol (%) against halotolerant bacterial strains, moderately halophilic bacterial strains, bacterial reference strains, extremely halophilic archaeal strains, and extremely halophilic archaeal reference strains DOI : https://doi.org/10.34314/jwv5ae27 En ligne : https://drive.google.com/file/d/1k433IxtoIH-El2k7ndk5zFzUu1IH5J7w/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=41287 [article]

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Examination of haloversatile bacteria on salted goatskin and inactivation of haloversatile bacteria via direct electric current / S. Kose in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIX, N° 4 (04/2024)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIX, N° 4 (04/2024) . - p. 184-197 Titre : Examination of haloversatile bacteria on salted goatskin and inactivation of haloversatile bacteria via direct electric current Type de document : texte imprimé Auteurs : S. Kose, Auteur ; P. Yilmaz, Auteur ; Meral Birbir, Auteur ; Yasar Birbir, Auteur Année de publication : 2024 Article en page(s) : p. 184-197 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Bactéries -- Comptage Bactéries -- Identification Bactéries haloversatiles Caractérisation Courants continus Cuirs et peaux -- Analyse Cuirs et peaux -- Détérioration Cuirs et peaux de chèvres Enzymes microbiennes Peaux salées Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Haloversatile bacteria are among the commonly found microorganisms that have the potential to damage hides and skins in the leather industry. Therefore, the objective of this study was to investigate the presence of haloversatile bacteria on salted goatskins, to characterize these microorganisms through the use of molecular and conventional test methods, to detect their impact on the skins, and finally find an effective solution to inactivate these microorganisms. Haloversatile bacteria were common inhabitants at salted goatskin samples obtained from the Tuzla Organized Leather Industry Zone in Türkiye. Total numbers of haloversatile bacteria, proteolytic haloversatile bacteria, and lipolytic haloversatile bacteria on ten salted goatskin samples ranged from 7×104 to 2.7×105 CFU/g, 1×104 to 8×104 CFU/g, and 1×104 to 1.3×105 CFU/g, respectively. In the present study, 88% of the isolates were protease-positive, 69% were lipase-positive, 8% were xylanase-positive, 27% were caseinase-positive, 23% were amylase-positive, 8% were DNase-positive, 31% were cellulasepositive, 54% were urease-positive, 100% were catalase-positive, and 54% were oxidase-positive. The bacterial isolates showed positive reactions for the utilization of different amino acids such as glycine, L-cysteine, L-proline, and L-threonine, having the highest rates of 88%, 80%, 80%, and 80%, respectively. However, L-histidine had a lower positive reaction rate of 31%. The halophilic bacterial isolates exhibited positive reactions for the utilization and acid production from different types of sugar, with glucose having the highest positive reaction rate of 81%, followed by maltose at 73%, xylose at 58%, galactose at 46%, and lactose at 42%. Haloversatile enzymeproducing bacteria were identified using biochemical and molecular methods, resulting in the identification of 17 different species. Micrographs obtained from the scanning electron microscope revealed the damage inflicted on the fresh goatskin structure by haloversatile bacteria. A direct electric current of 2.2 A was applied to the mixed culture of haloversatile bacteria for 25 minutes to find an effective inactivation method. The total count of the mixed culture of haloversatile bacteria decreased from 7.3×106 CFU/mL to 4 CFU/mL within 16 minutes. All seventeen haloversatile bacteria in the mixed culture were killed within 19 minutes. Note de contenu : - Collection of salted goatskin samples from tanneries and measurement of pH values - Determination of the total numbers of haloversatile bacteria, proteolytic, and lipolytic haloversatile bacteria on the salted goatskin samples - Isolation of haloversatile bacteria - Haloversatile bacterial identification - Determination of optimal growth conditions for haloversatile bacteria - Investigation of enzymatic properties of haloversatile bacteria - Utilization of different amino acids and carbon sources by haloversatile bacteria - Examination of the damage caused by enzyme-producing haloversatile bacteria on the goatskin sample using scanning electron microscope - Destruction of haloversatile bacteria using electric current - Examination of haloversatile bacterial cells before and after treatment with direct electric current using scanning electron microscopy - Table 1 : The salted skin sample codes, ph of salted skin samples, total haloversatile, total proteolytic haloversatile, total lipolytic haloversatile bacterial counts on salted goatskin samples (CFU/g) - Table 2 : The isolate codes, phylogenetically similar species, length (bp), similarity (%), accession number of haloversatile isolates obtained from salted goatskin samples - Table 3 : The effects of pH, NaCl contents and temperature values on the growth of haloversatile bacterial isolates - Table 4 : Enzymatic characteristics of haloversatile isolates obtained from salted goatskin samples - Table 5 : Utilization of different sugars and amino acids by haloversatile isolates - Table 6 : The pH values, temperature, voltage and the total counts (CFU/mL) of enzyme producing haloversatile bacteria in the direct electric current treatment En ligne : https://drive.google.com/file/d/1WN-TWYW9l8-TRlCWsX0w8KSiISJyWWKx/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40826 [article]

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