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Daneyko A, Höltzel A, Khirevich S, Tallarek U. Influence of the Particle Size Distribution on Hydraulic Permeability and Eddy Dispersion in Bulk Packings. Anal Chem 2011; 83:3903-10. [DOI: 10.1021/ac200424p] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hlushkou D, Bruns S, Höltzel A, Tallarek U. From Pore Scale to Column Scale Dispersion in Capillary Silica Monoliths. Anal Chem 2010; 82:7150-9. [DOI: 10.1021/ac101393b] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Bruns S, Müllner T, Kollmann M, Schachtner J, Höltzel A, Tallarek U. Confocal Laser Scanning Microscopy Method for Quantitative Characterization of Silica Monolith Morphology. Anal Chem 2010; 82:6569-75. [DOI: 10.1021/ac100909t] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Khirevich S, Daneyko A, Höltzel A, Seidel-Morgenstern A, Tallarek U. Statistical analysis of packed beds, the origin of short-range disorder, and its impact on eddy dispersion. J Chromatogr A 2010; 1217:4713-22. [DOI: 10.1016/j.chroma.2010.05.019] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 05/03/2010] [Accepted: 05/07/2010] [Indexed: 10/19/2022]
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Khirevich S, Höltzel A, Seidel-Morgenstern A, Tallarek U. Time and length scales of eddy dispersion in chromatographic beds. Anal Chem 2010; 81:7057-66. [PMID: 20337386 DOI: 10.1021/ac901187d] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Time and length scales as well as the magnitude of individual contributions to eddy dispersion in chromatographic beds are resolved. We address this issue by a high-resolution numerical analysis of flow and mass transport in computer-generated bulk (unconfined) packings of monosized, nonporous, incompressible, spherical particles and complementary confined cylindrical packings with a cylinder-to-particle diameter ratio of d(c)/d(p) = 20. The transient behavior of longitudinal and transverse dispersion is analyzed and correlated with the spatial scales of heterogeneity in the bulk and confined packings. Simulations were carried out until complete transcolumn equilibration in the confined packings was achieved to facilitate a quantitative study of the geometrical wall effect. Longitudinal plate height data calculated over a wide range of reduced velocities (0.1 < or = nu < or = 500) were fitted to the comprehensive Giddings equation. The determined transition velocities for individual contributions to eddy dispersion were found to be widely disparate. As a consequence, the total effect of eddy dispersion on the plate height curves can be approximated in the practical range of chromatographic operational velocities (5 < or = nu < or = 20) by a composite expression in which only the short-range interchannel contribution retains its coupling characteristics, while transchannel and transcolumn contributions appear as simple mass transfer velocity-proportional terms.
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Nischang I, Höltzel A, Tallarek U. Electrochromatographic retention of peptides on strong cation-exchange stationary phases. Electrophoresis 2010; 31:933-43. [DOI: 10.1002/elps.200900549] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Jung S, Höltzel A, Ehlert S, Mora JA, Kraiczek K, Dittmann M, Rozing GP, Tallarek U. Impact of Conduit Geometry on the Performance of Typical Particulate Microchip Packings. Anal Chem 2009; 81:10193-200. [DOI: 10.1021/ac902069x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Khirevich S, Höltzel A, Seidel-Morgenstern A, Tallarek U. Struktur-Transport-Analyse in Festbetten verschiedener Querschnittsgeometrien. CHEM-ING-TECH 2009. [DOI: 10.1002/cite.200950056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Khirevich S, Höltzel A, Ehlert S, Seidel-Morgenstern A, Tallarek U. Large-Scale Simulation von Fluss und Transport in rekonstruierten Festbetten. CHEM-ING-TECH 2009. [DOI: 10.1002/cite.200950055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Khirevich S, Höltzel A, Ehlert S, Seidel-Morgenstern A, Tallarek U. Large-Scale Simulation of Flow and Transport in Reconstructed HPLC-Microchip Packings. Anal Chem 2009; 81:4937-45. [DOI: 10.1021/ac900631d] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Khirevich S, Höltzel A, Hlushkou D, Seidel-Morgenstern A, Tallarek U. Structure-transport analysis for particulate packings in trapezoidal microchip separation channels. LAB ON A CHIP 2008; 8:1801-1808. [PMID: 18941678 DOI: 10.1039/b810688f] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
This article investigates the efficiency of particulate beds confined in quadrilateral microchannels by analyzing the three-dimensional fluid flow velocity field and accompanying hydrodynamic dispersion with quantitative numerical simulation methods. Random-close packings of uniform, solid (impermeable), spherical particles of diameter d(p) were generated by a modified Jodrey-Tory algorithm in eighteen different conduits with quadratic, rectangular, or trapezoidal cross-section at an average bed porosity (interparticle void fraction) of epsilon = 0.48. Velocity fields were calculated by the lattice Boltzmann method, and axial hydrodynamic dispersion of an inert tracer was simulated at Péclet numbers Pe = u(av)d(p)/D(m) (where u(av) is the average fluid flow velocity through a packing and D(m) the bulk molecular diffusion coefficient) from Pe = 5 to Pe = 30 by a Lagrangian particle-tracking method. All conduits had a cross-sectional area of 100d(p)(2) and a length of 1200d(p), translating to around 10(5) particles per packing. We present lateral porosity distribution functions and analyze fluid flow profiles and velocity distribution functions with respect to the base angle and the aspect ratio of the lateral dimensions of the different conduits. We demonstrate significant differences between the top and bottom parts of trapezoidal packings in their lateral porosity and velocity distribution functions, and show that these differences increase with decreasing base angle and increasing base-aspect ratio of a trapezoidal conduit, i.e., with increasing deviation from regular rectangular geometry. Efficiencies are investigated in terms of the axial hydrodynamic dispersion coefficients as a function of the base angle and base-aspect ratio of the conduits. The presented data support the conclusion that the efficiency of particulate beds in trapezoidal microchannels strongly depends on the lateral dimensions of the conduit and that cross-sectional designs based on large side-aspect-ratio rectangles with limited deviations from orthogonality are favorable.
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Nischang I, Höltzel A, Seidel-Morgenstern A, Tallarek U. Concentration polarization and nonequilibrium electroosmotic slip in hierarchical monolithic structures. Electrophoresis 2008; 29:1140-51. [DOI: 10.1002/elps.200700727] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Khirevich S, Höltzel A, Hlushkou D, Tallarek U. Impact of Conduit Geometry and Bed Porosity on Flow and Dispersion in Noncylindrical Sphere Packings. Anal Chem 2007; 79:9340-9. [DOI: 10.1021/ac071428k] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Höltzel A, Tallarek U. Ionic conductance of nanopores in microscale analysis systems: where microfluidics meets nanofluidics. J Sep Sci 2007; 30:1398-419. [PMID: 17623420 DOI: 10.1002/jssc.200600427] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In this tutorial review we illustrate the origin and dependence on various system parameters of the ionic conductance that exists in discrete nanochannels as well as in nanoporous separation and preconcentration units contained as hybrid configurations, membranes, packed beds, or monoliths in microscale liquid phase analysis systems. A particular complexity arises as external electrical fields are superimposed on internal chemical and electrical potential gradients for tailoring molecular transport. It is demonstrated that the variety of geometries in which the microfluidic/nanofluidic interfaces are realized share common, fundamental features of coupled mass and charge transport, but that phenomena behind the key steps in a particular application can be significantly tuned, depending on the morphology of a material. Thus, the understanding of morphology-related transport in internal and external electrical potential gradients is critical to the performance of a device. This addresses a variety of geometries (slits, channels, filters, membranes, random or regular networks of pores, etc.) and applications, e. g., the gating, sensing, preconcentration, and separation in multifunctional miniaturized devices. Inherently coupled mass and charge transport through ion-permselective (charge-selective) microfluidic/nanofluidic interfaces is analyzed with a stepwise-added complexity and discussed with respect to the morphology of the charge-selective spatial domains. Within this scenario, the electrostatics and electrokinetics in microfluidic and nanofluidic channels, as well as the electrohydrodynamics evolving at microfluidic/nanofluidic interfaces, where microfluidics meets nanofluidics, define the platform of central phenomena.
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Gebhardt K, Schimana J, Höltzel A, Dettner K, Draeger S, Beil W, Rheinheimer J, Fiedler HP. Aspochalamins A-D and aspochalasin Z produced by the endosymbiotic Fungus aspergillus niveus LU 9575. I. Taxonomy, fermentation, isolation and biological activities. J Antibiot (Tokyo) 2005; 57:707-14. [PMID: 15712664 DOI: 10.7164/antibiotics.57.707] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aspochalamins A-D, a family of new cytochalasan antibiotics have been isolated from Aspergillus niveus, an endosymbiotic fungus isolated from the gut of a woodlouse belonging to the family Trichoniscidae. Besides aspochalamins, aspochalasin Z, a new member of the aspochalasin family, as well as the known mycotoxins aspochalasin D and citreoviridins A/C and B were isolated from the mycelium. Aspochalamins showed cytostatic effects towards various tumor cell lines and a weak antibacterial activity against Gram-positive bacteria.
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Potterat O, Hostettmann K, Höltzel A, Jung G, Diehl PA, Petrini O. Boophiline, an antimicrobial sterol amide from the cattle tickboophilus microplus. Helv Chim Acta 2004. [DOI: 10.1002/hlca.19970800707] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Höltzel A, Dieter A, Schmid DG, Brown R, Goodfellow M, Beil W, Jung G, Fiedler HP. Lactonamycin Z, an Antibiotic and Antitumor Compound Produced by Streptomyces sanglieri Strain AK 623. J Antibiot (Tokyo) 2003; 56:1058-61. [PMID: 15015734 DOI: 10.7164/antibiotics.56.1058] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Gebhardt K, Schimana J, Müller J, Fiedler HP, Kallenborn HG, Holzenkämpfer M, Krastel P, Zeeck A, Vater J, Höltzel A, Schmid DG, Rheinheimer J, Dettner K. Screening for biologically active metabolites with endosymbiotic bacilli isolated from arthropods. FEMS Microbiol Lett 2002; 217:199-205. [PMID: 12480104 DOI: 10.1111/j.1574-6968.2002.tb11475.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Endosymbiotic bacteria from the genus Bacillus were isolated from different compartments of the gut of various members of insects (Hexapoda) and millipedes (Diplopoda). They were grown in submerged culture and investigated by biological assays and HPLC-diode array analysis regarding their production of bioactive metabolites, which were isolated and determined in structure. Known compounds and yet unknown derivatives from the primary metabolism were detected, as well as antibacterially and antifungally acting peptide antibiotics.
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Schimana J, Gebhardt K, Höltzel A, Schmid DG, Süssmuth R, Müller J, Pukall R, Fiedler HP. Arylomycins A and B, new biaryl-bridged lipopeptide antibiotics produced by Streptomyces sp. Tü 6075. I. Taxonomy, fermentation, isolation and biological activities. J Antibiot (Tokyo) 2002; 55:565-70. [PMID: 12195962 DOI: 10.7164/antibiotics.55.565] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
New lipopeptide antibiotics, colourless arylomycins A series and yellow arylomycins B series were detected in the culture filtrate and mycelium extracts of Streptomyces sp. Tü 6075 by HPLC-diode-array and HPLC-electrospray-mass-spectrometry screening. Arylomycins are a family of lipohexapeptide antibiotics, which represent the first examples of biaryl-bridged lipopeptides. They show antibiotic activities against Gram-positive bacteria.
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MESH Headings
- Anti-Bacterial Agents/biosynthesis
- Anti-Bacterial Agents/isolation & purification
- Anti-Bacterial Agents/pharmacology
- Chromatography, High Pressure Liquid
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- Microbial Sensitivity Tests
- Peptides, Cyclic/biosynthesis
- Peptides, Cyclic/isolation & purification
- Peptides, Cyclic/pharmacology
- Polymerase Chain Reaction
- RNA, Ribosomal, 16S/chemistry
- RNA, Ribosomal, 16S/genetics
- Sequence Analysis, DNA
- Soil Microbiology
- Streptomyces/chemistry
- Streptomyces/classification
- Streptomyces/genetics
- Streptomyces/metabolism
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Höltzel A, Schmid DG, Nicholson GJ, Stevanovic S, Schimana J, Gebhardt K, Fiedler HP, Jung G. Arylomycins A and B, new biaryl-bridged lipopeptide antibiotics produced by Streptomyces sp. Tü 6075. II. Structure elucidation. J Antibiot (Tokyo) 2002; 55:571-7. [PMID: 12195963 DOI: 10.7164/antibiotics.55.571] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structures of new lipopeptide antibiotics, arylomycins A and B, were elucidated by a combination of ESI-FTICR-mass spectrometry, NMR spectroscopy, Edman sequencing, and fatty acid and chiral amino acid analyses. The colourless arylomycins A share the peptide sequence of D-N-methylseryl2(D-MeSer2)-D-alanyl3-glycyl4-N-methyl- 4-hydroxyphenylglycyl5(MeHpg5)-L-alanyl6-tyrosine7 cyclised by a [3,3]biaryl bond between MeHpg5 and Tyr7. The yellow arylomycins B differ from arylomycins A by nitro substitution of Tyr7. The N-termini of arylomycins A and B are acylated with saturated C11-C15 fatty acids (fa1) comprising n, iso, and anteiso isomers. Arylomycins A and B represent the first examples of biaryl-bridged lipopeptides.
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Bischoff D, Pelzer S, Höltzel A, Nicholson GJ, Stockert S, Wohlleben W, Jung G, Süssmuth RD. Die Biosynthese von Glycopeptid-Antibiotika des Vancomycin-Typs - neue Einblicke in die Abfolge der Ringschlüsse. Angew Chem Int Ed Engl 2001. [DOI: 10.1002/1521-3757(20010504)113:9<1736::aid-ange17360>3.0.co;2-b] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Bischoff D, Pelzer S, Höltzel A, Nicholson GJ, Stockert S, Wohlleben W, Jung G, Süssmuth RD. The Biosynthesis of Vancomycin-Type Glycopeptide Antibiotics—New Insights into the Cyclization Steps. Angew Chem Int Ed Engl 2001; 40:1693-1696. [PMID: 11353482 DOI: 10.1002/1521-3773(20010504)40:9<1693::aid-anie16930>3.0.co;2-8] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Höltzel A, Jack RW, Nicholson GJ, Jung G, Gebhardt K, Fiedler HP, Süssmuth RD. Streptocidins A-D, novel cyclic decapeptide antibiotics produced by Streptomyces sp. Tü 6071. II. Structure elucidation. J Antibiot (Tokyo) 2001; 54:434-40. [PMID: 11480887 DOI: 10.7164/antibiotics.54.434] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structures of the new antibiotics streptocidins A approximately D were elucidated as cyclic decapeptides cyclo[L-Val1-L-Orn2-L-Leu3-D-Phe4-L-Pro5-L-Leu6-X7-L-Asn8-L-Gln9-X10] with X7=D-Trp (A, B, C) or D-Phe (D) and X10=L-Tyr (A), L-Trp (B, D), or D-Trp (C). The amino acid composition (including the configuration) of the substances was determined by chiral-phase GC-MS of the hydrolysates. The sequences were established by EDMAN degradation following linearisation of the cyclic peptides upon treatment with LiAlH4. NMR spectroscopic studies of streptocidins C and D confirmed the proposed sequences and provided conformational data which indicate a molecular topology of streptocidins C and D similar to those of tyrocidine A and gramicidin S.
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Gänzle MG, Höltzel A, Walter J, Jung G, Hammes WP. Characterization of reutericyclin produced by Lactobacillus reuteri LTH2584. Appl Environ Microbiol 2000; 66:4325-33. [PMID: 11010877 PMCID: PMC92303 DOI: 10.1128/aem.66.10.4325-4333.2000] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2000] [Accepted: 07/06/2000] [Indexed: 11/20/2022] Open
Abstract
Lactobacillus reuteri LTH2584 exhibits antimicrobial activity that can be attributed neither to bacteriocins nor to the production of reuterin or organic acids. We have purified the active compound, named reutericyclin, to homogeneity and characterized its antimicrobial activity. Reutericyclin exhibited a broad inhibitory spectrum including Lactobacillus spp., Bacillus subtilis, B. cereus, Enterococcus faecalis, Staphylococcus aureus, and Listeria innocua. It did not affect the growth of gram-negative bacteria; however, the growth of lipopolysaccharide mutant strains of Escherichia coli was inhibited. Reutericyclin exhibited a bactericidal mode of action against Lactobacillus sanfranciscensis, Staphylococcus aureus, and B. subtilis and triggered the lysis of cells of L. sanfranciscensis in a dose-dependent manner. Germination of spores of B. subtilis was inhibited, but the spores remained unaffected under conditions that do not permit germination. The fatty acid supply of the growth media had a strong effect on reutericyclin production and its distribution between producer cells and the culture supernatant. Reutericyclin was purified from cell extracts and culture supernatant of L. reuteri LTH2584 cultures grown in mMRS by solvent extraction, gel filtration, RP-C(8) chromatography, and anion-exchange chromatography, followed by rechromatography by reversed-phase high-pressure liquid chromatography. Reutericyclin was characterized as a negatively charged, highly hydrophobic molecule with a molecular mass of 349 Da. Structural characterization (A. Höltzel, M. G. Gänzle, G. J. Nicholson, W. P. Hammes, and G. Jung, Angew. Chem. Int. Ed. 39:2766-2768, 2000) revealed that reutericyclin is a novel tetramic acid derivative. The inhibitory activity of culture supernatant of L. reuteri LTH2584 corresponded to that of purified as well as synthetic reutericyclin.
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Höltzel A, Gänzle M, Nicholson G, Hammes W, Jung G. Das erste niedermolekulare Antibiotikum aus lebensmitteltechnologisch eingesetzten Milchsäurebakterien: Reutericyclin, eine neue Tetramsäure. Angew Chem Int Ed Engl 2000. [DOI: 10.1002/1521-3757(20000804)112:15<2886::aid-ange2886>3.0.co;2-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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