Wachstum von Bakterien log clony forminf units (CFU) Optische Dichte (OD)

Antibiotika Cephalosporin Cephalotin Chloramphenicol Penicillin Erythromycin

Antibiotika Rifampin Streptomycin

Antibiotika

Antibiotika-Resistenzmechanismen in Bakterien 1. Änderung des Wirkorts des Antibiotikums (Änderung des Angriffziels) durch Punktmutation (Streptomycin, Rifampin) mehrfache Änderung durch Rekombination (Mosaikgene, Penicillin) enzymatische Veränderung, z.B. durch Methylierung (Erythromycin) 2. Modifikation des Antibiotikums (Inaktivierung des Antibiotikums) Acetylierung (Chloramphenicol) Adenylierung (Kanamycin) Phosphorylierung (Aminoglycoside) 3. Spaltung des Antibiotikums ß-Lactamasen (Penicillin) 4. Schutzprotein (Abschirmung des Wirkorts) (Tetracyclin) 5. Efflux (Entfernen des Antibiotikums vom Wirkort) Efflux Pumpen, Multi-Drug Exporter, (Tetracyclin, Chloramphenicol)

Lantibiotika Nisin produziert von Lactococcus lactis Epidermin produziert von Staphylococcus epidermidis Gallidermin (eine Variante von Epidermin, die an Pos. 6 Leucin an Stelle von Isoleucin enthält) produziert von Staphylococcus gallinarum Lantibiotika sind antibiotisch wirksame Peptide mit der ungewöhnlichen Aminosäure Lanthionin Lanthionin

Lantibiotika

Lantibiotika Wirkungsweise der Lantibiotika Nisin und Epidermin (Gallidermin) Bei micromolaren Konzentrationen von Nisin oder Epidermin: Bildung von unspezifischen Poren. A Bei nanomolaren Konzentrationen von Nisin oder Epidermin: Bindung an Lipid II. Bildung von Rezeptor-vermittelten Poren. Hemmung der Peptidoglykanbiosynthese. B

Lactose Verwertung

Verwertung von Zuckern glkA Lactose Alternative lactose catabolic pathways in Staphylococci. Transport of lactose and galactose and their catabolism are shown. In S. aureus, lactose and galactose are transported by the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS). Internalized lactose-6-phosphate is hydrolyzed by a phospho--galactosidase to galactose-6-phosphate and glucose. Galactose-6-phosphate is catabolized through the tagatose-6-phosphate pathway. In S. xylosus and probably other staphylococcal species that do not possess a lactose PTS, a permease is responsible for the transport of lactose. Nonphosphorylated lactose is hydrolyzed by a -galactosidase to yield glucose and galactose. Galactose is then catabolyzed through the Leloir pathway. In both staphylococcal species, glucose-6-phosphate, produced by a glucose kinase, enters the Embden-Meyerhof-Parnas pathway, the main glycolytic pathway in staphylococci. Only the galactoside-specific genes and their encoded products are mentioned in the pathways. The following abbreviations have been used: CM: cytoplasmic membrane, EI: enzyme I, EIIAlac: lactose-specific enzyme IIA, EIICBlac: lactose-specific enzyme IICB, HPr: histidine-containing protein, -Gal: -galactosidase, P--Gal: phospho--galactosidase, G6P-Isomerase: galactose-6-phosphate isomerase, G1P-Uridyltransferase: galactose-1-phosphate uridyltransferase, T6P-Kinase: tagatose-6-phosphate kinase, T1,6DP-Aldolase: tagatose-1,6-diphosphate aldolase, UDP-Gal: UDP-galactose, UDP-Glc: UDP-glucose, UDP-G4-Epimerase: UDP-galactose-4 epimerase, PEP: phosphoenolpyruvate, P: phosphate, DP: diphosphate. In E. coli the Leloir pathway is operative initiated by lactose uptake by LacY permease and cleavage by the ß-Galactosidase encoded by lacZ.