Hans Zähner

Metabolic products of microorganisms

SummaryBoromycin, at a concentration of 0.05 μg/ml inhibits the synthesis of protein, RNA and DNA in whole cells of Bacillus subtilis. It is being antagonised by surface active compounds and is being bound to lipoprotein. Binding of the boromycin within the cell especially takes place at the cytoplasmic membrane.The inhibitory effect to Bacillus subtilis is being reversed by high concentration of potassium salts (e.g. 0.2 m KCl). The reversion is specific of potassium salts. After the adding of boromycin a discharge of potassium ions from the cells can be observed. The K+-Na+-activated ATP-ase of the cytoplasmic membrane is not influenced by boromycin. On an artificial membrane of carbon tetrachloride boromycin shows a low selectivity for potassium ions compared with sodium and lithium ions.The degradation of boromycin through alkaline and acid hydrolysis leads to a loss of antibiotic activity, due to the splitting off the boric acid from the molecule.

Purification and chemical characterization of staphyloferrin B, a hydrophilic siderophore from staphylococci

This paper describes the chemical characterization of staphyloferrin B, a new complexone type siderophore isolated from low iron cultures of Staphylococcus hyicus DSM 20459. Purification of the very hydrophilic metabolite was achieved by anion exchange high performance liquid chromatography HPLC. Mass spectrometry showed a molecular mass of 448 amu. Hydrolysis with 8 mHCl revealed the presence of l-2,3-diaminopropionic acid, citrate, ethylenediamine and succinic semialdehyde. The connections between the four building blocks were determined by two-dimensional nuclear magnetic resonance measurements. UV/Vis and circular dichroism spectra are consistent with the proposed structure, which could also be confirmed by precursor feeding. The siderophore activity of staphyloferrin B was demonstrated by iron transport measurements.

Purification of yersiniabactin : a siderophore and possible virulence factor of Yersinia enterocolitica

HPLC analysis revealed that Yersinia enterocolitica WA-C produced two substances under iron-limiting conditions one of which was identified as 2,3-dihydroxybenzoyl-L-serine. The other compound had iron-complexing activity and was called yersiniabactin. The fur mutant H1852 was shown to produce yersiniabactin constitutively in an iron-independent manner. Yersiniabactin was isolated by ethyl acetate extraction from the spent medium of H1852, size-fractionation chromatography and preparative HPLC. A catechol function was demonstrated with different chemical assays and by UV-visible spectroscopy. The molecular mass of yersiniabactin was determined to be 482 Da. Purified yersiniabactin stimulated growth of Y. enterocolitica and Escherichia coli phi under iron-limiting conditions and apparently served as an iron carrier. Transport of 55Fe-yersiniabactin was TonB-dependent, indicating a receptor-mediated uptake across the outer membrane. A pesticin-resistant mutant missing the receptor protein FyuA was unable to transport and use yersiniabactin as a siderophore.

Metabolic products of microorganisms. 185. The anthraquinones of the Aspergillus glaucus group. I. Occurrence, isolation, identification and antimicrobial activity.

The occurrence of emodin, erythroglaucin, physcion, physcion-9-anthrone, questin, catenarin, and catenarin-8-methyl ether in different species of the Aspergillus glaucus group (genus Eurotium) was investigated. So far catenarin-8-methyl ether (1, 4, 6-trihydroxy-8-methoxy-3-methylanthraquinone) has not been described as a natural product; it was therefore given the name rubrocristin. The chemical and physical properties of rubrocristin are reported. In addition a new violet pigment (C16H12O5) was isolated and characterized by its MS-, IR- and UV-spectra.The antimicrobial properties of all substances were examined in the agar diffusion assay. Gram-positive bacteria were the most sensitive organisms and catenarin was the most active naturally occurring substance. Synthetically obtained 1, 4, 6, 8-tetrahydroxy-anthraquinone was slightly more active than catenarin, whereas rubrocristin showed no antibacterial activity.

Production of desferrioxamine E and new analogues by directed fermentation and feeding fermentation

SummaryStreptomyces olivaceus TÜ 2718 produces the siderophore desferrioxamine E. Production depends on l-lysine and iron concentrations in the medium. With optimized conditions the yield of desferrioxamine E could be increased to 12g/1 in feeding fermentations. Supplementation of the basic production medium with natural and synthetic precursors of desferrioxamine E led to the production of twelve new analogues of desferrioxamine E.

Structure-activity relationships of the nikkomycins

The structure-activity relationships of different nikkomycins were studied to evaluate the structural requirements for a potent chitin synthase inhibitor. We investigated the transport of the nikkomycins via the peptide transport system of the yeast Yarrowia lipolytica and determined the kinetic parameters for nikkomycin Z uptake [Km = 24 microM, Vmax = 2.2 nmol min-1 (mg dry wt)-1]. We demonstrated that the beta-methyl group of the N-terminal amino acid of dipeptide nikkomycins protects the molecule against peptidase activity in crude cell-extracts of different fungi. Furthermore, the relationship between inhibition constants for chitin synthase, transport of the nikkomycins via the peptide transport system, susceptibility to degradation by cellular proteases and whole-cell activity of the nikkomycins are discussed.

Identification of Streptomyces olivaceus Tü 2353 genes involved in the production of the polyketide elloramycin

The genes for the production of elloramycin (ELM) from Streptomyces olivaceus (So) Tü2353 were cloned using a polyketide synthase gene probe from the tetracenomycin pathway. A cosmid clone (16F4) isolated from a gene library of So Tü2353 conferred tetracenomycin C and ELM resistance to S. lividans TK64 and complemented a mutation in So Tü2353R. Introduction of cosmid 16F4 into S. lividans TK64 resulted in the production of 8-demethyl-tetracenomycin C, an intermediate of ELM biosynthesis.

Ein neues antifungisches β-lactam-antibioticum der clavam-reihe

Abstract The novel β-lactam-antibiotic (-)-2-(2-hydroxyethyl)clavam ( 1 ) originales from cultures of Streptomyces antibioticus. The structure is shown by spectroscopic and degradative methods.

Fermentation and isolation of epidermin, a lanthionine containing polypeptide antibiotic from Staphylococcus epidermidis

SummaryStaphylococcus epidermidis TÜ 3298/DSM 3095 produces epidermin, a basic 21-residue peptide-amide antibiotic active against aerobic and anaerobic Gram-positive bacteria. Fermentations were performed by batch and feeding processes up to the 2001 scale. Highest yields were obtained when the first purification step was integrated into the fermentation process by on-line adsorption of the antibiotic. Isolation and purification by adsorption chromatography and ion exchange chromatography were performed batchwise.

Comparative studies on the fermentative production of lantibiotics by staphylococci

SummaryThe production of the lanthionine-containing polypeptide antibiotics gallidermin from Staphylococcus gallinarum TÜ 3928 and pep 5 from S. epidermidis 5 is investigated with respect to regulation and stimulation of productivity by media components, optimization of both the media used and the fermentation process and is compared to the production of the lantibiotic epidermin from S. epidermidis TÜ 3298. Efficient methods for rapid quantification of lantibiotics, optimization of the media and a primary enrichment by adsorption chromatography are reported.