Leif Alexander Garbe

Transient accumulation of γ-butyrolactone during degradation of bis(4-chloro-n-butyl) ether by diethylether-grown Rhodococcus sp. strain DTB

Rhodococcus sp. strain DTB (DSM 44534) grows aerobically on diethylether as sole source of carbon and energy. Dense cell suspension experiments showed that the induced ether-cleaving enzyme system attacks a broad range of ethers like tetrahydrofuran, phenetole and chlorinated alkylethers including Cα-substituted alkylethers. Identification of metabolites revealed that degradation of the ethers started by an initial attack of the ether bond. Diethylether-grown cells degraded bis(4-chloro-n-butyl) ether via an initial ether scission followed by the transient accumulation of γ-butyrolactone as intermediate at nearly stoichiometric concentrations.

Testing of antibiotic releasing implant coatings to fight bacteria in combat-associated osteomyelitis – an in-vitro study

PurposeSurgical procedures to prevent osteomyelitis after trauma can be supported by local application of antibiotics. This in-vitro study investigated the release and impact of antibiotics from implant coatings against bacteria associated with combat-related osteomyelitis.MethodsK-wires were coated with poly(D,L-lactide) and ciprofloxacin, gentamicin, colistin, daptomycin or cefoxitin in different concentrations. The release was quantified and antimicrobial activity tested for different gram-positive or gram-negative bacteria, alone and in combination. To exclude toxic effects, primary osteoblast-like cells were exposed to antibiotic coating concentrations.ResultsAll antibiotics alone and in combination showed an initial burst release with dose dependent antimicrobial activity and no negative effects on osteoblast-like cells, except for cefoxitin.ConclusionsImplant coatings can be customized with single or double antibiotic coatings to effectively fight different bacteria and also mixed infections in the treatment of a combat-acquired osteomyelitis. However, optimal drug load and degradation behaviour of individual antibiotics have to be considered.

The Peptide-catalyzed Maillard Reaction

The reaction pathways of amino acids and reducing sugars are now fully understood. The focus in the last few years, however, has turned to the reaction of peptides and proteins with reducing sugars. We have investigated the reaction of γ‐aminobutanoic acid, the heptapeptide Nα‐Acetyl‐Lys‐Lys‐β‐Ala‐Lys‐β‐Ala‐Lys‐Gly, and the model protein β‐casein in Maillard reactions with 1‐13C arabinose. Characterization of 13C‐labeled acetic acid and norfuraneol by gas chromatography–mass spectrometry and nuclear magnetic resonance revealed new formation pathways. The results demonstrate significant differences in the labeling pattern of the products depending on the amine used, indicating different formation pathways of acetic acid and norfuraneol.