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Seven new polyketides, for which the trivial names hyafurones A1–B (1–3), hyapyrrolines A (4) and B (5), and hyapyrones A (6) and B (7) are proposed, were isolated from the fermentation broth of the myxobacteria Hyalangium minutum,strains NOCB-2Tand Hym-3. Their structures were elucidated from NMR and HRESIMS data, and their geometric configuration was assigned based on NOE and vicinal 1H coupling data. Both hyafurone B (3) and hyapyrone B (7) inhibited growth of the Gram-positive bacterium Nocardia flava, while 7showed antifungal activity against Mucor hiemalis.

Sulfangolids are the first sulfate ester containing secondary metabolites from myxobacteria. The metabolites 1–4and the structurally related kulkenon (5) were isolated from different strains of the species Sorangium cellulosum. In the course of isolation all metabolites proved to be rather sensitive due to their conjugated double bond systems and the strong acidic nature of the sulfate ester in sulfangolids. The relative configuration of sulfangolid C (3) was assigned by extensive 1D and 2D NMR analysis and molecular modelling. In addition, the biosynthesis of 3was studied by feeding experiments.

Hen or egg?The polyketide‐based p‐quinone methide antibiotic, elansolid A3, was isolated from the gliding bacterium Chitinophaga sancti.It now appears probable that elansolid A3 is the underlying biosynthetic product of the atropisomeric macrolide antibiotics elansolid A1 and A2 (see scheme). Under mild basic conditions the interconversion of elansolid isomers A1–A3 was observed. Under mild acidic conditions a Grob‐type fragmentation of elansolid A3 led to the p‐hydroxy styryl isomer elansolid D.

Roimatacene (1) was isolated from the myxobacterium Cystobacter ferrugineusstrain Cb G35 in a bioactivity‐guided process, by following the antimicrobial activity against Escherichia coli. Since 1was extremely sensitive to oxygen, a protective isolation and handling protocol was developed, by utilizing the free radical scavenger 4‐ethoxyphenol. The structure of 1was determined by HRMS, 1D and 2D NMR spectroscopy and chemical derivatization to acetonides and Mosher esters to finally establish the absolute configuration. Methionine and acetate were identified as building blocks in the biosynthesis of 1by feeding experiments with differently 13C‐labeled precursors. The antimicrobial activity of 1was determined in a broad screening revealing 1to inhibit several Gram‐negative bacteria.

The applicability of a protein‐free medium for the production of recombinant human interleukin‐2 with baby hamster kidney cells in airlift bioreactors was investigated. For this purpose, a BHK‐21 cell line, adapted to grow and produce in protein‐free SMIF7 medium without forming spheroids in membrane‐aerated bubble‐free bioreactors, was used as the producer cell line. First, cultivation of the cells was established at a 20‐L scale using an internal loop airlift bioreactor system. During the culturing process the medium formulation was optimized according to the specific requirements associated with cultivation of mammalian cells under protein‐free conditions in a bubble‐aerated system. The effects of the addition of an antifoam agent on growth, viability, productivity, metabolic rates, and release of lactate dehydrogenase were investigated. Although it was possible to establish cultivation and production at a 20‐L scale without the use of antifoaming substances, the addition of 0.002% silicon‐oil‐based antifoaming reagent improved the cultivation system by completely preventing foam formation. This reduced the release of lactate dehydrogenase activity to the level found in bubble‐free aerated stirred tank membrane bioreactors and led to a reduction in generation doubling times by about 5 h (17%). Using the optimized medium formulation, cells were cultivated at a 1000‐L scale, resulting in a culture performance comparable to the 20‐L airlift bioreactor. For comparison, cultivations with protein‐containing SMIF7 medium were carried out at 20– and 1000‐L scales. The application of protein supplements did not lead to a significant improvement in the cultivation conditions. The results were also compared with experiments performed in a bubble‐free aerated stirred tank membrane bioreactor to evaluate the influence of bubbles on the investigated culture parameters. The data implied a higher metabolic activity of the cells in airlift bioreactors with a 150% higher glucose consumption rate. The results of this study clearly demonstrate the applicability of a protein‐free chemically defined medium for the production of recombinant proteins with BHK cells in airlift bioreactors.

A preliminary study of xanthan production by Xanthomonas campestriswas performed in an external‐circulation‐loop airlift (ECL‐AL) fermenter. An average of 25 g/L xanthan of good viscosity characteristics was obtained in a total fermentation time of 49 hours. Oxygen limitation was observed after 36 hours of fermentation time. It is conclusively demonstrated that the ECL‐AL fermenter can be used to economically produce xanthan. The key operating and design features are the liquid height, downcomer‐to‐riser cross‐sectional area ratio (AD/AR) and the orfice diameter of the air sparger.

AbstractWolfgang Kessler gives a report on the latest developments ofthe GATT negociations. The failure ofthe Uiruguay round in the autumn of 1990 and the irksome attempts at reanimation are depicted as a result of the strategy ofthe industrialized countries to bargain for their interests by demanding an extension oftheir free trade policy on additional parts of the world market. Kessler contrasts this strategy with a model of an ecologically and socially regulated world trade founded on world-wide agreed upon treaties that focus on a sustainable world economy.