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A new method is described for the selective isolation of species of Myxococcus directly from soil by dilution plating. The method involves suppression of competing microorganisms with antibiotics combined with air drying and wet heat treatment of soils. Fungi were eliminated by supplementing the plating medium with cycloheximide and nystatin. Non-sporulating bacteria were controlled by air drying soils and then heating aqueous soil dilutions for 10 min at 56 degrees C. The predominant sporulating bacteria in soil, Streptomyces and Bacillus, were suppressed by adding either tiacumicin B, ristocetin or vancomycin to the medium. Swarming of Myxococcus colonies was controlled with a casein digest-yeast extract plating medium (CY-C10 agar). Ultrasound treatment of soil suspensions gave the highest number of Myxococcus colonies in the soils studied, but these cultures could be recovered without ultrasound. Strains of Myxococcus fulvus, M. xanthus, M. coralloides, M. stipitatus and M. virescens were isolated from soil using this technique. Soils examined yielded one or two Myxococcus species per sample.

Determination of the mechanism of action of FK506 and cyclosporin A has yielded new molecular targets involved in signal transduction during T cell activation. A common target of FK506 and cyclosporin A is inhibition of activation of the NFAT transcription factor, for which a specific binding region is present in the promoter of the IL-2 gene. A reporter gene assay has been used to screen for agents that interfere with this early step in T cell activation. Simple aromatic compounds that block NFAT-dependent transcription and show in vitro immunosuppressive activity were isolated from the broth and mycelia of two Streptomyces sp. fermentations. The compounds were active at concentrations that were not directly cytotoxic.

A complex of 18-membered macrolide antibiotics has been discovered in the fermentation broth of strain AB718C-41. The producing culture, isolated from a soil sample collected in Hamden, Connecticut, was identified as a strain of Dactylosporangium aurantiacum and was designated D. aurantiacum subsp. hamdenesis subsp. nov. The antibiotic complex was produced in a New Brunswick 150-liter fermentor using a medium consisting of glucose, soybean oil, soybean flour, beef extract and inorganic salts. Several of the antibiotics were active against sensitive and multiple antibiotic-resistant strains of pathogenic Gram-positive bacteria.

Coumamidines are water-soluble basic antibiotics related to the glycocinnamoylspermidines. They are produced by a soil isolate designated Saccharopolyspora sp. AB 1167L-65. The coumamidines have broad spectrum activity and were selected in a screen for substances which inhibit Pseudomonas aeruginosa.