A detailed screening of the secondary metabolite pattern from Micromonospora sp. strain Tü 6368 resulted in the isolation of ten compounds belonging to five different structural families. The structures of the novel compounds 1-(a -ribofuranosyl)-lumichrome (3), retymicin (7), galtamycin B (11) and saquayamycin Z (14) were assigned by spectroscopic methods and chemical transformations. This strain fits our hypothesis that the metabolite analysis of biosynthetically talented strains leads readily to novel compounds.

A new xanthone compound named retymicin (1) was isolated together with galtamycin B (2) and saquayamycin Z (3), new members of the galtamycin and saquayamycin families, respectively, and the new lumichrome derivative 1-(a-ribofuranosyl)-lumichrome (4) from Micromonospora strain Tü 6368, isolated from a soil sample collected in Romania. Retymicin, galtamycin B and saquayamycin Z show cytostatic effects to various human tumor cell lines whereas saquayamycin Z is also active against Gram-positive bacteria.

Genome sequencing and bioinformatic analysis have identified numerous cryptic gene clusters that have the potential to produce novel natural products. Within this work, we identified a cryptic type II PKS gene cluster (skt) from Streptomyces sp. Tü6314. Facilitated by linear plus linear homologous recombination-mediated recombineering (LLHR), we directly cloned the skt gene cluster using the Streptomyces site-specific integration vector pSET152. Direct cloning allowed for rapid heterologous expression in Streptomyces coelicolor, leading to the identification and structural characterization of six polyketides (three known compounds and new streptoketides), four of which exhibit anti-HIV activities. Our study shows that the pSET152 vector can be directly used for LLHR, expanding the Rec/ET direct cloning toolbox and providing the possibility for rapid heterologous expression of gene clusters from Streptomyces.

A new octaketide named fogacin (1) was isolated from Streptomyces sp. (strain Tü 6319). Furthermore two shunt metabolites, SEK4b (2) and anhydroSEK4b (3), were detected and identified as nonenzymatically cyclized products of polyketide intermediates built during the biosynthesis of actinorhodin. SEK4b (2) as well as anhydroSEK4b (3) were previously described as metabolites of genetically engineered strains.Keywords polyketides, biosynthesis, shunt metabolites, SEK4b, HPLC screening Freshly isolated strains from soils collected at various sites in Romania were included in our HPLC-diode array screening program to detect novel secondary metabolites. Strain Tü 6319 which was isolated from an industrial contaminated soil near Fogaras, Romania, drew our attention because of its characteristic metabolite pattern, which appears analyzing the culture filtrate extract. Three of the metabolites were identified by means of our HPLC-UV-Vis database [2] as SEK4b (2) [3], and germicidins A and B [4], respectively. Two further metabolites did not correspond to any of the 834 reference compounds stored in our database. One of them was identified as anhydroSEK4b (3) [5], the second was named fogacin (1).Strain Tü 6319 was examined for a number of key properties known to be of value in streptomycete systematics. The presence of LL-diaminopimelic acid in the peptidoglycan together with its colonial characteristics allowed its assignment to the genus Streptomyces. Strain Tü 6319 shared a high 16S rRNA gene sequence with the closely related type strains Streptomyces coelescens DSM 40421, S. violaceolatus DSM 40438 and S. violaceoruber DSM 40049.Batch fermentation of strain Tü 6319 was carried out in 10-liter stirred tank fermenters (New Brunswick) in a medium that consisted of oat meal 2.0% in tap water (pH 7.3). The fermentation was conducted at 27°C for 168 hours with an aeration rate of 0.5 v/v/m and agitation of 200 rpm. Addition of 3% DMSO to the medium increased the production of 1 by 33%, reaching a maximum value of 10 mg/liter after 168 hours. Compound 1 was isolated from the culture filtrate (13 liters), loaded onto an Amberlite XAD-16 column (8ϫ40 cm) and eluted by increasing concentrations of MeOH. The 40% MeOH fraction that contained 1 was concentrated in vacuo, adjusted to pH 2, and extracted with ethyl acetate. The raw material was separated on a LiChroprep Diol column (2.6ϫ40 cm; Merck) applying a linear gradient CH 2 Cl 2 to a content of 5% MeOH within 3 hours at a flow rate of 5 ml/minute. A further metabolite (3) was separated from 1, and both compounds were purified by subsequent column chromatography on Sephadex LH-20 and Fractogel TSK HW-40 (each column 1.5ϫ90 cm, flow rate 15 ml/hour) using MeOH as eluent. Pure 1 was obtained in an amount of 8 mg.The antimicrobial activities of fogacin (1) and anhydro SEK4b (3) were examined by an agar plate diffusion assays. Compound 3 revealed a moderate inhibitory activity against Bacillus subtilis DSM 10 and

Other natural products U 0800 Biosynthetic Capacities of Actinomycetes. Part 36. Fogacin (I), a Novel Cyclic Octaketide Produced by Streptomyces Strain Tü 6319. -The two shunt metabolites (II) and (III) are detected and identified as non-enzymatically cyclized products of polyketide intermediates built during the biosynthesis of actinorhodin. -(RADZOM, M.; ZEECK*, A.; ANTAL, N.; FIEDLER, H.-P.; J.