Streptopyridines, volatile pyridine alkaloids produced by Streptomyces sp. FORM5

Abstract

Summary Streptomyces sp. FORM5 is a bacterium that is known to produce the antibiotic streptazolin and related compounds. We investigated the strain for the production of volatiles using the CLSA (closed-loop stripping analysis) method. Liquid and agar plate cultures revealed the formation of new 2-alkylpyridines (streptopyridines), structurally closely related to the already known 2-pentadienylpiperidines. The structures of the streptopyridines A to E were confirmed by total synthesis. The analysis of the liquid phase by solvent extraction or extraction with an Oasis adsorbent showed that streptazolin and 2-pentadienylpiperidine are the major compounds, while the streptopyridines are only minor components. In the gas phase, only the streptopyridines could be detected. Therefore, an orthogonal set of analysis is needed to assess the metabolic profile of bacteria, because volatile compounds are obviously overlooked by traditional analytical methods. The streptopyridines are strain specific volatiles that are accompanied by a broad range of headspace constituents that occur in many actinomycetes. Volatiles might be of ecological importance for the producing organism, and, as biosynthetic intermediates or shunt products, they can be useful as indicators of antibiotic production in a bacterium.

Homoserine Lactones, Methyl Oligohydroxybutyrates, and Other Extracellular Metabolites of Macroalgae‐Associated Bacteria of the Roseobacter Clade: Identification and Functions

“…[39] HPLC/MS is problematic for the analysis of low amountso fu nknown metabolites because no machine-independent spectral databases exist, ands tructurali nformation on the ESI spectra is scarce. We therefore chose to look into the data of the AHL GC/MS analyses to identify other metabolites produced by roseobacters and to evaluate their biological relevance.…”

Identification and Characterization of the Streptazone E Biosynthetic Gene Cluster in Streptomyces sp. MSC090213JE08

“…Incorporation of 13 C-labeledc ompoundsi nto streptazone derivativesd emonstrated that these compounds are synthesized through assembly of acetate units, thus indicating the involvement of polyketide synthases (PKSs) in their biosynthesis. [3,8,9] However,n ob iosynthetic gene clustero fastreptazone derivative has been discovered, and therefore there is limited information about their biosynthetic machineries.…”

Coupled Biosynthesis of Volatiles and Salinosporamide A in Salinispora tropica

“…Another interesting ketone is cyclohept-4-enone (37). Recently,t his compound was found in several actinomycetes,s uch as Streptomyces FORM5 [12] and Streptomycesa mbofaciens. [2] Compound 37 might derive from the phenylacetate biosynthetic pathway as previously suggested for tropone.…”

“…The last of these questions arose because we were recently able to show that in some cases the volatiles released by antibiotic‐producing strains likely originate from shunt metabolites of antibiotic biosynthesis. Streptomyces FORM5 emits streptopyridines as strain‐specific volatiles, the biosynthesis of which seems to be tightly connected to that of the also produced antibiotic streptazoline . Phaeobacter inhibens from the marine Roseobacter clade emits the volatile tropone, which is biosynthetically related to the antibiotic tropodithietic acid (TDA) .…”

“…pyridines as strain-specific volatiles, the biosynthesis of which seems to be tightly connected to that of the also produced antibiotic streptazoline. [12] Phaeobacter inhibens from the marine Roseobacter clade emits the volatile tropone, which is biosyntheticallyr elatedt ot he antibiotic tropodithietic acid (TDA). [11,13] Streptomycesa mbofaciens produces volatile blastmycinones and the corresponding antibiotic antimycins, whichs hare genes in their biosynthetic gene cluster.…”