Simone Edenhart (Jena / DE), Lukas Zehner (Jena / DE), Peter Hortschansky (Jena / DE), Maira Rosin (Jena / DE), Tina Netzker (Jena / DE), Volker Schroeckh (Jena / DE), Axel A. Brakhage (Jena / DE)
The Gram-positive soil bacterium Streptomyces iranensis is able to produce the secondary metabolite azalomycin F, an arginine-derived polyketide. Molecules of this group of arginoketides, have a broad antimicrobial activity, ranging from activity against Gram-positive bacteria, to anti-fungal and algicidal activity. Interestingly, azalomycin F exhibits not only an antimicrobial activity, but also affects various organisms at sublethal concentrations. The single-cell green alga Chlamydomonas reinhardtii for example reacts to sublethal dosis of azalomycin F by forming protective, multicellular structures, so called gloeocapsoids1 and by hiding in fungal mycelia2. In the fungi Aspergillus fumigatus and A. nidulans, sublethal concentrations of azalomycin F induce the expression of various secondary metabolite gene clusters3, 4. Since azalomycin F is able to affect a broad variety of organisms and thus may have a significant impact on structuring microbial consortia in soil, we are interested in finding out what triggers the production of this compound in S. iranensis. So far, we could link the bld-regulon, which is involved in both the Streptomyces life cycle and natural product biosynthesis, to the production of azalomycin F. Furthermore, we identified a cluster of LuxR regulators controlling the azalomycin F biosynthesis.
1 Krespach et al. (2021) Algicidal marginolactones induce the formation of gloeocapsoids, novel protective multicellular aggregates of Chlamydomonas reinhardtii. PNAS, 118, e2100892118.
2 Krespach et al. (2020) Lichen-like association of Chlamydomonas reinhardtii and Aspergillus nidulans protects algal cells from bacteria. The ISME Journal, 14, 2794-2805.
3 Stroe et al. (2020) Targeted induction of a silent gene cluster of Aspergillus fumigatus encoding the bacteria-specific spore germination inhibitor fumigermin by Streptomyces rapamycinicus. eLife, 9, e5254.
4 Krespach et al. (2023) Ubiquitous bacterial polyketides mediating cross-kingdom microbial interactions. Nature Microbiology, 8, 1348-1361.