Exploring the structural diversity of myxobacterial secondary metabolism

Myxobacteria are gram-negative bacteria commonly found in soil. They form swarm-like colonies which spread over surfaces and feed on other microorganisms. The most outstanding feature of myxobacteria is their ability to form fruiting bodies by which the different genera can be distinguished.

In the last years myxobacteria have been in the focus of natural products research and have become known as potent producers of secondary metabolites. To date more than fifty unique structural types have been isolated, among them compounds with promising biological activities, e.g. the epothilones [1] which are now in clinical studies as anticancer drugs.

In our screening program the myxobacterial strain 150 (morphologically characterized as a Polyangium or Nannocystis sp.) was singled out due to the results of TLC, LC-MS and NMR analyses. The next step was the cultivation of the strain in a large scale and subsequent extraction and fractionation. HPLC separation eventually yielded compound 150E, a new metabolite with an unusual ethyl residue connected to a polyunsaturated carbon chain. The structure was elucidated by applying mass spectrometry and different 1D- and 2D- NMR techniques.

Future work will address the biosynthesis and evaluation of the bioactivity of the compound.

Reference: 1. Gerth, K. et al. (1996), J. Antibiot. 49: 560–563