**6. Conclusion**

In summary, myxobacteria are highly adaptable cosmopolitans. They can grow/survive in various kind of habitats and areas of different, even extreme climatic conditions. In 1993, only 2 suborders, 4 families, 12 genera, and 38 species were assigned to the order Myxococcales [28], but in 2018, already 3 suborders, 10 families, 29 genera, and 58 species are described. Although the number of species grows every year, consideration of data from cultivation-independent studies reveals that we only see the tip of the diversity iceberg.

In 2010, 67 distinct core structures and about 500 derivatives were known from approximately 7500 myxobacterial strains [48]. Only seven years later, Herrmann et al. could refer to five natural product classes produced by myxobacteria [49]. These new molecules show such promising activity that several of them may serve as early lead structures for drug development. This shows the enormous potential of myxobacteria as producers of new, bioactive secondary metabolites. As mentioned by Müller and Wink, three of the most promising approaches toward finding novel anti-infectives from microorganisms are the use of biodiversity to find novel producers, the variation of culture conditions and induction of silent genes, and the exploitation of the genomic potential of producers via "genome mining" [119]. With focus on novel producers, the biggest challenge for microbiologists is to get access to the so far uncultivated bacteria.

**Acknowledgments:** I would like to thank Klaus Peter Conrad, Diana Telkemeyer and Birte Trunkwalter for taking the nice pictures of myxobacteria, Wera Collisi and Steffi Schulz for technical assistance, and Aileen Gollasch, and Sabrina Karwehl for HPLC-MS analyses.

**Conflicts of Interest:** The authors declare no conflict of interest.
