Myxobacteria in high moor and fen: An astonishing diversity in a neglected extreme habitat

Abstract

Increasing antibiotic resistances of numerous pathogens mean that myxobacteria, well known producers of new antibiotics, are becoming more and more interesting. More than 100 secondary metabolites, most of them with bioactivity, were described from the order Myxococcales. Especially new myxobacterial genera and species turned out to be reliable sources for novel antibiotics and can be isolated from uncommon neglected habitats like, for example, acidic soils. Almost nothing is known about the diversity of myxobacteria in moors, except some information from cultivation studies of the 1970s. Therefore, we evaluated the myxobacterial community composition of acidic high moor and fen both with cultivation-independent 16S rRNA clone bank analysis and with cultivation. Phylogenetic analyses of clone sequences revealed a great potential of undescribed myxobacteria in high moor and fen, whereby all sequences represent unknown taxa and were detected exclusively by cultivation-independent analyses. However, many clones were assigned to sequences from other cultivation-independent studies of eubacterial diversity in acidic habitats. Cultivation revealed different strains exclusively from the genus Corallococcus. Our study shows that the neglected habitat moor is a promising source and of high interest with regard to the cultivation of prospective new bioactive secondary metabolite producing myxobacteria.

Keywords: Myxococcales; biodiversity; bioprospecting; microbial ecology; phylogeny.

Figure 1

Section of a distance matrix tree based on 16S rRNA‐gene sequences of all 56 myxobacterial type strains and clone sequences from the present study as well as sequences from other cultivation‐independent studies of acidic soils. For a better clarity, only a section of the whole tree is shown. Sequences from OTUs So10–So13 are shown. W5: forward primer specific for Sorangiineae/Nannocystineae. C1 and C2: sampling site fen Am Sandbeek, soil; B4 and B9: Brockenfeld central high moor, soil. The section shows part of the Sorangiineae subfamily. Bar, 0.01 substitutions per nucleotide position. The full tree is shown as Figure S2

Figure 2

(a) Brockenfeld high moor; (b) Fen Am Sandbeek; (c–h) Photographs showing the morphology of isolated strains from moor. Phase‐contrast photomicrographs of (c) B2 fruiting bodies on CY agar; (d) fruiting bodies and swarm on P‐agar (e) B19 fruiting bodies on VY/2 agar (f) B29‐2 fruiting bodies on VY/2 agar (g) Corallococcus exiguus (DSM 14696^T) fruiting bodies and swarm on CY‐agar; (h) C. coralloides (DSM 2259^T) fruiting bodies on water agar with E. coli bait

Figure 3

Section of a distance matrix tree based on 16S rRNA‐gene sequences of myxobacterial type strains and cultures isolated from moor. Bootstrap values >70% are shown. The section presents Myxococcaceae‐family. Bar, 0.01 substitutions per nucleotide position