Meta-16S rRNA gene phylogenetic reconstruction reveals astonishing diversity of the cosmopolitan myxobacteria

Abstract

Numerous ecological studies for myxobacteria have been conducted well, but their true diversity hidden in plain sight remains to be explored. To bridge this gap, we here implemented a comprehensive survey of diversity and distribution of myxobacteria by using 4997 publicly available 16S rRNA gene sequences ([≥]1200 bp) collected from several hundreds of sites across multiple countries and regions. In the study, the meta-16S rRNA gene phylogenetic reconstruction clearly revealed that these sequences were classified to 998 species, 445 genera, 58 families, and 20 suborders, highlighting a considerable taxonomic diversity of myxobacteria, the great majority of which belonged to new taxa. Most cultured myxobacteria including the well-described type strains were strongly inclined to locate on the shallow branches of the phylogenetic tree; on the contrary, the majority of uncultured myxobacteria the deep branches. The geographical analysis of sequences based on their environmental categories clearly demonstrated that myxobacteria showed a nearly cosmopolitan distribution, despite the presence of some habitat-specific taxa, especially at genus and species levels. Among all abundant suborders, members of Suborder_4, Suborder_15, and Suborder_17 were more widely distributed in marine environments, the remaining suborders preferred to reside in terrestrial ecosystems, particularly in soils, indicating a potential selectivity of geographical distribution. In conclusion, this study profiles a clear framework of diversity and distribution of the cosmopolitan myxobacteria and sheds light on the isolation of the uncultured myxobacteria.\n\nIMPORTANCEMyxobacteria are an attractive bacterial group ubiquitous in soil and aquatic environments. However, the biodiversity and ecological preferences of myxobacteria remain poorly understood across heterogeneous environments. We analyzed thousands of publicly available and high-quality 16S rRNA gene sequences of myxobacteria by using the phylogenetic reconstruction. The study presented an astonishing diversity than that expected from the previous studies. This study further demonstrated that the culturability of myxobacteria was perfectly comparable to its phylogeny in the phylogenetic tree. The geographical analysis clearly indicated that myxobacteria showed a nearly cosmopolitan distribution, while some taxa exhibited obvious preferences for specific environmental conditions. Together, our study provides novel insights into the diversity, distributions, and ecological preferences of of myxobacteria from diverse environments and lays the foundation for innovation of isolation techniques and the discovery of new secondary metabolites.