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

Abstract

23Numerous ecological studies for myxobacteria have been conducted well, but their 24 true diversity hidden in plain sight remains to be explored. To bridge this gap, we here 25 implemented a comprehensive survey of diversity and distribution of myxobacteria by 26 using 4997 publicly available 16S rRNA gene sequences (≥1200 bp) collected from 27 several hundreds of sites across multiple countries and regions. In the study, the 28 meta-16S rRNA gene phylogenetic reconstruction clearly revealed that these 29 sequences were classified to 998 species, 445 genera, 58 families, and 20 suborders, 30 highlighting a considerable taxonomic diversity of myxobacteria, the great majority of 31 which belonged to new taxa. Most cultured myxobacteria including the 32 well-described type strains were strongly inclined to locate on the shallow branches of 33 the phylogenetic tree; on the contrary, the majority of uncultured myxobacteria the 34 deep branches. The geographical analysis of sequences based on their environmental 35 categories clearly demonstrated that myxobacteria showed a nearly cosmopolitan 36 distribution, despite the presence of some habitat-specific taxa, especially at genus 37 and species levels. Among all abundant suborders, members of Suborder_4, 38 Suborder_15, and Suborder_17 were more widely distributed in marine environments, 39 the remaining suborders preferred to reside in terrestrial ecosystems, particularly in 40 soils, indicating a potential selectivity of geographical distribution. In conclusion, this 41 study profiles a clear framework of diversity and distribution of the cosmopolitan 42 myxobacteria and sheds light on the isolation of the uncultured myxobacteria. 43 44 48thousands of publicly available and high-quality 16S rRNA gene sequences of 49 myxobacteria by using the phylogenetic reconstruction. The study presented an 50 astonishing diversity than that expected from the previous studies. This study further 51 demonstrated that the culturability of myxobacteria was perfectly comparable to its 52 phylogeny in the phylogenetic tree. The geographical analysis clearly indicated that 53 myxobacteria showed a nearly cosmopolitan distribution, while some taxa exhibited 54 obvious preferences for specific environmental conditions. Together, our study 55 provides novel insights into the diversity, distributions, and ecological preferences of 56 of myxobacteria from diverse environments and lays the foundation for innovation of 57 isolation techniques and the discovery of new secondary metabolites. 58 59 KRYWORDS: myxobacteria; phylogenetic diversity; geographical distribution; 60 environments 61 62 63 64 65 66 67 Myxobacteria are a large group of organisms, which taxonomically belong to the 68 order Myxococcales within the class Deltaproteobacteria (1). They are one of nature's 69 "endowed" and extensively dispersed in natural environments, preferentially in places 70 that are rich in microbes and organic matter. Myxobacteria are one of the fascinating 71 and unique bacteria by virtue of thei...