AUTHOR=Yang Yi , Zhang Yaozhi , Cápiro Natalie L. , Yan Jun 

TITLE=Genomic Characteristics Distinguish Geographically Distributed Dehalococcoidia

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.546063

DOI=10.3389/fmicb.2020.546063

ISSN=1664-302X

ABSTRACT=<p><italic>Dehalococcoidia</italic> (<italic>Dia</italic>) class microorganisms are frequently found in various pristine and contaminated environments. Metagenome-assembled genomes (MAGs) and single-cell amplified genomes (SAGs) studies have substantially improved the understanding of <italic>Dia</italic> microbial ecology and evolution; however, an updated thorough investigation on the genomic and evolutionary characteristics of <italic>Dia</italic> microorganisms distributed in geographically distinct environments has not been implemented. In this study, we analyzed available genomic data to unravel <italic>Dia</italic> evolutionary and metabolic traits. Based on the phylogeny of 16S rRNA genes retrieved from sixty-seven genomes, <italic>Dia</italic> microorganisms can be categorized into three groups, the terrestrial cluster that contains all <italic>Dehalococcoides</italic> and <italic>Dehalogenimonas</italic> strains, the marine cluster I, and the marine cluster II. These results reveal that a higher ratio of horizontally transferred genetic materials was found in the <italic>Dia</italic> marine clusters compared to that of the <italic>Dia</italic> terrestrial cluster. Pangenome analysis further suggests that <italic>Dia</italic> microorganisms have evolved cluster-specific enzymes (e.g., dehalogenase in terrestrial <italic>Dia</italic>, sulfite reductase in marine <italic>Dia</italic>) and biosynthesis capabilities (e.g., siroheme biosynthesis in marine <italic>Dia</italic>). Marine <italic>Dia</italic> microorganisms are likely adapted to versatile metabolisms for energy conservation besides organohalide respiration. The genomic differences between marine and terrestrial <italic>Dia</italic> may suggest distinct functions and roles in element cycling (e.g., carbon, sulfur, chlorine), which require interdisciplinary approaches to unravel the physiology and evolution of <italic>Dia</italic> in various environments.</p>