Evolution And Metabolism Analysis Of Bathyarchaeota Based On Metagenomics Technology

Microbiomes are abundant in marine sediments.It has been estimated that approximately 2.9×10²⁹ cells residing in marine sediments,which is roughly equal to the estimates of cell abundance in seawater.However,the phylogeny and metabolic functions remain largely unknown due to the lack of cultivated representative species in laboratory.Bathyarchaeota is globally distributed in the sedimentary ecosystem with high abundance.As an archaeal phylum,Bathyarchaeota has been divided into at least19 subgroups based on phylogenetic analysis.However,considering there is only limited genomic information in seven research articles,its versatile metabolic functions and ecological roles among different subgroups remain largely unknown.In this study,we try to explore the metabolic features,ecological functions and potential adaptations by using metagenomic technology which directly extract and analysis the total environmental DNA from two hyperthermal sediments.In this study,we reclassify the divisions for bathyarchaeotal lineages based on 16S r RNA gene sequences,revealing similar phylogeny compared to previous analysis,as well as four novel detected subgroups names as Bathy-3b/c,-20,-21 and-22,which remained unclassified in previous.We also reconstruct 16 metagenomic assembled genomes from two hydrothermal sediment samples in Guaymas Basin,and compare their phylogenies and metabolic profiles to other 26 public available bathyarchaeotal genomes.38 out of these genomes are spanned over 11 subgroups through phylogenetic analysis,while 4 genomes remain unclassified due to the lack of marker genes.We also reveal that majority of these lineages contain certain pathways considered as core metabolic features such as the protein degrading pathway,the glycolysis pathway,the reductive acetyl-Co A(Wood-Ljungdahl,WL)pathway and acetogenesis pathway.Bathy-15 contains both archaeal and bacterial type WL pathway,while all other genomes solely utilize the archaeal type WL pathway.Bathy-20 and-21 contain genes encoding phosphate acetyltransferase-acetate kinase(pta-ack)for acetogenesis while others encode acetate-Co A ligase(acd)instead.Moreever,different subgroups show versatile potentials for organic substances utilization,Bathy-20 in particular has advanced potential to utilize carbohydrates and organic sulfur compounds.Besides differences on metabolic abilities,members of Bathy-1,-20,-21 and-22 which retrieved in hydrothermal sediment samples from Guamas Basin exhibit hyperthermophilic life strategies.The core metabolic potentials of Bathyarchaeota are demonstrated as facultative anaerobic fermentation of protein and other organic matters,autotrophic inorganic carbon fixation through WL pathway as well as acetogenesis.This study reveals the complex intrasubgroup diversity and vertile metabolic features of Bathyarchaeota,identicating the various ecological roles of bathyarchaeotal lineages in different environments.