Distribution, abundance and ecogenomics of the cosmopolitan Gemmatimonadota group PAUC43f

Abstract

Abstract BackgroundThe phylum Gemmatimonadota comprises mainly uncultured microorganisms and presents a high level of diversity, similar to that of Proteobacteria or Actinobacteria. This diversity reflects the phylum’s wide range of functional capabilities, which allows its members to inhabit different environments such as soils, freshwater lakes, marine sediments, sponges or corals. Some studies have focused on the Gemmatimonadota present in soils or freshwater lakes, however, to date, the information about this group in the marine environment is very scarce. One of the most frequently retrieved Gemmatimonadota from marine environments is PAUC43f, an uncultured group that has been detected only by 16S rRNA gene sequence analyses, with not a single isolate or metagenome-assembled genome (MAG) affiliated with this group. ResultsHere, we carried out a broad study of the distribution, abundance, ecotaxonomy and potential metabolic capabilities of PAUC43f by mining information from 16S rRNA gene amplicon datasets, Gemmatimonadota MAGs, and fluorescent in situ hybridization (FISH). We detected PAUC43f in 4,965 amplicon datasets mainly from marine sediments, sponges, corals and saline soils and lakes around the world, which indicated this group is cosmopolitan and adapted to saline environments. PAUC43f represented a substantial fraction of the microbial community, mainly in sediments, sponges and soils where, in some cases, it could account for up to 34.3% of the 16S rRNA gene sequences. The potential metabolic capabilities inferred from the 39 PAUC43f MAGs suggested a facultatively aerobic and chemoorganotrophic metabolism, although some members could also oxidise hydrogen. Furthermore, PAUC43f could play a key environmental role as a N2O consumer as well as a supplier of cysteine, serine and thiamine. Finally, the design and test of a FISH probe provided experimental evidence of the presence, activity, and morphology of PAUC43f in marine sediments. We propose its renaming as “Candidatus Palaucibacterales”, in reference to the Republic of Palau where the first sequence of this group was recovered, and its classification as a new order within the Gemmatimonadota phylum and Gemmatimonadetes class.ConclusionsOur findings highlight the global distribution and the potentially relevant ecological roles of PAUC43f in different worldwide distributed environments, mainly as N2O scavengers as well as vitamin and amino acid suppliers.