Mannisto, M. K. | bioRxiv Science

bioRxiv2025

Draft genome sequence of a predatory bacterium from northern peatland soil

Predatory bacteria are abundant in soil, but their diversity and functions remain not fully understood, especially in subarctic regions. Here, we report strain 1-FT3.2, a predatory bacterium obtained from peatland soil in Northern Finland (Pallas, 68 {degrees}N). The bacterium was cultivated on Mucilaginibacter cryoferens FT3.2 as prey. Although a pure culture of strain 1-FT3.2 was not obtained, its draft genome was assembled from sequencing reads derived from the co-culture with its prey. The draft genome of 1-FT3.2 is 7.2 Mb in length and 81% complete. Genome analyses suggested that 1-FT3.2 belongs to the family Polyangiaceae (phylum Myxococcota), which comprises predatory bacteria. The genome annotation revealed (near-)complete metabolic modules of central carbon metabolism and aerobic respiration. Two proviral regions were predicted in the draft genome, both putatively representing tailed phages of the class Caudoviricetes. Several CRISPR-Cas system proteins were also identified. The draft genome sequence could be used in future comparative studies assessing the diversity of predatory bacteria in northern soils or other environments.

microbiology↗

bioRxiv2024

Tunturi virus isolates and metagenome-assembled viral genomes provide insights into the virome of Acidobacteriota in Arctic tundra soils

BackgroundArctic soils are climate-critical areas, where microorganisms play crucial roles in nutrient cycling processes. Acidobacteriota are phylogenetically and physiologically diverse bacteria that are abundant and active in Arctic tundra soils. Still, surprisingly little is known about acidobacterial viruses in general and those residing in the Arctic in particular. Here, we applied both culture-dependent and -independent methods to study the virome of Acidobacteriota in Arctic soils. ResultsFive virus isolates, Tunturi 1-5, were obtained from Arctic tundra soils, Kilpisjarvi, Finland (69{degrees}N), using Tunturibacter spp. strains originating from the same area as hosts. The new virus isolates have tailed particles with podo-(Tunturi 1, 2, 3), sipho-(Tunturi 4), or myovirus-like (Tunturi 5) morphologies. The dsDNA genomes of the viral isolates are 63-98 kbp long, except Tunturi 5, which is a jumbo phage with a 309-kbp genome. Tunturi 1 and Tunturi 2 share 88% overall nucleotide identity, while the other three are not related to one another. For over half of the open reading frames in Tunturi genomes, no functions could be predicted. To further assess the Acidobacteriota-associated viral diversity in Kilpisjarvi soils, bulk metagenomes from the same soils were explored and a total of 1881 viral operational taxonomic units (vOTUs) were bioinformatically predicted. Almost all vOTUs (98%) were assigned to the class Caudoviricetes. For 125 vOTUs, including five (near-)complete ones, Acidobacteriota hosts were predicted. Acidobacteriota-linked vOTUs were abundant across sites, especially in fens. Terriglobia-associated proviruses were observed in Kilpisjarvi soils, being related to proviruses from distant soils and other biomes. Approximately genus- or higher-level similarities were found between Tunturi viruses, Kilpisjarvi vOTUs, and other soil vOTUs, suggesting some shared groups of Acidobacteriota viruses across soils. ConclusionsThis study provides acidobacterial virus isolates as laboratory models for future research and adds insights into the diversity of viral communities associated with Acidobacteriota in tundra soils. Predicted virus-host links and viral gene functions suggest various interactions between viruses and their host microorganisms. Largely unknown sequences in the isolates and metagenome-assembled viral genomes highlight a need for more extensive sampling of Arctic soils to better understand viral functions and contributions to ecosystem-wide cycling processes in the Arctic.

microbiology↗