Magnetosome gene cluster containing bacteria in oxygen-stratified freshwater ecosystems of northern landscapes

Magnetotactic bacteria (MTB) are capable of magnetic navigation (magnetotaxis) through the intracellular biomineralization of membrane-bound magnetic nanoparticles, known as magnetosomes, which are regulated by magnetosome gene clusters (MGCs). Despite their ubiquity near the oxic-anoxic transition zone in various aquatic environments, the diversity, abundance, and biogeochemical roles of MTB remain poorly understood due to limited large-scale studies. Here, we conducted a metagenomic survey of MGC-containing bacteria across 38 oxygen-stratified freshwater environments of northern landscapes. We reconstructed 63 MGC-containing genomes affiliated with eight bacterial phyla, including Myxococcota. Putative MTB exhibited high relative abundance (up to 15.4% of metagenomic reads), with Deltaproteobacteria identified as the most ubiquitous and predominant group. Vertical distribution profile revealed that magnetotactic Deltaproteobacteria primarily inhabit low-oxygen niches, suggesting their magnetofossils might serve as a potential proxy for oxygen depletion. Our findings underscore the important ecological roles of putative MTB as key components of oxygen-stratified freshwater ecosystems of northern landscapes. Putative magnetotactic bacteria primarily inhabiting low-oxygen niches and their magnetofossils can serve as a potential proxy for oxygen depletion in freshwater ecosystems in northern landscapes, according to a metagenomic survey of 38 oxygen-stratified freshwater environments of that area.