Genomic and metabolic characterisation of a novel species Magnetominusculus dajiuhuensis DJH-1Ts sp. nov. from an acidic peatland

Abstract

Magnetotactic bacteria (MTB) are recognised widely for their ability to synthesise intracellular magnetite (Fe₃O₄) and/or greigite (Fe₃S₄) nanocrystals and align with Earth's magnetic field. They are crucial for understanding prokaryotic organelle biogenesis. MTB members of the Nitrospirota phylum (previously known as the Nitrospirae phylum) are of interest due to their important ecological roles in the biogeochemical cycling of iron and sulphur. Here, we introduce Magnetominusculus dajiuhuensis DJH-1^Ts, a newly discovered Nitrospirota MTB species that thrives in the acidic Dajiuhu Peatland of central China. By combining electron microscopy, 16S rRNA gene-based analysis and genome-resolved metagenomics, we elucidate its distinctive morphology, genomic features, and metabolic functions. The metagenome-assembled genome, assigned to the genus Magnetominusculus, family Magnetobacteriaceae, order Thermodesulfovibrionales, class Thermodesulfovibrionia according to the GTDB taxonomy, reveals an obligate anaerobe that lives in central China's largest wetland. We propose the formal name Magnetominusculus dajiuhuensis DJH-1^Ts sp. nov., following the SeqCode system. Genomic and metabolic characterisation of this novel species suggests its potential role in nitrogen, sulphur, and carbon metabolism in aquatic biogeochemistry, particularly in peatlands. The genome of this novel strain indicates that it harnesses the Wood-Ljungdahl pathway for carbon fixation and acetate metabolism in anaerobic conditions, while its potential role in nitrogen cycling is characterised by denitrification and nitrogen fixation. It also participates in reduction of sulphate to sulphide, indicating a role in sulphur cycling in its ecological niche. Taken together, the discovery and characterisation of Magnetominusculus dajiuhuensis DJH-1^Ts provide new insights into MTB diversity and ecological functions, particularly in peatland biogeochemistry.