Geochemical Characteristics Related to the Gregite-Producing Multicellular Magnetotactic Prokaryote Candidatus Magnetoglobus multicellularis in a Hypersaline Lagoon

We studied the geochemical properties of sediment layers where the gregite-producing multicellular magnetotactic prokaryote Candidatus Magnetoglobus multicellularis exists. The ratio of iron and bioavailable sulfur concentrations regulates the population density of this microorganism. The population density can reach 8.5 × 10² cells/cm³ at an iron to sulfur ratio of 0.5. In iron- and sulfur-rich environments, microorganisms concentrated in the upper region of the oxic-anoxic zone, following an increasing nitrogen gradient with a lower isotopic ¹⁵N/¹⁴N ratio. Candidatus Magnetoglobus multicellularis prefers environmental conditions that favor the biomineralization of greigite, but in situations where the nutrient availability is low, it moves to more suitable sites.